Humification plays a critical role in the environmental fate of organic wastes, and MnO_2 holds great promise for enhancing this reaction. However, the effects of MnO_2 on the enhancement of the humification reaction ...Humification plays a critical role in the environmental fate of organic wastes, and MnO_2 holds great promise for enhancing this reaction. However, the effects of MnO_2 on the enhancement of the humification reaction remain ambiguous. To better reveal the mechanism by which MnO_2 enhances the reaction and investigate the fate of the humification products, abiotic humification experiments were performed using increasing concentrations of dissolved organic matter(DOM) to a fixed amount of MnO_2. DOM was represented by model humic precursors consisting of catechol, glucose and glycine. The results indicate that the reduction of MnO_2 played a dominant role in the formation of fulvic-like acids(FLAs), and the subsequent reduction products, MnOOH and Mn(II), acted as catalysts in the formation of humic-like acids(HLAs). Moreover, CO_2 release occurred during the formation of FLAs, and a strong linear correlation between CO_2 release and the formation of FLAs was observed(p < 0.01), where 0.73–1.87 mg of CO_2 was released per mg dissolved organic carbon(DOC)FLAs. Furthermore, the concentration of MnO_2 had a pronounced influence on the product behavior, where a lower MnO_2 concentration decreased the quantity of FLAs produced.展开更多
Biochar has received increasing attention due to its applications as a soil amendment. Here, the chemical properties of solid and water-extractable fractions of four biochar samples were investigated. The results show...Biochar has received increasing attention due to its applications as a soil amendment. Here, the chemical properties of solid and water-extractable fractions of four biochar samples were investigated. The results showed that wood biochar and bamboo biochar samples were 60%-80% more hydrophobic than those of rice husk biochar and rice husk ash. In addition, the acidity was 3.88 mmol/g from the total functional groups and 1.03 mmol/g from the carboxyl groups/lactones/phenols found in the wood biochar sample, which were about 1.5 times greater than those of the bamboo biochar sample. These functional groups could be used to determine the sorptive capacity of biochar for ionic solutes and water content and to increase the degradation of compost organics. The wood biochar sample was found to have the most humification materials （fulvic acid-like material ＋ humic acid-like material） in the water-extractable fraction, which was 3-10 times higher than that in the rice husk biochar and rice husk ash; humified materials were not detected in the bamboo biochar sample. Humification materials in biochar may be involved in increasing the proportion of humic acid-like materials in humic-like substances within the compost product. Wood biochar had better hydrophobic, sorptive, aromatic, and humification properties compared to other biochars, suggesting that it may be used in composting in order to exert its effect as both a bulking agent and a composting amendment during the solid waste composting process.展开更多
Oxytetracycline(OTC)residues have been found in soil and water,and they may pose potential risks to agricultural ecological environments.One of the most impactful ways for OTC to enter the soil and water environments ...Oxytetracycline(OTC)residues have been found in soil and water,and they may pose potential risks to agricultural ecological environments.One of the most impactful ways for OTC to enter the soil and water environments is through excrement used as organic fertilizer.Therefore,it is important to remove OTC during manure composting and to understand the transformation of the organic materials during composting in the presence of OTC.In the present paper,chicken manure and wheat sawdust spiked with OTC were composted under different initial moisture contents(MC)to evaluate the degradation of OTC and changes of organic matter during the composting process.The MC has a significant effect on OTC degradation during composting.A higher MC of 65% was more conducive to OTC degradation(77.4%)and compost maturity compared to the lower MC.However,the higher MC of 65%could increase the ammonia volatilization by promoting nitrification compared to the lower MC.An increase in the initial MC could improve the composting temperature.NMR results illustrated that the presence of OTC could affect the internal transformation of aliphatics,and OTC inhibited compost humification.Thus,an initial MC of 55–65% can alleviate the impacts of OTC on humification during manure composting.展开更多
To predict future spatio-temporal patterns of climate change, we should fully understand the spatio-temporal patterns of climate change during the past millennium. But, we are not yet able to delineate the patterns be...To predict future spatio-temporal patterns of climate change, we should fully understand the spatio-temporal patterns of climate change during the past millennium. But, we are not yet able to delineate the patterns because the qualities of the retrieved proxy records and the spatial coverage of those records are not adequate. Northern Xinjiang of China is one of such areas where the records are not adequate. Here, we present a 500-yr land-surface moisture sequence from Heiyangpo Peat(48.34°N, 87.18°E, 1353 m a.s.l) in the southern Altai Mountains within northern Xinjiang. Specifically, peat carbon isotope value of cellulose(δ^(13)C_(cellulose)) was used to estimate the warm-season moisture variations and the degree of humification was used to constrain the δ^(13)C_(cellulose)-based hydrological interpretation. The climatic attributions of the interpreted hydrological variations were based on the warm-season temperature reconstructed from Belukha ice core and the warm-season precipitation inferred from the reconstructed Atlantic Multidecadal Oscillations(AMO). The results show that humification decreased and the δ^(13)C_(celluose)-suggested moisture decreased from ~1510 to ~1775 AD, implying that a constant dryingcondition may have inhibited peat decay. Our comparison with reconstructed climatic parameters suggests that the moisture-level decline was most likely resulted from a constant decline of precipitation. The results also show that humification kept a stable level and the δ^(13)C_(celluose)-suggested moisture also decreased from ~1775 to ~2013 AD, implying that peat decay in the acrotelm primarily did not depend on the water availability or an aerobic environment. Again, our comparison with reconstructed climatic parameters suggests that the land-surface moisturelevel decline was most likely resulted from a steady warming of growing-season temperature.展开更多
In order to understand the transport and humification processes of dissolved organic matter（DOM） within sediments of a semi-arid floodplain at Rifle,Colorado,fluorescence excitation–emission matrix（EEM） spectrosc...In order to understand the transport and humification processes of dissolved organic matter（DOM） within sediments of a semi-arid floodplain at Rifle,Colorado,fluorescence excitation–emission matrix（EEM） spectroscopy,humification index（HIX） and specific UV absorbance（SUVA） at 254 nm were applied for characterizing depth and seasonal variations of DOM composition.Results revealed that late spring snowmelt leached relatively fresh DOM from plant residue and soil organic matter down into the deeper vadose zone（VZ）.More humified DOM is preferentially adsorbed by upper VZ sediments,while non-or lesshumified DOM was transported into the deeper VZ.Interestingly,DOM at all depths undergoes rapid biological humification process evidenced by the products of microbial by-product-like（i.e.,tyrosine-like and tryptophan-like） matter in late spring and early summer,particularly in the deeper VZ,resulting in more humified DOM（e.g.,fulvic-acid-like and humic-acid-like substances） at the end of year.This indicates that DOM transport is dominated by spring snowmelt,and DOM humification is controlled by microbial degradation,with seasonal variations.It is expected that these relatively simple spectroscopic measurements（e.g.,EEM spectroscopy,HIX and SUVA） applied to depth-and temporally-distributed pore-water samples can provide useful insights into transport and humification of DOM in other subsurface environments as well.展开更多
The humification degree of fresh litter directly controls the accumulation of soil humus derived from plant litter,but very little information on this process is available.Planted forests are well known to restrict so...The humification degree of fresh litter directly controls the accumulation of soil humus derived from plant litter,but very little information on this process is available.Planted forests are well known to restrict soil fertility,which is often indicated by the soil humus level.In this study,fresh litter was collected during different plant phenological stages during 2016 and 2017 in a mixed plantation in Southwest China.The values of hue coefficientΔlogK(absorbance ratio of 400 nm and 600 nm on a logarithmic scale),optical density E4/E6(absorbance ratio of 400 nm and 600 nm)and A600/C(absorbance at 600 mm per mg of carbon per ml of extraction)and the concentration of extractable humus carbon(HC)were determined in four litter components(foliar,twigs,reproductive organs and miscellaneous)of the dominant species(Pterocarya stenoptera,Quercus acutissima,Cunninghamia lanceolata and Toxicodendron vernicifluum).All of the litter components exhibited obvious humification characteristics,and showed the highest concentration of extractable HC during the leaf maturation period.The miscellaneous and foliar litters showed greater humification than the other litter types.The components of Pterocarya stenoptera litter exhibited greater degrees of humification than those of the other species,with lowerΔlogK and E4/E6 values and higher A600/C values.The litter from coniferous and evergreen species showed lower humification than that from broad-leaf and deciduous species regardless of the litter component examined.The present results provide new insights into the management of plantations and theoretical data to accurately improve the quality of plantations and maintain soil fertility under a global change.展开更多
Studies of the living organic matter humification process are essential for understanding the carbon biogeochemical cycle. The aim of this study is to analyze relations between the properties of peat, peat humic acids...Studies of the living organic matter humification process are essential for understanding the carbon biogeochemical cycle. The aim of this study is to analyze relations between the properties of peat, peat humic acids and peat humification degree. The analysis has been done on samples of humic substances extracted from peat profiles in two ombrotrophic bogs and relations between peat age, decomposition and humification degree, botanical composition and properties of peat humic acids (elemental, functional composition) were studied. The found variability of peat properties is less significant than differences in the properties of peat-forming living matter, thus revealing the dominant impact of humification process on the properties of peat. Correspondingly, composition of peat humic acids is little affected by differences in the composition of precursor living organic material.展开更多
There is an overlooked problem which increasing microbial abundance while reducing nitrogen loss during composting.This study investigated the viability of spent mushroom substrate(SMS)as conditioners in the aerobic c...There is an overlooked problem which increasing microbial abundance while reducing nitrogen loss during composting.This study investigated the viability of spent mushroom substrate(SMS)as conditioners in the aerobic composting of kitchen waste(KW)with cattle manure(CM).The variation of temperature,pH,C/N,organic matter,cellulose,hemicelluloses,germination index(GI),and microflora structure were explored to evaluate the potential in accelerating maturity and nitrogen fixation by SMS addition.The results showed that the addition of SMS accelerated the heating rate,prolonged the high temperature time,and decreased organic matter,hemicellulose,and cellulose by 17.49%,23.61%,and 18.62%,respectively.The GI reached 105.86%with SMS addition,while 74.17%was found in control treatment after composting.SMS changed the microbial community composition and increased the species abundance.Proteiniclasticum,Clostridium XI and Azomonas were dominant bacteria,which increased the retention of nitrogen,promoted organic matter degradation and reduce compost time.The study can provide a feasible strategy for nitrogen fixation in the field of organic waste recycling.展开更多
The high organic carbon content in corn stalks(CS)and the rich nitrogen resources in sewage sludge(SS)render them ideal for the hydrothermal production of nitrogen-enriched hydrothermal humic acid(HHA).This study cond...The high organic carbon content in corn stalks(CS)and the rich nitrogen resources in sewage sludge(SS)render them ideal for the hydrothermal production of nitrogen-enriched hydrothermal humic acid(HHA).This study conducted co-hydrothermal humification experiments using varying ratios of CS to SS under two distinct mixing modes:1)co-hydrothermal carbonization of CS and SS,followed by alkaline hydrothermal humification to yield HHA,and 2)mixing CS-derived hydrochar with SS,followed by alkaline hydrothermal humification to yield HHA.The results indicated no significant difference in HHA yield between the modes when using equivalent raw material ratios.Importantly,the HHA produced did not pose a heavy metal risk.However,HHA from mode(1)had nearly double the nitrogen content compared to mode(2)and contained more valuable metal elements.The study confirmed that while co-hydrothermal humification of CS and SS did not significantly enhance HHA yield,it did markedly increase nitrogen content.Furthermore,HHA yield decreased with increasing SS content in the raw materials,likely due to SS's high ash content(52.4 wt%).In contrast,the nitrogen content in HHA increased with higher SS content,rising from 2.0 wt% to 3.8 wt% in mode(1)and from 1.1 wt%to 2.3 wt%in mode(2).Upon comprehensive analysis of both modes,the study suggests that mode(1)is more promising for engineering applications,as it facilitates the efficient disposal of a larger amount of SS.展开更多
Hydrothermal carbonization(HTC)converts wet biomass into hydrochar and a process liquid,but aromatic compounds in the products have been reported as a roadblock for soil applications as they can inhibit germination,pl...Hydrothermal carbonization(HTC)converts wet biomass into hydrochar and a process liquid,but aromatic compounds in the products have been reported as a roadblock for soil applications as they can inhibit germination,plant growth,and soil microbial activity.Here,we compared HTC and hydrothermal humification(HTH)of cow manure digestate while varying the initial alkaline content by adding KOH.HTH converted 37.5 wt%of the feedstock to artificial humic acids(A-HAs)found in both solid and liquid,twice that of HTC.HTH reduced phenolic and furanic aromatic compounds by over 70%in solids and 90%in liquids.The A-HAs in HTH resemble natural humic acids(N-HA),based on FTIR,UV-vis spectra,and CHN and XRD analysis.The HTH liquid possesses 60%higher total organic carbon(TOC)than HTC.Although one-third of TOC can be precipitated as A-HA,a high TOC concentration remains in the liquid,which is shown to be mainly organic acids.Therefore,we also evaluated the HTC and HTH liquids for anaerobic biomethane production,and found that compared to the original cow manure digestate,the HTH liquids increased methane yield by 110.3 to 158.6%,a significant enhancement relative to the 17.2%increase seen with HTC liquid.The strong reduction in organic acids during biogas production from HTH liquid indicates the potential for converting soluble byproducts into methane,while maintaining high A-HAs levels in the solid product.展开更多
Soil samples were collected from the areas surrounding Wuliangsuhai Lake in China. Dissolved organic matter （DOM） was extracted from the samples and characterized by fluorescence and UV-Vis spectra. Spectral propert...Soil samples were collected from the areas surrounding Wuliangsuhai Lake in China. Dissolved organic matter （DOM） was extracted from the samples and characterized by fluorescence and UV-Vis spectra. Spectral properties and humification degree of DOM were studied. The results indicated that both humic- and protein- like fluorophores were present in the DOM spectra, and the former was the dominant component. The analysis of humification （HIX） and r （A, C） indices revealed that the maximum humification degree in three agricultural soils （AAF, ASC, and ASW） was presented in the second soil layer （20-40 cm）. However, the humification degree of the two Halophytes soils （SSE and GKF） decreased with increasing depth. One index, I344/270, showed that humification degree increased gradually with an increasing proportion of humic-like acid. There was a significant positive correlation between humification degree （HIX） and aromaticity （SUVA254）, indicating that a higher aromaticity corresponded to a higher humification degree. Land use was an important factor responsible for the major difference of cation exchange capacity （CEC） in different soils, which led to a higher CEC value in the second soil layer for the three agricultural soils. CEC values and humification degree had the same trend for all five soils. The correlation analysis showed that there was a significant positive correlation between HIX and CEC,and a negative correlation between the r （A, C） index and CEC, indicating that humification degree increases gradually with increasing CEC values.展开更多
Humification plays a significant role in converting phenolic pollutants and forming heterogeneous polymers,but few studies have been performed to investigate exolaccase-started humification(ESH).Herein,the influences ...Humification plays a significant role in converting phenolic pollutants and forming heterogeneous polymers,but few studies have been performed to investigate exolaccase-started humification(ESH).Herein,the influences of lignin precursors(LPs)on exolaccase-induced bisphenol A(BPA)removal and humification were explored.In particular,the architectural features and botanical effects of the formed humification products were also tested.ESH was extremely beneficial in boosting BPA removal in the presence of LPs.Compared with LP-free(58.49%),100%of BPA was eliminated after the reaction with ESH for 72 h.Such a process was controlled by an exolaccasecaused random assembly of radicals,which generated a large number of hydrophobic polymers through nonspecific covalent binding of C–C and/or C–O.These humified polymers were extremely stable at pH 2.0–10.0 and20℃ to 80℃ and displayed unique functions,i.e.,scavenged 2,2-diphenyl-1-picrylhydrazyl/2,20-azinobis3-ethylbenzothiazoline-6-sulphonic acid radicals and exerted antioxidant capacities.More importantly,the functional polymers could act as auxin analogs to increase the germination index(>100%),plant biomass,and salt tolerance of radish seedlings.Our findings disclosed that ESH could not only be optimized to mitigate the ecological risks of phenolic pollutants and sequester organic carbon in environmental bioremediation,but the resulting abundant auxin analogs also contributed to agricultural productivity.展开更多
Soil organic carbon(SOC)affects the function of terrestrial ecosystem and plays a vital role in global carbon cycle.Yet,large uncertainty still existed regarding the changes in SOC stock and quality with forest succes...Soil organic carbon(SOC)affects the function of terrestrial ecosystem and plays a vital role in global carbon cycle.Yet,large uncertainty still existed regarding the changes in SOC stock and quality with forest succession.Here,the stock and quality of SOC at 1-m soil profile were investigated across a subalpine forest series,including shrub,deciduous broad-leaved forest,broadleaf-conifer mixed forest,middle-age coniferous forest and mature coniferous forest,which located at southeast of Tibetan Plateau.The results showed that SOC stock ranged from 9.8 to29.9 kg·m^(-2),and exhibited a hump-shaped response pattern across the forest successional series.The highest and lowest SOC stock was observed in the mixed forest and shrub forest,respectively.The SOC stock had no significant relationships with soil temperature and litter stock,but was positively correlated with wood debris stock.Meanwhile,the average percentages of polysaccharides,lignins,aromatics and aliphatics based on FTIR spectroscopy were 79.89%,0.94%,18.87%and 0.29%,respectively.Furthermore,the percentage of polysaccharides exhibited an increasing pattern across the forest successional series except for the sudden decreasing in the mixed forest,while the proportions of lignins,aromatics and aliphatics exhibited a decreasing pattern across the forest successional series except for the sudden increasing in the mixed forest.Consequently,the humification indices(HIs)were highest in the mixed forest compared to the other four successional stages,which means that the SOC quality in mixed forest was worse than other successional stages.In addition,the SOC stock,recalcitrant fractions and HIs decreased with increasing soil depth,while the polysaccharides exhibited an increasing pattern.These findings demonstrate that the mixed forest had higher SOC stock and worse SOC quality than other successional stages.The high proportion of SOC stock(66%at depth of 20-100 cm)and better SOC quality(lower HIs)indicate that deep soil have tremendous potential to store SOC and needs more attention under global chan ge.展开更多
A 45-d laboratory experiment was conducted to compare the effect of four crop straws on the transformations of organic matter （OM） during composting of sewage sludge. The four crop straws included rape straw, wheat ...A 45-d laboratory experiment was conducted to compare the effect of four crop straws on the transformations of organic matter （OM） during composting of sewage sludge. The four crop straws included rape straw, wheat straw, maize straw and rice straw. The following parameters such as temperature, OM, humic-like substances （HS）, fulvic-like acids （FA） and humic-like acids （HA） were determined. The degradation of OM and the formation of HS and HA could be described well by the first-order kinetic model, while the FA content fluctuated during composting. The maximal degradation rates of OM in the compost piles added with rape straw, wheat straw, maize straw and rice straw were 34.7, 46.9, 54.7 and 52.8%, respectively, and the final contents of HS were 118, 128, 141 and 134 g kg-1, respectively, while the humification indices were higher in the compost piles added with maize straw and wheat straw than in those with rice straw and rape straw. The results indicate that a higher hemicellulose content and a lower C/N ratio in crop straw can result in a higher rate of OM degradation and higher contents of HS, while a higher content of lignin can lead to a higher polymerization degree of humic substances in compost piles. The final compost piles added with maize straw has the highest contents of OM, total nitrogen and humus substance as well as the highest values of polymerization degree, while compost piles with rape straw have the highest potassium content and those with rice straw have the highest pH values.展开更多
Humic substances(HS),which are defined as a series of highly acidic,relatively high-molecular-weight,and yellow to black colored substances formed during the decay and transformation of plant and microbial remains,ubi...Humic substances(HS),which are defined as a series of highly acidic,relatively high-molecular-weight,and yellow to black colored substances formed during the decay and transformation of plant and microbial remains,ubiquitously occur in nature.Humic substances represent the largest stable organic carbon pool in terrestrial environments and are the central characteristic of the soil.However,the validity of the HS concept and the justification of their extraction procedure have been recently debated.Here,we argue that the traditional humic paradigm is still relevant.Humic substances are distinctive and complex because the extracted HS formed during the humification are chemically distinct from their precursors and are heterogeneous among soils.By reviewing the concept,formation pathways,and stabilization of HS,we propose that the key question facing soil scientists is whether HS are soil microbial residues or unique synthesized compounds.Without revealing the distinctiveness of HS,it is impossible to address this question,as the structure,composition,and reactivity of HS are still poorly known owing to the heterogeneity and geographical variability of HS and the limits of the currently available analytical techniques.In our view,the distinctiveness of HS is fundamental to the soil,and thus further studies should be focused on revealing the distinctiveness of HS and explaining why HS hold this distinctiveness.展开更多
The migration of soil dissolved organic carbon(DOC) from terrestrial to aquatic environments has important impacts on the adjacent water quality and the transport of organic and inorganic contaminants.However,few stud...The migration of soil dissolved organic carbon(DOC) from terrestrial to aquatic environments has important impacts on the adjacent water quality and the transport of organic and inorganic contaminants.However,few studies have investigated the sources and properties of DOC in riparian zones.A total of 34 soil samples were collected across four riparian buffer zones(Zones A-D) on Chongming Island,China.The vertical distributions of soil organic carbon(SOC) and DOC,fluorescence excitation-emission matrix(EEM) spectra of DOC and the optical indices,including fluorescence index(FI),index of recent autochthonous contribution(BIX),and humification index(HIX),were measured across the riparian environment to investigate the sources and fluorescence properties of DOC.The results showed that SOC stored in the surface soil(0-30 cm) accounted for 40%of the total soil profile SOC.The DOC accumulated in Zones A-C,which accounted for 5%of the SOC.The fluorescence EEM spectra of DOC showed that DOC contained humic-like and protein-like substances,which were mainly derived from recent plant debris by microbes.A large amount of humic-like substances were sorbed to minerals in the surface soil(0-30 cm).In addition,the riparian topography and soil physico-chemical properties(pH,EC and moisture) dictated the transformation and transport of DOC.The results suggested that EEMs could reveal the source of DOC in riparian soil systems,and that optical indices were complementary tools that revealed the characteristics of soil DOC and provided supplemental evidence about DOC sources.展开更多
Carbon of humus acids(HSAC) and dissolved organic carbon(DOC) are the most active forms of soil organic carbon(SOC) and play an important role in global carbon recycling. We investigated the concentrations of HSAC,wat...Carbon of humus acids(HSAC) and dissolved organic carbon(DOC) are the most active forms of soil organic carbon(SOC) and play an important role in global carbon recycling. We investigated the concentrations of HSAC,water-soluble organic carbon(WSOC),hot water-extractable organic carbon(HWOC) and SOC in soils under different vegetation types of four copper mine tailings sites with differing vegetation succession time periods in Tongling,China. The concentrations of HSAC,WSOC,HWOC and SOC increased with vegetation succession. WSOC concentration increased with the accumulation of SOC in the tailings,and a linearly positive correlation existed between the concentrations of HSAC and SOC in the tailings. However,the percentages of HSAC and DOC in the SOC decreased during vegetation succession. The rate of SOC accumulation was higher when the succession time was longer than 20 years,whereas the speeds of soil organic matter(SOM) decomposition and humification were slow,and the concentrations of HSAC and DOC increased slowly in the tailings. The percentage of carbon of humic acid(HAC) in HSAC increased with vegetation succession,and the values of humification index(HI),HAC/carbon of fulvic acid,also increased with the accumulation of HSAC and SOC in soils of the tailings sites. However,the HI value in the each of the tailings was less than 0.50. The humification rate of SOM was lower than the accumulation rate of SOM,and the level of soil fertility was still very low in the tailings even after 40 years of natural restoration.展开更多
The southern Changjiang River Estuary has attracted considerable attention from marine scientists because it is a highly biologically active area and is biogeochemically significant. Moreover, land-ocean interactions ...The southern Changjiang River Estuary has attracted considerable attention from marine scientists because it is a highly biologically active area and is biogeochemically significant. Moreover, land-ocean interactions strongly impact the estuary, and harmful algal blooms （HABs） frequently occur in the area. In October 2010 and May 2011, water samples of chromophoric dissolved organic matter （CDOM） were collected from the southern Changjiang River Estuary. Parallel factor analysis （PARAFAC） was used to assess the samples＇ CDOM composition using excitation-emission matrix （EEM） spectroscopy. Four components were identified： three were humic-like （C1, C2 and C3） and one was protein-like （C4）. Analysis based on spatial and seasonal distributions, as well as relationships with salinity, Chl a and apparent oxygen utilization （AOU）, revealed that terrestrial inputs had the most significant effect on the three humic-like Components C1, C2 and C3 in autumn. In spring, microbial processes and phytoplankton blooms were also important factors that impacted the three components. The protein-like Component C4 had autochthonous and allochthonous origins and likely represented a biologically labile component. CDOM in the southern Changjiang River Estuary was mostly affected by terrestrial inputs. Microbial processes and phytoplankton blooms were also important sources of CDOM, especially in spring. The fluorescence intensities of the four components were significantly higher in spring than in autumn. On average, C1, C2, C3, C4 and the total fluorescence intensity （TFI） in the surface, middle and bottom layers increased by 123%-242%, 105%-195%, 167%-665%, 483%-567% and 184%-245% in spring than in autumn, respectively. This finding corresponded with a Chl a concentration that was 16-20 times higher in spring than in autumn and an AOU that was two to four times lower in spring than in autumn. The humification index （HIX） was lower in spring that in autumn, and the fluorescence index （FI） was higher in spring than in autumn. This result indicated that the CDOM was labile and the biological activity was intense in spring.展开更多
to identify plant macrofossils,estimate peat humification and calculate hydroclimatic indices based on current bog species,with the overall aim of determining the climate conditions associated with evolution of the bo...to identify plant macrofossils,estimate peat humification and calculate hydroclimatic indices based on current bog species,with the overall aim of determining the climate conditions associated with evolution of the bog during the Medieval Climate Anomaly and the Little Ice Age.These proxies,together with historical and climate data,proved to be good indicators of the changes in bog surface wetness.Analysis:of the core led to identification of 9 different periods:two corresponding to the so-called Medieval Climate Anomaly(930 to 1345 AD,1075–665 calibrated years before present[cal.yr BP]);four corresponding to the Little Ice Age(1345 to 1905 AD;665–105 cal yr BP);and three corresponding to the last century(1905 to 2000 AD).The findings revealed a generally dry climate that lasted until the 14th century,followed by a transition to a long period with a more humid,but characteristically very variable climate,which ended at the beginning of the 20th century and was followed by a rapid transition to more humid conditions and finally,a change to drier conditions.The Medieval Climate Anomaly was indicated by the abundance of dry-adapted mosses(Leucobryum glaucum,Hypnum cupressiforme)and characterized by warm dry conditions and high levels of peat humification,with alternating wet phases.The LIA period was dated by a large abundance of Sphagnum species(an indicator of wetness)and a gradual increase in the humification index.However,four different climate phases were differentiated in this period.High-resolution reconstruction of the evolution of the CVM bog and the multiproxy approach have together enabled a more detailed identification of climatic variations in this area,which are generally consistent with the global models,as well as better definition of the elusive climatic oscillations in the last millennium and confirmation of the importance of local modulation of global models.The study provides new information and a detailed chronology of climatic events that will help to refine local modulation of the climate evolution model in the still quite unexplored region of the NW Iberian Peninsula,a key area for understanding the paleoclimatic dynamics in SW Europe.展开更多
This paper documents a 7800-year proxy record from the Shenjiadian peatland on the Sanjiang Plain in Northeast China.High-resolution plant macrofossil and colorimetric humification methods were used to reconstruct the...This paper documents a 7800-year proxy record from the Shenjiadian peatland on the Sanjiang Plain in Northeast China.High-resolution plant macrofossil and colorimetric humification methods were used to reconstruct the vegetation and hydrologic history from a 193 cm-long sedimentary profile.Detrended correspondence analysis(DCA) was applied to transform the raw plant macrofossil data into latent indices of peatland water level.The vegetation community transited from an Equisetum fluviatile community to a Carex lasiocarpa community at approximately 3800 cal yr BP and was followed by a Carex-shrub community at approximately 480 cal yr BP.Based on the plant macrofossil DCA axis 1 scores and humification values,we distinguished four hydrologic periods:a wet period from 7800 cal yr BP to 4500 cal yr BP,dry periods up to 1600 cal yr BP,drier periods until 300 cal yr BP,and the driest period from 300 cal yr BP until the present.Through a comparison with other climate records,we suggest that the East Asian summer monsoon(EAM) was the main driving force for vegetation and water level changes to the Shenjiadian peatland through its impacts on precipitation.展开更多
基金the financial support from the National Key Technology R&D Programs(No.2014BAC02B02)
文摘Humification plays a critical role in the environmental fate of organic wastes, and MnO_2 holds great promise for enhancing this reaction. However, the effects of MnO_2 on the enhancement of the humification reaction remain ambiguous. To better reveal the mechanism by which MnO_2 enhances the reaction and investigate the fate of the humification products, abiotic humification experiments were performed using increasing concentrations of dissolved organic matter(DOM) to a fixed amount of MnO_2. DOM was represented by model humic precursors consisting of catechol, glucose and glycine. The results indicate that the reduction of MnO_2 played a dominant role in the formation of fulvic-like acids(FLAs), and the subsequent reduction products, MnOOH and Mn(II), acted as catalysts in the formation of humic-like acids(HLAs). Moreover, CO_2 release occurred during the formation of FLAs, and a strong linear correlation between CO_2 release and the formation of FLAs was observed(p < 0.01), where 0.73–1.87 mg of CO_2 was released per mg dissolved organic carbon(DOC)FLAs. Furthermore, the concentration of MnO_2 had a pronounced influence on the product behavior, where a lower MnO_2 concentration decreased the quantity of FLAs produced.
基金supported by the National Basic Research Program (973) of China (No. 2012CB719801)the National High Technology Research and Development Program (863) of China (No. 2012AA063504)+1 种基金the Key Special Program on the Science and Technology for the Pollution Control and Treatment of Water Bodies (No. 2011ZX07303-004-03)the Fok Ying-Tong Education Foundation (No. 132012), and the Program of Shanghai Subject Chief Scientist (No. 10XD1404200)
文摘Biochar has received increasing attention due to its applications as a soil amendment. Here, the chemical properties of solid and water-extractable fractions of four biochar samples were investigated. The results showed that wood biochar and bamboo biochar samples were 60%-80% more hydrophobic than those of rice husk biochar and rice husk ash. In addition, the acidity was 3.88 mmol/g from the total functional groups and 1.03 mmol/g from the carboxyl groups/lactones/phenols found in the wood biochar sample, which were about 1.5 times greater than those of the bamboo biochar sample. These functional groups could be used to determine the sorptive capacity of biochar for ionic solutes and water content and to increase the degradation of compost organics. The wood biochar sample was found to have the most humification materials （fulvic acid-like material ＋ humic acid-like material） in the water-extractable fraction, which was 3-10 times higher than that in the rice husk biochar and rice husk ash; humified materials were not detected in the bamboo biochar sample. Humification materials in biochar may be involved in increasing the proportion of humic acid-like materials in humic-like substances within the compost product. Wood biochar had better hydrophobic, sorptive, aromatic, and humification properties compared to other biochars, suggesting that it may be used in composting in order to exert its effect as both a bulking agent and a composting amendment during the solid waste composting process.
基金This study was jointly supported by the National Key R&D Program of China(2018YFD0500206)the National Natural Science Foundation of China(31772395)+1 种基金the Fundamental Research Funds for Central Non-profit Scientific Institutions,China(1610132019046)the Science and Technology Support Project of Langfang,Hebei,China(2019013125).
文摘Oxytetracycline(OTC)residues have been found in soil and water,and they may pose potential risks to agricultural ecological environments.One of the most impactful ways for OTC to enter the soil and water environments is through excrement used as organic fertilizer.Therefore,it is important to remove OTC during manure composting and to understand the transformation of the organic materials during composting in the presence of OTC.In the present paper,chicken manure and wheat sawdust spiked with OTC were composted under different initial moisture contents(MC)to evaluate the degradation of OTC and changes of organic matter during the composting process.The MC has a significant effect on OTC degradation during composting.A higher MC of 65% was more conducive to OTC degradation(77.4%)and compost maturity compared to the lower MC.However,the higher MC of 65%could increase the ammonia volatilization by promoting nitrification compared to the lower MC.An increase in the initial MC could improve the composting temperature.NMR results illustrated that the presence of OTC could affect the internal transformation of aliphatics,and OTC inhibited compost humification.Thus,an initial MC of 55–65% can alleviate the impacts of OTC on humification during manure composting.
基金financially supported by Chinese Natural Science International Cooperation Program Foundation Grant (No. 41361140361)Chinese Natural Science Foundation Grant (No. U1203821L08)Chinese Academy Sciences International Cooperation Program (No. GJHZ201315)
文摘To predict future spatio-temporal patterns of climate change, we should fully understand the spatio-temporal patterns of climate change during the past millennium. But, we are not yet able to delineate the patterns because the qualities of the retrieved proxy records and the spatial coverage of those records are not adequate. Northern Xinjiang of China is one of such areas where the records are not adequate. Here, we present a 500-yr land-surface moisture sequence from Heiyangpo Peat(48.34°N, 87.18°E, 1353 m a.s.l) in the southern Altai Mountains within northern Xinjiang. Specifically, peat carbon isotope value of cellulose(δ^(13)C_(cellulose)) was used to estimate the warm-season moisture variations and the degree of humification was used to constrain the δ^(13)C_(cellulose)-based hydrological interpretation. The climatic attributions of the interpreted hydrological variations were based on the warm-season temperature reconstructed from Belukha ice core and the warm-season precipitation inferred from the reconstructed Atlantic Multidecadal Oscillations(AMO). The results show that humification decreased and the δ^(13)C_(celluose)-suggested moisture decreased from ~1510 to ~1775 AD, implying that a constant dryingcondition may have inhibited peat decay. Our comparison with reconstructed climatic parameters suggests that the moisture-level decline was most likely resulted from a constant decline of precipitation. The results also show that humification kept a stable level and the δ^(13)C_(celluose)-suggested moisture also decreased from ~1775 to ~2013 AD, implying that peat decay in the acrotelm primarily did not depend on the water availability or an aerobic environment. Again, our comparison with reconstructed climatic parameters suggests that the land-surface moisturelevel decline was most likely resulted from a steady warming of growing-season temperature.
基金partially performed at the Molecular Foundry,Lawrence Berkeley National Laboratorysupported as part of the Sustainable Systems Scientific Focus Area program at Lawrence Berkeley National Laboratorysupported by the U.S.Department of Energy,Office of Science,Office of Biological and Environmental Research,Subsurface Biogeochemical Research Program,through Contract No.DE-AC02-05CH11231 between Lawrence Berkeley National Laboratory and the U.S.Department of Energy
文摘In order to understand the transport and humification processes of dissolved organic matter（DOM） within sediments of a semi-arid floodplain at Rifle,Colorado,fluorescence excitation–emission matrix（EEM） spectroscopy,humification index（HIX） and specific UV absorbance（SUVA） at 254 nm were applied for characterizing depth and seasonal variations of DOM composition.Results revealed that late spring snowmelt leached relatively fresh DOM from plant residue and soil organic matter down into the deeper vadose zone（VZ）.More humified DOM is preferentially adsorbed by upper VZ sediments,while non-or lesshumified DOM was transported into the deeper VZ.Interestingly,DOM at all depths undergoes rapid biological humification process evidenced by the products of microbial by-product-like（i.e.,tyrosine-like and tryptophan-like） matter in late spring and early summer,particularly in the deeper VZ,resulting in more humified DOM（e.g.,fulvic-acid-like and humic-acid-like substances） at the end of year.This indicates that DOM transport is dominated by spring snowmelt,and DOM humification is controlled by microbial degradation,with seasonal variations.It is expected that these relatively simple spectroscopic measurements（e.g.,EEM spectroscopy,HIX and SUVA） applied to depth-and temporally-distributed pore-water samples can provide useful insights into transport and humification of DOM in other subsurface environments as well.
基金This study was supported by the National Natural Science Foundation of China(31470636)Specialized Fund for the Post-Disaster Reconstruction and Heritage Protection in Sichuan Province(No.5132202019000128)the Open Fund for Ecological Restoration and Conservation for Forest and Wetland Key Laboratory of Sichuan Province(No.2020KFKT01).
文摘The humification degree of fresh litter directly controls the accumulation of soil humus derived from plant litter,but very little information on this process is available.Planted forests are well known to restrict soil fertility,which is often indicated by the soil humus level.In this study,fresh litter was collected during different plant phenological stages during 2016 and 2017 in a mixed plantation in Southwest China.The values of hue coefficientΔlogK(absorbance ratio of 400 nm and 600 nm on a logarithmic scale),optical density E4/E6(absorbance ratio of 400 nm and 600 nm)and A600/C(absorbance at 600 mm per mg of carbon per ml of extraction)and the concentration of extractable humus carbon(HC)were determined in four litter components(foliar,twigs,reproductive organs and miscellaneous)of the dominant species(Pterocarya stenoptera,Quercus acutissima,Cunninghamia lanceolata and Toxicodendron vernicifluum).All of the litter components exhibited obvious humification characteristics,and showed the highest concentration of extractable HC during the leaf maturation period.The miscellaneous and foliar litters showed greater humification than the other litter types.The components of Pterocarya stenoptera litter exhibited greater degrees of humification than those of the other species,with lowerΔlogK and E4/E6 values and higher A600/C values.The litter from coniferous and evergreen species showed lower humification than that from broad-leaf and deciduous species regardless of the litter component examined.The present results provide new insights into the management of plantations and theoretical data to accurately improve the quality of plantations and maintain soil fertility under a global change.
文摘Studies of the living organic matter humification process are essential for understanding the carbon biogeochemical cycle. The aim of this study is to analyze relations between the properties of peat, peat humic acids and peat humification degree. The analysis has been done on samples of humic substances extracted from peat profiles in two ombrotrophic bogs and relations between peat age, decomposition and humification degree, botanical composition and properties of peat humic acids (elemental, functional composition) were studied. The found variability of peat properties is less significant than differences in the properties of peat-forming living matter, thus revealing the dominant impact of humification process on the properties of peat. Correspondingly, composition of peat humic acids is little affected by differences in the composition of precursor living organic material.
基金funded by the Key Research and Development Projects of Heilongjiang Province(Grant No.2022ZX02C14)the Technological Project of Heilongjiang Province“the Open Competition Mechanism to Select the Best Candidates”(Grant No.2022ZXJ05C01)National Key R&D Program of China(Grant No.2023YFD1501000)。
文摘There is an overlooked problem which increasing microbial abundance while reducing nitrogen loss during composting.This study investigated the viability of spent mushroom substrate(SMS)as conditioners in the aerobic composting of kitchen waste(KW)with cattle manure(CM).The variation of temperature,pH,C/N,organic matter,cellulose,hemicelluloses,germination index(GI),and microflora structure were explored to evaluate the potential in accelerating maturity and nitrogen fixation by SMS addition.The results showed that the addition of SMS accelerated the heating rate,prolonged the high temperature time,and decreased organic matter,hemicellulose,and cellulose by 17.49%,23.61%,and 18.62%,respectively.The GI reached 105.86%with SMS addition,while 74.17%was found in control treatment after composting.SMS changed the microbial community composition and increased the species abundance.Proteiniclasticum,Clostridium XI and Azomonas were dominant bacteria,which increased the retention of nitrogen,promoted organic matter degradation and reduce compost time.The study can provide a feasible strategy for nitrogen fixation in the field of organic waste recycling.
基金financially supported by the Major Program of National Natural Science Foundation of China(No.52091543).
文摘The high organic carbon content in corn stalks(CS)and the rich nitrogen resources in sewage sludge(SS)render them ideal for the hydrothermal production of nitrogen-enriched hydrothermal humic acid(HHA).This study conducted co-hydrothermal humification experiments using varying ratios of CS to SS under two distinct mixing modes:1)co-hydrothermal carbonization of CS and SS,followed by alkaline hydrothermal humification to yield HHA,and 2)mixing CS-derived hydrochar with SS,followed by alkaline hydrothermal humification to yield HHA.The results indicated no significant difference in HHA yield between the modes when using equivalent raw material ratios.Importantly,the HHA produced did not pose a heavy metal risk.However,HHA from mode(1)had nearly double the nitrogen content compared to mode(2)and contained more valuable metal elements.The study confirmed that while co-hydrothermal humification of CS and SS did not significantly enhance HHA yield,it did markedly increase nitrogen content.Furthermore,HHA yield decreased with increasing SS content in the raw materials,likely due to SS's high ash content(52.4 wt%).In contrast,the nitrogen content in HHA increased with higher SS content,rising from 2.0 wt% to 3.8 wt% in mode(1)and from 1.1 wt%to 2.3 wt%in mode(2).Upon comprehensive analysis of both modes,the study suggests that mode(1)is more promising for engineering applications,as it facilitates the efficient disposal of a larger amount of SS.
文摘Hydrothermal carbonization(HTC)converts wet biomass into hydrochar and a process liquid,but aromatic compounds in the products have been reported as a roadblock for soil applications as they can inhibit germination,plant growth,and soil microbial activity.Here,we compared HTC and hydrothermal humification(HTH)of cow manure digestate while varying the initial alkaline content by adding KOH.HTH converted 37.5 wt%of the feedstock to artificial humic acids(A-HAs)found in both solid and liquid,twice that of HTC.HTH reduced phenolic and furanic aromatic compounds by over 70%in solids and 90%in liquids.The A-HAs in HTH resemble natural humic acids(N-HA),based on FTIR,UV-vis spectra,and CHN and XRD analysis.The HTH liquid possesses 60%higher total organic carbon(TOC)than HTC.Although one-third of TOC can be precipitated as A-HA,a high TOC concentration remains in the liquid,which is shown to be mainly organic acids.Therefore,we also evaluated the HTC and HTH liquids for anaerobic biomethane production,and found that compared to the original cow manure digestate,the HTH liquids increased methane yield by 110.3 to 158.6%,a significant enhancement relative to the 17.2%increase seen with HTC liquid.The strong reduction in organic acids during biogas production from HTH liquid indicates the potential for converting soluble byproducts into methane,while maintaining high A-HAs levels in the solid product.
基金Acknowledgements This work was financially supported by the National Social Science Fund （12CGLI 18）, the National Natural Science Foundation of China （Grant Nos. 41503110 and 51208020） and the Open Foundation of Jiangsu Key Laboratory for Biomass-based Energy and Enzyme Technology, Huaiyin Normal University （JSBEET1309）.
文摘Soil samples were collected from the areas surrounding Wuliangsuhai Lake in China. Dissolved organic matter （DOM） was extracted from the samples and characterized by fluorescence and UV-Vis spectra. Spectral properties and humification degree of DOM were studied. The results indicated that both humic- and protein- like fluorophores were present in the DOM spectra, and the former was the dominant component. The analysis of humification （HIX） and r （A, C） indices revealed that the maximum humification degree in three agricultural soils （AAF, ASC, and ASW） was presented in the second soil layer （20-40 cm）. However, the humification degree of the two Halophytes soils （SSE and GKF） decreased with increasing depth. One index, I344/270, showed that humification degree increased gradually with an increasing proportion of humic-like acid. There was a significant positive correlation between humification degree （HIX） and aromaticity （SUVA254）, indicating that a higher aromaticity corresponded to a higher humification degree. Land use was an important factor responsible for the major difference of cation exchange capacity （CEC） in different soils, which led to a higher CEC value in the second soil layer for the three agricultural soils. CEC values and humification degree had the same trend for all five soils. The correlation analysis showed that there was a significant positive correlation between HIX and CEC,and a negative correlation between the r （A, C） index and CEC, indicating that humification degree increases gradually with increasing CEC values.
基金This work was financially supported by the National Natural Science Foundation of China(42277019 and 42207470)the Natural Science Foundation of Anhui Province,China(2208085QD116)the Natural Science Research Project of Education Department of Anhui Province,China(KJ2021A0136 and KJ2021A0083).
文摘Humification plays a significant role in converting phenolic pollutants and forming heterogeneous polymers,but few studies have been performed to investigate exolaccase-started humification(ESH).Herein,the influences of lignin precursors(LPs)on exolaccase-induced bisphenol A(BPA)removal and humification were explored.In particular,the architectural features and botanical effects of the formed humification products were also tested.ESH was extremely beneficial in boosting BPA removal in the presence of LPs.Compared with LP-free(58.49%),100%of BPA was eliminated after the reaction with ESH for 72 h.Such a process was controlled by an exolaccasecaused random assembly of radicals,which generated a large number of hydrophobic polymers through nonspecific covalent binding of C–C and/or C–O.These humified polymers were extremely stable at pH 2.0–10.0 and20℃ to 80℃ and displayed unique functions,i.e.,scavenged 2,2-diphenyl-1-picrylhydrazyl/2,20-azinobis3-ethylbenzothiazoline-6-sulphonic acid radicals and exerted antioxidant capacities.More importantly,the functional polymers could act as auxin analogs to increase the germination index(>100%),plant biomass,and salt tolerance of radish seedlings.Our findings disclosed that ESH could not only be optimized to mitigate the ecological risks of phenolic pollutants and sequester organic carbon in environmental bioremediation,but the resulting abundant auxin analogs also contributed to agricultural productivity.
基金the financial support from the National Natural Science Foundation of China(Nos.32001139,32071554)。
文摘Soil organic carbon(SOC)affects the function of terrestrial ecosystem and plays a vital role in global carbon cycle.Yet,large uncertainty still existed regarding the changes in SOC stock and quality with forest succession.Here,the stock and quality of SOC at 1-m soil profile were investigated across a subalpine forest series,including shrub,deciduous broad-leaved forest,broadleaf-conifer mixed forest,middle-age coniferous forest and mature coniferous forest,which located at southeast of Tibetan Plateau.The results showed that SOC stock ranged from 9.8 to29.9 kg·m^(-2),and exhibited a hump-shaped response pattern across the forest successional series.The highest and lowest SOC stock was observed in the mixed forest and shrub forest,respectively.The SOC stock had no significant relationships with soil temperature and litter stock,but was positively correlated with wood debris stock.Meanwhile,the average percentages of polysaccharides,lignins,aromatics and aliphatics based on FTIR spectroscopy were 79.89%,0.94%,18.87%and 0.29%,respectively.Furthermore,the percentage of polysaccharides exhibited an increasing pattern across the forest successional series except for the sudden decreasing in the mixed forest,while the proportions of lignins,aromatics and aliphatics exhibited a decreasing pattern across the forest successional series except for the sudden increasing in the mixed forest.Consequently,the humification indices(HIs)were highest in the mixed forest compared to the other four successional stages,which means that the SOC quality in mixed forest was worse than other successional stages.In addition,the SOC stock,recalcitrant fractions and HIs decreased with increasing soil depth,while the polysaccharides exhibited an increasing pattern.These findings demonstrate that the mixed forest had higher SOC stock and worse SOC quality than other successional stages.The high proportion of SOC stock(66%at depth of 20-100 cm)and better SOC quality(lower HIs)indicate that deep soil have tremendous potential to store SOC and needs more attention under global chan ge.
基金funded by the the Key Technologied R&D Program of China during the 12th Five-Year Plan period (2013BAJ11B03)the Science & Technology Commission of Chongqing, China (CSTC, 2008AC7013)
文摘A 45-d laboratory experiment was conducted to compare the effect of four crop straws on the transformations of organic matter （OM） during composting of sewage sludge. The four crop straws included rape straw, wheat straw, maize straw and rice straw. The following parameters such as temperature, OM, humic-like substances （HS）, fulvic-like acids （FA） and humic-like acids （HA） were determined. The degradation of OM and the formation of HS and HA could be described well by the first-order kinetic model, while the FA content fluctuated during composting. The maximal degradation rates of OM in the compost piles added with rape straw, wheat straw, maize straw and rice straw were 34.7, 46.9, 54.7 and 52.8%, respectively, and the final contents of HS were 118, 128, 141 and 134 g kg-1, respectively, while the humification indices were higher in the compost piles added with maize straw and wheat straw than in those with rice straw and rape straw. The results indicate that a higher hemicellulose content and a lower C/N ratio in crop straw can result in a higher rate of OM degradation and higher contents of HS, while a higher content of lignin can lead to a higher polymerization degree of humic substances in compost piles. The final compost piles added with maize straw has the highest contents of OM, total nitrogen and humus substance as well as the highest values of polymerization degree, while compost piles with rape straw have the highest potassium content and those with rice straw have the highest pH values.
基金supported by the National Natural Science Foundation of China(Nos.41571231 and 41201221)the National Key Research and Development Program of China(No.2016YFD0200304)+3 种基金the Scientific Instrument and Equipment Development Project of Chinese Academy Sciences(CAS)(No.YJKYYQ20170058)the Natural Science Foundation of Jiangsu Province,China(No.BK2012496)the Youth Innovation Promotion Association,CAS(No.2017362)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(No.19KJB180010)。
文摘Humic substances(HS),which are defined as a series of highly acidic,relatively high-molecular-weight,and yellow to black colored substances formed during the decay and transformation of plant and microbial remains,ubiquitously occur in nature.Humic substances represent the largest stable organic carbon pool in terrestrial environments and are the central characteristic of the soil.However,the validity of the HS concept and the justification of their extraction procedure have been recently debated.Here,we argue that the traditional humic paradigm is still relevant.Humic substances are distinctive and complex because the extracted HS formed during the humification are chemically distinct from their precursors and are heterogeneous among soils.By reviewing the concept,formation pathways,and stabilization of HS,we propose that the key question facing soil scientists is whether HS are soil microbial residues or unique synthesized compounds.Without revealing the distinctiveness of HS,it is impossible to address this question,as the structure,composition,and reactivity of HS are still poorly known owing to the heterogeneity and geographical variability of HS and the limits of the currently available analytical techniques.In our view,the distinctiveness of HS is fundamental to the soil,and thus further studies should be focused on revealing the distinctiveness of HS and explaining why HS hold this distinctiveness.
基金supported by the Major Science and Technology Program for Water Pollution Control and Treatment of China(Nos.2011ZX07303-001 and 2014ZX07303-003)the State Key Laboratory of Soil and Sustainable Agriculture,Institute of Soil Science,Chinese Academy of Sciences(No.Y412201426)
文摘The migration of soil dissolved organic carbon(DOC) from terrestrial to aquatic environments has important impacts on the adjacent water quality and the transport of organic and inorganic contaminants.However,few studies have investigated the sources and properties of DOC in riparian zones.A total of 34 soil samples were collected across four riparian buffer zones(Zones A-D) on Chongming Island,China.The vertical distributions of soil organic carbon(SOC) and DOC,fluorescence excitation-emission matrix(EEM) spectra of DOC and the optical indices,including fluorescence index(FI),index of recent autochthonous contribution(BIX),and humification index(HIX),were measured across the riparian environment to investigate the sources and fluorescence properties of DOC.The results showed that SOC stored in the surface soil(0-30 cm) accounted for 40%of the total soil profile SOC.The DOC accumulated in Zones A-C,which accounted for 5%of the SOC.The fluorescence EEM spectra of DOC showed that DOC contained humic-like and protein-like substances,which were mainly derived from recent plant debris by microbes.A large amount of humic-like substances were sorbed to minerals in the surface soil(0-30 cm).In addition,the riparian topography and soil physico-chemical properties(pH,EC and moisture) dictated the transformation and transport of DOC.The results suggested that EEMs could reveal the source of DOC in riparian soil systems,and that optical indices were complementary tools that revealed the characteristics of soil DOC and provided supplemental evidence about DOC sources.
基金Supported by the National High Technology Research and Development Program(863 Program)of China(No.2006AA06Z359)the National Environmental Protection Public Welfare Science and Technology Research Program of China(No.201009041)the Special Foundation for Young Scientists of Anhui Province,China(No.2010SQRL150)
文摘Carbon of humus acids(HSAC) and dissolved organic carbon(DOC) are the most active forms of soil organic carbon(SOC) and play an important role in global carbon recycling. We investigated the concentrations of HSAC,water-soluble organic carbon(WSOC),hot water-extractable organic carbon(HWOC) and SOC in soils under different vegetation types of four copper mine tailings sites with differing vegetation succession time periods in Tongling,China. The concentrations of HSAC,WSOC,HWOC and SOC increased with vegetation succession. WSOC concentration increased with the accumulation of SOC in the tailings,and a linearly positive correlation existed between the concentrations of HSAC and SOC in the tailings. However,the percentages of HSAC and DOC in the SOC decreased during vegetation succession. The rate of SOC accumulation was higher when the succession time was longer than 20 years,whereas the speeds of soil organic matter(SOM) decomposition and humification were slow,and the concentrations of HSAC and DOC increased slowly in the tailings. The percentage of carbon of humic acid(HAC) in HSAC increased with vegetation succession,and the values of humification index(HI),HAC/carbon of fulvic acid,also increased with the accumulation of HSAC and SOC in soils of the tailings sites. However,the HI value in the each of the tailings was less than 0.50. The humification rate of SOM was lower than the accumulation rate of SOM,and the level of soil fertility was still very low in the tailings even after 40 years of natural restoration.
基金The National Natural Science Foundation of China under contract No.41376106the Major Science and Technology Program for Water Pollution Control and Treatment under contract No.2012ZX07501
文摘The southern Changjiang River Estuary has attracted considerable attention from marine scientists because it is a highly biologically active area and is biogeochemically significant. Moreover, land-ocean interactions strongly impact the estuary, and harmful algal blooms （HABs） frequently occur in the area. In October 2010 and May 2011, water samples of chromophoric dissolved organic matter （CDOM） were collected from the southern Changjiang River Estuary. Parallel factor analysis （PARAFAC） was used to assess the samples＇ CDOM composition using excitation-emission matrix （EEM） spectroscopy. Four components were identified： three were humic-like （C1, C2 and C3） and one was protein-like （C4）. Analysis based on spatial and seasonal distributions, as well as relationships with salinity, Chl a and apparent oxygen utilization （AOU）, revealed that terrestrial inputs had the most significant effect on the three humic-like Components C1, C2 and C3 in autumn. In spring, microbial processes and phytoplankton blooms were also important factors that impacted the three components. The protein-like Component C4 had autochthonous and allochthonous origins and likely represented a biologically labile component. CDOM in the southern Changjiang River Estuary was mostly affected by terrestrial inputs. Microbial processes and phytoplankton blooms were also important sources of CDOM, especially in spring. The fluorescence intensities of the four components were significantly higher in spring than in autumn. On average, C1, C2, C3, C4 and the total fluorescence intensity （TFI） in the surface, middle and bottom layers increased by 123%-242%, 105%-195%, 167%-665%, 483%-567% and 184%-245% in spring than in autumn, respectively. This finding corresponded with a Chl a concentration that was 16-20 times higher in spring than in autumn and an AOU that was two to four times lower in spring than in autumn. The humification index （HIX） was lower in spring that in autumn, and the fluorescence index （FI） was higher in spring than in autumn. This result indicated that the CDOM was labile and the biological activity was intense in spring.
基金the support of the Xunta de Galicia government(Spain)through projects INCITE09-200-019-PR and Consolidacion e Estructuracion 2018 GRC GI-1243-GEMAP,ED431C 2018/32。
文摘to identify plant macrofossils,estimate peat humification and calculate hydroclimatic indices based on current bog species,with the overall aim of determining the climate conditions associated with evolution of the bog during the Medieval Climate Anomaly and the Little Ice Age.These proxies,together with historical and climate data,proved to be good indicators of the changes in bog surface wetness.Analysis:of the core led to identification of 9 different periods:two corresponding to the so-called Medieval Climate Anomaly(930 to 1345 AD,1075–665 calibrated years before present[cal.yr BP]);four corresponding to the Little Ice Age(1345 to 1905 AD;665–105 cal yr BP);and three corresponding to the last century(1905 to 2000 AD).The findings revealed a generally dry climate that lasted until the 14th century,followed by a transition to a long period with a more humid,but characteristically very variable climate,which ended at the beginning of the 20th century and was followed by a rapid transition to more humid conditions and finally,a change to drier conditions.The Medieval Climate Anomaly was indicated by the abundance of dry-adapted mosses(Leucobryum glaucum,Hypnum cupressiforme)and characterized by warm dry conditions and high levels of peat humification,with alternating wet phases.The LIA period was dated by a large abundance of Sphagnum species(an indicator of wetness)and a gradual increase in the humification index.However,four different climate phases were differentiated in this period.High-resolution reconstruction of the evolution of the CVM bog and the multiproxy approach have together enabled a more detailed identification of climatic variations in this area,which are generally consistent with the global models,as well as better definition of the elusive climatic oscillations in the last millennium and confirmation of the importance of local modulation of global models.The study provides new information and a detailed chronology of climatic events that will help to refine local modulation of the climate evolution model in the still quite unexplored region of the NW Iberian Peninsula,a key area for understanding the paleoclimatic dynamics in SW Europe.
基金Under the auspices of Chinese Academy of Sciences/State Administration of Foreign Experts Affairs(CAS/SAFEA)International Partnership Program for Creative Research Teams(No.KZZD-EW-TZ-07)National Basic Research Program of China(No.2012CB956100)National Natural Science Foundation of China(No.41271209,41401099)
文摘This paper documents a 7800-year proxy record from the Shenjiadian peatland on the Sanjiang Plain in Northeast China.High-resolution plant macrofossil and colorimetric humification methods were used to reconstruct the vegetation and hydrologic history from a 193 cm-long sedimentary profile.Detrended correspondence analysis(DCA) was applied to transform the raw plant macrofossil data into latent indices of peatland water level.The vegetation community transited from an Equisetum fluviatile community to a Carex lasiocarpa community at approximately 3800 cal yr BP and was followed by a Carex-shrub community at approximately 480 cal yr BP.Based on the plant macrofossil DCA axis 1 scores and humification values,we distinguished four hydrologic periods:a wet period from 7800 cal yr BP to 4500 cal yr BP,dry periods up to 1600 cal yr BP,drier periods until 300 cal yr BP,and the driest period from 300 cal yr BP until the present.Through a comparison with other climate records,we suggest that the East Asian summer monsoon(EAM) was the main driving force for vegetation and water level changes to the Shenjiadian peatland through its impacts on precipitation.
