Nano zero valent iron particles (nZVI) are popular the last few years because of the numerous applications in remediation of a wide range of pollutants in contaminated soils and aquifers. The nZVI particles can be 10 ...Nano zero valent iron particles (nZVI) are popular the last few years because of the numerous applications in remediation of a wide range of pollutants in contaminated soils and aquifers. The nZVI particles can be 10 - 1000 times more reactive than granular or micro-scale ZVI particles due to the small particle size, large specific surface area and high reactivity. An alternative green synthesis procedure was used for the production of nano zero valent iron particles (nZVI) using green tea (GT) extract, which is characterized by its high antioxidant content. Polyphenols in green tea extract possess double role in the synthesis of nZVI, because they not only reduce ferric cations, but also protect nZVI from oxidation and agglomeration as capping agents. The objective of current study was to simulate ata laboratory scale the attachment of GT-nZVI particles on soil material and study the effectiveness of attached nanoparticles for removing hexavalent chromium (Cr(VI)) from contaminated groundwater flowing through the porous soil bed. Column tests were carried out with various flowrates in order to examine the effect of contact time between the attached on porous medium nZVI and the flow-through solution on Cr(VI) reduction. After the completion of column tests the soil material in each column was split in 5 vertical sections, which were further subjected to chemical analyses and leaching tests. According to the results of the study increasing the contact time favors the reduction and removal of Cr(VI) from the aqueous phase. The reductive precipitation of Cr can be described as a reaction that follows a pseudo-first order kinetic law, with rate constant equal to k = 0.0243 ± 0.0011 min-1. Leaching tests indicated that precipitated chromium is not soluble. In the examined soil material, the total amount of precipitated Cr was found to range between 280 and 890 mg/(kg soil), while soluble Cr was less than 1.4 mg/kg and most probably it was due to the presence of residual Cr(VI) solution in the porosity of soil.展开更多
With the rapid economic expansion, environmental degradation has become increasingly sever during the past three decades. Soil pollutions associated with toxic organic compounds and heavy metals have been identified i...With the rapid economic expansion, environmental degradation has become increasingly sever during the past three decades. Soil pollutions associated with toxic organic compounds and heavy metals have been identified in China. The accumulation of heavy metals in soils and its impact on food safety is of increasing concern. It has been reported that more than 20 million ha of land have been contaminated with heavy metals that can result in the potential health risks to human beings and soil ecosystems. This can potentially jeopardize the food security in China. Accumulation of heavy metals in suburb and rural soils is closely related to many anthropogenic activities, such as application of fertilizers and pesticides, irrigation of wastewater, discharge of mining, improper disposal of metal containing wastes, land application of animal manures, sewage sludge and coal combustion residues. Arable crops and vegetables in suburb and rural can take up heavy metals from contaminated soils, which is one of the main pathways of introducing heavy metals to human food chain. Events related to soil and vegetable contamination, food safety and human health risks, e.g., rice and vegetables with elevated concentrations of cadmium, are often reported in the media in recent years. The Chinese government has recently developed a number of new policies for prevention of soils from further soil contamination, and remediation of contaminated soils. This presentation will provide a comprehensive review on heavy metal pollution in soils and its impacts on food security in China, and also summarize some new technologies for remediation of soils contaminated with heavy metals.展开更多
In order to assess effects of Summer Fishing Moratorium (SFM) in Daya Bay, variations in stock density, fish diversity, fish species composition, fish body length and weight, and bio-environments during the pre-SFM (M...In order to assess effects of Summer Fishing Moratorium (SFM) in Daya Bay, variations in stock density, fish diversity, fish species composition, fish body length and weight, and bio-environments during the pre-SFM (May in 2015) and post-SFM (August in 2015) in Daya Bay were analyzed, based on trawl survey data. Results showed that the average stock density in the post-SFM was 5.65 times of that in the pre-SFM, and the average species numbers in the post-SFM was 1.76 times of that in the pre-SFM. Analysis of fish body length and weight indicated that fish grew faster during the SFM, and body weight was more uniform in the post-SFM. In the post-SFM, the Shannon-Wiener diversity index and Pielou evenness index increased by 0.36 and 0.14, respectively, indicating that the fish biodiversity and community structure improved. SFM alleviated fishing intensity, recovered and conserved coastal fish resource. In order to improve efficiency and impacts of SFM and to promote sustainable development of coastal fish resource, prolonging the time of SFM, reducing the number of coastal fishing boats and enforcing the conservation of fish resources were suggested.展开更多
Elucidating the factors that determine the effects of temporal and spatial variation of nutrients is important for analyzing the characteristics of an ecosystem. The goal of this paper was to estimate how values obtai...Elucidating the factors that determine the effects of temporal and spatial variation of nutrients is important for analyzing the characteristics of an ecosystem. The goal of this paper was to estimate how values obtained using a particular sampling approach correlated with the actual data for an entire plot. The mesh partition method was employed to divide an integrated observing field (IOF) located at the Haibei National Field Research Station of an alpine grassland ecosystem, China, into 25 subplots. Five of the 25 subplots were randomly selected for soil sampling and to determine the source of variations in soil nutrient content from 2001 to 2012. The results showed that, contributions of temporal and spatial variation in available nitrogen in the 0 - 10 cm soil layer accounted for 47.3% and 52.7%, respectively. The contribution of spatial variance was higher than that of temporal variance especially in the surface soil layers. The available soil nitrogen content in the alpine meadow was not obviously affected by fluctuations in rainfall and temperature. Increasing the number of samples could reduce calculation errors in measuring available soil nitrogen content, while collecting a reasonable number of samples can save time and labor.展开更多
Tourism carbon emission is one of the important factors affecting ecological environment. In order to clarify the trend and changing characteristics of tourism carbon emissions, academia has carried out quantitative r...Tourism carbon emission is one of the important factors affecting ecological environment. In order to clarify the trend and changing characteristics of tourism carbon emissions, academia has carried out quantitative research on tourism carbon footprint. Based on the theory of carbon footprint, this study analyzes the tourism carbon emissions in Sichuan Province from 2004 to 2018 through three indexes: tourism carbon footprint, carbon carrying capacity and net carbon footprint. The results show that the carbon footprint of tourism in Sichuan Province shows an increasing trend. During the fifteen years, it increases by 20.2 times from 427.59 million tons to 9505.95 million tons. The carbon carrying capacity of tourism is increasing year by year except in 2008. Sichuan Province was in a carbon surplus before 2012. The carbon carrying capacity is greater than the carbon footprint, which is friendly to the ecological environment. After 2012, Sichuan Province is in a state of carbon deficit, and the ecological pressure is increasing, which is not conducive to human survival.展开更多
District Ghizer is a rugged mountainous territory which experiences several landslides each year. There are 16 major landslide areas and 53 villages that are at high risk to hazards. Keeping in view the severity of na...District Ghizer is a rugged mountainous territory which experiences several landslides each year. There are 16 major landslide areas and 53 villages that are at high risk to hazards. Keeping in view the severity of natural hazards, the present study was designed to generate landslide susceptibility map based on twelve causative factors viz., slope, aspect, elevation, drainage network, Stream Power Index (SPI), Topographic Wetness Index (TWI), lithological units, fault lines, rainfall, road network, land cover and soil texture. Soil texture was determined by particle size analysis and data for other factors were acquired from freely available sources. Analytical Hierarchy Process (AHP) was employed to identify major landslide causative factors in the district Ghizer. Further, a temporal assessment from 1999 till 2015 was generated to assess the impact of land cover change on landslides. It indicated that the barren soil/ exposed rocks and glaciers have reduced while the vegetation and water classes have shown increment. The total area that lies in moderate to very high landslide susceptible zones was 74.38%, while slope is the main landslide causative factor in the district Ghizer. Validation of the susceptibility map showed 88.1% of the landslides in the study area had occurred in the moderate to very high susceptible zones.展开更多
As a widespread problem, heavy metals contamination in soil has drawn considerable study interest, especially for the farmlands around mine area. A variety of pollution evaluation methods have been compared including ...As a widespread problem, heavy metals contamination in soil has drawn considerable study interest, especially for the farmlands around mine area. A variety of pollution evaluation methods have been compared including both traditional physical and chemical analysis methods as well as ecological assessment methods. And the combination of multiple assessment methods was recommended to get a comprehensive and through soil heavy metal pollution evaluation.展开更多
Phosphorus is one of the major nutrients that have been identified as a limited resource that would end up earlier than predicted at the rate of current consumption. Therefore, attempts to recover phosphorus from wast...Phosphorus is one of the major nutrients that have been identified as a limited resource that would end up earlier than predicted at the rate of current consumption. Therefore, attempts to recover phosphorus from waste and its subsequent use are a concern of current researchers. Nevertheless, recovery of nutrients from wastewater is cumbersome because nutrients such as phosphates () and nitrates () prefer to remain in aqueous phase rather than being adsorbed on solid matrixes. Investigation of adsorption of available - P from simulated brackish water, on granulated solid waste material, prepared by crushed autoclaved aerated concrete (CAAC), and subsequent use of the material as phosphate fertilizer would be the focus of this research. Treatment of nutrient-rich brackish water is important because such water is discharged in huge volume at the time of harvesting of shrimp aquaculture ponds. Experiments conducted in simulated brackish water confirmed non-linear adsorption association with changing distribution coefficient (KD) which attributed the maximum removal of about 98% - P from 100 mgdm-3solution at its value of 40. The non-linear adsorption supported by both the Langumuir and the Freundlich isotherm models simultaneously satisfied monolayer adsorption and multilayer adsorption depicted by the regression coefficients of greater than .99 by the linearized forms of the isotherm models. Moreover, promising phosphate uptakes characteristics are exhibited by the adsorbent at the process of repetitive adsorption which resulted in 12 g/kg uptake of phosphate at 81% efficiency. The adsorbent seems to be used as a slow-released phosphorus fertilizer at the end of its life as an adsorbent.展开更多
Up to date, tropical mountainous ecosystems still lack in depth information on soil and environmental characteristics which are major factors limiting optimum crop production. The objective of this work was to study s...Up to date, tropical mountainous ecosystems still lack in depth information on soil and environmental characteristics which are major factors limiting optimum crop production. The objective of this work was to study soil characteristics and to evaluate the land capability level for the production of some common tropical crops in mountainous ecosystem soils of North West Cameroon. Soil sampling was done following a randomized complete block design (RCBD) with four replications for three topographic positions (upslope, midslope and footslope) and at two depths (0 - 20 cm and 20 - 100 cm). It was completed by standard laboratory analyses. The fertility capability classification (FCC) system enabled to identify soil limitations and to classify soils into FCC units. Land and climate were evaluated by simple limitation and parametric methods. Globally, the soils were dark-colored, sandy clayey to clayey, compact and very acidic (pHH2O = 4.3 - 5.8). The organic matter (3.7% - 5.1% dry matter), total nitrogen (0.08% - 0.56%) and available phosphorus (22.1 to 30.9 mg?kg?1) recorded for the 0 - 20 cm depth then reduced with depth but midslope values were also lower. The C/N ratio varied between 9 and 45. Low C/N values appeared mostly in 0 - 20 cm depth at the upslope and downslope soils and subsurface soils of midslope position. Exchangeable Ca was very low to low (1.43 - 3.6 cmol + kg?1), Mg was very low to low (0.39 - 1.5 cmol + kg?1), K was low to medium (0.2 - 0.54 cmol + kg?1) and Na was very low (?1). The sum of exchangeable bases was very low (3.02 - 5.19 cmol + kg?1), cation exchange capacity was low to moderate (8.60 - 25.6 cmol + kg?1) and base saturation was very low to low (19.27% - 36.97%). Leaching of bases under heavy rainfall is a major cause of soil acidification under humid topical ecosystems. The Ca/Mg/K ratio was unbalanced and Mg was the most relatively concentrated base in all the soils. There was a clear variation of most of the soil properties along the slope and with depth. The soils were classified in the FCC system as aek for the upslope soils, Caek for the midslope soils and Cagk for the footslope soils. The principal limitations to production of huckleberry, beans, maize and potatoes were heavy rainfall, wetness, steep slope, soil texture/structure and low soil fertility. These constraints might be overcome by farming at the end of the raining season, contour ploughing, terracing, fertilization and liming.展开更多
Constructed wetlands are engineered structures designed to simulate processes of natural wetlands to mitigate anthropogenic organic and inorganic materials to shelter soil and water resources. This review focuses on t...Constructed wetlands are engineered structures designed to simulate processes of natural wetlands to mitigate anthropogenic organic and inorganic materials to shelter soil and water resources. This review focuses on the global interest in constructed wetland application to sustain soil health and water quality and water abundance. Engineering criterion remains a function of nutrient chemistry and load with suitability factors including the local soil and hydrogeology constraints, climate, vegetation selection, the degree of required influent improvement, and reactor types and sizes. Future research needs to focus on: 1) reactor designs criteria, 2) the biology of the microbial community, 3) selection criteria for native vegetation, and 4) criteria to reapply treated water to foster land productivity, especially for region’s experiencing water deficiencies.展开更多
Irrigation water supply is one of the vital components for sustainable rice farming, which is becoming a limiting resource in the changing climatic condition. An experiment was conducted at the research field of Bangl...Irrigation water supply is one of the vital components for sustainable rice farming, which is becoming a limiting resource in the changing climatic condition. An experiment was conducted at the research field of Bangladesh Agricultural University, Mymensingh during dry season from January-June of 2017 to investigate the suitability of Alternate Wet and Dry Irrigation (AWDI) for sustainable rice production and reducing methane emission. The modern rice variety BINA Dhan 10 was used as test crop. There were five irrigation treatments viz. T<sub>1</sub> (saturated condition), T<sub>2</sub> (continuous flooded, 5 cm standing water), T<sub>3</sub> (AWDI-10 cm;irrigated when water level fell 10 cm from surface), T<sub>4</sub> (AWDI-15 cm;irrigated when water level fell 15 cm from surface) and T<sub>5</sub> (AWDI-20 cm;irrigated when water level fell 20 cm from surface). Results of the field trial showed satisfactory grain yield and low seasonal methane emission along with significantly high irrigation water savings (%) in AWDI treated field plots. Among the treatments, T<sub>3</sub> (AWDI-10 cm) and T<sub>4</sub> (AWDI-15 cm) showed higher yield performance (6250kg<span style="color:#4F4F4F;font-family:-apple-system, " font-size:14px;white-space:normal;background-color:#f7f7f7;"=""><sup>.</sup></span>ha<span style="color:#FFFFFF;font-family:" white-space:normal;background-color:#d46399;"=""><span style="color: rgb(79, 79, 79);" font-size:14px;white-space:normal;background-color:#ffffff;"=""><sup>-</sup></span></span><sup>1</sup> and 5810 kg<span style="color:#4F4F4F;font-family:-apple-system, " font-size:14px;white-space:normal;background-color:#f7f7f7;"=""><sup>.</sup></span>ha<sup><span style="white-space:nowrap;">-</span>1</sup>, respectively) with lower CH<sub>4</sub> emission (reduced up to 36% and 40%, respectively) compared to continuous flooded treatment (T2, CF 5 cm water). In AWDI field plots less irrigation frequency (6 - 9) was required which significantly saved the amount of irrigation water (12% - 24%). Although T<sub>5</sub> (AWDI-20 cm) showed the highest water savings (24%) and lowest CH<sub>4</sub> emission (reduced up to 50%);however the lowest grain yield (4283 kg<span style="color:#4F4F4F;font-family:-apple-system, " font-size:14px;white-space:normal;background-color:#f7f7f7;"=""><sup>.</sup></span>ha<span style="color: rgb(79, 79, 79);" font-size:14px;white-space:normal;background-color:#ffffff;"=""><sup>-</sup></span><sup>1</sup>) was found under this treatment. On the other hand, continuously irrigated (T2, 5 cm standing water) field plot showed lower yield (4783 kg<span style="color:#4F4F4F;font-family:-apple-system, " font-size:14px;white-space:normal;background-color:#f7f7f7;"=""><sup>.</sup></span>ha<sup><span style="color:#4F4F4F;font-family:-apple-system, " font-size:14px;white-space:normal;background-color:#ffffff;"="">-</span>1</sup>) but significantly higher methane emissions compared to other treatments during rice cultivation. Water productivity index was also found higher in AWDI treated field plots compared to continuously irrigated field plot. At the reproductive stage of rice plant well-developed aerenchyma tissue was observed in root cortex under the continuous irrigated field plot, which indicates higher diffusion pathway of methane gas from root rhizosphere to the atmosphere compared to other treatments. Therefore, alternate wet and dry irrigation water management practice may be recommended at farmers’ level for sustainable rice production and reducing methane emission during dry winter Boro season which will reduce the cost of production by water saving as well as energy saving.展开更多
The concentrations of twenty five heavy metals adsorbed to fine fraction of particulate matter, PM2.5 (d ≤ 2.5 μm) have been experimentally analysed at a sampling site located at the kerbside along a National Highwa...The concentrations of twenty five heavy metals adsorbed to fine fraction of particulate matter, PM2.5 (d ≤ 2.5 μm) have been experimentally analysed at a sampling site located at the kerbside along a National Highway in Delhi city, India. The sampling has been carried out for 12-hour using Ecotech Intruments, APM550. The PM2.5 has been collected on PTFE filter papers for the winter season. Later, the filter papers have been analysed for various heavy metal concentrations using ED-XRF. It has been observed that the metals concentrations are in this trend: Si > K > S > Ca = Fe > Zn = Pb > Br. it is observed that Si has high co-relation with Ca, Fe and K, which may be due to crustal origin of all three elements;while S, Br and Pb may be from vehicular exhaust emissions and/or abrasions due to brake and tyre wear. The potential health risks associated with different carcinogenic heavy metals have also been calculated. One of the health risk indicators, the excess cancer risk (ECR), is found to be in the order as As > Cd > Pb > Cr > Ni.展开更多
For submerged vegetated flow, the velocity profile has two distinctive distributions in the vegetation layer in the lower region and the surface layer in the upper non-vegetated region. Based on a mixing-layer analogy...For submerged vegetated flow, the velocity profile has two distinctive distributions in the vegetation layer in the lower region and the surface layer in the upper non-vegetated region. Based on a mixing-layer analogy, different analytical models have been proposed for the velocity profile in the two layers. This paper evaluates the four analytical models of Klopstra et al., Defina & Bixio, Yang et al. and Nepf against a wide range of independent experimental data available in the literature. To test the applicability and robust of the models, the author used the 19 datasets with various relative depths of submergence, different vegetation densities and bed slopes (1.8 × 10?6 - 4.0 × 10?3). This study shows that none of the models can predict the velocity profiles well for all datasets. The three models except Yang’s model performed reasonably well in certain cases, but Yang’s model failed in most the cases studied. It was also found that the Defina model is almost the same as the Klopstra model, if the same mixing length scale of eddies (λ) is used. Finally, close examination of the mixing length scale of eddies (λ) in the Defina model showed that when λ/h = 1/40(H/h)1/2, this model can predict velocity profiles well for all the datasets used.展开更多
Duckweed is a group of aquatic plants with the potential of wastewater remediation and fast accumulation of biomass. The accumulated biomass, rich in cellulose, starch and protein, can be used for biofuel, bio-fertili...Duckweed is a group of aquatic plants with the potential of wastewater remediation and fast accumulation of biomass. The accumulated biomass, rich in cellulose, starch and protein, can be used for biofuel, bio-fertilizer, animal feed and human food. Characterization of natural biodiversity of duckweed species is essential for the germplasm preservation and various practical applications. We have collected samples of duckweed in eastern China and characterized species biodiversity by genotyping, using chloroplast (atpF-atpH and psbK-psbI spacers). Spirodela polyrhiza was revealed as a clear dominant duckweed species in all locations of the area. Other duckweed species were identified as Landoltia punctata, Lemna aequinoctialis and Lemna turionifera. Selected isolates of these four species were used in the experiments to estimate their potential in removing nitrogen and phosphorus nutrients from municipal and industrial wastewater sampled at the local sewage plants. Duckweed was able to reduce the concentration of nitrogen up to 98% and phosphorus up to 96%. The presented data demonstrates high efficiency of the local duckweed isolates for bioremediation of different types of wastewater and the great potential of duckweed for wastewater treatment when incorporated into the purification chain.展开更多
Qinhuangdao is a provincial municipality under the jurisdiction of Hebei Province and a coastal city in China. Beidaihe is a district under the jurisdiction of Qinhuangdao and is a famous seaside scenic area. Alliance...Qinhuangdao is a provincial municipality under the jurisdiction of Hebei Province and a coastal city in China. Beidaihe is a district under the jurisdiction of Qinhuangdao and is a famous seaside scenic area. Alliance Peak, located in Beidaihe seashore scenic West. Jinshan mouth is the peak of the Union Peak, located in the easternmost Beidaihe waterfront. In this paper, we use the observed data of air negative ions in the Beidaihe, Qinhuangdao, Jinshanzui and Lianfeng Mountains for seven years to study the distribution characteristics of negative air ions in different ecological environments through meteorological observation. Research shows that the annual mean of air anion concentration fluctuates less. The annual mean is 1730 ind·cm-3, and the difference between the highest and lowest concentrations is 535 ind·cm-3. The average air anion concentration was the highest in August at 7785 ind·cm-3 and the lowest in January at 365 ind·cm-3. Negative air ions have obvious spatial characteristics, and negative ion concentrations of the sea and forest air are significantly high. The average annual mean of the sea is 3902 ind·cm-3, and that of the forest is 5403 ind·cm-3. The concentration of air anion changes daily, and daytime concentration is significantly lower than nighttime concentration. The highest peak appears at night or in the morning, while the lowest value appears between noon and afternoon. Inter-annual features and concentration of negative air ions, as well as annual rain days, total rainfall, thunderstorm days, and average relative humidity, are negatively related to the annual average temperature and sunshine hours. However, in the average concentration of negative air ions, the average correlation test of meteorological elements was insignificant. The air anion concentration is negatively correlated with the PM2.5 concentration of fine particulate matter. The concentrations of nitrogen dioxide, sulfur dioxide, and carbon monoxide in the fine particulate matter are negatively correlated with the ozone concentration, which is positively correlated with ozone concentration and is tested by significance. Atmospheric discharge (thunderstorm) can produce a considerable amount of air anion. Air negative ions are an important indicator of air quality, which is of great significance to the living environment. The distribution of negative ions in the study space and its influencing factors in order to provide a basis for air quality assessment in the region and provide references for the long-term research on air anion in different urban areas.展开更多
Taking a certain area in Sichuan Province as the object of this study, this paper adopts fuzzy mathematics method to make an evaluation on ecological risks of heavy metal in soil of this area. On calculation of factor...Taking a certain area in Sichuan Province as the object of this study, this paper adopts fuzzy mathematics method to make an evaluation on ecological risks of heavy metal in soil of this area. On calculation of factors’ weights, the traditional method of giving weight according to pollutants’ concentrations fails to consider the toxicity of heavy metals, and can’t reflect their actual ecological effect. With reference to the toxicity coefficient in potential ecological risk index evaluation, this article revises the traditional fuzzy mathematics evaluation model and puts forward a new method to calculate factors’ weight by incorporating toxicity levels in weight setting. The results of this study indicate: surface soil of this area was good in general, with 91.2% samples belonging to the first level, 7.77% samples belonging to the second level, and only 1.03% belonging to the third level. Compared with the results of the evaluation method of the reality content of soil, soil quality is better than the results of the quantitative evaluation, and is closer to the actual local conditions.展开更多
Land surface displacement caused by landslides is among the most damaging phenomena in northern Morocco. In this paper, we measure ground deformation in the Chefchaouen area which is a zone characterized by geological...Land surface displacement caused by landslides is among the most damaging phenomena in northern Morocco. In this paper, we measure ground deformation in the Chefchaouen area which is a zone characterized by geological formations and structurally complex losses that promote instability (landslide, mudflow, block falls, etc.) leading to slow to extremely slow deformation phenomena, which require an interferometric study, using the DinSAR (differential interferometric synthetic Aperture Radar) technique with sentinel 1 images in bance C, which is a powerful tool for the detection and analysis of interferences and monitoring of ground deformations. We worked on four areas of the study area. Its points are provided by the direction of the roads, which generates Interferograms and then deformation maps with precision in mm/year.展开更多
The utility of a spatially-explicit, exposure-based model was examined for its suitability as a tool for rapidly assessing surface water vulnerability in watershed planning. This simple GIS-model uses three types of e...The utility of a spatially-explicit, exposure-based model was examined for its suitability as a tool for rapidly assessing surface water vulnerability in watershed planning. This simple GIS-model uses three types of easily obtainable spatial information: (1) sources of land use-induced change;(2) intensity of watershed drainage;and (3) sensitivity of drainage basins to change. This model was applied to the Thomas Brook watershed in Nova Scotia, Canada, which has been the site of previous studies, conducted over multiple years, using detailed, effects-based, hydrologic models. Doing so allowed us the opportunity to compare the two approaches. Results showed a good concordance in the derived mapped outputs between the two models. Given the rapid ease and inexpensive cost of using the GIS, exposure-based model, we believe it to offer great promise in terms of prioritizing locations for further study or for intervention of best management practices, as well as for planning where to best direct future water-sensitive development through build-out analyses.展开更多
Talcose rocks from Itagunmodi and Igun areas within the Ilesa Schist Belt, southwestern Nigeria, were studied to determine their compositional affinities and industrial properties. The talcose bodies occurred as lenso...Talcose rocks from Itagunmodi and Igun areas within the Ilesa Schist Belt, southwestern Nigeria, were studied to determine their compositional affinities and industrial properties. The talcose bodies occurred as lensoid enclaves closely associated with amphibolites and quartz-mica schist. Petrographic and X-ray diffraction-aided mineralogical studies reveal that the talcose rocks are of the talc-chlorite schist variety composed predominantly of talc (average 73.63%), subordinate chlorite (average 16.08%) and accessory lizardite (average 6.5%). Total whole rock characterization of the samples using Lithium Fusion digestion revealed high mean concentrations of SiO2 (57.53%), MgO (24.84%) and Fe2O3 (7.73%) with significant enrichment of Ni, Co and Cr;and low values of Ba, Rb, Sr, V, Cu and Pb. The talc-chlorite schists plotted in the peridotitic komatiite field of the Al2O3-(FeO + TiO2)-MgO diagram. Water Absorption Capacity ranges from 6.25% - 8.20%, Loss on Ignition is 4.8% - 6.1% while Linear Shrinkage is 1.25% - 1.70% and firing colour is brown to dark-brown. The overall compositional features of the talcose rocks of the area, which were hitherto uncharacterized, show their suitability as raw materials for paint, coloured pottery, ceramic insulation, textile, rubber and plastic manufacture with varying beneficiation requirements. Their high trace element content however, makes them unsuitable for use in pharmaceutical and cosmetic applications.展开更多
Water quality monitoring has one of the highest priorities in surface water protection policy. Many variety approaches are being used to interpret and analyze the concealed variables that determine the variance of obs...Water quality monitoring has one of the highest priorities in surface water protection policy. Many variety approaches are being used to interpret and analyze the concealed variables that determine the variance of observed water quality of various source points. A considerable proportion of these approaches are mainly based on statistical methods, multivariate statistical techniques in particular. In the present study, the use of multivariate techniques is required to reduce the large variables number of Nile River water quality upstream Cairo Drinking Water Plants (CDWPs) and determination of relationships among them for easy and robust evaluation. By means of multivariate statistics of principal components analysis (PCA), Fuzzy C-Means (FCM) and K-means algorithm for clustering analysis, this study attempted to determine the major dominant factors responsible for the variations of Nile River water quality upstream Cairo Drinking Water Plants (CDWPs). Furthermore, cluster analysis classified 21 sampling stations into three clusters based on similarities of water quality features. The result of PCA shows that 6 principal components contain the key variables and account for 75.82% of total variance of the study area surface water quality and the dominant water quality parameters were: Conductivity, Iron, Biological Oxygen Demand (BOD), Total Coliform (TC), Ammonia (NH3), and pH. However, the results from both of FCM clustering and K-means algorithm, based on the dominant parameters concentrations, determined 3 cluster groups and produced cluster centers (prototypes). Based on clustering classification, a noted water quality deteriorating as the cluster number increased from 1 to 3. However the cluster grouping can be used to identify the physical, chemical and biological processes creating the variations in the water quality parameters. This study revealed that multivariate analysis techniques, as the extracted water quality dominant parameters and clustered information can be used in reducing the number of sampling parameters on the Nile River in a cost effective and efficient way instead of using a large set of parameters without missing much information. These techniques can be helpful for decision makers to obtain a global view on the water quality in any surface water or other water bodies when analyzing large data sets especially without a priori knowledge about relationships between them.展开更多
文摘Nano zero valent iron particles (nZVI) are popular the last few years because of the numerous applications in remediation of a wide range of pollutants in contaminated soils and aquifers. The nZVI particles can be 10 - 1000 times more reactive than granular or micro-scale ZVI particles due to the small particle size, large specific surface area and high reactivity. An alternative green synthesis procedure was used for the production of nano zero valent iron particles (nZVI) using green tea (GT) extract, which is characterized by its high antioxidant content. Polyphenols in green tea extract possess double role in the synthesis of nZVI, because they not only reduce ferric cations, but also protect nZVI from oxidation and agglomeration as capping agents. The objective of current study was to simulate ata laboratory scale the attachment of GT-nZVI particles on soil material and study the effectiveness of attached nanoparticles for removing hexavalent chromium (Cr(VI)) from contaminated groundwater flowing through the porous soil bed. Column tests were carried out with various flowrates in order to examine the effect of contact time between the attached on porous medium nZVI and the flow-through solution on Cr(VI) reduction. After the completion of column tests the soil material in each column was split in 5 vertical sections, which were further subjected to chemical analyses and leaching tests. According to the results of the study increasing the contact time favors the reduction and removal of Cr(VI) from the aqueous phase. The reductive precipitation of Cr can be described as a reaction that follows a pseudo-first order kinetic law, with rate constant equal to k = 0.0243 ± 0.0011 min-1. Leaching tests indicated that precipitated chromium is not soluble. In the examined soil material, the total amount of precipitated Cr was found to range between 280 and 890 mg/(kg soil), while soluble Cr was less than 1.4 mg/kg and most probably it was due to the presence of residual Cr(VI) solution in the porosity of soil.
文摘With the rapid economic expansion, environmental degradation has become increasingly sever during the past three decades. Soil pollutions associated with toxic organic compounds and heavy metals have been identified in China. The accumulation of heavy metals in soils and its impact on food safety is of increasing concern. It has been reported that more than 20 million ha of land have been contaminated with heavy metals that can result in the potential health risks to human beings and soil ecosystems. This can potentially jeopardize the food security in China. Accumulation of heavy metals in suburb and rural soils is closely related to many anthropogenic activities, such as application of fertilizers and pesticides, irrigation of wastewater, discharge of mining, improper disposal of metal containing wastes, land application of animal manures, sewage sludge and coal combustion residues. Arable crops and vegetables in suburb and rural can take up heavy metals from contaminated soils, which is one of the main pathways of introducing heavy metals to human food chain. Events related to soil and vegetable contamination, food safety and human health risks, e.g., rice and vegetables with elevated concentrations of cadmium, are often reported in the media in recent years. The Chinese government has recently developed a number of new policies for prevention of soils from further soil contamination, and remediation of contaminated soils. This presentation will provide a comprehensive review on heavy metal pollution in soils and its impacts on food security in China, and also summarize some new technologies for remediation of soils contaminated with heavy metals.
文摘In order to assess effects of Summer Fishing Moratorium (SFM) in Daya Bay, variations in stock density, fish diversity, fish species composition, fish body length and weight, and bio-environments during the pre-SFM (May in 2015) and post-SFM (August in 2015) in Daya Bay were analyzed, based on trawl survey data. Results showed that the average stock density in the post-SFM was 5.65 times of that in the pre-SFM, and the average species numbers in the post-SFM was 1.76 times of that in the pre-SFM. Analysis of fish body length and weight indicated that fish grew faster during the SFM, and body weight was more uniform in the post-SFM. In the post-SFM, the Shannon-Wiener diversity index and Pielou evenness index increased by 0.36 and 0.14, respectively, indicating that the fish biodiversity and community structure improved. SFM alleviated fishing intensity, recovered and conserved coastal fish resource. In order to improve efficiency and impacts of SFM and to promote sustainable development of coastal fish resource, prolonging the time of SFM, reducing the number of coastal fishing boats and enforcing the conservation of fish resources were suggested.
文摘Elucidating the factors that determine the effects of temporal and spatial variation of nutrients is important for analyzing the characteristics of an ecosystem. The goal of this paper was to estimate how values obtained using a particular sampling approach correlated with the actual data for an entire plot. The mesh partition method was employed to divide an integrated observing field (IOF) located at the Haibei National Field Research Station of an alpine grassland ecosystem, China, into 25 subplots. Five of the 25 subplots were randomly selected for soil sampling and to determine the source of variations in soil nutrient content from 2001 to 2012. The results showed that, contributions of temporal and spatial variation in available nitrogen in the 0 - 10 cm soil layer accounted for 47.3% and 52.7%, respectively. The contribution of spatial variance was higher than that of temporal variance especially in the surface soil layers. The available soil nitrogen content in the alpine meadow was not obviously affected by fluctuations in rainfall and temperature. Increasing the number of samples could reduce calculation errors in measuring available soil nitrogen content, while collecting a reasonable number of samples can save time and labor.
文摘Tourism carbon emission is one of the important factors affecting ecological environment. In order to clarify the trend and changing characteristics of tourism carbon emissions, academia has carried out quantitative research on tourism carbon footprint. Based on the theory of carbon footprint, this study analyzes the tourism carbon emissions in Sichuan Province from 2004 to 2018 through three indexes: tourism carbon footprint, carbon carrying capacity and net carbon footprint. The results show that the carbon footprint of tourism in Sichuan Province shows an increasing trend. During the fifteen years, it increases by 20.2 times from 427.59 million tons to 9505.95 million tons. The carbon carrying capacity of tourism is increasing year by year except in 2008. Sichuan Province was in a carbon surplus before 2012. The carbon carrying capacity is greater than the carbon footprint, which is friendly to the ecological environment. After 2012, Sichuan Province is in a state of carbon deficit, and the ecological pressure is increasing, which is not conducive to human survival.
文摘District Ghizer is a rugged mountainous territory which experiences several landslides each year. There are 16 major landslide areas and 53 villages that are at high risk to hazards. Keeping in view the severity of natural hazards, the present study was designed to generate landslide susceptibility map based on twelve causative factors viz., slope, aspect, elevation, drainage network, Stream Power Index (SPI), Topographic Wetness Index (TWI), lithological units, fault lines, rainfall, road network, land cover and soil texture. Soil texture was determined by particle size analysis and data for other factors were acquired from freely available sources. Analytical Hierarchy Process (AHP) was employed to identify major landslide causative factors in the district Ghizer. Further, a temporal assessment from 1999 till 2015 was generated to assess the impact of land cover change on landslides. It indicated that the barren soil/ exposed rocks and glaciers have reduced while the vegetation and water classes have shown increment. The total area that lies in moderate to very high landslide susceptible zones was 74.38%, while slope is the main landslide causative factor in the district Ghizer. Validation of the susceptibility map showed 88.1% of the landslides in the study area had occurred in the moderate to very high susceptible zones.
文摘As a widespread problem, heavy metals contamination in soil has drawn considerable study interest, especially for the farmlands around mine area. A variety of pollution evaluation methods have been compared including both traditional physical and chemical analysis methods as well as ecological assessment methods. And the combination of multiple assessment methods was recommended to get a comprehensive and through soil heavy metal pollution evaluation.
文摘Phosphorus is one of the major nutrients that have been identified as a limited resource that would end up earlier than predicted at the rate of current consumption. Therefore, attempts to recover phosphorus from waste and its subsequent use are a concern of current researchers. Nevertheless, recovery of nutrients from wastewater is cumbersome because nutrients such as phosphates () and nitrates () prefer to remain in aqueous phase rather than being adsorbed on solid matrixes. Investigation of adsorption of available - P from simulated brackish water, on granulated solid waste material, prepared by crushed autoclaved aerated concrete (CAAC), and subsequent use of the material as phosphate fertilizer would be the focus of this research. Treatment of nutrient-rich brackish water is important because such water is discharged in huge volume at the time of harvesting of shrimp aquaculture ponds. Experiments conducted in simulated brackish water confirmed non-linear adsorption association with changing distribution coefficient (KD) which attributed the maximum removal of about 98% - P from 100 mgdm-3solution at its value of 40. The non-linear adsorption supported by both the Langumuir and the Freundlich isotherm models simultaneously satisfied monolayer adsorption and multilayer adsorption depicted by the regression coefficients of greater than .99 by the linearized forms of the isotherm models. Moreover, promising phosphate uptakes characteristics are exhibited by the adsorbent at the process of repetitive adsorption which resulted in 12 g/kg uptake of phosphate at 81% efficiency. The adsorbent seems to be used as a slow-released phosphorus fertilizer at the end of its life as an adsorbent.
文摘Up to date, tropical mountainous ecosystems still lack in depth information on soil and environmental characteristics which are major factors limiting optimum crop production. The objective of this work was to study soil characteristics and to evaluate the land capability level for the production of some common tropical crops in mountainous ecosystem soils of North West Cameroon. Soil sampling was done following a randomized complete block design (RCBD) with four replications for three topographic positions (upslope, midslope and footslope) and at two depths (0 - 20 cm and 20 - 100 cm). It was completed by standard laboratory analyses. The fertility capability classification (FCC) system enabled to identify soil limitations and to classify soils into FCC units. Land and climate were evaluated by simple limitation and parametric methods. Globally, the soils were dark-colored, sandy clayey to clayey, compact and very acidic (pHH2O = 4.3 - 5.8). The organic matter (3.7% - 5.1% dry matter), total nitrogen (0.08% - 0.56%) and available phosphorus (22.1 to 30.9 mg?kg?1) recorded for the 0 - 20 cm depth then reduced with depth but midslope values were also lower. The C/N ratio varied between 9 and 45. Low C/N values appeared mostly in 0 - 20 cm depth at the upslope and downslope soils and subsurface soils of midslope position. Exchangeable Ca was very low to low (1.43 - 3.6 cmol + kg?1), Mg was very low to low (0.39 - 1.5 cmol + kg?1), K was low to medium (0.2 - 0.54 cmol + kg?1) and Na was very low (?1). The sum of exchangeable bases was very low (3.02 - 5.19 cmol + kg?1), cation exchange capacity was low to moderate (8.60 - 25.6 cmol + kg?1) and base saturation was very low to low (19.27% - 36.97%). Leaching of bases under heavy rainfall is a major cause of soil acidification under humid topical ecosystems. The Ca/Mg/K ratio was unbalanced and Mg was the most relatively concentrated base in all the soils. There was a clear variation of most of the soil properties along the slope and with depth. The soils were classified in the FCC system as aek for the upslope soils, Caek for the midslope soils and Cagk for the footslope soils. The principal limitations to production of huckleberry, beans, maize and potatoes were heavy rainfall, wetness, steep slope, soil texture/structure and low soil fertility. These constraints might be overcome by farming at the end of the raining season, contour ploughing, terracing, fertilization and liming.
文摘Constructed wetlands are engineered structures designed to simulate processes of natural wetlands to mitigate anthropogenic organic and inorganic materials to shelter soil and water resources. This review focuses on the global interest in constructed wetland application to sustain soil health and water quality and water abundance. Engineering criterion remains a function of nutrient chemistry and load with suitability factors including the local soil and hydrogeology constraints, climate, vegetation selection, the degree of required influent improvement, and reactor types and sizes. Future research needs to focus on: 1) reactor designs criteria, 2) the biology of the microbial community, 3) selection criteria for native vegetation, and 4) criteria to reapply treated water to foster land productivity, especially for region’s experiencing water deficiencies.
文摘Irrigation water supply is one of the vital components for sustainable rice farming, which is becoming a limiting resource in the changing climatic condition. An experiment was conducted at the research field of Bangladesh Agricultural University, Mymensingh during dry season from January-June of 2017 to investigate the suitability of Alternate Wet and Dry Irrigation (AWDI) for sustainable rice production and reducing methane emission. The modern rice variety BINA Dhan 10 was used as test crop. There were five irrigation treatments viz. T<sub>1</sub> (saturated condition), T<sub>2</sub> (continuous flooded, 5 cm standing water), T<sub>3</sub> (AWDI-10 cm;irrigated when water level fell 10 cm from surface), T<sub>4</sub> (AWDI-15 cm;irrigated when water level fell 15 cm from surface) and T<sub>5</sub> (AWDI-20 cm;irrigated when water level fell 20 cm from surface). Results of the field trial showed satisfactory grain yield and low seasonal methane emission along with significantly high irrigation water savings (%) in AWDI treated field plots. Among the treatments, T<sub>3</sub> (AWDI-10 cm) and T<sub>4</sub> (AWDI-15 cm) showed higher yield performance (6250kg<span style="color:#4F4F4F;font-family:-apple-system, " font-size:14px;white-space:normal;background-color:#f7f7f7;"=""><sup>.</sup></span>ha<span style="color:#FFFFFF;font-family:" white-space:normal;background-color:#d46399;"=""><span style="color: rgb(79, 79, 79);" font-size:14px;white-space:normal;background-color:#ffffff;"=""><sup>-</sup></span></span><sup>1</sup> and 5810 kg<span style="color:#4F4F4F;font-family:-apple-system, " font-size:14px;white-space:normal;background-color:#f7f7f7;"=""><sup>.</sup></span>ha<sup><span style="white-space:nowrap;">-</span>1</sup>, respectively) with lower CH<sub>4</sub> emission (reduced up to 36% and 40%, respectively) compared to continuous flooded treatment (T2, CF 5 cm water). In AWDI field plots less irrigation frequency (6 - 9) was required which significantly saved the amount of irrigation water (12% - 24%). Although T<sub>5</sub> (AWDI-20 cm) showed the highest water savings (24%) and lowest CH<sub>4</sub> emission (reduced up to 50%);however the lowest grain yield (4283 kg<span style="color:#4F4F4F;font-family:-apple-system, " font-size:14px;white-space:normal;background-color:#f7f7f7;"=""><sup>.</sup></span>ha<span style="color: rgb(79, 79, 79);" font-size:14px;white-space:normal;background-color:#ffffff;"=""><sup>-</sup></span><sup>1</sup>) was found under this treatment. On the other hand, continuously irrigated (T2, 5 cm standing water) field plot showed lower yield (4783 kg<span style="color:#4F4F4F;font-family:-apple-system, " font-size:14px;white-space:normal;background-color:#f7f7f7;"=""><sup>.</sup></span>ha<sup><span style="color:#4F4F4F;font-family:-apple-system, " font-size:14px;white-space:normal;background-color:#ffffff;"="">-</span>1</sup>) but significantly higher methane emissions compared to other treatments during rice cultivation. Water productivity index was also found higher in AWDI treated field plots compared to continuously irrigated field plot. At the reproductive stage of rice plant well-developed aerenchyma tissue was observed in root cortex under the continuous irrigated field plot, which indicates higher diffusion pathway of methane gas from root rhizosphere to the atmosphere compared to other treatments. Therefore, alternate wet and dry irrigation water management practice may be recommended at farmers’ level for sustainable rice production and reducing methane emission during dry winter Boro season which will reduce the cost of production by water saving as well as energy saving.
文摘The concentrations of twenty five heavy metals adsorbed to fine fraction of particulate matter, PM2.5 (d ≤ 2.5 μm) have been experimentally analysed at a sampling site located at the kerbside along a National Highway in Delhi city, India. The sampling has been carried out for 12-hour using Ecotech Intruments, APM550. The PM2.5 has been collected on PTFE filter papers for the winter season. Later, the filter papers have been analysed for various heavy metal concentrations using ED-XRF. It has been observed that the metals concentrations are in this trend: Si > K > S > Ca = Fe > Zn = Pb > Br. it is observed that Si has high co-relation with Ca, Fe and K, which may be due to crustal origin of all three elements;while S, Br and Pb may be from vehicular exhaust emissions and/or abrasions due to brake and tyre wear. The potential health risks associated with different carcinogenic heavy metals have also been calculated. One of the health risk indicators, the excess cancer risk (ECR), is found to be in the order as As > Cd > Pb > Cr > Ni.
文摘For submerged vegetated flow, the velocity profile has two distinctive distributions in the vegetation layer in the lower region and the surface layer in the upper non-vegetated region. Based on a mixing-layer analogy, different analytical models have been proposed for the velocity profile in the two layers. This paper evaluates the four analytical models of Klopstra et al., Defina & Bixio, Yang et al. and Nepf against a wide range of independent experimental data available in the literature. To test the applicability and robust of the models, the author used the 19 datasets with various relative depths of submergence, different vegetation densities and bed slopes (1.8 × 10?6 - 4.0 × 10?3). This study shows that none of the models can predict the velocity profiles well for all datasets. The three models except Yang’s model performed reasonably well in certain cases, but Yang’s model failed in most the cases studied. It was also found that the Defina model is almost the same as the Klopstra model, if the same mixing length scale of eddies (λ) is used. Finally, close examination of the mixing length scale of eddies (λ) in the Defina model showed that when λ/h = 1/40(H/h)1/2, this model can predict velocity profiles well for all the datasets used.
文摘Duckweed is a group of aquatic plants with the potential of wastewater remediation and fast accumulation of biomass. The accumulated biomass, rich in cellulose, starch and protein, can be used for biofuel, bio-fertilizer, animal feed and human food. Characterization of natural biodiversity of duckweed species is essential for the germplasm preservation and various practical applications. We have collected samples of duckweed in eastern China and characterized species biodiversity by genotyping, using chloroplast (atpF-atpH and psbK-psbI spacers). Spirodela polyrhiza was revealed as a clear dominant duckweed species in all locations of the area. Other duckweed species were identified as Landoltia punctata, Lemna aequinoctialis and Lemna turionifera. Selected isolates of these four species were used in the experiments to estimate their potential in removing nitrogen and phosphorus nutrients from municipal and industrial wastewater sampled at the local sewage plants. Duckweed was able to reduce the concentration of nitrogen up to 98% and phosphorus up to 96%. The presented data demonstrates high efficiency of the local duckweed isolates for bioremediation of different types of wastewater and the great potential of duckweed for wastewater treatment when incorporated into the purification chain.
文摘Qinhuangdao is a provincial municipality under the jurisdiction of Hebei Province and a coastal city in China. Beidaihe is a district under the jurisdiction of Qinhuangdao and is a famous seaside scenic area. Alliance Peak, located in Beidaihe seashore scenic West. Jinshan mouth is the peak of the Union Peak, located in the easternmost Beidaihe waterfront. In this paper, we use the observed data of air negative ions in the Beidaihe, Qinhuangdao, Jinshanzui and Lianfeng Mountains for seven years to study the distribution characteristics of negative air ions in different ecological environments through meteorological observation. Research shows that the annual mean of air anion concentration fluctuates less. The annual mean is 1730 ind·cm-3, and the difference between the highest and lowest concentrations is 535 ind·cm-3. The average air anion concentration was the highest in August at 7785 ind·cm-3 and the lowest in January at 365 ind·cm-3. Negative air ions have obvious spatial characteristics, and negative ion concentrations of the sea and forest air are significantly high. The average annual mean of the sea is 3902 ind·cm-3, and that of the forest is 5403 ind·cm-3. The concentration of air anion changes daily, and daytime concentration is significantly lower than nighttime concentration. The highest peak appears at night or in the morning, while the lowest value appears between noon and afternoon. Inter-annual features and concentration of negative air ions, as well as annual rain days, total rainfall, thunderstorm days, and average relative humidity, are negatively related to the annual average temperature and sunshine hours. However, in the average concentration of negative air ions, the average correlation test of meteorological elements was insignificant. The air anion concentration is negatively correlated with the PM2.5 concentration of fine particulate matter. The concentrations of nitrogen dioxide, sulfur dioxide, and carbon monoxide in the fine particulate matter are negatively correlated with the ozone concentration, which is positively correlated with ozone concentration and is tested by significance. Atmospheric discharge (thunderstorm) can produce a considerable amount of air anion. Air negative ions are an important indicator of air quality, which is of great significance to the living environment. The distribution of negative ions in the study space and its influencing factors in order to provide a basis for air quality assessment in the region and provide references for the long-term research on air anion in different urban areas.
文摘Taking a certain area in Sichuan Province as the object of this study, this paper adopts fuzzy mathematics method to make an evaluation on ecological risks of heavy metal in soil of this area. On calculation of factors’ weights, the traditional method of giving weight according to pollutants’ concentrations fails to consider the toxicity of heavy metals, and can’t reflect their actual ecological effect. With reference to the toxicity coefficient in potential ecological risk index evaluation, this article revises the traditional fuzzy mathematics evaluation model and puts forward a new method to calculate factors’ weight by incorporating toxicity levels in weight setting. The results of this study indicate: surface soil of this area was good in general, with 91.2% samples belonging to the first level, 7.77% samples belonging to the second level, and only 1.03% belonging to the third level. Compared with the results of the evaluation method of the reality content of soil, soil quality is better than the results of the quantitative evaluation, and is closer to the actual local conditions.
文摘Land surface displacement caused by landslides is among the most damaging phenomena in northern Morocco. In this paper, we measure ground deformation in the Chefchaouen area which is a zone characterized by geological formations and structurally complex losses that promote instability (landslide, mudflow, block falls, etc.) leading to slow to extremely slow deformation phenomena, which require an interferometric study, using the DinSAR (differential interferometric synthetic Aperture Radar) technique with sentinel 1 images in bance C, which is a powerful tool for the detection and analysis of interferences and monitoring of ground deformations. We worked on four areas of the study area. Its points are provided by the direction of the roads, which generates Interferograms and then deformation maps with precision in mm/year.
文摘The utility of a spatially-explicit, exposure-based model was examined for its suitability as a tool for rapidly assessing surface water vulnerability in watershed planning. This simple GIS-model uses three types of easily obtainable spatial information: (1) sources of land use-induced change;(2) intensity of watershed drainage;and (3) sensitivity of drainage basins to change. This model was applied to the Thomas Brook watershed in Nova Scotia, Canada, which has been the site of previous studies, conducted over multiple years, using detailed, effects-based, hydrologic models. Doing so allowed us the opportunity to compare the two approaches. Results showed a good concordance in the derived mapped outputs between the two models. Given the rapid ease and inexpensive cost of using the GIS, exposure-based model, we believe it to offer great promise in terms of prioritizing locations for further study or for intervention of best management practices, as well as for planning where to best direct future water-sensitive development through build-out analyses.
文摘Talcose rocks from Itagunmodi and Igun areas within the Ilesa Schist Belt, southwestern Nigeria, were studied to determine their compositional affinities and industrial properties. The talcose bodies occurred as lensoid enclaves closely associated with amphibolites and quartz-mica schist. Petrographic and X-ray diffraction-aided mineralogical studies reveal that the talcose rocks are of the talc-chlorite schist variety composed predominantly of talc (average 73.63%), subordinate chlorite (average 16.08%) and accessory lizardite (average 6.5%). Total whole rock characterization of the samples using Lithium Fusion digestion revealed high mean concentrations of SiO2 (57.53%), MgO (24.84%) and Fe2O3 (7.73%) with significant enrichment of Ni, Co and Cr;and low values of Ba, Rb, Sr, V, Cu and Pb. The talc-chlorite schists plotted in the peridotitic komatiite field of the Al2O3-(FeO + TiO2)-MgO diagram. Water Absorption Capacity ranges from 6.25% - 8.20%, Loss on Ignition is 4.8% - 6.1% while Linear Shrinkage is 1.25% - 1.70% and firing colour is brown to dark-brown. The overall compositional features of the talcose rocks of the area, which were hitherto uncharacterized, show their suitability as raw materials for paint, coloured pottery, ceramic insulation, textile, rubber and plastic manufacture with varying beneficiation requirements. Their high trace element content however, makes them unsuitable for use in pharmaceutical and cosmetic applications.
文摘Water quality monitoring has one of the highest priorities in surface water protection policy. Many variety approaches are being used to interpret and analyze the concealed variables that determine the variance of observed water quality of various source points. A considerable proportion of these approaches are mainly based on statistical methods, multivariate statistical techniques in particular. In the present study, the use of multivariate techniques is required to reduce the large variables number of Nile River water quality upstream Cairo Drinking Water Plants (CDWPs) and determination of relationships among them for easy and robust evaluation. By means of multivariate statistics of principal components analysis (PCA), Fuzzy C-Means (FCM) and K-means algorithm for clustering analysis, this study attempted to determine the major dominant factors responsible for the variations of Nile River water quality upstream Cairo Drinking Water Plants (CDWPs). Furthermore, cluster analysis classified 21 sampling stations into three clusters based on similarities of water quality features. The result of PCA shows that 6 principal components contain the key variables and account for 75.82% of total variance of the study area surface water quality and the dominant water quality parameters were: Conductivity, Iron, Biological Oxygen Demand (BOD), Total Coliform (TC), Ammonia (NH3), and pH. However, the results from both of FCM clustering and K-means algorithm, based on the dominant parameters concentrations, determined 3 cluster groups and produced cluster centers (prototypes). Based on clustering classification, a noted water quality deteriorating as the cluster number increased from 1 to 3. However the cluster grouping can be used to identify the physical, chemical and biological processes creating the variations in the water quality parameters. This study revealed that multivariate analysis techniques, as the extracted water quality dominant parameters and clustered information can be used in reducing the number of sampling parameters on the Nile River in a cost effective and efficient way instead of using a large set of parameters without missing much information. These techniques can be helpful for decision makers to obtain a global view on the water quality in any surface water or other water bodies when analyzing large data sets especially without a priori knowledge about relationships between them.
