This study examines the socio-economic profile of livestock farmers in coastal Côte d’Ivoire. A total of 43 people were interviewed using well-structured questionnaires. The collected data were analyzed using de...This study examines the socio-economic profile of livestock farmers in coastal Côte d’Ivoire. A total of 43 people were interviewed using well-structured questionnaires. The collected data were analyzed using descriptive methods. The results showed that local Lagoon breeders are divided into two zones: southwest and southeast. Breeders in the south-western region are generally located in two sub-prefectures of the Tabou Department (Grabo and Oulodio). Tabou’s department alone accounts for 42% of the Lagoon breed in Côte d’Ivoire. Agriculture in this area is traditionally sedentary, practiced for social reasons. On the other hand, the south-eastern zone, located in the departments of Aboisso, Adzopé, Agboville, Grand-Lahou, Jacqueville, Abidjan, Dabou and Sikensi, represents 58% of the Lagoon breeding area in Côte d’Ivoire. This second group is characterised by improved breeding. Most of the farmers interviewed in this zone breed for economic reasons. However, the risk of cross-breeding, which already affects the local Lagoon breed, could be increased by the presence of other species such as the Zebu and Ndamas, or even the Baoulé, in this south-eastern herd.展开更多
Selenium is a trace element that can have both beneficial and harmful effects on aquatic life. The Aby Lagoon is a coastal environment in Côte d’Ivoire that receives selenium inputs from various natural and anth...Selenium is a trace element that can have both beneficial and harmful effects on aquatic life. The Aby Lagoon is a coastal environment in Côte d’Ivoire that receives selenium inputs from various natural and anthropogenic sources. The aim of this study was to assess the levels of selenium in the sediments of the Aby Lagoon and its tributaries, the Tanoe River and the Tendo Lagoon, and to examine the spatial and seasonal variations of selenium concentrations. Sediment samples were collected from different sites and seasons, and selenium concentrations were measured by atomic fluorescence spectrometry. The results showed that the average concentration of selenium in the sediments of the Aby Lagoon was 0.82 mg/kg, indicating moderate contamination. The concentration of selenium varied between sites and seasons, with higher values in the channel of the Tendo Lagoon and during the dry season. The study highlighted the complexity of selenium dynamics in aquatic ecosystems, and the need to take into account seasonal and spatial variability as well as interactions between environmental factors. The study also suggested potential ecotoxicological risks for some sensitive organisms in certain areas of the lagoon. This study contributes to the knowledge of the dynamics of selenium in lagoon ecosystems and to the assessment of the environmental risks associated with its presence.展开更多
Lagoons are ecosystems for biodiversity and the livelihoods of coastal communities. The main objective of the study was to analyze the variability of arsenic concentrations in gastropods and bivalves in the Aby and Te...Lagoons are ecosystems for biodiversity and the livelihoods of coastal communities. The main objective of the study was to analyze the variability of arsenic concentrations in gastropods and bivalves in the Aby and Tendo lagoons, taking into account spatial, seasonal and hydrological variations. The study was carried out in four stages spread over two successive hydroclimatic cycles, including two seasons during the rainy season and two more during the dry season. The samples were taken in two areas of the Aby and Tendo lagoons. Arsenic levels were measured by ICP-MS. The results showed that mean arsenic concentrations in the muscles of organisms in Aby Lagoon ranged from 0.01 to 1.26 μg As/g, with a mean and median of 0.17 and 0.06 μg As/g, respectively. Fish had the highest levels of arsenic, followed by crustaceans, while molluscs and plants had lower and comparable concentrations of As. Arsenic concentrations in tilapia and jawbones varied significantly between sites and seasons, with higher concentrations at Tendo and during the rainy season. Arsenic concentrations in gastropods and bivalves were significantly higher than those of other species, with averages of 0.74 and 1.03 mg As/kg, respectively.展开更多
Oyster aquaculture in Oualidia Lagoon,Morocco,has suffered from poor water quality and water confinement in its upstream region.Tidal asymmetry(TA)has been suggested as a possible cause,and a sediment trap was dredged...Oyster aquaculture in Oualidia Lagoon,Morocco,has suffered from poor water quality and water confinement in its upstream region.Tidal asymmetry(TA)has been suggested as a possible cause,and a sediment trap was dredged in 2011 to mitigate this condition.This study addresses TA in the lagoon using field measurements and numerical modeling in the presence of the sediment trap.Results indicate that the lagoon is flood-dominated mostly in its upstream end,where frictional forces exceed inertia accelerations during the tidal cycle and fine sediments settle on the tidal flats and inside the sediment trap.However,this study shows that a large mass of suspended sediments is exported to the ocean,which is contrary to expectations in flood-dominated lagoons.Defining the sediment trap as the rehabilitation scenario S1,the impacts of three additional scenarios on TA are examined.These are scenario S2(dredging the upstream section of the main channel),scenario S3(dredging the channels surrounding the flood delta near the inlets),and scenario S4(raising the ocean level by 0.5 m following climate change predictions).Results show that none of these scenarios modify the tidal flood dominance in the lagoon,although scenarios S2 and S4 decrease its intensity in the upstream region.Nevertheless,all scenarios still contribute to a significant export of sediments to the ocean.This suggests that lagoon management activities should not rely on tidal asymmetry analyses that normally predict upstream sediment transport in flood-dominated lagoons.展开更多
Existing empirical methods for interpreting the consolidation yield stress and the overconsolidation ratio （OCR） in clays from piezocone tests are briefly reviewed. It can be seen that no universal correlation exist...Existing empirical methods for interpreting the consolidation yield stress and the overconsolidation ratio （OCR） in clays from piezocone tests are briefly reviewed. It can be seen that no universal correlation exists for all worldwide sites. However, for a given clay deposit, there does exist a most appropriate method to reflect the consolidation yield stress and the OCR based on piezocone test data. Three empirical methods are compared based on the piezocone test data collected on Lixia River lagoonal deposit soil sites in the north of Jiangsu province. The objective of this study is to evaluate the validity of the existing relationships linking the consolidation yield stress to piezocone test data and identify the appropriate method for Lixia River lagoonal deposit soil. It is shown that the correlation based on the net tip resistance has much higher accuracy for estimating the consolidation yield stress of lagoonal deposit soil than other methods.展开更多
The study of fish communities from coastal lagoons allows a better understanding of role of these organisms in these systems, and the effect of anthropogenic impact. The aim of the present study was to determine the c...The study of fish communities from coastal lagoons allows a better understanding of role of these organisms in these systems, and the effect of anthropogenic impact. The aim of the present study was to determine the community structure, in particular dominance of fish species associated to soft bottoms in the lagoon of La Paz. Six bimonthly samplings were carried out in seven localities from November 2016 to September 2017 and physicochemical parameters were recorded. Analysis of temperature showed differences between two marked seasons, warm and cold. Species richness showed differences between months and localities. Shannon-Weaver index and Pielou’s evenness showed significant differences only between months. Simpson’s index suggests a high diversity. According to the BVI, 15 species from the families Haemulidae, Sciaenidae and Gerreidae, were the most biologically important. Zoogeographic affinity analysis showed that 58% of the species prefer the Province of Cortez. Dominant species recorded in this study play a key role in soft-bottom systems like the lagoon of La Paz.展开更多
Groyne system modification is described related to restoration efforts to Koggaia lagoon, Sri Lanka.The large-scale unplanned sand removal at the lagoon mouth shifted the formation of sand bar towards the lagoon and m...Groyne system modification is described related to restoration efforts to Koggaia lagoon, Sri Lanka.The large-scale unplanned sand removal at the lagoon mouth shifted the formation of sand bar towards the lagoon and made adverse effects on its ecosystem. After the removal of the natural sand bar, groyne system was constructed to avoid sand deposition in the lagoon and to protect the highway bridge （across the lagoon outlet channel） from the wave attack. The existing groyne system resulted the lagoon mouth being permanently open to sea which in turn led to many environmental problems. Groyne system modification is proposed in this study to reduce the sea water intrusion.Water budget and two-dimensional depth averaged hydrodynamic model were developed for understanding the hydrologic and flow characteristics of the lagoon. Numerical experiments was performed at lagoon mouth area for two cases： （1） existing condition and （2） proposed rubble mound groyne system condition. Comparison of results was obtained for both cases to describe flow pattern at lagoon mouth. Results further showed, the width should be reduced to a maximum of 40 m. Proposed mouth width （40 m） pushed the salting factor towards 0.5 from 0.68. Salting factor reduction with the groyne modification may result a predominant influence of fresh water which may in turn lead lagoon to a fresh water ecosystem.展开更多
This study aims to apply a hydrogeological approaches and analysis of the 2021 flood event of Tasi-Tolu Lagoon to achieve four specific goals. Firstly, the study seeks to determine the natural characteristics of the l...This study aims to apply a hydrogeological approaches and analysis of the 2021 flood event of Tasi-Tolu Lagoon to achieve four specific goals. Firstly, the study seeks to determine the natural characteristics of the lagoon, which include factors such as size, depth, water quality, and ecosystem composition. Secondly, the influence of precipitation on the water volume in the lagoon will be examined. This analysis involves assessing historical rainfall patterns in the region, as well as the amount and frequency of precipitation during the 2021 flood event. Thirdly, the hydrogeologic and geologic conditions of the lagoon will be evaluated. This involves examining factors such as the type and structure of the soil and bedrock, the presence of aquifers or other underground water sources, and the movement of water through the surrounding landscape. Finally, the study seeks to assess the risk of future flooding in Tasi-Tolu Lagoon, based on the insights gained from the previous analyses. Overall, this study’s goal is to provide a comprehensive understanding of the hydrogeological factors that contribute to flooding in Tasi-Tolu Lagoon. This knowledge could be used to inform flood mitigation strategies or to improve our ability to predict and respond to future flooding events in the region.展开更多
The problems of flooding, bank erosion and even the breaching of the barrier beach by the Grand-Popo lagoon are a concern in the south-western Beninese river-lagoon complex. The present study aims to improve the knowl...The problems of flooding, bank erosion and even the breaching of the barrier beach by the Grand-Popo lagoon are a concern in the south-western Beninese river-lagoon complex. The present study aims to improve the knowledge of the factors controlling the hydro-sedimentary functioning of this lagoon of Grand-Popo. It was based on bathymetric and sedimentological studies and the analysis of physical-chemical parameters of the water and allowed to know the morphology of the lagoon bottom and the distribution of sedimentary facies according to the intensity of the water current. The salinity of the lagoon waters shows a west-east gradient passing thus from 0‰ to 0.78‰ in the main direction of flow. Over the whole lagoon system, the average liquid flows vary from <span style="color:#4F4F4F;font-family:-apple-system, "font-size:16px;white-space:normal;background-color:#FFFFFF;">-</span>38.499 to 159.13 m<sup>3</sup>/s. The bathymetry indicates depths varying from 0.4 to 6.5 m, revealing type V and type U lagoon bottoms which reflect acute bottom concavities marked by hollowing under the effect of strong currents or by sandy terraces resulting from the continuous input of sediments carried by the Mono River. These sediments are heterogeneously distributed in the lagoon bottom and vary from free sand to mud. Given the complexity of the factors that control the hydro-sedimentary functioning of the Grand-Popo lagoon, it is recommended that periodic hydrological and bathymetric monitoring be carried out to locate exceptional variations in water levels to prevent not only the risks of overflowing lagoon waters and the flooding that follows but also spectacular erosion of the lagoon banks.展开更多
To examine treatment and remediation of a wastewater lagoon with poor biodegradability, a typical wastewater lagoon in Tianjin, China, was treated and remedied using microelectrolysis and modified demand aeration tank...To examine treatment and remediation of a wastewater lagoon with poor biodegradability, a typical wastewater lagoon in Tianjin, China, was treated and remedied using microelectrolysis and modified demand aeration tank （DAT）/intermittent aeration tank （IAT） methods. After pretreatment by microelectrolysis, the removal efficiency of chemical oxygen demand （COD） was up to 64.6% and the ratio of BOC/COD in the effluent increased from 0.013 to 0.609. The removal rates of CODcr and NH4＋-N were affected by sludge backflow rate, mixed liquor suspended solids （MLSS）, and hydraulic retention time （HRT） in the modified DAT/IAT reactor. The highest removal rates of CODcr and NH4＋-N were up to 78.9% and 62.6%, respectively, when the sludge backflow rate was 38.0 mL/min, the total HRT was 8.0 hr and MLSS was 4088.0 mg/L. In this case, some protozoa and metazoa were observed in activated sludge and biofilm carriers. Most of chrominance was removed by microelectrolysis treatment, while the modified DAT/IAT methods were more effective for CODcr and NH4＋-N removal.展开更多
The Marano and Grado Lagoon is well known for being contaminated by mercury（Hg） from the Idrija mine（Slovenia） and the decommissioned chlor-alkali plant of Torviscosa（Italy）.Experimental activities were conducte...The Marano and Grado Lagoon is well known for being contaminated by mercury（Hg） from the Idrija mine（Slovenia） and the decommissioned chlor-alkali plant of Torviscosa（Italy）.Experimental activities were conducted in a local fish farm to understand Hg cycling at the sediment–water interface. Both diffusive and benthic fluxes were estimated in terms of chemical and physical features. Mercury concentration in sediments（up to 6.81 μg/g）showed a slight variability with depth, whereas the highest methylmercury（MeHg） values（up to 10 ng/g） were detected in the first centimetres. MeHg seems to be produced and stored in the 2–3 cm below the sediment–water interface, where sulphate reducing bacteria activity occurs and hypoxic–anoxic conditions become persistent for days. DMeHg in porewaters varied seasonally（from 0.1 and 17% of dissolved Hg（DHg）） with the highest concentrations in summer. DHg diffusive effluxes higher（up to 444 ng/m^2/day） than those reported in the open lagoon（~ 95 ng/m^2/day）, whereas DMeHg showed influxes in the fish farm（up to-156 ng/m^2/day）. The diurnal DHg and DMeHg benthic fluxes were found to be higher than the highest summer values previously reported for the natural lagoon environment. Bottom sediments, especially in anoxic conditions, seem to be a significant source of MeHg in the water column where it eventually accumulates. However, net fluxes considering the daily trend of DHg and DMeHg, indicated possible DMeHg degradation processes. Enhancing water dynamics in the fish farm could mitigate environmental conditions suitable for Hg methylation.展开更多
Year-round investigations were carried out to address the population dynamics of amphipod Ampithoe val- ida and its potential regulating factors in the Yundang Lagoon （a eutrophic subtropical coastal lagoon in Xiamen...Year-round investigations were carried out to address the population dynamics of amphipod Ampithoe val- ida and its potential regulating factors in the Yundang Lagoon （a eutrophic subtropical coastal lagoon in Xiamen City, China） from October 2007 to October 2008. The results show that A. valida population was largely composed of juveniles and reached a peak abundance （12.02× 10^3 ind./m2） in March, but sharply shrunk in July. The monthly variation pattern ofA. valida seemed to follow that of Ulva lactuca which is the main food resource for A. valida, indicating a strong influence of food availability on A. valida popu- lation dynamics. Life cycle studies in laboratory indicate that A. valida adopted an r-selected life strategy, e.g., rapid growth rate （0.216-0.302 mm/d）, consecutive breeding （4-10 times）, short reproductive rhythm （9-17 d） and huge fecundity （24-192 eggs or 6-94 juveniles per brood）, which contributed to the fast pop- ulation growth ofA. valida from January to March. Although temperature may also be a significant cause, A. valida could grow quickly and show normal reproductive traits （i.e., the timing of sexual differentiation or maturity, the reproductive rhythm, the number of broods all through its lifespan and offspring produc- tion） in temperature between 15-30~ C. Therefore, the temperature variation in the lagoon water should not account for the sharp variation of A. valida population by affecting the survival, growth and reproduction of the amphipod. However, negative correlation between water temperature and U. lactuca biomass in the lagoon suggested that temperature could have indirectly affected the population dynamics ofA. ualida by affecting its food availability. The authors conclude that, in the Yundang Lagoon, the population dynamics ofA. validawas mainly controlled by the food availability rather than water temperature.展开更多
The Venice Lagoon is exposed to atmospheric pollutants from industrial activities, thermoelectric power plants, petrochemical plants, incinerator, domestic heating, ship traffic, glass factories and vehicular emission...The Venice Lagoon is exposed to atmospheric pollutants from industrial activities, thermoelectric power plants, petrochemical plants, incinerator, domestic heating, ship traffic, glass factories and vehicular emissions on the mainland. In 2005, construction began on the mobile dams （MOSE）, one dam for each channel connecting the lagoon to the Adriatic Sea as a barrier against high tide. These construction works could represent an additional source of pollutants. PM10 samples were taken on random days between 2007 and 2010 at three different sites： Punta Sabbioni, Chioggia and Malamocco, located near the respective dam construction worksites. Chemical analyses of V, Cr, Fe, Co, Ni, Cu, Zn, As, Mo, Cd, Sb, T1 and Pb in PM10 samples were performed by Inductively coupled plasma- quadrupole mass spectrometry （ICP-QMS） and results were used to identify the main aerosol sources. The correlation of measured data with meteorology, and source apportionment, failed to highlight a contribution specifically associated to the emissions of the MOSE construction works. The comparison of the measurements at the three sites showed a substantial homogeneity of metal concentrations in the area. Source apportionment with principal component analysis （PCA） and positive matrix factorization （PMF） showed that a four principal factors model could describe the sources of metals in PM10. Three of them were assigned to specific sources in the area and one was characterised as a source of mixed origin （anthropogenic and crustal）. A specific anthropogenic source of PM10 rich in Ni and Cr, active at the Chioggia site, was also identified.展开更多
Rapid urbanization has resulted in pervasive occurrence of antibiotic resistance genes(ARGs)in urban aquatic ecosystems.However,limited information is available concerning the ARG profiles and the forces responsible f...Rapid urbanization has resulted in pervasive occurrence of antibiotic resistance genes(ARGs)in urban aquatic ecosystems.However,limited information is available concerning the ARG profiles and the forces responsible for their assembly in urban landscape lagoon systems.Here,we employed high-throughput quantitative PCR(HT-q PCR)to characterize the spatial variations of ARGs in surface and core sediments of Yundang Lagoon,China.The results indicated that the average richness and absolute abundance of ARGs were 11 and 53 times higher in the lagoon sediments as compared to pristine reference Tibetan lake sediments,highlighting the role of anthropogenic activities in ARG pollution.Co-occurrence network analysis indicated that various anaerobic prokaryotic genera belonging to Alpha-,Deltaproteobacteria,Bacteroidetes,Euryarchaeota,Firmicutes and Synergistetes were the potential hosts of ARGs.The partial least squares-path modeling(PLS-PM)analysis revealed positive and negative indirect effects of physicochemical factors and heavy metals on the lagoon ARG profiles,via biotic factors,respectively.The horizontal(mediated by mobile genetic elements)and vertical(mediated by prokaryotic communities)gene transfer may directly contribute the most to drive the abundance and composition of ARGs,respectively.Furthermore,the neutral community model demonstrated that the assembly of sediment ARG communities was jointly governed by deterministic and stochastic processes.Overall,this study provides novel insights into the diversity and distribution of ARGs in the benthic habitat of urban lagoon systems and underlying mechanisms for the spread and proliferation of ARGs.展开更多
The characteristics of grain-size,total organic carbon (TOC) and total nitrogen (TN) contents,TOC/TN ratios,stable carbon isotope (δ^(13)C) and ^(210)Pb dating were measured in six sediment cores from the Xiaohai Lag...The characteristics of grain-size,total organic carbon (TOC) and total nitrogen (TN) contents,TOC/TN ratios,stable carbon isotope (δ^(13)C) and ^(210)Pb dating were measured in six sediment cores from the Xiaohai Lagoon.The results show distinct spatial and temporal variations in sedimentation patterns.The sediments are dominated by clayey silt,sandy silt and by silty sand in the southern,middle lagoon and the northern lagoon,respectively.TOC and TN contents decline from south to north.Sedimentation rates,determined by ^(210)Pb dating,tend to decrease from south to middle.However,the determination of sedimentation rate in the north is difficult.These spatial variations are related to the variations in sediment sources and hydrodynamic conditions in the Xiaohai Lagoon.The variations of organic matter signatures can be divided into two stages in the cores from the southern and middle lagoon.Before 1988,the organic matter signatures are relatively stable.The contribution of terrestrial organic carbon sources varies between 60% and 85%.After 1988,the organic matter signatures demonstrate significant variations.TOC and TN contents increase rapidly,TOC/TN ratios decrease,δ^(13)C values shift to higher and the contribution of terrestrial organic carbon sources decreases to 40%-50%.The contributions of phytoplankton organic matter have increased in the sediment since 1988.Increasing aquaculture activities have had a significant impact on organic matter signatures since 1988.The sedimentation rates have increased rapidly in the southern and middle lagoon since 1988 due to the anthropogenic activities which include aquaculture,mining and deforestation.These activities have caused eutrophication and increased siltation in the southern and middle lagoon.展开更多
The Isonzo River has been demonstrated to be a continuing point source of mercury（Hg）in the Gulf of Trieste although the Idrija mine was last active in 1996. The present study aims to investigate the role of the sus...The Isonzo River has been demonstrated to be a continuing point source of mercury（Hg）in the Gulf of Trieste although the Idrija mine was last active in 1996. The present study aims to investigate the role of the suspended particulate matter（SPM） associated with tidal fluxes to disperse particulate Hg（PHg） into the Grado coastal lagoon system. PHg concentrations（avg. 3.11 ± 2.62 μg/g, d.w.）, notwithstanding the ebb or flood tides, were significantly higher than the local sediment background（0.13 μg/g）. The relative affinity of Hg for the particulate phase in surface waters was confirmed by higher average distribution coefficient（Kd） values（5.6–6.7）. PHg contents showed the highest values in ebb tide conditions, thus suggesting their origin from the erosion of tidal flats and saltmarshes of the lagoon. When compared to river discharge, high PHg surface concentrations in flood tide are related to rainfall events occurring within the river basin. Results can be used to make an indicative assessment of the amount of Hg bound to SPM which is transported in and out of the lagoon basin following the action of tidal fluxes. A simple estimation provides a negative budget for the Grado lagoon sub-basin which loses between 0.14 and 1.16 kg of PHg during a tidal semi-cycle. This conclusion is in agreement with the evidence of morphological deterioration which has emerged from recent studies on the lagoon environment, and which testifies to a current sedimentary loss from the lagoon into the northern Adriatic Sea.展开更多
An understanding of the sedimentary environment in relation to its controlling factors is of great importance in coastal geomorphology,ecology,tourism and aquaculture studies.We attempt to deal with this issue,using a...An understanding of the sedimentary environment in relation to its controlling factors is of great importance in coastal geomorphology,ecology,tourism and aquaculture studies.We attempt to deal with this issue,using a case study from the Xincun Lagoon,Hainan Island in southern China.For the study,surficial sediment samples were collected,together with hydrodynamic and bathymetric surveys,during August 2013.Numerical simulation was carried out to obtain high-spatial resolution tidal current data.The sediment samples were analyzed to derive mean grain size,sorting coefficient,skewness and kurtosis,together with the sand,silt and clay contents.The modern sedimentary environments were classified using system cluster and principal component analyses.Grain size analysis reveals that the sediments are characterized by extremely slightly sandy silty mud（ESSSM） and slightly silty sand（SSS）,which are distributed in the central lagoon and near-shore shallow water areas,respectively.Mean grain size varies from 0 to 8.0Ф,with an average of 4.6Ф.The silt content is the highest,i.e.,52% on average,with the average contents of sand and clay being 43% and 5%,respectively.There exists a significant correlation between mean size and water depth,suggesting that the surficial sediments become finer with increasing water depth.Cluster analyses reveals two groups of samples.The first group is characterized by mean grain size of more than 5.5Ф,whilst the second group has mean grain size of below 3.5Ф.Further,these groups also have different correlations between mean grain size and the other grain size parameters.In terms of the tidal current,the average values of the root mean square velocity（RMSV） are 7.5 cm/s and 6.9 cm/s on springs and neaps,respectively.For the RMSVs that are higher than 4 cm/s,a significant positive correlation is found between the content of the 63–125 μm fraction and the RMSV,suggesting that the RMSV determines the variability of the very fine sand fraction.Based on system cluster and principal component analyses（PCA）,the modern sedimentary environments are classified into three types according to the grain size parameters,RMSVs and water depth data.The results suggest the importance of grain size parameters and high-spatial resolution hydrodynamic data in differentiating the coastal sedimentary environments.展开更多
Coastal lagoons provide many important services to human society,but their year-round use for aquaculture introduces large amounts of sewage.The contamination of antibiotic resistance genes(ARGs)is therefore of great ...Coastal lagoons provide many important services to human society,but their year-round use for aquaculture introduces large amounts of sewage.The contamination of antibiotic resistance genes(ARGs)is therefore of great concern.In this study,50 ARGs subtypes,two integrase genes(intl1,intl2),and 16S rRNA genes were detected by high-throughput quantitative PCR,and standard curves of all target genes were prepared for quantification.The occurrence and distribution of ARGs in a typical coastal lagoon(XinCun lagoon,China)were comprehensively explored.We detected 44 and 38 subtypes of ARGs in the water and sediment,respectively,and discuss the various factors influencing the fate of ARGs in the coastal lagoon.Macrolides-lincosamides-streptogramins B was the primary ARG type,and macB was the predominant subtype.Antibiotic efflux and antibiotic inactivation were the main ARG resistance mechanisms.The XinCun lagoon was divided into eight functional zones.The ARGs showed a distinct spatial distribution owing to the influence of microbial biomass and anthropogenic activity in different functional zones.Fishing rafts,abandoned fish ponds,the town sewage zone,and mangrove wetlands provided a large quantity of ARGs to the XinCun lagoon.Nutrients and heavy metals also significantly correlated with the fate of the ARGs,especially NO_(2)^(−)-N and Cu,which cannot be ignored.It is noteworthy that lagoon-barrier systems coupled with persistent pollutant inputs result in coastal lagoons acting as a“buffer pool”for ARGs,which can then accumulate and threaten the offshore environment.展开更多
Stabilization lagoons are economic systems that are built for treatment of municipal, industrial and agricultural wastewater;these systems are used in rural communities. Objective of this article is to present the hyd...Stabilization lagoons are economic systems that are built for treatment of municipal, industrial and agricultural wastewater;these systems are used in rural communities. Objective of this article is to present the hydrodynamics flow in lagoon system considering 6 screens with 7 channels containing curved forms with slopes suitable to stabilize the flow along each channel, and approach a piston flow. Hydrodynamics of this system with IBER software was analyzed, where was considered the velocity and hydraulic gradient, using Froude number. Also transport of total suspended solids was modelled. Efficiency in the treatment with this design was evaluated, using parameters such as, pH, conductivity, alkalinity, hardness, total solids, dissolved oxygen, redox potential and Chemical Oxygen Demand (COD). Through the results, a homogeneous transport was observed, mainly dissolved oxygen which was concordant with redox potential and COD, also through the curves, short circuits were minimized, avoiding dead zones and making treatment more efficient, finally were possible to comply with regulations of Mexico NOM-001-SEMARNAT-1996 of discharges and the NOM-003-SEMARNAT-1997 for water of agricultural use.展开更多
The Caofeidian Reclamation Project has been the biggest reclamation project in China so far, in which 310 km^2 sea areas were reclaimed along the coast of Hebei Province, and it also bring about many problems and defe...The Caofeidian Reclamation Project has been the biggest reclamation project in China so far, in which 310 km^2 sea areas were reclaimed along the coast of Hebei Province, and it also bring about many problems and defects for large reclaiming area. The study focuses on the influences of the engineering exerted on evolution of the Laolonggou Lagoon with the methods of topographical measurement and surface sediment analysis. The results demonstrate that the topographical changes in the Laolonggou Lagoon had been controlled obviously by the engineering at three stages. Besides, blocking and reopening of the shoal tidal channel also affected the geological environment of the lagoon area. In the aspect of topographical change, the Laolonggou Inlet first experienced deposition after the shoal tidal channel was blocked, followed by short-time eroding for quarrying and cofferdam construction in the east, then depositing slowly after the reclaiming activity ceased, and finally eroding after the shoal tidal channel was reopened. The project, particularly cofferdam construction led to the movement of the Laolonggou Inlet axis from west to east for 50 – 100 m. In the aspect of sediment variation, the reclamation project and hydrodynamic change resulted in the variation in compositions and distribution pattern. The western lagoon area has become land mainly constituted by silt, while the sediments in the eastern area have turned finer in size. After the shoal tidal channel was reopened, the current velocity in the Laolonggou Inlet has been enhanced, making the sediments at the bottom become coarser. The sediments around the Caofeidian foreland went through a process of changing in grain size from fine to coarse and back to fine again, and the sediments are mainly constituted by silt at present.展开更多
文摘This study examines the socio-economic profile of livestock farmers in coastal Côte d’Ivoire. A total of 43 people were interviewed using well-structured questionnaires. The collected data were analyzed using descriptive methods. The results showed that local Lagoon breeders are divided into two zones: southwest and southeast. Breeders in the south-western region are generally located in two sub-prefectures of the Tabou Department (Grabo and Oulodio). Tabou’s department alone accounts for 42% of the Lagoon breed in Côte d’Ivoire. Agriculture in this area is traditionally sedentary, practiced for social reasons. On the other hand, the south-eastern zone, located in the departments of Aboisso, Adzopé, Agboville, Grand-Lahou, Jacqueville, Abidjan, Dabou and Sikensi, represents 58% of the Lagoon breeding area in Côte d’Ivoire. This second group is characterised by improved breeding. Most of the farmers interviewed in this zone breed for economic reasons. However, the risk of cross-breeding, which already affects the local Lagoon breed, could be increased by the presence of other species such as the Zebu and Ndamas, or even the Baoulé, in this south-eastern herd.
文摘Selenium is a trace element that can have both beneficial and harmful effects on aquatic life. The Aby Lagoon is a coastal environment in Côte d’Ivoire that receives selenium inputs from various natural and anthropogenic sources. The aim of this study was to assess the levels of selenium in the sediments of the Aby Lagoon and its tributaries, the Tanoe River and the Tendo Lagoon, and to examine the spatial and seasonal variations of selenium concentrations. Sediment samples were collected from different sites and seasons, and selenium concentrations were measured by atomic fluorescence spectrometry. The results showed that the average concentration of selenium in the sediments of the Aby Lagoon was 0.82 mg/kg, indicating moderate contamination. The concentration of selenium varied between sites and seasons, with higher values in the channel of the Tendo Lagoon and during the dry season. The study highlighted the complexity of selenium dynamics in aquatic ecosystems, and the need to take into account seasonal and spatial variability as well as interactions between environmental factors. The study also suggested potential ecotoxicological risks for some sensitive organisms in certain areas of the lagoon. This study contributes to the knowledge of the dynamics of selenium in lagoon ecosystems and to the assessment of the environmental risks associated with its presence.
文摘Lagoons are ecosystems for biodiversity and the livelihoods of coastal communities. The main objective of the study was to analyze the variability of arsenic concentrations in gastropods and bivalves in the Aby and Tendo lagoons, taking into account spatial, seasonal and hydrological variations. The study was carried out in four stages spread over two successive hydroclimatic cycles, including two seasons during the rainy season and two more during the dry season. The samples were taken in two areas of the Aby and Tendo lagoons. Arsenic levels were measured by ICP-MS. The results showed that mean arsenic concentrations in the muscles of organisms in Aby Lagoon ranged from 0.01 to 1.26 μg As/g, with a mean and median of 0.17 and 0.06 μg As/g, respectively. Fish had the highest levels of arsenic, followed by crustaceans, while molluscs and plants had lower and comparable concentrations of As. Arsenic concentrations in tilapia and jawbones varied significantly between sites and seasons, with higher concentrations at Tendo and during the rainy season. Arsenic concentrations in gastropods and bivalves were significantly higher than those of other species, with averages of 0.74 and 1.03 mg As/kg, respectively.
基金supported by the Funding from the Ministry of Equipment and Transport,Kingdom of Morocco.
文摘Oyster aquaculture in Oualidia Lagoon,Morocco,has suffered from poor water quality and water confinement in its upstream region.Tidal asymmetry(TA)has been suggested as a possible cause,and a sediment trap was dredged in 2011 to mitigate this condition.This study addresses TA in the lagoon using field measurements and numerical modeling in the presence of the sediment trap.Results indicate that the lagoon is flood-dominated mostly in its upstream end,where frictional forces exceed inertia accelerations during the tidal cycle and fine sediments settle on the tidal flats and inside the sediment trap.However,this study shows that a large mass of suspended sediments is exported to the ocean,which is contrary to expectations in flood-dominated lagoons.Defining the sediment trap as the rehabilitation scenario S1,the impacts of three additional scenarios on TA are examined.These are scenario S2(dredging the upstream section of the main channel),scenario S3(dredging the channels surrounding the flood delta near the inlets),and scenario S4(raising the ocean level by 0.5 m following climate change predictions).Results show that none of these scenarios modify the tidal flood dominance in the lagoon,although scenarios S2 and S4 decrease its intensity in the upstream region.Nevertheless,all scenarios still contribute to a significant export of sediments to the ocean.This suggests that lagoon management activities should not rely on tidal asymmetry analyses that normally predict upstream sediment transport in flood-dominated lagoons.
基金Jiangsu Transportation Research Program Fund (No03Y007)
文摘Existing empirical methods for interpreting the consolidation yield stress and the overconsolidation ratio （OCR） in clays from piezocone tests are briefly reviewed. It can be seen that no universal correlation exists for all worldwide sites. However, for a given clay deposit, there does exist a most appropriate method to reflect the consolidation yield stress and the OCR based on piezocone test data. Three empirical methods are compared based on the piezocone test data collected on Lixia River lagoonal deposit soil sites in the north of Jiangsu province. The objective of this study is to evaluate the validity of the existing relationships linking the consolidation yield stress to piezocone test data and identify the appropriate method for Lixia River lagoonal deposit soil. It is shown that the correlation based on the net tip resistance has much higher accuracy for estimating the consolidation yield stress of lagoonal deposit soil than other methods.
文摘The study of fish communities from coastal lagoons allows a better understanding of role of these organisms in these systems, and the effect of anthropogenic impact. The aim of the present study was to determine the community structure, in particular dominance of fish species associated to soft bottoms in the lagoon of La Paz. Six bimonthly samplings were carried out in seven localities from November 2016 to September 2017 and physicochemical parameters were recorded. Analysis of temperature showed differences between two marked seasons, warm and cold. Species richness showed differences between months and localities. Shannon-Weaver index and Pielou’s evenness showed significant differences only between months. Simpson’s index suggests a high diversity. According to the BVI, 15 species from the families Haemulidae, Sciaenidae and Gerreidae, were the most biologically important. Zoogeographic affinity analysis showed that 58% of the species prefer the Province of Cortez. Dominant species recorded in this study play a key role in soft-bottom systems like the lagoon of La Paz.
文摘Groyne system modification is described related to restoration efforts to Koggaia lagoon, Sri Lanka.The large-scale unplanned sand removal at the lagoon mouth shifted the formation of sand bar towards the lagoon and made adverse effects on its ecosystem. After the removal of the natural sand bar, groyne system was constructed to avoid sand deposition in the lagoon and to protect the highway bridge （across the lagoon outlet channel） from the wave attack. The existing groyne system resulted the lagoon mouth being permanently open to sea which in turn led to many environmental problems. Groyne system modification is proposed in this study to reduce the sea water intrusion.Water budget and two-dimensional depth averaged hydrodynamic model were developed for understanding the hydrologic and flow characteristics of the lagoon. Numerical experiments was performed at lagoon mouth area for two cases： （1） existing condition and （2） proposed rubble mound groyne system condition. Comparison of results was obtained for both cases to describe flow pattern at lagoon mouth. Results further showed, the width should be reduced to a maximum of 40 m. Proposed mouth width （40 m） pushed the salting factor towards 0.5 from 0.68. Salting factor reduction with the groyne modification may result a predominant influence of fresh water which may in turn lead lagoon to a fresh water ecosystem.
文摘This study aims to apply a hydrogeological approaches and analysis of the 2021 flood event of Tasi-Tolu Lagoon to achieve four specific goals. Firstly, the study seeks to determine the natural characteristics of the lagoon, which include factors such as size, depth, water quality, and ecosystem composition. Secondly, the influence of precipitation on the water volume in the lagoon will be examined. This analysis involves assessing historical rainfall patterns in the region, as well as the amount and frequency of precipitation during the 2021 flood event. Thirdly, the hydrogeologic and geologic conditions of the lagoon will be evaluated. This involves examining factors such as the type and structure of the soil and bedrock, the presence of aquifers or other underground water sources, and the movement of water through the surrounding landscape. Finally, the study seeks to assess the risk of future flooding in Tasi-Tolu Lagoon, based on the insights gained from the previous analyses. Overall, this study’s goal is to provide a comprehensive understanding of the hydrogeological factors that contribute to flooding in Tasi-Tolu Lagoon. This knowledge could be used to inform flood mitigation strategies or to improve our ability to predict and respond to future flooding events in the region.
文摘The problems of flooding, bank erosion and even the breaching of the barrier beach by the Grand-Popo lagoon are a concern in the south-western Beninese river-lagoon complex. The present study aims to improve the knowledge of the factors controlling the hydro-sedimentary functioning of this lagoon of Grand-Popo. It was based on bathymetric and sedimentological studies and the analysis of physical-chemical parameters of the water and allowed to know the morphology of the lagoon bottom and the distribution of sedimentary facies according to the intensity of the water current. The salinity of the lagoon waters shows a west-east gradient passing thus from 0‰ to 0.78‰ in the main direction of flow. Over the whole lagoon system, the average liquid flows vary from <span style="color:#4F4F4F;font-family:-apple-system, "font-size:16px;white-space:normal;background-color:#FFFFFF;">-</span>38.499 to 159.13 m<sup>3</sup>/s. The bathymetry indicates depths varying from 0.4 to 6.5 m, revealing type V and type U lagoon bottoms which reflect acute bottom concavities marked by hollowing under the effect of strong currents or by sandy terraces resulting from the continuous input of sediments carried by the Mono River. These sediments are heterogeneously distributed in the lagoon bottom and vary from free sand to mud. Given the complexity of the factors that control the hydro-sedimentary functioning of the Grand-Popo lagoon, it is recommended that periodic hydrological and bathymetric monitoring be carried out to locate exceptional variations in water levels to prevent not only the risks of overflowing lagoon waters and the flooding that follows but also spectacular erosion of the lagoon banks.
基金supported by the Tianjin Committee of Science and Technology as a Special Innovative Project (No. 08FDZDSF03402)the National Hi-Tech Research and Development Program (863) of China (No.2007AA061201)the Open Fund Project from the Key Laboratory of Pollution Process and Environmental Criteria (Ministry of Education),Nankai University,China
文摘To examine treatment and remediation of a wastewater lagoon with poor biodegradability, a typical wastewater lagoon in Tianjin, China, was treated and remedied using microelectrolysis and modified demand aeration tank （DAT）/intermittent aeration tank （IAT） methods. After pretreatment by microelectrolysis, the removal efficiency of chemical oxygen demand （COD） was up to 64.6% and the ratio of BOC/COD in the effluent increased from 0.013 to 0.609. The removal rates of CODcr and NH4＋-N were affected by sludge backflow rate, mixed liquor suspended solids （MLSS）, and hydraulic retention time （HRT） in the modified DAT/IAT reactor. The highest removal rates of CODcr and NH4＋-N were up to 78.9% and 62.6%, respectively, when the sludge backflow rate was 38.0 mL/min, the total HRT was 8.0 hr and MLSS was 4088.0 mg/L. In this case, some protozoa and metazoa were observed in activated sludge and biofilm carriers. Most of chrominance was removed by microelectrolysis treatment, while the modified DAT/IAT methods were more effective for CODcr and NH4＋-N removal.
基金supported by the University of Trieste (Finanziamento di Ateneo per progetti di ricerca scientifica-FRA 2014,ref.Stefano Covelli)
文摘The Marano and Grado Lagoon is well known for being contaminated by mercury（Hg） from the Idrija mine（Slovenia） and the decommissioned chlor-alkali plant of Torviscosa（Italy）.Experimental activities were conducted in a local fish farm to understand Hg cycling at the sediment–water interface. Both diffusive and benthic fluxes were estimated in terms of chemical and physical features. Mercury concentration in sediments（up to 6.81 μg/g）showed a slight variability with depth, whereas the highest methylmercury（MeHg） values（up to 10 ng/g） were detected in the first centimetres. MeHg seems to be produced and stored in the 2–3 cm below the sediment–water interface, where sulphate reducing bacteria activity occurs and hypoxic–anoxic conditions become persistent for days. DMeHg in porewaters varied seasonally（from 0.1 and 17% of dissolved Hg（DHg）） with the highest concentrations in summer. DHg diffusive effluxes higher（up to 444 ng/m^2/day） than those reported in the open lagoon（~ 95 ng/m^2/day）, whereas DMeHg showed influxes in the fish farm（up to-156 ng/m^2/day）. The diurnal DHg and DMeHg benthic fluxes were found to be higher than the highest summer values previously reported for the natural lagoon environment. Bottom sediments, especially in anoxic conditions, seem to be a significant source of MeHg in the water column where it eventually accumulates. However, net fluxes considering the daily trend of DHg and DMeHg, indicated possible DMeHg degradation processes. Enhancing water dynamics in the fish farm could mitigate environmental conditions suitable for Hg methylation.
基金Public Science and Technology Research Funds Projects of Ocean under contract No.201205009-3Key Sci-Tech Program of Xiamen City under contract No.3502Z20102004
文摘Year-round investigations were carried out to address the population dynamics of amphipod Ampithoe val- ida and its potential regulating factors in the Yundang Lagoon （a eutrophic subtropical coastal lagoon in Xiamen City, China） from October 2007 to October 2008. The results show that A. valida population was largely composed of juveniles and reached a peak abundance （12.02× 10^3 ind./m2） in March, but sharply shrunk in July. The monthly variation pattern ofA. valida seemed to follow that of Ulva lactuca which is the main food resource for A. valida, indicating a strong influence of food availability on A. valida popu- lation dynamics. Life cycle studies in laboratory indicate that A. valida adopted an r-selected life strategy, e.g., rapid growth rate （0.216-0.302 mm/d）, consecutive breeding （4-10 times）, short reproductive rhythm （9-17 d） and huge fecundity （24-192 eggs or 6-94 juveniles per brood）, which contributed to the fast pop- ulation growth ofA. valida from January to March. Although temperature may also be a significant cause, A. valida could grow quickly and show normal reproductive traits （i.e., the timing of sexual differentiation or maturity, the reproductive rhythm, the number of broods all through its lifespan and offspring produc- tion） in temperature between 15-30~ C. Therefore, the temperature variation in the lagoon water should not account for the sharp variation of A. valida population by affecting the survival, growth and reproduction of the amphipod. However, negative correlation between water temperature and U. lactuca biomass in the lagoon suggested that temperature could have indirectly affected the population dynamics ofA. ualida by affecting its food availability. The authors conclude that, in the Yundang Lagoon, the population dynamics ofA. validawas mainly controlled by the food availability rather than water temperature.
基金support of theItalian Ministry of Infrastructure and Transport-Venice Water Authority-through its dealer Consorzio Venezia Nuova
文摘The Venice Lagoon is exposed to atmospheric pollutants from industrial activities, thermoelectric power plants, petrochemical plants, incinerator, domestic heating, ship traffic, glass factories and vehicular emissions on the mainland. In 2005, construction began on the mobile dams （MOSE）, one dam for each channel connecting the lagoon to the Adriatic Sea as a barrier against high tide. These construction works could represent an additional source of pollutants. PM10 samples were taken on random days between 2007 and 2010 at three different sites： Punta Sabbioni, Chioggia and Malamocco, located near the respective dam construction worksites. Chemical analyses of V, Cr, Fe, Co, Ni, Cu, Zn, As, Mo, Cd, Sb, T1 and Pb in PM10 samples were performed by Inductively coupled plasma- quadrupole mass spectrometry （ICP-QMS） and results were used to identify the main aerosol sources. The correlation of measured data with meteorology, and source apportionment, failed to highlight a contribution specifically associated to the emissions of the MOSE construction works. The comparison of the measurements at the three sites showed a substantial homogeneity of metal concentrations in the area. Source apportionment with principal component analysis （PCA） and positive matrix factorization （PMF） showed that a four principal factors model could describe the sources of metals in PM10. Three of them were assigned to specific sources in the area and one was characterised as a source of mixed origin （anthropogenic and crustal）. A specific anthropogenic source of PM10 rich in Ni and Cr, active at the Chioggia site, was also identified.
基金supported by the National Natural Science Foundation of China(Nos.31470539 and U1805244)the Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(No.2019QZKK0503)+1 种基金the 9th China-Croatia Science and Technology cooperation committee program(No.9–21)supported by the China Scholarship Council(No.201804910668)。
文摘Rapid urbanization has resulted in pervasive occurrence of antibiotic resistance genes(ARGs)in urban aquatic ecosystems.However,limited information is available concerning the ARG profiles and the forces responsible for their assembly in urban landscape lagoon systems.Here,we employed high-throughput quantitative PCR(HT-q PCR)to characterize the spatial variations of ARGs in surface and core sediments of Yundang Lagoon,China.The results indicated that the average richness and absolute abundance of ARGs were 11 and 53 times higher in the lagoon sediments as compared to pristine reference Tibetan lake sediments,highlighting the role of anthropogenic activities in ARG pollution.Co-occurrence network analysis indicated that various anaerobic prokaryotic genera belonging to Alpha-,Deltaproteobacteria,Bacteroidetes,Euryarchaeota,Firmicutes and Synergistetes were the potential hosts of ARGs.The partial least squares-path modeling(PLS-PM)analysis revealed positive and negative indirect effects of physicochemical factors and heavy metals on the lagoon ARG profiles,via biotic factors,respectively.The horizontal(mediated by mobile genetic elements)and vertical(mediated by prokaryotic communities)gene transfer may directly contribute the most to drive the abundance and composition of ARGs,respectively.Furthermore,the neutral community model demonstrated that the assembly of sediment ARG communities was jointly governed by deterministic and stochastic processes.Overall,this study provides novel insights into the diversity and distribution of ARGs in the benthic habitat of urban lagoon systems and underlying mechanisms for the spread and proliferation of ARGs.
基金The National Natural Science Foundation of China (NSFC) under contract No. 40376014a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘The characteristics of grain-size,total organic carbon (TOC) and total nitrogen (TN) contents,TOC/TN ratios,stable carbon isotope (δ^(13)C) and ^(210)Pb dating were measured in six sediment cores from the Xiaohai Lagoon.The results show distinct spatial and temporal variations in sedimentation patterns.The sediments are dominated by clayey silt,sandy silt and by silty sand in the southern,middle lagoon and the northern lagoon,respectively.TOC and TN contents decline from south to north.Sedimentation rates,determined by ^(210)Pb dating,tend to decrease from south to middle.However,the determination of sedimentation rate in the north is difficult.These spatial variations are related to the variations in sediment sources and hydrodynamic conditions in the Xiaohai Lagoon.The variations of organic matter signatures can be divided into two stages in the cores from the southern and middle lagoon.Before 1988,the organic matter signatures are relatively stable.The contribution of terrestrial organic carbon sources varies between 60% and 85%.After 1988,the organic matter signatures demonstrate significant variations.TOC and TN contents increase rapidly,TOC/TN ratios decrease,δ^(13)C values shift to higher and the contribution of terrestrial organic carbon sources decreases to 40%-50%.The contributions of phytoplankton organic matter have increased in the sediment since 1988.Increasing aquaculture activities have had a significant impact on organic matter signatures since 1988.The sedimentation rates have increased rapidly in the southern and middle lagoon since 1988 due to the anthropogenic activities which include aquaculture,mining and deforestation.These activities have caused eutrophication and increased siltation in the southern and middle lagoon.
文摘The Isonzo River has been demonstrated to be a continuing point source of mercury（Hg）in the Gulf of Trieste although the Idrija mine was last active in 1996. The present study aims to investigate the role of the suspended particulate matter（SPM） associated with tidal fluxes to disperse particulate Hg（PHg） into the Grado coastal lagoon system. PHg concentrations（avg. 3.11 ± 2.62 μg/g, d.w.）, notwithstanding the ebb or flood tides, were significantly higher than the local sediment background（0.13 μg/g）. The relative affinity of Hg for the particulate phase in surface waters was confirmed by higher average distribution coefficient（Kd） values（5.6–6.7）. PHg contents showed the highest values in ebb tide conditions, thus suggesting their origin from the erosion of tidal flats and saltmarshes of the lagoon. When compared to river discharge, high PHg surface concentrations in flood tide are related to rainfall events occurring within the river basin. Results can be used to make an indicative assessment of the amount of Hg bound to SPM which is transported in and out of the lagoon basin following the action of tidal fluxes. A simple estimation provides a negative budget for the Grado lagoon sub-basin which loses between 0.14 and 1.16 kg of PHg during a tidal semi-cycle. This conclusion is in agreement with the evidence of morphological deterioration which has emerged from recent studies on the lagoon environment, and which testifies to a current sedimentary loss from the lagoon into the northern Adriatic Sea.
基金The National Natural Science Foundation of China under contract No.41530962
文摘An understanding of the sedimentary environment in relation to its controlling factors is of great importance in coastal geomorphology,ecology,tourism and aquaculture studies.We attempt to deal with this issue,using a case study from the Xincun Lagoon,Hainan Island in southern China.For the study,surficial sediment samples were collected,together with hydrodynamic and bathymetric surveys,during August 2013.Numerical simulation was carried out to obtain high-spatial resolution tidal current data.The sediment samples were analyzed to derive mean grain size,sorting coefficient,skewness and kurtosis,together with the sand,silt and clay contents.The modern sedimentary environments were classified using system cluster and principal component analyses.Grain size analysis reveals that the sediments are characterized by extremely slightly sandy silty mud（ESSSM） and slightly silty sand（SSS）,which are distributed in the central lagoon and near-shore shallow water areas,respectively.Mean grain size varies from 0 to 8.0Ф,with an average of 4.6Ф.The silt content is the highest,i.e.,52% on average,with the average contents of sand and clay being 43% and 5%,respectively.There exists a significant correlation between mean size and water depth,suggesting that the surficial sediments become finer with increasing water depth.Cluster analyses reveals two groups of samples.The first group is characterized by mean grain size of more than 5.5Ф,whilst the second group has mean grain size of below 3.5Ф.Further,these groups also have different correlations between mean grain size and the other grain size parameters.In terms of the tidal current,the average values of the root mean square velocity（RMSV） are 7.5 cm/s and 6.9 cm/s on springs and neaps,respectively.For the RMSVs that are higher than 4 cm/s,a significant positive correlation is found between the content of the 63–125 μm fraction and the RMSV,suggesting that the RMSV determines the variability of the very fine sand fraction.Based on system cluster and principal component analyses（PCA）,the modern sedimentary environments are classified into three types according to the grain size parameters,RMSVs and water depth data.The results suggest the importance of grain size parameters and high-spatial resolution hydrodynamic data in differentiating the coastal sedimentary environments.
基金The research was supported by the Hainan Provincial Joint Project of Sanya Yazhou Bay Science and Technology City(No.2021CXLH0009)the National Natural Science Foundation of China(Nos.41976222 and 42006195)+4 种基金the Scientific Research Foundation of Hainan Tropical Ocean University(No.RHDRC202201)the Science and Technology Project of Yazhou Bay Innovation Institute of Hainan Tropical Ocean University(No.2022CXYZD002)the National Key Research and Development Program of China(No.2019YFD0901104)the Open Fund for the Key Laboratory of Global Change and Marine-Atmospheric Chemistry(No.GCMAC 2010)the Open Fund of State Key Laboratory of Environmental Chemistry and Ecotoxicology(No.KF2018-05).
文摘Coastal lagoons provide many important services to human society,but their year-round use for aquaculture introduces large amounts of sewage.The contamination of antibiotic resistance genes(ARGs)is therefore of great concern.In this study,50 ARGs subtypes,two integrase genes(intl1,intl2),and 16S rRNA genes were detected by high-throughput quantitative PCR,and standard curves of all target genes were prepared for quantification.The occurrence and distribution of ARGs in a typical coastal lagoon(XinCun lagoon,China)were comprehensively explored.We detected 44 and 38 subtypes of ARGs in the water and sediment,respectively,and discuss the various factors influencing the fate of ARGs in the coastal lagoon.Macrolides-lincosamides-streptogramins B was the primary ARG type,and macB was the predominant subtype.Antibiotic efflux and antibiotic inactivation were the main ARG resistance mechanisms.The XinCun lagoon was divided into eight functional zones.The ARGs showed a distinct spatial distribution owing to the influence of microbial biomass and anthropogenic activity in different functional zones.Fishing rafts,abandoned fish ponds,the town sewage zone,and mangrove wetlands provided a large quantity of ARGs to the XinCun lagoon.Nutrients and heavy metals also significantly correlated with the fate of the ARGs,especially NO_(2)^(−)-N and Cu,which cannot be ignored.It is noteworthy that lagoon-barrier systems coupled with persistent pollutant inputs result in coastal lagoons acting as a“buffer pool”for ARGs,which can then accumulate and threaten the offshore environment.
文摘Stabilization lagoons are economic systems that are built for treatment of municipal, industrial and agricultural wastewater;these systems are used in rural communities. Objective of this article is to present the hydrodynamics flow in lagoon system considering 6 screens with 7 channels containing curved forms with slopes suitable to stabilize the flow along each channel, and approach a piston flow. Hydrodynamics of this system with IBER software was analyzed, where was considered the velocity and hydraulic gradient, using Froude number. Also transport of total suspended solids was modelled. Efficiency in the treatment with this design was evaluated, using parameters such as, pH, conductivity, alkalinity, hardness, total solids, dissolved oxygen, redox potential and Chemical Oxygen Demand (COD). Through the results, a homogeneous transport was observed, mainly dissolved oxygen which was concordant with redox potential and COD, also through the curves, short circuits were minimized, avoiding dead zones and making treatment more efficient, finally were possible to comply with regulations of Mexico NOM-001-SEMARNAT-1996 of discharges and the NOM-003-SEMARNAT-1997 for water of agricultural use.
基金supported by the National Natural Science Foundation of China (No. 40876033)the China Geological Survey Project (No. DD20160144)。
文摘The Caofeidian Reclamation Project has been the biggest reclamation project in China so far, in which 310 km^2 sea areas were reclaimed along the coast of Hebei Province, and it also bring about many problems and defects for large reclaiming area. The study focuses on the influences of the engineering exerted on evolution of the Laolonggou Lagoon with the methods of topographical measurement and surface sediment analysis. The results demonstrate that the topographical changes in the Laolonggou Lagoon had been controlled obviously by the engineering at three stages. Besides, blocking and reopening of the shoal tidal channel also affected the geological environment of the lagoon area. In the aspect of topographical change, the Laolonggou Inlet first experienced deposition after the shoal tidal channel was blocked, followed by short-time eroding for quarrying and cofferdam construction in the east, then depositing slowly after the reclaiming activity ceased, and finally eroding after the shoal tidal channel was reopened. The project, particularly cofferdam construction led to the movement of the Laolonggou Inlet axis from west to east for 50 – 100 m. In the aspect of sediment variation, the reclamation project and hydrodynamic change resulted in the variation in compositions and distribution pattern. The western lagoon area has become land mainly constituted by silt, while the sediments in the eastern area have turned finer in size. After the shoal tidal channel was reopened, the current velocity in the Laolonggou Inlet has been enhanced, making the sediments at the bottom become coarser. The sediments around the Caofeidian foreland went through a process of changing in grain size from fine to coarse and back to fine again, and the sediments are mainly constituted by silt at present.
