The chemical and isotopic characteristics of the water and suspended particulate materials（SPM） in the Yangtze River were investigated on the samples collected from 25 hydrological monitoring stations in the mainste...The chemical and isotopic characteristics of the water and suspended particulate materials（SPM） in the Yangtze River were investigated on the samples collected from 25 hydrological monitoring stations in the mainsteam and 13 hydrological monitoring stations in the major tributaries during 2003 to 2007. The water samples show a large variation in both δD（ 30‰ to 112‰） and δ18O（ 3.8‰ to 15.4‰） values. Both δD and δ18O values show a decrease from the river head to the Jinsha Jiang section and then increase downstream to the river mouth. It is found that the oxygen and hydrogen isotopic compositions of the Yangtze water are controlled by meteoric precipitation, evaporation, ice（and snow） melting and dam building. The Yangtze SPM concentrations show a large variation and are well corresponded to the spatial and temporal changes of flow speed, runoff and SPM supply, which are affected by the slope of the river bed, local precipitation rate, weathering intensity, erosion condition and anthropogenic activity. The Yangtze SPM consists of clay minerals, clastic silicate and carbonate minerals, heavy minerals, iron hydroxide and organic compounds. From the upper to lower reaches, the clay and clastic silicate components in SPM increase gradually, but the carbonate components decrease gradually, which may reflect changes of climate and weathering intensity in the drainage area. Compared to those of the upper crust rocks, the Yangtze SPM has lower contents of SiO2, CaO, K2 O and Na2 O and higher contents of TFe2 O3 and trace metals of Co, Ni, Cu, Zn, Pb and Cd. The ΣREE in the Yangtze SPM is also slightly higher than that of the upper crust. From the upper to lower reaches, the CaO and MgO contents in SPM decrease gradually, but the SiO2 content increases gradually, corresponding to the increase of clay minerals and decrease of the carbonates. The δ30SiSPM values（ 1.1‰ to 0.3‰） of the Yangtze SPM are similar to those of the average shale, but lower than those of the granite rocks（ 0.3‰ to 0.3‰）, reflecting the effect of silicon isotope fractionation in silicate weathering process. The δ30SiSPM values of the Yangtze SPM show a decreasing trend from the upper to the middle and lower reaches, responding to the variation of the clay content. The major anions of the river water are HCO 3, SO 4 2, Cl, NO 3, SiO 4 4 and F and the major cations include Ca2＋, Na＋, Mg2＋, K＋ and Sr2＋. The good correlation between HCO3-content and the content of Ca2＋may suggest that carbonate dissolution is the dominate contributor to the total dissolved solid（TDS） of the Yangtze River. Very good correlations are also found among contents of Cl, SO4 2, Na＋, Mg2＋, K＋and Sr2＋, indicating the important contribution of evaporite dissolution to the TDS of the Yangtze River. High TDS contents are generally found in the head water, reflecting a strong effect of evaporation in the Qinghai-Tibet Plateau. A small increase of the TDS is generally observed in the river mouth, indicating the influence of tidal intrusion. The F and NO3 contents show a clear increase trend from the upstream to downstream, reflecting the contribution of pesticides and fertilizers in the Chuan Jiang section and the middle and lower reaches. The DSi shows a decrease trend from the upstream to downstream, reflecting the effect of rice and grass growth along the Chuan Jiang section and the middle and lower reaches. The dissolved Cu, Zn and Cd in the Yangtze water are all higher than those in world large rivers, reflecting the effect of intensive mining activity along the Yangtze drainage area. The Yangtze water generally shows similar REE distribution pattern to the global shale. The δ30SiDiss values of the dissolved silicon vary from 0.5‰ to 3.7‰, which is the highest among those of the rivers studied. The δ30SiDiss values of the water in the Yangtze mainsteam show an increase trend from the upper stream to downstream. Its DSi and δ30SiDiss are influenced by multiple processes, such as weathering process, phytolith growth in plants, evaporation, phytolith dissolution, growth of fresh water diatom, adsorption and desorption of aqueous monosilicic acid on iron oxide, precipitation of silcretes and formation of clays coatings in aquifers, and human activity. The δ34SSO4 values of the Yangtze water range from 1.7‰ to 9.0‰. The SO4 in the Yangtze water are mainly from the SO4 in meteoric water, the dissolved sulfate from evaporite, and oxidation of sulfide in rocks, coal and ore deposits. The sulfate reduction and precipitation process can also affect the sulfur isotope composition of the Yangtze water. The87Sr/86Sr ratios of the Yangtze water range from 0.70823 to 0.71590, with an average value of 0.71084. The87Sr/86Sr ratio and Sr concentration are primary controlled by mixing of various sources with different87Sr/86Sr ratios and Sr contents, including the limestone, evaporite and the silicate rocks. The atmospheric precipitation and anthropogenic inputs can also contribute some Sr to the river. The δ11B values of the dissolved B in the Yangtze water range from 2.0‰ to 18.3‰, which is affected by multifactors, such as silicate weathering, carbonate weathering, evaporite dissolution, atmospheric deposition, and anthropogenic inputs.展开更多
The chemical and isotopic characteristics of the water and suspended particulate materials （SPM） in the Yellow River were investigated on the samples collected from 29 hydrological monitoring stations in the mainste...The chemical and isotopic characteristics of the water and suspended particulate materials （SPM） in the Yellow River were investigated on the samples collected from 29 hydrological monitoring stations in the mainstem and several major tributaries during 2004 to 2007. The JD and δ^18O values of the Yellow River water vary in large ranges from -32%0 to -91‰ and from -3.1‰ to -12.5‰, respectively. The characters of H and O isotope variations indicate that the major sources of the Yellow River water are meteoric water and snow melting water, and water cycle in the Yellow River basin is affected strongly by evaporation process and human activity. The average SPM content （9.635 g/L） of the Yellow River is the highest among the world large rivers. Compared with the Yangtze River, the Yellow River SPM has much lower clay content and significantly higher contents of clastic silicates and carbonates. In comparison to the upper crust rocks, the Yellow River SPM contains less SiO2, CaO, K2O and Na2O, but more TFe203, Co, Ni, Cu, Zn, Pb and Cd. The abnormal high Cd contents found in some sample may be related to local industrial activity. The REE contents and distribution pattern of the Yellow River SPM are very close to the average value of the global shale. The average δ^30Sisp in the Yellow River （-0.11‰） is slightly higher than the average value （-0.22‰） of the Yangtze River SPM. The major factors controlling the δ^30Si SPM of the Yellow River are the soil supply, the isotopic composition of the soil and the climate conditions. The TDS in the Yellow River are the highest among those of world large rivers. Fair correlations are observed among Cl, Na^＋, K^＋, and Mg^2＋ contents of the Yellow River water, indicating the effect of evaporation. The Ca^2＋ and Sr^2＋ concentrations show good correlation to the SO42 concentration rather than HCO3-concentration, reflecting its origin from evaporates. The NO3-contents are affected by farmland fertilization. The Cu, Zn and Cd contents in dissolved load of the Yellow River water are all higher than those of average world large rivers, reflecting the effect of human activity. The dissolved load in the Yellow River water generally shows a REE distribution pattern parallel to those for the Yangtze River and the Xijiang River. The δ^30Si values of the dissolved silicon vary in a range from 0.4%0 to 2.9%0, averaging 1.34%o. The major processes controlling the Dsi weathering process of silicate rocks, growth of and δ^30SiDiss of the Yellow River water are the phytolith in plants, evaporation, dissolution of phytolith in soil, growth of fresh water diatom, adsorption and desorption of aqueous monosilicic acid on iron oxide and human activities. The average δ^30^SiDiss value of the Yellow River is significantly lower than that of the Nile River, Yangtze River and Siberia rivers, but higher than those of other rivers, reflecting their differences in chemical weathering and biological activity. The δ^34SSO4 values of the Yellow River water range from -3.8%0 to 14.1%o, averaging 7.97%0. There is some correlation between SO4^2- content and δ^34SSO4. The factors controlling the δ^34SSO4 of the Yellow River water are the SO4 in the meteoric water, the SO4 from gypsum or anhydrite in evaporite rocks, oxidation and dissolution of sulfides in the mineral deposits, magmatic rocks and sedimentary rocks, the sulfate reduction and precipitation process and the sulfate from fertilizer. The ^87Sr/^86Sr ratios of all samples range from 0.71041 to 0.71237, averaging 0.71128. The variations in the ^87Sr/^86Sr ratio and Sr concentration of river water are primarily caused by mixing of waters of various origins with different 87Sr/S6Sr ratios and Sr contents resulting from water-rock interaction with different rock types.展开更多
Fine particles in seawater commonly form large porous aggregates. Aggregate density and settling velocity determine the behavior of this suspended particulate matter(SPM) within the water column.However, few studies o...Fine particles in seawater commonly form large porous aggregates. Aggregate density and settling velocity determine the behavior of this suspended particulate matter(SPM) within the water column.However, few studies of aggregate particles over a continental shelf have been undertaken. In our case study, properties of aggregate particles, including size and composition, over the continental shelf of the North Yellow Sea were investigated. During a scienti?c cruise in July 2016, in situ ef fective particle size distributions of SPM at 10 stations were measured, while temperature and turbidity measurements and samples of water were obtained from surface, middle, and bottom layers. Dispersed and inorganic particle size distributions were determined in the laboratory. The in situ SPM was divided into(1) small particles(<32 μm),(2) medium particles(32–256 μm) and(3) large particles(>256 μm). Large particles and medium particles dominated the total volume concentrations(VCs) of in situ SPM. After dispersion, the VCs of medium particles decreased to low values(<0.1 μL/L). The VCs of large particles in the surface and middle layers also decreased markedly, although they had higher peak values(0.1–1 μL/L). This suggests that almost all in situ medium particles and some large particles were aggregated, while other large particles were single particles. Correlation analysis showed that primary particles <32 μm in?uenced the formation of these aggregates. Microscopic examination revealed that these aggregates consisted of both organic and inorganic ?ne particles, while large particles were mucus-bound organic aggregates or individual plankton.The vertical distribution of coarser particles was clearly related to water strati?cation. Generally, medium aggregate particles were dominant in SPM of the bottom layer. A thermocline blocked resuspension of?ne material into upper layers, yielding low VCs of medium-sized aggregate particles in the surface layer.Abundant large biogenic particles were present in both surface and middle layers.展开更多
The present study aimed to evaluate multi-element concentrations(Al,As,Ca,Cd,Co,Cr,Cu,Fe,Mg,Mn,Mo,Ni,Pb,Sr)in suspended particulate material(SPM)collected from Ensenada de La Paz(ELP)lagoon,Baja California Sur,Mexico ...The present study aimed to evaluate multi-element concentrations(Al,As,Ca,Cd,Co,Cr,Cu,Fe,Mg,Mn,Mo,Ni,Pb,Sr)in suspended particulate material(SPM)collected from Ensenada de La Paz(ELP)lagoon,Baja California Sur,Mexico in two different periods(September and May)to comprehend their origin,geochemical behavior,mass transfer and associated ecotoxicological risks.The 24 hr variation coefficient of volumetric SPM levels were found to be 51.7%in September and 40.5%in May,signifying the effects of oceanic waters.The calculated enrichment factor(EF)values for all the studied elements were of higher magnitude because of the high surface area and oxide nature of SPM,and in this study,Mo had the highest EF of 46.77 probably due to its origin from continental weathering.From the ecotoxicological perspective,the integrated toxic risk index revealed low toxic risk to the benthic community.However,the mean-ERM-Quotient calculated using the particulate concentrations of As,Cd,Cr,Cu,Ni,Pb indicated 9%probability of toxicity to biota.The comprehensive geochemical and ecotoxicological assessment of particulate metal concentrations in the ELP lagoon signify low to moderate contamination.展开更多
Transitional ecosystems,estuaries and the coastal seas,are distinctively affected by natural and anthropogenic factors.Organic matter(OM)originating from terrestrial sources is exported by rivers and forms a key compo...Transitional ecosystems,estuaries and the coastal seas,are distinctively affected by natural and anthropogenic factors.Organic matter(OM)originating from terrestrial sources is exported by rivers and forms a key component of the global biogeochemical cycles.Most previous studies focused on the bulk biochemical and anthropogenic aspects affecting these ecosystems.In the present study,we examined the sources and fate of OM entrained within suspended particulate matter(SPM)of the Zuari River and its estuary,west coast of India.Besides using amino acid(AA)enantiomers(L-and D-forms)as biomarkers,other bulk biochemical parameters viz.particulate organic carbon(POC),δ13C,particulate nitrogen(PN),δ15N and chlorophyll a were analyzed.Surprisingly no significant temporal variations were observed in the parameters analyzed;nonetheless,salinity,POC,δ13C,PN,δ15N,glutamic acid,serine,alanine,tyrosine,leucine and D-aspartic acid exhibited significant spatial variability suggesting source differentiation.The POC content displayed weak temporal variability with low values observed during the post-monsoon season attributed to inputs from mixed sources.Estuarine samples were less depleted than the riverine samples suggesting contributions from marine plankton in addition to contributions from river plankton and terrestrial C3 plants detritus.Labile OM was observed during the monsoon and post-monsoon seasons in the estuarine region.More degraded OM was noticed during the pre-monsoon season.Principal component analysis was used to ascertain the sources and factors influencing OM.Principally five factors were extracted explaining 84.52%of the total variance.The first component accounted for 27.10%of the variance suggesting the dominance of tidal influence whereas,the second component accounted for heterotrophic bacteria and their remnants associated with the particulate matter,contributing primarily to the AA pool.Based on this study we ascertained the role of the estuarine turbidity maximum(ETM)controlling the sources of POM and its implications to small tropical rivers.Thus,changes in temporal and regional settings are more likely to affect the natural biogeochemical cycles of small tropical rivers.展开更多
Content and distribution patterns of rare earth dements （REEs） in the suspended particulate material （SPM） of Daliao River system were investigated and compared with those in the fiver and sea sediments, loess, an...Content and distribution patterns of rare earth dements （REEs） in the suspended particulate material （SPM） of Daliao River system were investigated and compared with those in the fiver and sea sediments, loess, and soils of China. Twenty-seven samples of SPM were taken in Daliao River system and digested with various acids followed by ICP-MS analysis for REEs and ICP-OES analysis for Al, Fe, Mn, Ti, Mg, Ca, Na, and K, to measure the total concentrations of these elements. Results indicated that the spatial change in the content of REEs was great, with the coefficient of variance （CV） from 84% to 105%, while the contents of REEs were significantly correlated with each other. Chondrite-normalized patterns of REEs were characterized by higher enrichment of light REEs than heavy REEs, and a depletion of Eu in the SPM was generally found. The positive anomaly of Eu in the SPM of Xi River was due to anthropogenic source in Shenyang City. Furthermore, chondfite- and upper continent crust-normalized patterns of REEs in the SPM of Daliao River system, sediments of Yangtze River and Yellow River, sediments of Yellow Sea, East Sea, South Sea of China, and loess and soil of China, were very similar to one another. These demonstrated that the weathering and sedimentary processes resulted in constant REE distribution not only in the typical sedimentary rocks, but also in the modem riverine particle, sea sediments, loess, and soils.展开更多
基金supported by the National Natural Science Foundation of China (Item No. 40673005)the Ministry of Science and Technology (2004DIB3J081)the Geological Survey of China (200320130-006)
文摘The chemical and isotopic characteristics of the water and suspended particulate materials（SPM） in the Yangtze River were investigated on the samples collected from 25 hydrological monitoring stations in the mainsteam and 13 hydrological monitoring stations in the major tributaries during 2003 to 2007. The water samples show a large variation in both δD（ 30‰ to 112‰） and δ18O（ 3.8‰ to 15.4‰） values. Both δD and δ18O values show a decrease from the river head to the Jinsha Jiang section and then increase downstream to the river mouth. It is found that the oxygen and hydrogen isotopic compositions of the Yangtze water are controlled by meteoric precipitation, evaporation, ice（and snow） melting and dam building. The Yangtze SPM concentrations show a large variation and are well corresponded to the spatial and temporal changes of flow speed, runoff and SPM supply, which are affected by the slope of the river bed, local precipitation rate, weathering intensity, erosion condition and anthropogenic activity. The Yangtze SPM consists of clay minerals, clastic silicate and carbonate minerals, heavy minerals, iron hydroxide and organic compounds. From the upper to lower reaches, the clay and clastic silicate components in SPM increase gradually, but the carbonate components decrease gradually, which may reflect changes of climate and weathering intensity in the drainage area. Compared to those of the upper crust rocks, the Yangtze SPM has lower contents of SiO2, CaO, K2 O and Na2 O and higher contents of TFe2 O3 and trace metals of Co, Ni, Cu, Zn, Pb and Cd. The ΣREE in the Yangtze SPM is also slightly higher than that of the upper crust. From the upper to lower reaches, the CaO and MgO contents in SPM decrease gradually, but the SiO2 content increases gradually, corresponding to the increase of clay minerals and decrease of the carbonates. The δ30SiSPM values（ 1.1‰ to 0.3‰） of the Yangtze SPM are similar to those of the average shale, but lower than those of the granite rocks（ 0.3‰ to 0.3‰）, reflecting the effect of silicon isotope fractionation in silicate weathering process. The δ30SiSPM values of the Yangtze SPM show a decreasing trend from the upper to the middle and lower reaches, responding to the variation of the clay content. The major anions of the river water are HCO 3, SO 4 2, Cl, NO 3, SiO 4 4 and F and the major cations include Ca2＋, Na＋, Mg2＋, K＋ and Sr2＋. The good correlation between HCO3-content and the content of Ca2＋may suggest that carbonate dissolution is the dominate contributor to the total dissolved solid（TDS） of the Yangtze River. Very good correlations are also found among contents of Cl, SO4 2, Na＋, Mg2＋, K＋and Sr2＋, indicating the important contribution of evaporite dissolution to the TDS of the Yangtze River. High TDS contents are generally found in the head water, reflecting a strong effect of evaporation in the Qinghai-Tibet Plateau. A small increase of the TDS is generally observed in the river mouth, indicating the influence of tidal intrusion. The F and NO3 contents show a clear increase trend from the upstream to downstream, reflecting the contribution of pesticides and fertilizers in the Chuan Jiang section and the middle and lower reaches. The DSi shows a decrease trend from the upstream to downstream, reflecting the effect of rice and grass growth along the Chuan Jiang section and the middle and lower reaches. The dissolved Cu, Zn and Cd in the Yangtze water are all higher than those in world large rivers, reflecting the effect of intensive mining activity along the Yangtze drainage area. The Yangtze water generally shows similar REE distribution pattern to the global shale. The δ30SiDiss values of the dissolved silicon vary from 0.5‰ to 3.7‰, which is the highest among those of the rivers studied. The δ30SiDiss values of the water in the Yangtze mainsteam show an increase trend from the upper stream to downstream. Its DSi and δ30SiDiss are influenced by multiple processes, such as weathering process, phytolith growth in plants, evaporation, phytolith dissolution, growth of fresh water diatom, adsorption and desorption of aqueous monosilicic acid on iron oxide, precipitation of silcretes and formation of clays coatings in aquifers, and human activity. The δ34SSO4 values of the Yangtze water range from 1.7‰ to 9.0‰. The SO4 in the Yangtze water are mainly from the SO4 in meteoric water, the dissolved sulfate from evaporite, and oxidation of sulfide in rocks, coal and ore deposits. The sulfate reduction and precipitation process can also affect the sulfur isotope composition of the Yangtze water. The87Sr/86Sr ratios of the Yangtze water range from 0.70823 to 0.71590, with an average value of 0.71084. The87Sr/86Sr ratio and Sr concentration are primary controlled by mixing of various sources with different87Sr/86Sr ratios and Sr contents, including the limestone, evaporite and the silicate rocks. The atmospheric precipitation and anthropogenic inputs can also contribute some Sr to the river. The δ11B values of the dissolved B in the Yangtze water range from 2.0‰ to 18.3‰, which is affected by multifactors, such as silicate weathering, carbonate weathering, evaporite dissolution, atmospheric deposition, and anthropogenic inputs.
基金supported by the National Natural Science Foundation of China(Item No.40673005)the Ministry of Science and Technology(Item No. 2004DIB3J081)the Geological Survey of China(Item No.200320130-006)
文摘The chemical and isotopic characteristics of the water and suspended particulate materials （SPM） in the Yellow River were investigated on the samples collected from 29 hydrological monitoring stations in the mainstem and several major tributaries during 2004 to 2007. The JD and δ^18O values of the Yellow River water vary in large ranges from -32%0 to -91‰ and from -3.1‰ to -12.5‰, respectively. The characters of H and O isotope variations indicate that the major sources of the Yellow River water are meteoric water and snow melting water, and water cycle in the Yellow River basin is affected strongly by evaporation process and human activity. The average SPM content （9.635 g/L） of the Yellow River is the highest among the world large rivers. Compared with the Yangtze River, the Yellow River SPM has much lower clay content and significantly higher contents of clastic silicates and carbonates. In comparison to the upper crust rocks, the Yellow River SPM contains less SiO2, CaO, K2O and Na2O, but more TFe203, Co, Ni, Cu, Zn, Pb and Cd. The abnormal high Cd contents found in some sample may be related to local industrial activity. The REE contents and distribution pattern of the Yellow River SPM are very close to the average value of the global shale. The average δ^30Sisp in the Yellow River （-0.11‰） is slightly higher than the average value （-0.22‰） of the Yangtze River SPM. The major factors controlling the δ^30Si SPM of the Yellow River are the soil supply, the isotopic composition of the soil and the climate conditions. The TDS in the Yellow River are the highest among those of world large rivers. Fair correlations are observed among Cl, Na^＋, K^＋, and Mg^2＋ contents of the Yellow River water, indicating the effect of evaporation. The Ca^2＋ and Sr^2＋ concentrations show good correlation to the SO42 concentration rather than HCO3-concentration, reflecting its origin from evaporates. The NO3-contents are affected by farmland fertilization. The Cu, Zn and Cd contents in dissolved load of the Yellow River water are all higher than those of average world large rivers, reflecting the effect of human activity. The dissolved load in the Yellow River water generally shows a REE distribution pattern parallel to those for the Yangtze River and the Xijiang River. The δ^30Si values of the dissolved silicon vary in a range from 0.4%0 to 2.9%0, averaging 1.34%o. The major processes controlling the Dsi weathering process of silicate rocks, growth of and δ^30SiDiss of the Yellow River water are the phytolith in plants, evaporation, dissolution of phytolith in soil, growth of fresh water diatom, adsorption and desorption of aqueous monosilicic acid on iron oxide and human activities. The average δ^30^SiDiss value of the Yellow River is significantly lower than that of the Nile River, Yangtze River and Siberia rivers, but higher than those of other rivers, reflecting their differences in chemical weathering and biological activity. The δ^34SSO4 values of the Yellow River water range from -3.8%0 to 14.1%o, averaging 7.97%0. There is some correlation between SO4^2- content and δ^34SSO4. The factors controlling the δ^34SSO4 of the Yellow River water are the SO4 in the meteoric water, the SO4 from gypsum or anhydrite in evaporite rocks, oxidation and dissolution of sulfides in the mineral deposits, magmatic rocks and sedimentary rocks, the sulfate reduction and precipitation process and the sulfate from fertilizer. The ^87Sr/^86Sr ratios of all samples range from 0.71041 to 0.71237, averaging 0.71128. The variations in the ^87Sr/^86Sr ratio and Sr concentration of river water are primarily caused by mixing of waters of various origins with different 87Sr/S6Sr ratios and Sr contents resulting from water-rock interaction with different rock types.
基金Supported by the National Natural Science Foundation of China(No.41476045)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA11030103)
文摘Fine particles in seawater commonly form large porous aggregates. Aggregate density and settling velocity determine the behavior of this suspended particulate matter(SPM) within the water column.However, few studies of aggregate particles over a continental shelf have been undertaken. In our case study, properties of aggregate particles, including size and composition, over the continental shelf of the North Yellow Sea were investigated. During a scienti?c cruise in July 2016, in situ ef fective particle size distributions of SPM at 10 stations were measured, while temperature and turbidity measurements and samples of water were obtained from surface, middle, and bottom layers. Dispersed and inorganic particle size distributions were determined in the laboratory. The in situ SPM was divided into(1) small particles(<32 μm),(2) medium particles(32–256 μm) and(3) large particles(>256 μm). Large particles and medium particles dominated the total volume concentrations(VCs) of in situ SPM. After dispersion, the VCs of medium particles decreased to low values(<0.1 μL/L). The VCs of large particles in the surface and middle layers also decreased markedly, although they had higher peak values(0.1–1 μL/L). This suggests that almost all in situ medium particles and some large particles were aggregated, while other large particles were single particles. Correlation analysis showed that primary particles <32 μm in?uenced the formation of these aggregates. Microscopic examination revealed that these aggregates consisted of both organic and inorganic ?ne particles, while large particles were mucus-bound organic aggregates or individual plankton.The vertical distribution of coarser particles was clearly related to water strati?cation. Generally, medium aggregate particles were dominant in SPM of the bottom layer. A thermocline blocked resuspension of?ne material into upper layers, yielding low VCs of medium-sized aggregate particles in the surface layer.Abundant large biogenic particles were present in both surface and middle layers.
基金support of the CONACYTFORDECYT-PRONACES/6364/2020 projectthe funding granted by SIP projects 20181094 and 20196679。
文摘The present study aimed to evaluate multi-element concentrations(Al,As,Ca,Cd,Co,Cr,Cu,Fe,Mg,Mn,Mo,Ni,Pb,Sr)in suspended particulate material(SPM)collected from Ensenada de La Paz(ELP)lagoon,Baja California Sur,Mexico in two different periods(September and May)to comprehend their origin,geochemical behavior,mass transfer and associated ecotoxicological risks.The 24 hr variation coefficient of volumetric SPM levels were found to be 51.7%in September and 40.5%in May,signifying the effects of oceanic waters.The calculated enrichment factor(EF)values for all the studied elements were of higher magnitude because of the high surface area and oxide nature of SPM,and in this study,Mo had the highest EF of 46.77 probably due to its origin from continental weathering.From the ecotoxicological perspective,the integrated toxic risk index revealed low toxic risk to the benthic community.However,the mean-ERM-Quotient calculated using the particulate concentrations of As,Cd,Cr,Cu,Ni,Pb indicated 9%probability of toxicity to biota.The comprehensive geochemical and ecotoxicological assessment of particulate metal concentrations in the ELP lagoon signify low to moderate contamination.
基金The National Natural Science Foundation of China under contract No.41530960
文摘Transitional ecosystems,estuaries and the coastal seas,are distinctively affected by natural and anthropogenic factors.Organic matter(OM)originating from terrestrial sources is exported by rivers and forms a key component of the global biogeochemical cycles.Most previous studies focused on the bulk biochemical and anthropogenic aspects affecting these ecosystems.In the present study,we examined the sources and fate of OM entrained within suspended particulate matter(SPM)of the Zuari River and its estuary,west coast of India.Besides using amino acid(AA)enantiomers(L-and D-forms)as biomarkers,other bulk biochemical parameters viz.particulate organic carbon(POC),δ13C,particulate nitrogen(PN),δ15N and chlorophyll a were analyzed.Surprisingly no significant temporal variations were observed in the parameters analyzed;nonetheless,salinity,POC,δ13C,PN,δ15N,glutamic acid,serine,alanine,tyrosine,leucine and D-aspartic acid exhibited significant spatial variability suggesting source differentiation.The POC content displayed weak temporal variability with low values observed during the post-monsoon season attributed to inputs from mixed sources.Estuarine samples were less depleted than the riverine samples suggesting contributions from marine plankton in addition to contributions from river plankton and terrestrial C3 plants detritus.Labile OM was observed during the monsoon and post-monsoon seasons in the estuarine region.More degraded OM was noticed during the pre-monsoon season.Principal component analysis was used to ascertain the sources and factors influencing OM.Principally five factors were extracted explaining 84.52%of the total variance.The first component accounted for 27.10%of the variance suggesting the dominance of tidal influence whereas,the second component accounted for heterotrophic bacteria and their remnants associated with the particulate matter,contributing primarily to the AA pool.Based on this study we ascertained the role of the estuarine turbidity maximum(ETM)controlling the sources of POM and its implications to small tropical rivers.Thus,changes in temporal and regional settings are more likely to affect the natural biogeochemical cycles of small tropical rivers.
基金the National Basic Key Research Program of China (2004CB418502)the National Natural Science Foundation of China (40671002)
文摘Content and distribution patterns of rare earth dements （REEs） in the suspended particulate material （SPM） of Daliao River system were investigated and compared with those in the fiver and sea sediments, loess, and soils of China. Twenty-seven samples of SPM were taken in Daliao River system and digested with various acids followed by ICP-MS analysis for REEs and ICP-OES analysis for Al, Fe, Mn, Ti, Mg, Ca, Na, and K, to measure the total concentrations of these elements. Results indicated that the spatial change in the content of REEs was great, with the coefficient of variance （CV） from 84% to 105%, while the contents of REEs were significantly correlated with each other. Chondrite-normalized patterns of REEs were characterized by higher enrichment of light REEs than heavy REEs, and a depletion of Eu in the SPM was generally found. The positive anomaly of Eu in the SPM of Xi River was due to anthropogenic source in Shenyang City. Furthermore, chondfite- and upper continent crust-normalized patterns of REEs in the SPM of Daliao River system, sediments of Yangtze River and Yellow River, sediments of Yellow Sea, East Sea, South Sea of China, and loess and soil of China, were very similar to one another. These demonstrated that the weathering and sedimentary processes resulted in constant REE distribution not only in the typical sedimentary rocks, but also in the modem riverine particle, sea sediments, loess, and soils.
