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1.
The Serthalaikkadu creek in Muthupet mangroves region is the only E–W trending coastal strip in the SE coast of India and it also acts as a barrier to natural disasters. Natural, anthropogenic signals and accumulation of elements were studied by collecting sediments from two cores. Textural parameters were studied in detail and carbonates (CaCO3), organic carbon (OC), major (Si, Al, Fe, Na, K, Ca, Mg, P) and trace elements (Mn, Cr, Cu, Ni, Co, Pb, Zn) were determined. Textural parameters, CaCO3, OC and Al-normalized pattern of elements indicate depositional events in core samples that can be directly related to natural events during the last decade. The calculated enrichment, anthropogenic factors and comparison of data indicate that the observed trace metals (especially Pb, Co) are enriched mainly due to the anthropogenic activities in the land as well as in the coastal zone (Palk Strait).  相似文献   

2.
Grain size parameters, trace metals (Co, Cu, Ni, Pb, Cr, Zn, Ba, Zr and Sr) and total organic matter (TOM) of 38 surficial sediments and a sediment core of west-four Pearl River Estuary region were analyzed. The spacial distribution and the transportation procession of the chemical element in surficial sediments were studied mainly. Multivariate statistics are used to analyses the interrelationship of metal elements, TOM and the grain size parameters. The results demonstrated that terrigenous sediment taken by the rivers are main sources of the trace metal elements and TOM, and the lithology of parent material is a dominating factor controlling the trace metal composition in the surficial sediment. In addition, the hydrodynamic condition and landform are the dominating factors controlling the large-scale distribution, while the anthropogenic input in the coastal area alters the regional distribution of heavy metal elements Co, Cu, Ni, Pb, Cr and Zn. The enrichment factor (EF) analysis was used for the differentiation of the metal source between anthropogenic and naturally occurring, and for the assessment of the anthropogenic influence, the deeper layer content of heavy metals were calculated as the background values and Zr was chosen as the reference element for Co, Cu, Ni, Pb, Cr and Zn. The result indicate prevalent enrichment of Co, Cu, Ni, Pb and Cr, and the contamination of Pb is most obvious, further more, the peculiar high EF value sites of Zn and Pb probably suggest point source input.  相似文献   

3.
To investigate trace elements in wet precipitation over the Tibetan Plateau (TP), a total of 79 event-based precipitation samples were collected from September 2007 to September 2008 at Nam Co Station. Samples were analyzed for concentrations of Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, and Pb using inductively coupled plasma-mass spectrometry (ICP-MS). The annual volume-weighted concentrations of elements were generally comparable to other background sites, and much lower than urban areas. The enrichment factors (EF) showed that, in comparison with the Tibetan soils, the wet precipitation had elevated concentrations of Cr, Co, Ni, Cu, Zn, Cd and Pb, probably indicating their anthropogenic origins. Other elements (Al, Fe, Mn and V) with enrichment factor value of <10 may derive mainly from crustal sources. The principal component analysis further confirmed the two different groups of elements in wet deposition samples. The backward trajectories were calculated for each precipitation event using the NOAA HYSPLIT model. The results indicated significant differences of EF for trace elements of anthropogenic origin between the summer monsoon and non-monsoon seasons. The data obtained in the present study indicated that pollutants can affect remote high altitude regions like the Tibetan Plateau through long-range transport, especially in the summer monsoon season.  相似文献   

4.
Surface slices of 20 sediment cores, off southwestern Taiwan, and bed sediment of River Kaoping were measured for major and trace elements (Al, As, Ca, Cd, Cl, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, P, Pb, S, Si, Ti, V, and Zn) to evaluate the geochemical processes responsible for their distribution, including elemental contamination. Major element/Al ratio and mean grain size indicate quartz-dominated, coarse grained sediments that likely derived from sedimentary rocks of Taiwan and upper crust of Yangtze Craton. Bi-plot of SiO2 versus Fe2O3T suggests the possible iron enrichment in sediments of slag dumping sites. Highest concentrations of Cr, Mn, P, S, and Zn found in sediments of dumping sites support this. Correlation analysis shows dual associations, detrital and organic carbon, for Cr, P, S, and V with the latter association typical for sediments in dumping sites. Normalization of trace elements to Al indicates high enrichment factors (>2) for As, Cd, Pb, and Zn, revealing contamination. Factor analysis extracted four geochemical associations with the principal factor accounted for 25.1% of the total variance and identifies the combined effects of dumped iron and steel slag-induced C–S–Fe relationship owing to authigenic precipitation of Fe–Mn oxyhydroxides and/or metal sulfides, and organic matter complexation of Fe, Mn, Ca, Cr, P, and V. Factors 2, 3, and 4 reveal detrital association (Ti, Al, Ni, Pb, Cu, and V), effect of sea salt (Cl, Mg, Na, and K) and anthropogenic component (As and Zn)-carbonate link, respectively, in the investigated sediments.  相似文献   

5.
Data are presented for trace element concentrations determined in the <63 μm fraction of streambed sediment samples collected at 24 sites on the island of O‘ahu, Hawai‘i. Sampling sites were classified as urban, agricultural, mixed (urban/agricultural), or forested based on their dominant land use, although the mixed land use at selected sampling sites consisted of either urban and agricultural or forested and agricultural land uses. Forest dominated sites were used as reference sites for calculating enrichment factors.Trace element concentrations were compared to concentrations from studies conducted in the conterminous United States using identical methods and to aquatic-life guidelines provided by the Canadian Council of Ministers of the Environment. A variety of elements including Pb, Cr, Cu and Zn exceeded the aquatic-life guidelines in selected samples. All of the Cr and Zn values and 16 of 24 Cu values exceeded their respective guidelines. The potential toxicity of elements exceeding guidelines, however, should be considered in the context of strong enrichments of selected trace elements attributable to source rocks in Hawai‘i, as well as in the context of the abundance of fine-grained sediment in the streambed of O‘ahu streams.Statistical methods including cluster analysis, Kruskal–Wallis non-parametric test, correlation analysis, and principal component analysis (PCA) were used to evaluate differences and elucidate relationships between trace elements and sites. Overall, trace element distributions and abundances can be correlated to three principal sources of elements. These include basaltic rocks of the volcanic edifice (Fe, Al, Ni, Co, Cr, V and Cu), carbonate/seawater derived elements (Mg, Ca, Na and Sr), and elements enriched owing to anthropogenic activity (P, Sn, Cd, Sn, Ba and Pb). Anthropogenic enrichment gradients were observed for Ba, Cd, Pb, Sn and Zn in the four streams in which sediments were collected upstream and downstream.The findings of this study are generally similar to but differ slightly from previous work on sediments and suspended particulate matter in streams, from two urban watersheds of O‘ahu, Hawai‘i. Inter-element associations in the latter were often stronger and indicated a mixture of anthropogenic, agricultural and basaltic sources of trace elements. Some elements fell into different statistical categories in the two studies, owing in part to differences in study design and the hydrogeological constraints on the respective study areas.  相似文献   

6.
Global data are presented for sources of atmospheric input for 20 trace metals, and the relative importance of natural and anthropogenic sources is assessed. Interference factors are calculated as (total anthropogenic emissions/total natural emissions) × 100. For lithophile metals such as Fe and Mn, interference factors are small. In contrast, the atmophile metals, such as As, Se and Hg, exhibit large interference factors. A significant degree of correlation exists between interference factors and enrichment factors, where enrichment factor is defined as the metal/Al ratio in atmospheric particulates divided by the metal/Al ratio in soils. For many of the trace metals, enrichment factors are of the same order of magnitude at high latitudes in both the Northern and Southern Hemispheres, and are larger at high latitude than at mid latitude.A simple mathematical model is used to calculate present-day enrichment factors in both hemispheres based on natural and anthropogenic influxes, effluxes, and transfer between hemispheres. The calculated enrichment factors are in good agreement with the observed enrichment factors for lithophile metals at both mid and high latitude, and for atmophile metals at mid latitude. However, calculated enrichment factors for atmophile metals are lower than observed enrichment factors at high latitude. To explain these results, we propose that for Hg, As and Se, and perhaps for other atmophile metals, there are significant fluxes from the sea surface to the atmosphere. If the estimated low-temperature fluxes of As, Se and Hg from the land and sea surfaces are included in the interference factor calculations for these metals, the factors are reduced to less than 100%.  相似文献   

7.
本研究对湘江下游河床沉积物进行了元素地球化学分析,在认识沉积物元素地球化学特征、甄别人为源与自然源重金属的基础上,估算了沉积物的元素地球化学背景值。结果表明:SiO2、TiO2、Al2O3、Fe2O3、K2O等主量元素及V、Co、Cr、Ba、Sc、U、Sr、Ga、Ge、Rb、Nb、Y、REE等微量元素在沉积物中含量变化相对稳定(Cv<0.2),分布相对均匀,且富集不明显(EF<2.0,Sr明显亏损)。而MnO、MgO、CaO、Na2O、P2O5等主量元素,及Cd、Mn、Cu、Pb、Zn等重金属在沉积物中含量变化大(Cv>0.25),分布极不均匀,且沉积物中重金属明显富集(EF>2.0)。主成分及Pearson线性相关性分析显示,沉积物中不明显富集的微量元素主要赋存于难溶硅酸盐矿物相中,为自然源元素。而沉积物中显著富集的重金属主要赋存于铁—锰氧化物等矿物相中,为有人为源叠加的元素。故针对不同来源特征的元素用不同的方法进行了背景值计算,求得沉积物中47个元素的背景值。再利用元素比值等方法对所得背景值进行检验。结果表明,本文得到的湘江沉积物元素背景值合理,可用作流域沉积物重金属污染评价参考。  相似文献   

8.
The present paper deals with major and trace elements geochemistry of the groundwater from Nalgonda district, Telangana. The study area is very important in terms of anthropogenic activity like rapid industrial, urban development, pesticides, pharmaceutical, granite polishing and agro based industries. Inductively coupled plasma mass spectrometer (ICPMS) was employed to determine the concentration of trace elements in collected groundwater samples (bore well). These probe elements were further categorized as toxic elements (Pb, As, Cd, and V), alkaline earths (Sr and Ba), alkali metals (Li, Rb), transition metals (Cr, Mo and Ni), metallic elements (Cu, Fe, Zn, Al, Co), and other non-metallic elements (Se and Si). The groundwater quality was examined in perspective of Indian as well as World Health Organization drinking water standards. Based on the analytical results, groundwater in the study area is found to be slightly alkaline in nature and very hard, the average abundance of the major cations and anions is in the order of Ca+<Na+<Mg+<K+ and Cl-<HCO3 ?<CO3 ?<SO4 ?<NO3 ?<F– respectively. The dominant hydro chemical facies of groundwater is Na+ - HCO 3 – – Cl– and Na+ - Cl– – HCO– 3 types.The results of trace elements shows that concentration of Pb, As, Cd, V in collected samples exceeding the desirable limits, and in the case of alkaline, alkali, transition, non-metallic elements, seventy per cent of the samples crossed the desirable limits, but all metallic elements viz. Cu, Fe, Zn, Al, Co is within the limits as per Indian as well as World Health Organizations drinking water standards. Factor analysis results shows that seven factors emerged as a significant contributor to the groundwater contamination is about 65.32 per cent. The spatial variation maps decipher trace elemental concentrations both geogenic and anthropogenic origin, by three zones i.e. ‘low’, ‘moderate’ and ‘high’ of the study area based on environment using Arc-GIS. High concentrations of trace elements are indicative of phenomenal rise in chemical composition and likely to have its origin from silicate weathering reactions and dissolution/precipitation processes supported by rainfall and anthropogenic activities, indiscriminate use of fertilizers/pesticides, and disposal of waste and sewage, release of reactive pollutants into the atmosphere by industries. Hence, this work is of immense societal benefit in terms of prevailing human health hazards in the study area with a direct relevance to such industrially populated regions elsewhere.  相似文献   

9.
The biogeochemistry of organic lacustrine sediments (sapropels) has been poorly studied in Siberia. In this paper we show the specifics of sapropel formation caused by low pH and mineralization of water by the example of Lake Ochki in Cisbaikalia. The main sources of organic matter are zoo- and phytoplankton, which concentrate mostly basic chemical elements and also some alkaline, alkali-earth, and chalcophile elements and move them to the sediment. The calculated enrichment factors (EF) have shown that the lake plankton is strongly enriched with phosphorus and chalcophile elements. The calculations have also revealed a great contribution of the plankton to the elemental composition of sapropel (Mebio, %): P (-100), Cd (57), Br (45), Hg (40), Se and Na (30), Zn (23), K (21), and Ca (15). Elements are rather uniformly distributed throughout the 3.2 m thick sapropel layer. Lithophile elements (Al, Sc, Ti, Y, Zr, Nb) and LREE are mostly from a terrigenous source. The high contents of mobile elements (Cd, Sb, Sn, Pb, Zn) in the upper part of sapropel are probably due to anthropogenic factors. The high Cu and Zn contents in some sapropel layers are probably related to the inflow of deep-level groundwaters, and the elevated contents of Hg, Cd, and Sb might have been caused by forest fires.  相似文献   

10.
Improving the geochemical database available for characterising potential natural and anthropogenic aerosol sources from South America and Southern Africa is a critical precondition for studies aimed at understanding trace metal controls on the marine biogeochemical cycles of the South Atlantic Ocean. We here present new elemental and isotopic data for a wide range of sample types from South America and Southern Africa that are potentially important aerosol sources. This includes road dust from Buenos Aires and lichen samples from Johannesburg, soil dust from Patagonia, volcanic ash from the Andean volcanic belt, and aerosol samples from São Paulo. All samples were investigated for major (Al, Ca, Fe, Mg, Na, K, Mn) and trace element (Cd, Co, Cr, Cu, Ni, Pb, REE, Sc, Th, Y, V, Zn) concentrations and Nd and Pb isotopic compositions. We show that diagrams of 208Pb/207Pb vs. εNd, 208Pb/207Pb vs. Pb/Al, 1/[Pb], Zn/Al, Cd/Al, Cu/Al, and εNd vs. Pb/Al, and 1/[Nd] are best suited to separate South American and South African source regions as well as natural and anthropogenic sources. A subset of samples from Patagonia and the Andes was additionally subjected to separation of a fine (<5?μm) fraction and compared to the composition of the bulk sample. We show that differences in the geochemical signature of bulk samples between individual regions and source types are significantly larger than between grain sizes. Jointly, these findings present an important step forward towards a quantitative assessment of aeolian trace metal inputs to the South Atlantic Ocean.  相似文献   

11.
This study describes the geochemical and physico-chemical characterization of contaminant status of six wetlands of the lower uMngeni River floodplain, KwaZulu-Natal Province, South Africa. At all sites, organic matter content, calcium carbonate and metal concentrations were highest within the fine-sediment dominated surface laminae, decreasing with depth. Exceptions were displayed by arsenic (As), nickel (Ni) and vanadium (V), presumed to be derived from normal geochemical processes. Geochemical indicies indicated high contamination factors for lead (Pb) and V, pointing to moderate anthropogenic metal pollution contribution. Most conspicuous are the contamination high factors for Pb across most sites. Fe and Pb contamination is ubiquitous in all surface laminae, with contamination factors being either border-line, moderate or of high contamination. Enrichment factors for As, Mn and P at site S6 indicate possible anthropogenic sources. The data also shows a possibility of anthropogenic input of P and Zn at site S3. Apart from the enrichment factors established for Ni across all sites, all other metals indicate some degree of enrichment. A range of variable results for the mid to deeper laminae are indicative of natural processes with some human influence. Results of ANOVA confirm the above. Principal component analysis reveals a 46.4% variance from component 1 elements (Al, Ca, Cr, Cu, Fe, Mg, Mn and Zn) and a 17.8% variance from component 2 (Al, Cu and Fe). Given the rapid rate of development in this region, the protection of these floodplain wetlands must receive high conservation priority from the local municipality.  相似文献   

12.
Milazzo Peninsula soils and substrates are extremely variable, composed of acidic, mafic and ultramafic metamorphic rocks, carbonatic sedimentary rocks, and sometimes volcanic rocks, thus contributing to a mixed influence on their chemical composition. Moreover, the region is highly polluted due to atmospheric releases from anthropogenic activities, such as refinery industry. In addition, emissions of airborne particles from volcanic eruptions are also likely to fall to the ground and provide trace elements to the soils. The purpose of this study is to distinguish between anthropogenic and geogenic sources contributing to the concentrations of metals in soils by studying their distribution in major and trace elements in relation to substrates. As regards geogenic sources, the major elements composition of soils comes firstly from metamorphic rocks, secondly from carbonates, and to a minor extent from volcanic rocks. Enrichment factors calculations relative to substrate rocks, and using Th as reference element, show that the soils are enriched in As, Pb, Zn, and Ni. Rare earth elements (REEs) patterns normalized to substrate rocks exhibit enrichment in light REEs and a positive anomaly in Gd, indicating anthropogenic contributions in the soil composition. REE ratios and trace elements were plotted to investigate the relationships between anthropogenic sources and substrates in soils compositions. The graphs of La/Ni vs La/Gd and La/Ce vs La/Nd show that soils plot on a line toward substrate rocks on one side, and toward an end member which is represented by a spent catalyst and atmospheric particles emitted by refinery activities. Plots of La vs Cr, and V vs La show similar trends, whereas plots of Zn vs Ni and Pb vs V suggest that another end member, which is unidentified, contributes to soil enrichment in Zn and Pb. A binary mixing model applied to the most Zn enriched soil suggests that anthropogenic inputs from refinery emissions may have contributed to 16% of the anomalies in La/Gd. These results suggest that the trace element composition of Milazzo's peninsula soils partly bears the signature of atmospheric emissions of the refinery.  相似文献   

13.
A complex of analytical methods (atomic absorption spectroscopy AAS, synchrotron radiation X-ray fluorescence SR-XRF, and instrumental neutron activation analysis INAA) were used for analyses of 40 trace elements. In compliance with the conventional biogeochemical methods, enrichment factors EF were calculated for plankton relative to the average concentrations of elements in continental clay (shale) preliminarily normalized to Sc. In order to understand the concentration specifics of trace elements in living organisms inhabiting aquatic ecosystems of variable salt composition and geochemical characteristics, chemical speciation of elements was calculated for the brines of salt lakes by the WATEQ4F and Selektor-S computer programs. The enrichment of plankton in Hg in Lake Bol’shoe Yarovoe is caused not only by the chemistry of the mineralized brine (bittern), as follows from the Hg speciation in it, but also by anthropogenic contamination (Hg-bearing wastes from the Altaikhimprom chemical plants in the town of Yarovoe).  相似文献   

14.
Farming is the major source of income for the villagers of North-central Sri Lanka. However, chronic kidney disease of unknown etiology is a major health hazard in the area and it is assumed that agricultural contaminants are the major causative agents. This study focuses on the geochemistry of soils in the area to determine possible natural and anthropogenic impacts of the problem. X-ray fluorescence analysis was used to determine the abundance of selected major and trace elements. Results show that geo-enrichment for many elements indicates slight to significant variations between agricultural and non-agricultural soils. Geoaccumulation index (I geo) shows higher pollution levels of Pb and V (2 < I geo < 3) and very lower pollution levels of As, Zn, Cu, Fe and Mn (1 < I geo < 2) in agricultural soils. However, I geo for non-agricultural soils implies lack of contaminations (I geo < 1). Positive correlations of As with Pb and Zn and negative correlations with Cu, Ni and Cr suggest that they may have derived from different sources such as sulfide minerals of basement rocks, fertilizers and agrochemicals. The results of this study suggest that there is no significant threat from As and other trace elements to soils. The accumulation of these elements in agricultural fields may have been effectively controlled by seasonal farming practices. However, there is a potential environmental risk from elements such as Pb and V due to their significant enrichment in soils.  相似文献   

15.
Groundwater samples collected from both open and bore wells in an area of about 270 km2 from Madras City, India, have been analyzed for major ions (HCO3, Cl, Si, Na, Ca, and Mg) and trace elements (As, Se, B, V, Cr, Fe, Co, Pb, Cu, Zn, Cd, Mn, Ni, Mo, and Ba). The study reveals that the quality of potable water has deteriorated to a large extent. Seawater intrusion into the aquifer has been observed in nearly 50 percent of the study area. The toxic elements (As and Se) have already exceeded the maximum permissible limits of drinking water in almost the entire city. A positive correlation of As and Se with other toxic metals such as V, Cr, Fe, B, etc., indicates that all these elements are anthropogenic in origin. Applying multivariate analysis, the source for trace elements in groundwater has been grouped into two major factors: pollution and mobilization factors. The groundwater in the study area is largely contaminated by organic effluents and reflects the intensity of pollution caused by the overlying soil sediment and rapid infiltration of the pollutants.  相似文献   

16.
Samples collected from a 0.87 m snow pit at a high altitude site in the Cho Oyu range, Himalayas were measured for V, Cr, Mn, Co, Ni, Cu, Zn, As, Rb, Sr, Cd, Sn, Sb, Ba, Tl, Pb, Bi, Th, and U using inductively coupled plasma mass spectrometry. In addition, major ions, oxygen stable isotopes, and microparticles were also measured to assist the interpretation of seasonal variation of trace elements. The trace elements show a distinct seasonality, i.e., higher concentrations during the non-monsoon season than those during the monsoon season. Significant correlation is observed between Ba and the other trace elements. Crustal enrichment factor (EFc) analysis indicates that V, Mn, Co, Ni, Rb, Sr, and Th originate mainly from crustal dust, while anthropogenic inputs make an important contribution to the other trace elements (i.e., Cu, Zn, As, Cd, Sn, Sb, Ti, Pb, Bi, and U). Evidence from air mass back trajectories suggests that atmospheric trace element pollution reaching the studied area is transported dominantly by Indian summer monsoon during the monsoon season, while it is transported mainly by the westerlies during the non-monsoon season.  相似文献   

17.
The main aims of the present study are to identify the major factors affecting hydrogeochemistry of groundwater resources in the Marand plain, NW Iran and to evaluate the potential sources of major and trace elements using multivariate statistical analysis such as hierarchical clustering analysis (HCA) and factor analysis (FA). To achieve these goals, groundwater samples were collected in three sampling periods in September 2013, May 2014 and September 2014 and analyzed with regard to ions (e.g., Ca2+, Mg2+, Na+ and K+, HCO3 ?, SO4 2?, Cl?, F? and NO3 ?) and trace metals (e.g., Cr, Pb, Cd, Mn, Fe, Al and As). The piper diagrams show that the majority of samples belong to Na–Cl water type and are followed by Ca–HCO3 and mixed Ca–Na–HCO3. Cross-plots show that weathering and dissolution of different rocks and minerals, ion exchange, reverse ion exchange and anthropogenic activities, especially agricultural activities, influence the hydrogeochemistry of the study area. The results of the FA demonstrate that 6 factors with 81.7% of total variance are effective in the overall hydrogeochemistry, which are attributed to geogenic and anthropogenic impacts. The HCA categorizes the samples into two clusters. Samples of cluster C1, which appear to have higher values of some trace metals like Pb and As, are spatially located at the eastern and central parts of the plain, while samples of cluster C2, which express the salinization of the groundwater, are situated mainly westward with few local exceptions.  相似文献   

18.
Geochemical, mineralogical and textural analyses were carried out in core sediments off Adyar estuary, Bay of Bengal, India to record the contamination trend from urban and industrial activities during the historical past. Quartz, feldspar, kaolinite, chlorite and illite were the main lithogenic and clay minerals; carbonate was the predominant biogenic mineral. Trace metals (Fe, Al, Cu, Cr, Ni, Pb and Zn) indicate more enrichment in the surface sediment layers due to recent anthropogenic activities. The mean anthropogenic factor (AF) values for trace metals in core sediments decreased in the following order: Cr > Ni > Zn > Cu > Pb. The pollution load index (PLI) values in Adyar core sediments ranged from 1 to 1.25 with an average of 1.07. Based on AF, PLI, and sediment quality guidelines values for trace metals, significant metal enrichment and ecological risk were obtained in upper-most sediment layer. Multivariate statistical methods such as correlation matrix, principal component analysis and cluster analysis were carried out to find the relationships among the texture size, metals and minerals. The pollution of Adyar estuarine sediments was started in the 1960s, responding to the rapid economic development in Chennai coastal and Adyar estuarine region in the last five decades. Despite these high concentrations in the upper layer, development and expansion of industries are still continuing. The stricter regulations for the discharge and remediation of sediments are urgent for the conservation of environments and human health.  相似文献   

19.
This study investigated the temporal variations of major and trace element contents and controlling factors in the upper reaches of the Xijiang River, SW China. The results showed the major ions principally derived from the weathering of carbonate and silicate rocks, with a seasonal variation impacted by the monsoonal climate. The contents of dissolved trace elements also varied seasonally in the two main tributaries: the Nanpan and Beipan rivers. Most dissolved trace elements such as Mn, Zn and Pb being affected by anthropogenic contributions displayed a large seasonal variability, from onefold to hundred-fold, while V, Rb and U show a relative stable trend uncorrelated with the different seasons, suggesting a natural origin by rock weathering. Suspended particle matter in the Nanpan and Beipan rivers was depleted in Ca, Mg, Na, K and Sr, but enriched in Al, Fe and Sb compared to the upper crust (UC) values. A binary mixture of silicate-rich and carbonate-rich sources dominates the behavior of elements such as Ca and Sr in riverine sediments, while a third end-member with an anthropogenic signature influenced the content of trace elements like Mn, Sb, Pb, Zn, Cd, Cr and Cu. The enrichments of Sb relative to the UC would be related to the mining activity in the studied area. The study highlights the importance of investigating temporal variations of major and trace element contents of rivers controlled by the monsoon climate and impacted by human activity.  相似文献   

20.
The distributions of particulate elements (Al, P, Mn, Fe, Co, Cu, Zn, Cd, and Pb), dissolved trace metals (Mn, Fe, Co, Cu, Zn, and Cd), and dissolved nutrients (nitrate, phosphate, and silicic acid) were investigated in the Gulf of the Farallones, a region of high productivity that is driven by the dynamic mixing of the San Francisco Bay plume, upwelled waters, and California coastal surface waters. Particulate metals were separated into >10 and 0.4-10 μm size-fractions and further fractionated into leachable (operationally defined with a 25% acetic acid leach) and refractory particulate concentrations. Dissolved metals (< 0.4 μm pore-size filtrate) were separated into colloidal (0.03-0.4 μm) and soluble (<0.03 μm) fractions. The percent leachable particulate fractions ranged from 2% to 99% of the total particulate concentration for these metals with Mn and Cd being predominantly leachable and Fe and Al being predominantly refractory. The leachable particulate Pb concentration was associated primarily with suspended sediments from San Francisco Bay and was a tracer of the plume in coastal waters. The particulate trace metal data suggest that the leachable fraction was an available source of trace metal micronutrients to the primary productivity in coastal waters. The dissolved trace metals in the San Francisco Bay plume and freshly upwelled surface waters were similar in concentration, with the exception of Cu and Co, which exhibited relatively high concentrations in plume waters and served as tracers of this water mass. The dissolved data and estimates of the plume dynamics suggest that the impact of anthropogenic inputs of nutrients and trace metals in the San Francisco Bay plume contributes substantially to the concentrations found in the Gulf of the Farallones (10-50% of estimated upwelled flux values), but does not greatly disrupt the natural stoichiometric balance of trace metal and nutrient elements within coastal waters given the similarity in concentrations to sources in upwelled water. In all, the data from this study demonstrate that the flux of dissolved nutrients and bioactive trace metals from the San Francisco Bay plume contribute to the high and relatively constant phytoplankton biomass observed in the Gulf of the Farallones.  相似文献   

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