The Dublin SURGE Project: geochemical baseline for heavy metals in topsoils and spatial correlation with historical industry in Dublin,Ireland

The Dublin SURGE (Soil Urban Geochemistry) Project is Dublin’s first baseline survey of heavy metals and persistent organic pollutants in topsoils and is part of a Europe-wide initiative to map urban geochemical baselines in ten cities. 1,058 samples were collected as part of a stratified random sampling programme in the greater Dublin area to give an overview of baseline conditions in the city. Samples were analysed for 31 inorganic elements including heavy metals. Analysis of results indicates that the concentrations of lead, copper, zinc and mercury are strongly influenced by human activities, with elevated concentrations in the city docklands, inner city and heavy industry areas. Sources of heavy metals in these areas may include historical industry, coal burning, re-use of contaminated soil, modern traffic and leaded paint and petrol. Concentrations of other inorganic elements in topsoil show patterns which are strongly related to regional bedrock parent material. The spatial distributions of heavy metals, in particular Pb and As, are explored in detail with respect to regional geology and the influence of historical industry on soil quality. Exploratory data, geostatistical and correlation analyses suggest that the concentrations of heavy metals tend to increase as the intensity of historical industrial activity increases. In particular, drinks production, power generation, oil/gas/coal, metals and textile historical industries appear to be the contamination source for several heavy metals. The data provide a geochemical baseline relevant to the protection of human health, compliance with environmental legislation, land use planning and urban regeneration.     

Spatial Variations of Heavy Metals in the East China Sea Continental Shelf Surface Sediments

Surface sediments collected from continental shelf of the East China Sea were analyzed for heavy metals (iron, manganese, copper, zinc, lead, cadmium), carbonate, organic carbon contents, and grain sizes. the range of concentrations observed were iron: 0.3-1.3 wt%, manganese: 2.3-14 μmole/g, copper: 7.1-184 μmole/g, zinc: 0.16-0.77μmiole/g, lead: 15-98 μmole/g, cadmium: 0.17-3.9 μmole/g, carbonate: 3.6-87 wt%, sand: 10-100%, silt: 0-70% and clay: 0-50%.

A zonal distribution pattern of the heavy metals was found in the East China Sea Continental shelf sediments. High concentrations of most heavy metals, organic carbon and fine-grained sediments were observed in the inner shelf zone, especially those near the discharge of the Yangtze River. Concentrations of these heavy metals decreased from the inner shelf to the shelf break region. High concentrations of metals were also found in sediments near Taiwan. Iron concentrations decreased north-east of the central shelf region. High concentrations of cadmium were found in the shelf break region where biogenic carbonate is predominant. This study showed that biogenic carbonate in the East China Sea shelf break region and the terrigenous sediments from the Yangtze River and island of Taiwan were the major sources of heavy metals. Heavy metal concentrations were strongly influenced by the content of the coarse-grained quartz sand present in the sediments.     

Spatial Variations of Heavy Metals in the East China Sea Continental Shelf Surface Sediments

Surface sediments collected from continental shelf of the East China Sea were analyzed for heavy metals (iron, manganese, copper, zinc, lead, cadmium), carbonate, organic carbon contents, and grain sizes. the range of concentrations observed were iron: 0.3-1.3 wt%, manganese: 2.3-14 μmole/g, copper: 7.1-184 μmole/g, zinc: 0.16-0.77μmiole/g, lead: 15-98 μmole/g, cadmium: 0.17-3.9 μmole/g, carbonate: 3.6-87 wt%, sand: 10-100%, silt: 0-70% and clay: 0-50%.

A zonal distribution pattern of the heavy metals was found in the East China Sea Continental shelf sediments. High concentrations of most heavy metals, organic carbon and fine-grained sediments were observed in the inner shelf zone, especially those near the discharge of the Yangtze River. Concentrations of these heavy metals decreased from the inner shelf to the shelf break region. High concentrations of metals were also found in sediments near Taiwan. Iron concentrations decreased north-east of the central shelf region. High concentrations of cadmium were found in the shelf break region where biogenic carbonate is predominant. This study showed that biogenic carbonate in the East China Sea shelf break region and the terrigenous sediments from the Yangtze River and island of Taiwan were the major sources of heavy metals. Heavy metal concentrations were strongly influenced by the content of the coarse-grained quartz sand present in the sediments.     

上海城市公园灰尘重金属污染及其潜在生态风险评价

通过对上海城市公园灰尘重金属含量的调查,发现上海城市公园灰尘重金属Pb、Zn、Cu、Cr、Cd和Ni含量的平均值分别为416.63 mg/kg、906.29 mg/kg2、35.89 mg/kg1、62.59 mg/kg1、.58 mg/kg和92.19 mg/kg,同上海市土壤环境背景值相比,均处于较高的积累水平。公园灰尘重金属空间上的分布特征表现为:内外环线之间公园灰尘各重金属元素含量平均值均高于内环线内公园;通过分析判定公园灰尘中较高的重金属含量可能主要源于交通和工业造成的污染。运用潜在生态危害指数法来评价上海城市公园灰尘重金属污染状况,发现单种重金属造成的潜在生态危害表现为:Cd>Pb>Cu>Ni>Zn>Cr;公园灰尘6种重金属潜在生态危害达到一个相当高的水平,在所调查的公园中,63.6%的公园灰尘重金属生态危害达到极高水平,29.5%的公园达到高水平,6.8%的公园处于较高水平。     

Spatial distribution and controlling factors of heavy metals contents in paddy soil and crop grains of rice–wheat cropping system along highway in East China

There is consensus concerning the heavy metal pollution from traffic emission on roadside agricultural land. However, few efforts have been paid on examining the contamination characteristics of heavy metals in roadside paddy-upland rotation field, and especially in combination with detailed quantitative analysis. In this study, we investigated the concentrations of heavy metals (Pb, Cd, Cr and Zn) in soil and crop grains of the rice-wheat cropping system along a major highway in East China in 2008 and analyzed the spatial distribution characteristics of heavy metals and their influencing factors with GIS and Classification and Regression Trees (CART). Significantly elevated levels of heavy metals in soil, rice and wheat grains indicated the heavy metals contamination of traffic emission in roadside rice-wheat rotation field. The contamination levels of Cd, Cr and Zn in wheat grain were higher than rice grain, while that of Pb showed an opposite trend. Obvious dissimilarities in the spatial distributions of heavy metals contents were found between in the soil, rice and wheat grains, indicating that the heavy metals contents in the roadside crop grains were not only determined by the concentrations of heavy metals in the paddy soil. Results of CART analysis showed that the spatial variation of the heavy metals contents in crop grains was mainly affected by the soil organic matter or soil pH, followed by the distance from highway and wind direction. Our findings have important implications for the environmental assessment and crop planning for food security along the highway.     

攀枝花市水系沉积物与土壤中重金属的地球化学特征比较

水系沉积物和土壤都是表生作用的产物,是环境中污染物质的重要受纳体,但两者在物质来源和受纳污染物方面又有不同。重金属通过不同方式进入到水系沉积物和土壤之中产生污染,对于区域环境具有重要的影响。为了了解攀枝花市水系沉积物和土壤中重金属元素地球化学特征的异同和污染状况,在攀枝花市范围内系统采集了水系沉积物和土壤样品,从环境地球化学角度,应用地球化学方法研究了攀枝花市水系沉积物及土壤中重金属的地球化学特征,应用地质累积指数法评价了污染情况,并对二者进行了比较研究。结果表明,攀枝花市水系沉积物中重金属的含量普遍高于土壤;水系沉积物和土壤中重金属的分布具有相似的特征;水系沉积物中重金属的污染程度高于土壤,但总体上来说,重金属的污染程度较小。两者的污染程度不同是因为接受污染物的方式不同;两者的分布趋势相同,说明具有相同或相近的污染来源。     

上海宝山区农业用地土壤重金属空间分异规律及分布特征研究

利用地理信息系统(GIS)和地统计分析方法对宝山区农业用地土壤重金属(As,Cd,Cr,Hg,Pb)空间分异规律和分布特征进行研究.结果表明,区内农业用地土壤中5种重金属均表现为中等空间变异性;在全局趋势上,Cd为一次全局趋势,其余重金属元素都表现为二次趋势;5种元素在空间上均存在明显的方向效应;Cr,Hg和Pb具有强烈的空间相关性,As和Cd具有中等强度的空间相关性;5种重金属的空间变程由大到小分别为Hg,Pb,Cr,As和Cd.土壤重金属As,Cd,Cr,Hg和Pb平均含量分别为7.31mg.kg-1、0.24 mg.kg-1、107.89 mg.kg-1、0.15 mg.kg-1和38.54 mg.kg-1,分别是上海土壤背景值的0.80,1.81,1.44,1.43和1.51倍.宝山区南部农业用地土壤重金属污染程度普遍高于北部.从宝山区各镇农业用地土壤重金属污染看,Cr和Pb普遍污染严重,而基本不存在As污染.同期降尘污染调查表明,降尘重金属是本区土壤重金属污染的最重要来源.     

Heavy-metal distribution and risk assessment of sediment and fish from El-Mex Bay, Alexandria, Egypt

Heavy metals are increasingly being released into natural waters from geological and anthropogenic sources. The distribution of several heavy metals (Cr, Cu, Cd, Pb, Zn, and Hg) was investigated in muscle, gill, and liver in two different fish species seasonally collected in El-Mex Bay (autumn 2004-summer 2005). In order to evaluate the pollution status of the Bay, the concentrations of the selected metals in the labile and total fractions were analysed in sediment samples collected from eight sites in El-Mex Bay during autumn 2004. Also, the Index of Geoaccumulation (I_geo) for the sediment was estimated. The total and labile fractions of the selected metals in sediment samples were 15.2 and 62.8 μg g^-1 dw for Cu, 1.8 and 5.0 μg g^-1 dw for Cd, 79.1 and 130.3 μg g^-1 dw for Zn, 0.2 and 1.2 μg g^-1 dw for Hg, 35.8 and 93.0 μg g^-1 dw for Pb, and 13.9 and 31.0 μg g^-1 dw for Cr. The concentrations of all metals were lower in flesh than those recorded in liver and gill due to their physiological roles. The metal pollution index for fish was calculated. Health hazard calculations for the contaminated sediments and fish consumption were calculated to evaluate the effect of pollution on health.     

典型工业城市大气降尘中重金属分布特征及其来源解析---以济南市为例

污染源解析是城市大气环境精准防治的重要基础。为探究典型工业城市大气降尘中重金属污染分布特征和污染源解析,本研究在济南市域内采集了35个大气降尘样品,分析了样品中重金属浓度及其空间分布特征,采用正定矩阵因子分析模型(Positive Matrix Factorization,PMF)解析降尘中重金属来源。研究结果表明,降尘中Mn、Fe、Co、Ni、Cu、Zn、As和Pb浓度平均值分别为501.4、29884.6、8.2、24.8、44.3、153.9、12.5、40.1 mg·kg^-1,其中Zn、Cu和Pb的地累积指数(Geoaccumulation Index,I_geo)分别为1.17、1.06和1.01,属于中度污染;钢铁冶炼较为发达的钢城区降尘中Mn、Fe、Co、Cu和As浓度显著高于其他区县,其浓度平均值分别为1172.4、73577.3、17.0、139.7、32.3 mg·kg^-1,而Zn和Pb在历下区、槐荫区等人口密集区域最高浓度可达351.5 mg·kg^-1和114.0 mg·kg^-1;PMF分析结果表明,济南市降尘重金属主要存在4个贡献源,分别为土壤源、工业源、交通源和混合源,贡献率分别为46.8%、26.6%、15.2%和11.4%。其中,重金属Co、Cu、Fe主要来自土壤源,Mn主要来自于土壤源和工业源的贡献,Ni主要来自于土壤源和混合源,交通源对降尘中Pb和Zn的贡献率较高,As则主要来自于工业源。本研究结果可为济南市大气环境精准防控政策的制定提供理论依据。     

太湖、巢湖沉积物中重金属污染的总量特征及其区域性差异

选取太湖、巢湖污染较为严重的区域为研究对象,采集季节性沉积物柱状样,以0.5cm的间距高精度分割样品,分析其中的Fe,Mn,Cu,Zn等重金属元素的含量,对沉积物中重金属的总量特征及季节性变化特征进行了分析,得出以下结论:太湖、巢湖沉积物中重金属的总量均呈现出Fe>Mn>Zn>Cu的特征,季节性变化幅度为Mn>Fe>Zn>Cu,重金属元素的地球化学性质对其季节性变化有很大的影响.同时,不同的区域背景差异(如元素丰度、污染状况等)导致了太湖、巢湖采样点沉积物中重金属元素季节性特征的差异.     

滨海滩涂不同围垦年代垦区农作物重金属累积特征及其与氮、磷的关系

为探明滨海滩涂围垦区农作物重金属累积特征及其与围垦年代、作物氮磷含量及化学计量比的关系,采集盐城地区不同围垦年代(围垦20、30、40、60年)农田4种主要作物(大麦、小麦、油菜、蚕豆)样品63个,测定了其根、茎叶和籽粒中Cd、Cu、Zn、Pb、Hg、As及全氮(N)、全磷(P)和粗蛋白(CP)含量,分析了重金属累积特征及与围垦年代、N、P、CP及N/P比的关系,并采用单因子污染指数法和内梅罗综合污染指数法对重金属污染程度和安全水平进行了评价。结果表明,1)围垦农田作物整株各指标含量分别为Cd (0.52±0.94)、Cu (12.98±16.00)、Zn (34.93±27.91)、Pb (3.50±5.88)、Hg (0.0063±0.0063)、As (1.94±3.72) mg·kg~(-1)及N(13.69±8.27)、P (5.98±2.24)、CP (79.55±49.54) g·kg~(-1);籽粒中则分别为(0.0059±0.020)、(1.83±1.48)、(11.13±4.45)、(0.09±0.30)、(0.0023±0.0036)、(0.0021±0.0048) mg·kg~(-1)及(19.21±7.68)、(6.04±1.64)、(111.78±47.81) g·kg~(-1); 2)作物重金属均表现为根茎叶籽粒,N和CP与之相反,表现为根茎叶籽粒,而P则表现为根籽粒茎叶; 3)不同围垦年代之间作物重金属、N、P、CP含量、N/P比及综合污染指数(Pz)均没有显著差异(P0.05); 4)各作物籽粒6种重金属单因子污染指数均值均小于1,除个别样品Pb超标(超标率11%)外,其他重金属均未超标; 5)作物籽粒重金属Pz均值为0.38,表明该地区作物重金属总体处于安全级,但大麦、小麦、油菜籽粒均有样品Pb含量超过警戒线,个别样品甚至达到重度污染水平; 6)作物整株各重金属之间、重金属与P之间均存在显著正相关(P0.01),而重金属与N、CP、N/P存在显著负相关(P0.01),在籽粒中则相关性均不显著(P0.05)。以上结果显示,盐城滨海滩涂围垦区作物重金属累积与围垦时间关系不大,其含量目前尚处于可接受范围内,但Pb污染值得关注,作物重金属与P之间存在一定的相互促进作用,而与N存在一定的拮抗作用,高氮低磷的机体养分状况有助于降低重金属含量。     

北部湾潮间带沉积物中重金属和多氯联苯的分布特征及生态风险评价

选择北部湾9个典型采样点,研究了潮间带沉积物中重金属和多氯联苯(PCBs)的分布特征和生态风险.分析结果表明,Hg、As、Cu、Pb、Zn、Cd、Cr等重金属和总PCBs的平均含量分别为0.100、10.00、19.89、45.97、208.65、0.098、17.86 mg.kg-1和1.48!g.kg-1.重金属和PCBs表现出不同的空间变化规律.相关性分析表明,北部湾潮间带的重金属主要来自人为污染;沉积物的粒度参数和有机质含量等性质特征是影响PCBs分布和迁移的重要因素;重金属和PCBs总量之间不存在明显的相关性.生态风险评价结果表明,PCBs和Cd是北部湾潮间带最主要的生态风险因子,Zn和PCBs是优势污染物;研究区域总体处于中等生态风险等级,表明沿岸港口和临海工业等人为活动已经对北部湾滨海地区造成了一定的环境压力.     

Effect of environmental forcing on the fate of nutrients, dissolved organic matter and heavy metals released by a coastal wastewater pipeline

Discharges of nutrients, urea, dissolved organic matter and heavy metals by a sewage underwater pipeline are analysed in comparison to environmental conditions in a shallow coastal zone. Variable thermo-haline stratifications of the water column and currents in upper (2.62-34.97 cm s^-1) and deeper (0.83-10.91 cm s^-1) layers drive vertical diffusion and lateral transport of wastewaters. Loads of reactive phosphorus (0.13 tons d^-1) and ammonium (1.62 tons d^-1) by the pipeline are not negligible compared to the major river loads in the gulf. High concentrations of urea (≤11.51 μmol N dm^-3) were found in the area of wastewater release. Ammonium uptake (6.14-534 nmol N dm^-3 h^-1) strongly exceeded nitrate uptake (0.19-138 nmol N dm^-3 h^-1), indicating that discharges of ammonium by the pipeline are actively assimilated by plankton community even at low levels of light. Distribution of Zn (≤27.7 ppb), Cu (≤25.6 ppb), Cd (≤0.80 ppb) and Pb (≤13.5 ppb) in the water column and the measurement of their complex-forming capacity in seawater did not indicate a persistent perturbation of the pelagic environment due to heavy metals.     

Heavy metals and organic carbon in sediments from the Tuy River basin,Venezuela

The Tuy River basin, located in north-central Venezuela with an annual average temperature of 27°C and precipitation of 140 cm, was selected to conduct a geochemical study of bottom sediments, with the object of establishing the natural and human influences in the abundance and distribution of Fe, Mn, Cr, Co, Cu, Ni, Pb, Zn and organic carbon. The basin is lithologically divided into two sub-basins, north and south. The north sub-basin drains a iow-grade metasedimentary terrain with a population density of 800 persons km^–2 and approximateiy 600 industrial sites, while the south sub-basin in underlain by metavolcanic and ultramafic rocks, with a population density of less than 10 persons km^–2.Stream bottom sediment samples (150) were collected during the years of 1979–1986 in 16 unpolluted sites and 13 polluted sites. The sediments were air dried at room temperature and sieved through a 120 stainless steel mesh (125 m). Samples of grain size smaller than 125 m were analysed, the heavy metals being determined by atomic absorption spectrometry and the organic carbon (Corg) by dry combustion.The higher concentrations of heavy metals and organic carbon found in the pristine areas were in the south sub-basin, especially in those areas with higher annual precipitation and tropical forest. This indicated that the metavolcanic and ultramafic rocks yield higher concentrations of heavy metals than the metasedimentary rocks. It was also noted that the higher concentrations of Cr and Ni are associated with the ultramafic rocks. The results obtained from the sediment samples collected in the polluted sites showed that the elements Pb, Zn and Corg are enriched up to 4 times as a result of ail the human activities taking place in the basin. Organic carbon is an excellent indicator of domestic wastewater, Pb and Zn are good indicators of the automotive traffic and industrial effluents. The concentrations of each heavy metal did not show any significant correlation with grain size fractions; however, the concentration of organic carbon did show a negative correlation with grain size. The lithological, climatic and vegetation influence in the abundance of heavy metals and organic carbon in stream sediments clearly indicates the necessity of establishing background levels for the area under study when carrying out studies in environmental geochemistry.     

Evaluation of dilute hydrochloric acid and acid ammonium oxalate as extractants for some heavy metals from Nile River sediments

The suitability of a 0.5 M HCl solution for extraction of Fe, Mn, Cd, Co, Cu, Pb, and Zn from Nile River sediments was evaluated by comparing its effectiveness with that of conventional acid ammonium oxalate (Tamm's solution) and aqua regia extraction solutions. The present study has shown that although the extraction data indicate that both 0.5 M HCl and acid ammonium oxalate solutions are able to extract heavy metals simultaneously from the adsorbed, organic, and precipitated phases of Nile sediments, the 0.5 M HCl solution is preferred. It provides a rapid, reliable, and inexpensive method of measuring environmentally mobile metal concentrations in the aquatic sediments. From an analytical chemistry point of view, the 0.5 M HCl extracts do not clog the atomizer of the spectrophotometer. Extraction with dilute HCl solution obviates the need to use chemicals, some of which are toxic or not available readily as a high-purity grade. A standard extraction method should be relatively simple, to conduct a routine analysis of large numbers of sediment samples, yet at the same time it should provide sufficient information for assessment of the environmental impact of particulate metals. Therefore, extraction with 0.5 M HCl solution is very suitable for heavy-metal pollution monitoring in the Nile River     

Geochemical index of trace metals in the surficial sediments from the western continental shelf of India, Arabian Sea

The present study focuses on the determination and abundance of trace metals (viz. Cu, Ni, Zn, Cr, Co, Cd, Mn and Fe) in the surficial sediments of west coast of Arabian Sea along the Indian subcontinent. Sediment samples were collected from three transects along the western continental shelf of Arabian Sea. The enrichment of Fe and Mn in coastal oxic-sediments indicates the precipitation of these redox sensitive elements as Fe- and Mn-hydroxides and oxides, whereas the low Fe and Mn concentrations in the oxygen deficient sediments of deeper stations reflects the dissolution of their hydroxides and oxides. Concentrations of fairly redox insensitive trace metals like Cu, Ni, Zn, Cr and Cd (with the exceptions of Cr) showed higher values at nearshore sediments, then it decreased towards seaward and again showed a slight increase at oxygen minimum stations in all the three transects. This geochemical variability in their distributional characteristics is mainly associated with the extent to which the precipitation or dissolution of Fe- and Mn-oxides/hydroxides occur since the scavenging or releasing effects of Fe- and Mn-oxides/hydroxides act as significant ‘sinks’ or ‘sources’ of heavy metals. The change in wind pattern, coastal upwelling and increased productivity are also the reported factors which influence the biogeochemical cycling of trace metals in the surface sediments of west coast of India. Enrichment factor generally showed a high gradient accumulation from nearshore to shelf.     

食物中重金属的生物可给性和生物有效性的研究方法和应用进展

食品安全问题是直接关系到人民健康的重大民生问题。随着民众生活质量的不断提升,人们对食物质量的关注度越来越高。目前,重金属污染问题是食品安全的一个重要议题。而且,食物中重金属的生物可给性和生物有效性的测定结果已逐渐代替重金属的全量结果进行评价。因此,本文系统介绍了生物可给性和生物有效性的定义及相关关系,综述了生物可给性和生物有效性的多种研究方法的适用性及优缺点,着重总结了饮食习惯和肠道微生物对重金属生物可给性和生物有效性的影响,指出研究者应根据自己的研究目的选择不同的体外消化方法,饮食习惯和肠道微生物均极大地影响着食物中重金属的生物可给性和生物有效性,并在此基础上对食物中重金属的生物可给性和生物有效性研究今后的发展方向进行了展望。     

Importance of background values in assessing the impact of heavy metals in river ecosystems: case study of Tisza River,Serbia

The main objective of this paper is to evaluate how a choice of different background values may affect assessing the anthropogenic heavy metal pollution in sediments from Tisza River (Serbia). The second objective of this paper is to underline significance of using geochemical background values when establishing quality criteria for sediment. Enrichment factor (EF), geoaccumulation index (I _geo), pollution load index (PLI), and potential ecological risk index (PERI) were calculated using different background values. Three geochemical (average metal concentrations in continental crust, average metal concentrations in shale, and average metal concentrations in non-contaminated core sediment samples) and two statistical methods (delineation method and principal component analyses) were used for calculating background values. It can be concluded that obtained information of pollution status can be more dependent on the use of background values than the index/factor chosen. The best option to assess the potential river sediment contamination is to compare obtained concentrations of analyzed elements with concentrations of mineralogically and texturally comparable, uncontaminated core sediment samples. Geochemical background values should be taken into account when establishing quality criteria for soils, sediments, and waters. Due to complexity of the local lithology, it is recommended that environmental monitoring and assessment include selection of an appropriate background values to gain understanding of the geochemistry and potential source of pollution in a given environment.     

Ameliorants to immobilize Cd in rice paddy soils contaminated by abandoned metal mines in Korea

The Yarlung Tsangbo (YT) is a large river running across southern Tibet and has significant effects on its lower reaches, the Ganges–Brahmaputra Basin. In order to investigate the geochemical features of the YT, 18 surface sediment samples were collected; ten trace element concentrations were measured for bulk sediments and two fine grain size fractions. Meanwhile, basic physicochemical parameters and element concentrations of river water were also analyzed. Results indicated that the river water was alkaline (pH 8.42) and that dissolved oxygen was mainly controlled by river water temperature. Some elements (e.g., Zn and Ni) showed close negative relationship to mean grain size of the sediments. Concentrations of most heavy metals, except As of the YT bulk sediments, were similar to those of Upper Crustal Concentration and its lower reaches, indicating almost no anthropogenic impact. Arsenic of the YT sediments was derived fundamentally from the parent rocks of the YT Basin and was far higher than that of its lower reaches. This indicates that relatively small amounts of As from the study area were transported down to the Brahmaputra River under present, relatively dry climatic conditions. However, more YT sediments might have been transported to its low reaches during the Holocene due to the wet climate, giving high As concentration in Holocene sediments of the Ganges–Brahmaputra Basin. Thus, As transported by the YT may produce important influence on the Ganges–Brahmaputra Basin and contribute to its high As concentration in groundwater.     

利用藻红外测试技术研究多种重金属溶液对滇池铜绿微囊藻的毒性作用

为考察多种重金属同时存在的混合溶液对藻类的生物毒性,选择Cr(Ⅲ)、Pb(Ⅱ)、Hg(Ⅱ)、Cd(Ⅱ)、Mn(Ⅱ)5种重金属,以按照国家饮用水卫生标准限值浓度配制的单一重金属溶液和多种重金属混合溶液为受试样品,并利用本实验室开发的藻红外测试技术,评价了低浓度下单一重金属溶液和多种重金属共存溶液对藻的生物毒性。实验结果显示:按照饮用水标准限值配制的5种单一重金属溶液均未观察到对藻有生物毒性,但在多种重金属共存的27个不同组合的混合溶液中,有73.1%的样品表现出明显的生物毒性;藻响应出现率与混合溶液中重金属的总浓度呈正相关关系(r=0.8942)。当多种重金属以二元至五元混合时,藻响应出现率分别为50%、80%、100%、100%,表明随着重金属组分的增加,混合溶液的毒性作用越来越显著。当不同混合溶液的重金属总浓度大于0.11 mg·L-1时,平均累积藻响应占比显著上升到93%,表明重金属混合溶液中藻的毒性与总浓度之间存在剂量响应关系。采用平均藻响应出现率分析,结果显示混合溶液中不同重金属的相对影响顺序为:Cr(Ⅲ)87.5%>Pb(Ⅱ)和Hg(Ⅱ)58.3%>Cd(Ⅱ)和Mn(Ⅱ)54.3%,表明Cr(Ⅲ)表现出的藻毒性远高出其他重金属。现行的水质标准通常采用单一指标和限值,本研究结果表明采用单一指标不能有效规避多种污染物共存体系的环境风险。