鄂东南云中湖近50a沉积物微量元素记录

近年来湖北省通山县九宫山风景区的云中湖污染日益严重,已引起诸多关注,然而目前并不清楚该湖生态环境变化轨迹以及原因。通过对云中湖沉积物年代学、微量元素、有机碳和粒度分析,结合聚类分析和地质累积指数等方法,揭示近50a云中湖环境变化历史。结果表明,云中湖沉积物中14种微量元素含量随深度呈相似的变化趋势,且两两之间呈显著正相关关系,反映元素输入物源的一致性。在20世纪80年代前,湖底沉积物中微量元素含量变化很小,表明流域环境变化较小,20世纪80年代以来微量元素含量呈波动变化,其中在10和4 cm深度出现2次明显低值,下部低值与沉积物粒度增粗相对应,这可能是由于气候和人为旅游开发原因所致;顶部低值与有机碳含量增加相一致,反映了水体富营养化过程以及有机质输入对沉积元素的稀释作用。1993年以来元素V/Cr比值明显增加并超过2.0,反映底层水体向缺氧状态转变。各元素的地质累积指数小于0.5,表明云中湖重金属污染程度处于较轻水平。综合分析云中湖沉积物研究记录可知,20世纪90年代之前云中湖湖泊环境相对稳定,20世纪90年代以后流域环境发生明显变化,水体环境呈恶化趋势。     

秦淮河表层沉积物毒害微量元素分布特征及污染评价

在秦淮河流域采集河流表层沉积物样品,研究其毒害微量元素含量的空间分布和生态风险.流域沉积物中毒害微量元素的含量表现出明显的空间分异.Hg、Cd、Pb、Cu和Zn受流域城市化过程的影响最为显著,其富集主要集中在流域中、下游的老城区、新城区和城乡过渡区.As的分布除了与城市工业企业的排污有关外,还可能受农业活动的影响.毒害...     

青海湖流域主要河口区沉积物中重金属元素生态风险评价

为摸清青海湖流域重金属的污染现状,对流域内11处河口区0~5 cm层沉积物进行调查取样,分析测定了表层沉积物中Zn、Cu、Pb、Hg、Ni、As、Cd和Cr 8种重金属元素含量,并对其来源、生态风险及污染状况进行评价。结果显示:(1)青海湖流域沉积物中8种重金属含量和介于151.61~277.31 mg·kg~(-1),平均值为209.65 mg·kg~(-1),略高于青海湖流域表层土壤环境背景值。重金属含量由高到低依次为As、Zn、Cr、Ni、Cu、Pb、Cd和Hg,其中As、Cr和Zn占8种重金属总含量的73.63%。青海湖流域重金属元素间具有相似来源,人类对重金属元素的影响主要体现在交通运输和农业活动上。重金属地累积系数I_(geo)从大到小依次为As、Hg、Cd、Cu、Cr、Ni、Zn和Pb,其中As的污染程度为偏中度,平均地累积指数I_(geo)为1.67。重金属潜在生态风险值从大到小依次为Hg、Cd、As、Cu、Ni、Pb、Cr和Zn,其中Hg、Cd和As对综合潜在生态风险指数I_R的平均贡献率分别为40.76%、25.56%和25.53%。(2)近年来青海湖流域内的交通运输、农业废水、小城镇化及旅游开发等人类活动造成的重金属排放问题已经开始显现,流域生态系统的自净能力不能将所有重金属元素均净化至低风险水平。因此,必须加强对中小河流与季节性河流中重金属元素的监测和预警,制定出针对性的治理和修复措施,保证青海湖流域内不受重金属污染的威胁。     

电子废物不当处置的重金属污染及其环境风险评价 Ⅳ. 电子废物不当回收地区流域水体沉积物的重金属污染

为了解电子废物不当处置活动对小流域内水体沉积物金属污染的影响,采集了位于广东省清远市龙塘镇和石角镇的电子废物焚烧和酸解活动核心区内水塘和水库的0～40cm沉积物以及附近河流大燕河表层(0～5cm)沉积物样本,分析了样本中的金属(水塘、水库:Zn、Cu、Pb、Cd、Cr;大燕河:Zn、Cu、Pb、Cd、Cr、Ni、Mg、Mn)含量.作为对照,对珠江口伶仃洋沉积物中的5种重金属(Zn、Cu、Pb、Cd、Cr)含量也进行了分析.结果表明,1)在核心区内,5种重金属的平均含量在接近酸解作坊的水塘沉积物中呈Cu(766.16mg·kg-1)>Zn(181.12mg·kg-1)>Pb(129.56mg·kg-1)>Cr(1.89mg·kg-1)≈Cd(1.12mg·kg-1),在其下游的水库沉积物中呈现相同的规律,但水塘沉积物的Cu、Zn、Pb含量均高于水库.水塘、水库沉积物重金属含量分布规律明显不同于伶仃洋沉积物,与伶仃洋沉积物相比,核心区水体沉积物Cu含量特别高,是伶仃洋沉积物的7～17倍,Pb和Cd则分别是伶仃洋的2.3～3.0倍和1.9～2.4倍,Zn、Cr含量与伶仃洋沉积物相近.2)Zn含量在核心区水体沉积物中均呈现出在20.0～30.0cm深度最高的趋势,Cu、Pb含量在水库沉积物中也有类似的表现,说明该深度的沉积物可能是电子废物回收处置活动最频繁的时期形成的,近年来随着政府取缔工作的加强,电子废物非法处置活动的减少,Zn、Cu、Pb含量有明显的下降.3)大燕河沉积物中6种重金属(Zn、Cu、Pb、Cr、Cd、Ni)的总含量表现为中游下段(1261.3mg·kg-1)>中游中段(1049.2mg·kg-1)>中游上段(401.8mg·kg-1)>上游(364.6mg·kg-1)>下游(215.4mg·kg-1).Cu、Zn、Pb和Cr含量均在中游下段的沉积物中出现最大值,次大值出现在中游中段,Ni、Cd在中游中段出现最大值,次大值出现在中游下段.中游中、下段沉积物中金属含量最大值和其上游(或中游上段)河段含量最低值的比值呈现Cu(10.1)>Cr(7.8)>Zn(3.8)>Cd(2.0)>Pb(1.9)>Ni(1.8),显示这些重金属主要从中游中、下段进入大燕河沉积物,其中Cu污染最为严重,而Cr污染可能与水土流失或当地其他活动释放的Cr有关.4)比较流域内土壤和各种沉积物以及伶仃洋沉积物中重金属的构成比例发现,核心区土壤和沉积物以及大燕河沉积物中的重金属具有明显的同源性.随着离源区距离的增加,重金属的构成比例中最明显的变化是Cu的比例下降以及Zn的比例上升。     

黄柏河梯级水库沉积物营养盐与重金属分布特征及污染评价

黄柏河为长江左岸的一级支流,是宜昌市重要的水源地和长江流域最大的磷矿基地之一,评价其沉积物营养盐和重金属污染特征,对于揭示高磷矿背景区域沉积物的污染状况及其控制与管理具有重要意义,也是当前长江大保护形势下的必然需求。分别采集了黄柏河4个梯级水库库首、库中和库尾的表层沉积物,研究分析了沉积物中营养盐和重金属的质量分数及分布特征,采用综合污染指数法和有机污染指数法评价了表层沉积物营养盐污染状况,使用潜在生态风险指数法和地累积指数法评价了沉积物6种重金属的污染状况。结果表明:黄柏河梯级水库表层沉积物总有机碳(TOC)和总氮(TN)平均质量分数分别为26.9 g·kg~(-1)和1 500.4 mg·kg~(-1),其中最下游的尚家河水库质量分数最小,TOC和TN污染主要处于轻度到中度污染水平;总磷(TP)质量分数空间差异性较大,介于622.2—9 631.5 mg·kg~(-1)之间,受流域磷矿矿点分布以及水库拦截作用的影响,TP分布从上游至下游呈现递减的趋势,流域整体处于磷重度污染水平。重金属锌(Zn)、铅(Pb)、铜(Cu)、砷(As)、镉(Cd)和汞(Hg)的平均质量分数分别为128.63、39.37、27.95、10.23、0.35、0.26 mg·kg~(-1),潜在生态风险指数和地累积指数评价表明黄柏河梯级水库表层沉积物Hg的生态风险较高,其次为Cd,剩余4种重金属的生态风险较低。沉积物碳氮比(TOC/TN)和Pearson相关性分析指出,沉积物有机质来源主要为陆源性输入,重金属Hg和Cd输入可能分别与面源性的TN输入和磷矿开采导致的TP输入具有同源性。     

南京主要湖泊表层沉积物中重金属污染潜在生态风险评价

为掌握南京城市湖泊表层沉积物中重金属的污染概况及其潜在生态风险,选取玄武湖、月牙湖、紫霞湖、琵琶湖和前湖5个主要湖泊为研究对象,应用电感耦合等离子体原子发射光谱法( ICP - AES)分析表层沉积物中Cd、Cr、Cu、Ni、Pb和Zn含量,并采用地累积指数法和潜在生态风险指数法对重金属污染风险和潜在生态危害进行评价.结果表明,湖泊表层沉积物中Cd、Cr、Cu、Ni、Pb和Zn含量分别为0.8～5.1、10.3 ～67.6、6.2 ～70.5、未检出～53.2、12.9 ～ 55.9和40.6 ～456.3 mg·kg -1.地累积指数法评价结果显示,6种重金属元素累积程度由高到低依次为Cd、Zn、Pb、Cu、Ni和Cr,其中Cd处于偏中等累积到重累积水平.潜在生态风险指数法评价结果显示,表层沉积物重金属污染最严重的是月牙湖,其次是前湖和紫霞湖,这3个湖泊都处于中等潜在生态风险状态,琵琶湖和玄武湖处于低潜在生态风险状态.     

滇池沉积物中重金属污染特征及其生态风险评估

采集了滇池北部和中心区域2根柱状沉积物样品,分析其常量元素（Fe、Mn、Al、Ti、Ca、K）、微量元素（Ba、Sr、Cu、Pb、Zn、V、Cd）剖面分布特征,并采用H？kanson潜在生态危害指数法对典型重金属（Cd、Cu、Zn、Pb）进行了污染潜在生态风险评估。结果表明：沉积物中常量元素以Fe2O3、CaO及Al2O3为主,MnO、K2O及TiO2含量较少,变化范围是Fe2O3为8.0～14.9%、MnO为0.1～0.2%、Al2O3为9.0～20.1%、TiO2为1.5%～2.8%、CaO为0.4～21.7%、K2O为1.5～2.0%;微量元素Pb, Cd, Zn, Ba, Cu, Sr 及V含量均较高,变化范围是Pb为73.8～105.3 mg·kg^-1、Cd为1.0～3.4 mg·kg^-1、Zn为123.4～210.6 mg·kg^-1、Ba为264.8～435.7 mg·kg^-1、Cu为77.5～133.5 mg·kg^-1、Sr为34.9～137.5 mg·kg^-1以及V为177.7～284.7 mg·kg^-1。尤其表层0～12 cm内（1950 s以后）,各元素含量值均明显高于12 cm以下各值,20世纪50年代后滇池流域内工农业发展及污染物输入是造成金属元素含量累积的主要因素。沉积物中典型重金属Cu、Zn、Pb、Cd污染潜在生态风险评估结果：Cu、Zn和Pb处于中度污染,且C if 值越接近表层（0～12 cm）其值越高,这表明自1950S后污染程度不断加重,其中 Cd 累积与污染比较严重,分析多种元素的多因子污染参数之和C d表明滇池沉积物中多种元素污染整体处于“较高”污染程度,分析多种元素的潜在生态风险指数RI表明滇池沉积物中重金属潜在生态风险处于“很高”水平。同时,滇池北部沉积物中重金属潜在危害较严重且近年来污染有加重趋势。     

闽北建溪流域表层沉积物营养元素分布特征及生态风险评价

为了解闽江上游流域沉积物环境的现状,本文研究闽北建溪流域表层沉积物中营养元素的分布特征及生态风险,描述了表层沉积物中有机碳(TOC)、总氮(TN)和总磷(TP)的含量分布,运用单因子指数法进行生态风险评价,并分析碳、氮、磷的比例,阐述其相关关系及其环境意义.结果表明,沉积物中TOC、TN和TP的含量均值分别为3.05%、1858.05 mg·kg~(-1)和624.68 mg·kg~(-1),对多数底栖生物处于安全范围; TOC的单因子污染指数范围为2.0—5.8,TN污染指数范围为2.3—4.4,TP指数范围则为0.4—1.7,具有潜在的生态风险;沉积物营养元素比值中TOC/TN均值为16.9,TOC/TP均值为53.7,TN/TP均值为3.2,表明建溪流域沉积物营养元素受内、外源共同输入影响,且以外源作用为主导,其中林地营养物质输出是沉积物营养累积的主要原因之一.总体而言,建溪流域沉积物TN的生态风险较高且主要受流域面源排放影响,TOC与TP的生态风险较低.因此,应着重加强流域氮素面源污染调查并对重点污染源加以严控,减轻流域总氮的生态风险.     

湘江长沙段沉积物重金属污染特征及其评价

本研究用沉积柱钻探取样法获得湘江长沙段沉积物样品,利用等离子质谱仪(ICP-MS)分析沉积物中9种重金属含量,并利用X射线衍射仪(XRD)分析沉积物的矿物组成.在此基础上,利用地累积指数和潜在生态风险指数等方法,评价沉积物重金属污染程度.结果表明,湘江长沙段沉积物中重金属含量变化较大(CV﹥0.20),分布不均一.其中Mn、Zn、Pb、Cu、Cr、Co、Ni达中等-显著富集程度,而V、Th无明显富集.地累积指数和潜在生态风险评价结果显示,长沙段沉积物中Pb、Zn、Mn、Cu达偏中度至偏重度污染,Cr、Co、Ni、Th为轻污染.重金属存在轻至中等程度的潜在生态风险,其风险程度大小排序为:PbCuNiCoZnMnCrV.沉积物中Mn、Cu、Zn、Pb、Co、Ni、Cr、V可能与流域中上游矿石冶炼等人为活动带入有关,而Th可能来自流域岩石风化等自然过程.流域重金属污染防治中,应密切关注Mn、Cu、Zn、Pb等重金属引起的污染.     

清潩河流域沉积物重金属形态分布特征及风险评价

清潩河是淮河流域沙颍河重要支流,贯穿许昌市区,承担流域内许昌、长葛市的防洪排涝、纳污及农灌功能。沉积物是水体的重要组成部分,分析沉积物中重金属的含量及形态的分布特征,对于流域水污染控制和治理,维护水体安全具有重大意义。选取干流及其支流共计30个点位,按照所属状态分为4个区域,对沉积物进行了采集,采用Tessier连续提取法对沉积物中重金属进行形态分析,基于地累积指数法(Igeo)、潜在生态风险指数法(RI)和风险编码法(RAC)对其进行风险评估。结果表明:(1)清潩河流域沉积物中8种主要重金属元素,除As和Cu以外均显著高于河南省环境土壤背景值,Igeo与RI评价表明流域呈现一定环境风险,Cd和Zn是主要的污染因子,同时部分点位的Hg、Cu、Cr高于河南省环境土壤背景值,污染最严重的区域为许昌市区段;Cd是该次调研中生物有效态占比最高的金属,在许昌市上游点位含量显著增加;(2)RAC结果指示Cd、Zn的生物有效态在农村区域高于城市,清潩河许昌市下游区域具有最高的风险系数,流域整体沉积物中重金属风险性表现为:CdZnCuPbCrAs;(3)通过聚类分析和相关性分析发现重金属形态在农村与城市区域分布不同,城市区域与Cu的碳酸盐结合态及铁锰氧化物结合态呈显著的负相关性,而Cd及Zn的铁锰氧化物结合态同农村农田地区呈显著的正相关性,这可能与区域间具有不同的污染特征有关。     

Assessment of enrichment,geo-accumulation and ecological risk of heavy metals in surface sediments of the Msimbazi mangrove ecosystem,coast of Dar es Salaam,Tanzania

Results of the assessment of enrichment, accumulation and the ecological risk associated with three heavy metals (Cd, Cu and Pb) and one metalloid (As) in surface sediments of Msimbazi estuary are presented. Surface sediment samples (0–5 cm) were collected from Msimbazi River estuary in September 2016 using handheld PVC short corers. Long-sediment cores from the site were also collected using PVC pipes and their vertical profiles of metals concentrations assessed with the aim of establishing site-specific baseline metals concentrations. The established site-specific baseline values were used for the determination of normalised enrichment factors (EF) and geoaccumulation (Igeo) of metals instead of using average crustal values. Iron-based enrichment factors show that the sediments of Msimbazi have experienced enrichment of metals that originate from anthropogenic sources of pollution (EF > 1). Geo-accumulation results indicate that Msimbazi sediments can be designated as uncontaminated to moderately-contaminated with As, Cd and Pb (class 1–2). Geoaccumulation indices for Cu indicate that sediment can be designated as uncontaminated to moderately contaminated (class 1) and moderately to strongly contaminated (class 3). Results show further that the Ecological Risk associated with the accumulation of these metals in Msimbazi sediments was low based on Hakanson approach.     

Use of the digestive gland of the oyster Crassostrea rhizophorae (Guilding, 1828) as a bioindicator of Zn,Cd and Cu contamination in estuarine sediments (south-east Brazil)

This study demonstrates the accumulation of Zn, Cd and Cu in the digestive gland of the oyster Crassostrea rhizophorae in response to the contamination of sediments and discusses the potential use of this specific organ in monitoring metal contamination in tropical areas. Sediment and oyster samples were collected from coastal Rio de Janeiro sites with different levels of human impact: Sepetiba Bay, Guanabara Bay and the Paraty coast. Metal concentrations were measured using inductively coupled plasma optical emission spectrometry (ICP OES). Significant statistical differences (p<0.001; p<0.05) were observed for Zn and Cd concentrations in the digestive gland; the highest Zn concentrations were found at Sepetiba, followed by Guanabara and Paraty. The highest digestive gland Cd concentrations were found at Paraty, followed by Sepetiba and Guanabara. These concentrations were proportional to those found in the sediments. There was no significant difference (p>0.05) in Cu among the sampling sites. The highest digestive-gland Cu concentration was also found at Sepetiba, followed by Guanabara. The biosediment accumulation factor indicated a gradient of sediment contamination for Zn and Cd. The digestive gland of C. rhizophorae can be a potential indicator of trace metal contamination in sediments from tropical estuarine environments.     

脱硫石膏对重金属污染沉积物中Cd的稳定固定化作用

研究了掺杂不同比例脱硫石膏的沉积物中Cd的吸附热力学特征及其稳定固定化效果。实验将脱硫石膏掺杂比例不同的沉积物与不同初始质量浓度的Cd溶液混合、振荡、离心后测定上清液中Cd的质量浓度,结果表明,脱硫石膏掺杂量不同的沉积物吸附Cd的热力学过程均符合Langmuir吸附等温线;脱硫石膏掺杂比例的提高增强了沉积物对溶液中Cd的吸持能力,二者显著正相关;脱硫石膏的掺杂还削弱了溶液中Cd初始质量浓度对其固定率的影响,使研究中8个初始质量浓度下沉积物对Cd的固定率均维持在较高水平。通过16个时间点对连续搅拌下的沉积物样品溶液中Cd质量浓度的测定,研究了模拟重金属污染沉积物和自然沉积物掺杂脱硫石膏前后对照了其中Cd的稳定性,结果表明,脱硫石膏的掺杂降低了沉积物中Cd的释放量,并将实验条件下两种沉积物中Cd的固定率均保持在99.2%以上且保持相对平稳状态。同时,脱硫石膏的掺杂可导致吸附体系pH的升高,促进了Cd与固相介质之间由吸附向沉淀作用的转化,从而提高了沉积物中Cd的稳定性,有利于重金属污染沉积物中Cd的稳定固定化。     

Source and Effect of Heavy Metal Pollution in the Coastal Taiwan Sediments

Coastal sediments and oyster farming is severely affected by the industrial effluents in the coastal region near LuGong, Taiwan. Surficial sediments and oyster samples were collected from a coastal area near a major electro-plating industry. Spatial variation in heavy metal contents in sediments was studied in relationship to the main pathway of contamination and geochemical association with natural constituents of the sediments.

Spatial trends of heavy metals in the sediment reflected inputs of pollutants from the poorly-treated electro-plating effluents in the surrounding county and transported downstream by the Yang-tse-tru River. Effluent related heavy metal (Zn, Cu, Cd) is extremely high in the study region sediments. the highest concentrations were observed near shore, especially upstream in the Yang-tse-tru River sediments. Heavy metal concentrations decreased rapidly in a seaward direction. Heavy metal concentrations in near shore sediments were as high as some highly industrialized harbour sediments in the USA (e.g. Boston and San Diego).

Significant differences and high concentrations of heavy metals were also observed in oysters from the study region. Heavy metals from the study region were two to five times higher than in oysters from other pristine areas in Taiwan.     

Evaluating heavy metal contamination of riverine sediment cores in different land-use areas

• Metal pollution was studied in riverine sediments from different land-use areas. • Cd was the most serious heavy metal contaminant in riverine sediment cores. • Riverine sediment cores from industrial area were most polluted by heavy metals. • B1 fraction determined metal pollution, risk and toxicity in riverine sediments. Anthropogenic activities are regarded as the main sources of heavy metal pollution, yet few studies have investigated the effects of land-use setting on heavy metal accumulation in riverine sediments. Based on both total contents and geochemical fractions, heavy metal pollution, risk and toxicity were determined in riverine sediment cores from different land-use areas (mountain area- MA, farm area- FA, city area- CA, and industrial area- IA) of the Yang River Basin in North China. The results showed that FA had higher contents of riverine sedimentary Cu; CA had higher contents of Cd; IA had higher contents of both Cd and Zn. Most riverine sediments from FA and IA were contaminated with the investigated metals, although these concentrations were evaluated to have low potential ecological risk and no toxicity to benthic organisms. However, a high proportion of Cd in the B1 fraction of riverine sediments in IA indicating high risk should receive more attention. The B1 fraction largely determined the contamination, risk and toxicity levels associated with heavy metals in the riverine sediments of the Yang River Basin.     

Chronic renal failure among farm families in cascade irrigation systems in Sri Lanka associated with elevated dietary cadmium levels in rice and freshwater fish (Tilapia)

Chronic renal failure (CRF), in the main agricultural region under reservoir based cascade irrigation in Sri Lanka has reached crisis proportion. Over 5,000 patients in the region are under treatment for CRF. The objective of this study is to establish the etiology of the CRF. Concentrations of nine heavy metals were determined in sediments, soils of reservoir peripheries, water and Nelumbo nucifera (lotus) grown in five major reservoirs that supply irrigation water. All five reservoirs carried higher levels of dissolved cadmium (Cd), iron (Fe) and lead (Pb). Dissolved Cd in reservoir water ranged from 0.03 to 0.06 mg/l. Sediment Cd concentration was 1.78-2.45 mg/kg. No arsenic (As) was detected. Cd content in lotus rhizomes was 253.82 mg/kg. The Provisional Tolerable Weekly Intake (PTWI) of Cd based on extreme exposure of rice is 8.702-15.927 mug/kg body weight (BW) for different age groups, 5-50 years. The PTWI of Cd due to extreme exposure of fish is 6.773-12.469 mug/kg BW. The PTWI on a rice staple with fish is 15.475-28.396 mug/kg BW. The mean urinary cadmium (UCd) concentration in CRF patients of age group 40-60 years was 7.58 mug Cd/g creatinine and in asymptomatic persons UCd was 11.62 mug Cd/g creatinine, indicating a chronic exposure to Cd. The possible source of Cd in reservoir sediments and water is Cd-contaminated agrochemicals. The CRF prevalent in north central Sri Lanka is a result of chronic dietary intake of Cd, supported by high natural levels of fluoride in drinking water, coupled with neglecting of routine de-silting of reservoirs for the past 20 years.     

Heavy Metal Contamination and Distribution in the Urban Environment of Guangzhou, SE China

Ever-increasing heavy metal accumulation in the urban environment of Guangzhou, the largest light industrial production base and one of the most rapidly developing cities in China, poses a serious threat to environment as well as to human health in the region. As a sink or source, urban deposits are good indicators of the level and extent of heavy metal accumulation in the surface environment. The aim of this preliminary study was to examine the distribution of heavy metal contamination in the urban environment of Guangzhou. It was based on a systematic sampling of road dusts and corresponding gully sediments along major roads running mainly through commercial and residential to industrial districts of the city. In addition to road dusts and gully sediments, ceiling dusts from the Pearl River Tunnel were also collected to characterize anthropogenic emissions dominated by traffic-related activities. In general, the level of Cd, Cu, Pb and Zn contaminations were more severe on the industrialized side of Guangzhou than on the western side where heavy traffic and industrial activities were limited. The primary determinants of the level of heavy metal contamination and the distribution of this contamination in the urban environment of Guangzhou were the site-specific conditions of its urban setting, particularly the types of industries, the nature of the traffic flow, sample residence times and variations in grain size of the particulate contaminants. This study highlights the complexity of the urban system and indicates that in just such a system individual urban components should be interlinked to assess the long-term environmental and health effects of heavy metal contamination. Among the heavy metals tested – Cd, Cu, Pb and Zn – the level of Zn contamination was the most severe and widespread, and thus requires immediate attention.     

长江南京段近岸沉积物中重金属富集特征与形态分析

在对长江南京段八卦洲和杨中两个冲积洲近岸沉积物及其优势野生植物中A1、Cu、zn、Cr、Pb、Nj和Cd元素含量分析的基础上,分别考查了这些重金属的富集系数(EF)和生物富集因子(BCF),并采用BCR连续提取法对Cd的赋存形态进行了研究.结果表明,本区域长江近岸沉积物和野生植物中重金属存在不同程度的富集现象,两洲沉积物中Cu、Cr、Pb、Ni、Cd均有富集趋势,各元素EF>1的样品占总样品比例分别为Cu 50%、Cr40%、Pb40%、Ni 40%、Cd20%.而在野生桐蒿和芦蒿两种优势植物中Cd富集显著,其中桐蒿的BCF平均值高达2.57.采用BCR连续提取法对沉积物中Cd进行形态分析,结果显示,沉积物中Cd主要以酸溶/交换态(B1)和可还原态(B2)为主,二者分别为31.7%和45.5%,占到总量的70%以上,B1态远高于一般土壤和沉积物中重金属的分布,表现出很强的迁移性和生物可利用性.新生成沉积物较老沉积物中的B1态有显著增加,反映出沉积物越新,Cd的迁移性越强的趋势.研究结果说明长江城市段近岸沉积物中Cd受近期人为因素影响明显,具有一定的生态风险.     

Cadmium contamination in Tianjin agricultural soils and sediments: relative importance of atmospheric deposition from coal combustion

Cadmium (Cd) in coal, fly ash, slag, atmospheric deposition, soils and sediments collected from Tianjin, northern China, were measured to provide baseline information and determine possible Cd sources and potential risk. The concentrations of Cd in coal, fly ash and atmospheric deposition were much higher than the soil background values. Fallout from coal-fired thermal power plants, heating boilers and industrial furnaces has increased the Cd concentration in soils and sediments in Tianjin. The concentrations of Cd in soils of suburban areas were significantly higher than in rural areas, suggesting that coal burning in Tianjin may have an important impact on the local physical environment. Cd from coal combustion is readily mobilized in soils. It is soluble and can form aqueous complexes and permeate river sediments. The high proportion of mobile Cd affects the migration of Cd in soils and sediments, which may pose an environmental threat in Tianjin due to the exposure to Cd and Cd compounds via the food chain. This study may provide a window for understanding and tracing sources of Cd in the local environment and the risk associated with Cd bioaccessibility.     

Heavy metal accumulation in algae and sediments of the Black Sea coast of Turkey

The paper reports heavy metal accumulation in algae collected at four stations and in sediments at three stations on the Black Sea coast of Turkey. The metals analysed are Cd, Co, Cr, Cu, Fe, Pb, Sb and Zn. The metal content of algae increased generally (with some exceptions) from 1991 till 1993 in ?ile and Sinop. In the sediments Sb in ?ile, As in Riva, Fe, Zn in Sinop are high. According to these findings the metal pollution increased in Turkish area of the Black Sea during the years investigated.