Discovery,Genesis and Significance of Metallic Minerals in Evaporate Series in the Kuqa Basin

A large-scale evaporate series is developed in Paleogene-Neogene strata in the Kuqa basin. The series is composed mainly of evaporate with thin beds of clastic rock （mainly mudstone and siltstone）. In grayish white medium- and coarse-grained sandstone in Miocene strata, the formation of copper minerals is in close connection with brine. In joint planes, which are developed in vertical strata, are filled with gypsum. Gypsum and copper-mineralized sandstone contains enormous copper minerals, mainly atacamite. According to the SEM analysis for salt rock, gypsum rock, limestone, grayish green siltstone, grayish white medium-coarse-grained sandstone, some minerals are composed of metallic elements including Au, Ag, Cu, Zn, Pb, Co, Ni and U etc., in which Au occurs in a native form, Cu occurs in a native form or as atacamite in salt rock, gypsum rock and limestone, Ag occurs as silver sulfide in gypsum, and Zn, Pb, Co, Ni, U occur as compounds along with the above metallic ions in evaporate or clastic rock. From SEM images, we can see that metallic elements or their compounds （oxides or sulfides） ＂take root＂ as grains in salt or gypsum crystals, which belong to primary chemical sedimentation along with evaporate, while some grains ＂float＂ on surface of salt or gypsum. In the former case, mineral grains were formed together with salt （gypsum） crystals; while in the latter case, minerals were enriched from internal metallic ions （Paleogene evaporate samples） or external metallic ions （Neogene gypsum samples） in the late stage of evaporate formation. The metallic ions in Paleogene evaporate samples might originate from weathered or denudated materials in the south Tianshan Mountains. The metallic ions in the Neogene evaporate samples might be from metal- bearing brine, which migrated upward to surface along fractures and leached into evaporate （gypsum）. Occurrence of metallic minerals and their compounds （elementary substance） in Paleogene evaporate proves that diversified metallic minerals exist in evaporate. The source of metallic ions in the Neogene evaporate series shows that evaporate could provide materials for late-stage metallic mineralization.

Geochemical evidences of trace metal anomalies for finding hydrocarbon microseepage in the petroliferous regions of the Tatipaka and Pasarlapudi areas of Krishna Godavari Basin,India

The long-term seepage of hydrocarbons, either as macroseepage or microseepage, can set up near-surface oxidation reduction zones that favor the development of a diverse array of chemical and mineralogical changes. The bacterial oxidation of light hydrocarbons can directly or indirectly bring about significant changes in the values of pH and Eh of the surrounding environment, thereby also changing the stability fields of the different mineral species present in that environment. The paper reports the role of hydrocarbon microseepage in surface alterations of trace metal concentrations. In this study trace metal alterations were mapped that appear to be associated with hydrocarbon microseepages in the oil/ gas fields. A total of 50 soil samples were collected near oil and gas fields of the Tatipaka and Pasarlapudi areas of the Krishna Godavari Basin, Andhra Pradesh. The soil samples were collected from a depth of 2-2.5 m. The paper reports the chemical alterations associated with trace metals in soils that are related to hydrocarbon microseepages above some of the major oil and gas fields of this petroliferous region. Trace metals, such as scandium （Sc）, vanadium （V）, chromium （Cr）, cobalt （Co）, nickel （Ni）, copper （Cu）, zinc （Zn）, barium （Ba） and strontium （Sr）, in soil samples were analyzed using inductively coupled plasma- mass spectrometry （ICP-MS）. The concentrations of Sc （8 to 40 mg/kg）, V （197 to 489 mg/kg）, Cr （106 to 287 mg/kg）, Co （31 to 52 mg/kg）, Ni （65 to 110 mg/kg）, Cu （88 to 131 mg/kg）, Zn （88 to 471 mg/kg）, Ba （263 to 3,091 mg/kg） and Sr （119 to 218 mg/kg） were obtained. It was observed that the concentrations of trace elements were tremendously increased when they were compared with their normal concentrations in soils. The analysis of adsorbed soil gas showed the presence of high concentrations of YC2＋ （C2H6, C3H8 and n-C4H10） ranging from 7 to 222 μg/kg respectively. Integrated studies of trace elements over adsorbed light gaseous hydrocarbons （2C2＋） anomalies showed good correlation with the existing oil and gas wells. The carbon isotopic composition of δ13C1 of the samples ranges between -36.6%o to -22.7‰ （Pee Dee Belemnite） values indicate thermogenic origin, which presents convincing evidence that the adsorbed soil gases collected from these sediments are of catagenetic origin. The increase in the concentrations of trace metals near oil/gas producing areas, suggests a soil chemical change to a reducing environment, presumably due to the influence of hydrocarbon microseepage, which could be applied with other geoscientific data to identify areas of future hydrocarbon exploration in frontier areas.

Mining and Seasonal Variation of the Metals Concentration in the Puyango River Basin—Ecuador

The Puyango River Basin covers approximately an area of 4400 km2, it is located in Southern of Ecuador, with Calera and Amarillo rivers as tributaries. In this region, one of the main activities is small scale gold and silver mining. Currently there are 110 processing plants on the bank of Calera and Amarillo rivers, causing a significant degradation of natural resources. A seasonal comparison of metal concentrations in surface water, sediments and particulate matter from the Puyango River and its effluents is made. It was done a differentiation between natural contaminations with the anthropogenic one generated by mining activity. Samples were taken during dry season (2004) and rainy season (2006), and analyzed physicochemical parameters, anions and cations and the concentrations of heavy metals. The results show a clear influence of gold mining in Puyango River contamination, starting with its tributaries, Calera and Amarillo rivers, which have the highest concentrations of heavy metals from the basin, corresponding with the location of the mineral processing plants.

Evaluation of Four Anthropogenic Activity Impacts on Heavy Metal Quality of the Kumba River in the South West Region of Cameroon

Anthropogenic activities have contributed to pollution of water bodies through deposition of diverse pollutants amongst which are heavy metals. These pollutants, which at times are above the maximum concentration levels recommended, are detrimental to the quality of the water, soil and crops (plant) with subsequent human health risks. The objective of the work was to evaluate the impacts of human-based activities on the heavy metal properties of surface water with focus on the Kumba River basin. Field observations, interviews, field measurements and laboratory analyses of different water samples enabled us to collect the different data. The results show four main human-based activities within the river basin (agriculture, livestock production, domestic waste disposal and carwash activities) that pollute surface water. Approximately 20.61 tons of nitrogen and phosphorus from agricultural activities, 156.48 tons of animal wastes, 2517.5 tons of domestic wastes and 1.52 tons of detergent from carwash activities were deposited into the river each year. A highly significant difference at 1% was observed between the upstream and downstream heavy metal loads in four of the five heavy metals tested except for copper that was not significant. Lead concentrations were highest in all the activities with an average of 2.4 mg∙L−1 representing 57.81%, followed by zinc with 1.596 mg∙L−1 (38.45%) and manganese with 0.155 mg∙L−1 (3.74%) for the different anthropogenic activities thus indicating that these activities highly lead to pollution of the Kumba River water. The level of zinc and manganese was significantly influenced at ρ 005 by anthropogenic activities though generally the variations were in the order: carwash (3.196 mg∙L−1) < domestic waste disposal (3.347 mg∙L−1) < agriculture (4.172 mg∙L−1) < livestock (4.886 mg∙L−1) respectively and leading to a total of 14.04 tons of heavy metal pollutants deposited each day.

The Impact of Za’atari Refugee Camp on the Water Quality in Amman-Zarqa Basin

Za’atari camp is the largest refugee camp in Jordan. It was first established in 2012 to host Syrian refugees. Currently the camp hosts more than 81,000 refugees, with no proper sanitary system which might pose a major threat to surface resources in the area. An investigation was done at Za’atari refugees’ camp to find the impact of refugees settling on surface and groundwater quality. Surface water quality of surface runoff generated from thirty rain fall events were collected during the winter season of 2013/2014 from the major Wadi that passes through the camp and small ponds within the camp after the rainfall event. The collected samples were analyzed for acidity (pH), the electrical connectivity (EC), total dissolved solids (TDS), nutrients (NO3<sup style='margin-left:-7px;'>- and PO4<sup style='margin-left:-7px;'>3-) and selected heavy metals (Mn, Cd, Zn, Pb and Ni) in addition to biological oxygen demand (BOD5), chemical oxygen demand (COD) and intestinal worms (Total Coliform, E. cali). The results showed that there are significant variations in the EC as well as with TDS between the sites due to fluctuating amounts of water used for different activities within the camp as it was highest in the center of the camp where most of the refugees settle decreasing away from the center. The pH values were within the specifications of the World Health Organization and the Jordanian Standards. For nutrients, nitrate concentration was low with high phosphate ions which are most probably from detergents origin.

汾河流域地表水金属元素分布特征与健康风险评价

为研究汾河流域地表水中金属污染特征及其健康危害程度,本文采集汾河流域主要支流入河口及干流断面水样39组,检测As、Cu、Pb、Zn、Hg、Ni、Mn、Fe和Co共9种金属元素含量,利用多元统计分析法、水环境健康风险评价模型分析了流域地表水中金属元素分布特征及对成人与儿童产生的健康危害.结果表明,研究区主要超标元素为Hg、Fe和Mn,污染区主要分布于汾河干流中下游和支流.汾河干流上游Fe、Mn、Zn和Co变化幅度较大,中游、下游次之;各支流金属元素含量差异较大.多元统计分析显示,Hg和As主要来源于工业污染及农业污染等;Cu、Pb、Zn、Ni、Co、Fe和Mn来源于工农业生产和交通运输.健康风险评价表明,汾河流域各河段健康总风险为汾河支流>汾河下游>汾河中游>汾河上游,汾河中下游和支流健康风险危害较大,健康风险均为中等;经饮用水途径造成的健康风险儿童是成人的1.15倍,儿童更易受到金属元素的危害;As为支流浍河和昌源河的主要致癌因子;各河段优先控制金属元素为As、Co、Pb、Fe和Hg.

Geochemical contamination in the mine affected soil of Raniganj Coalfield——A river basin scale assessment

The study aimed to assess the heavy metals(K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, As, Pb, Sr, Zr) contamination in the soil of mine affected Singaran river basin and to analyse spatial variation in the contamination level considering 32 soil samples. Elemental analysis of soil samples has been performed through Energy Dispersive X-ray Analysis(EDX) to quantify the elemental concentration(mg kgà1). Heavy metal concentrations have been assessed through geo-accumulation index(Igeo) and enrichment factor(EF).Indices showed soils have moderate accumulation of most of the metals with moderate enrichment of Sr,Zr, Zn, Cu and Ni. Soil contamination level assessment has been carried out using indices like Contamination Factor(CF), degree of contamination(C_(deg)), modified degree of contamination(m C_(deg)) and Pollution Load Index(PLI). CF shows moderate to considerable contamination by Sr, Zr, Ca, Cu, Mn, Zn and Ni. Mean indices values(m C_(deg)and PLI for the entire basin are 3.38 and 2.23 respectively) show low to moderate level of soil contamination. These indices result have been mapped and analysed in GIS platform to get spatial variation of pollution level. Opencast mines dominate middle catchment area and so is comparatively contaminated. Sample sites 11, 18 and 25 evidenced high values of all indices of pollution load. From the ecological standpoint Ecological Risk Factor(Er) and Potential Ecological Risk Index(RI) have been estimated to assess regional threat to native soil environment and it shows low ecological risk potential. Analysis shows that mine dominated soil of the entire Singaran basin is less contaminated in all respect but tends to the moderate contamination level at the mid-catchment area,especially by Sr, Zr, Zn, Cu and Ni.

骆马湖流域表层沉积物重金属分布特征及风险评价

对骆马湖流域表层沉积物中的重金属分布特征及潜在生态风险进行评估,分析了枯水期、平水期和丰水期3个时段内10种重金属元素(铬、镍、铜、镉、铅、锑、砷、汞、铍、铊)的浓度水平、空间分布和来源。采用潜在生态风险指数法对沉积物中的重金属风险进行了评估。结果显示,镍、铜、镉、铅在部分水期平均浓度高于江苏土壤环境背景值,汞和铊无点位超过背景值,且与其他水体相比,骆马湖流域沉积物重金属污染整体处在中低水平。沉积物中重金属除镉外整体单项生态风险较低,各点位综合潜在风险水平属于中等及以下范畴。相关性分析和主成分分析揭示了重金属污染主要源自工业和农业。

峨眉河流域土壤重金属元素污染评价

应用原子荧光分光光度法和原子吸收分光光度法测定重金属As、Hg、Cu、Zn、Ni、Pb、Cd和Cr在峨眉河流域土壤中的分布情况,根据单因子污染指数法和内梅罗综合污染指数法,并结合国家土壤环境质量标准GB 15618-2018进行分析和评价峨眉河流域土壤的重金属污染程度。结果表明,As、Hg、Cu、Zn、Ni、Pb、Cd和Cr含量分别为1.48~4.64、0.14~0.36、34.00~370.00、212.00~818.00、0.00~2.00、5.00~53.00、0.10~1.20、0.00~476.00 mg/kg。变异系数显示Cu和Pb的分布最不均匀,受人类活动影响较为强烈;而土壤中Cu、Zn含量普遍超标,按单因子污染指数污染程度依次为Zn>Cu>Cd>Hg>Cr>Pb=As>Ni。

Hydrogeochemical Characteristics and Quality Assessment of Surface Water in an Agricultural Area in Equatorial Africa: The Mungo River Basin, South West Cameroon, Central Africa

The Mungo River and its tributaries represent the major sources of water supply for agriculture and drinking purposes for the Douala city and the south western agricultural region of Cameroon. In this study, the surface water hydrochemistry was investigated at 12 locations to determine the hydrochemical and heavy metals characteristics and to assess the suitability for drinking and irrigational purposes. Results of water samples collected along the main channel and tributaries showed that the major ions were dominated by Ca2+ > Na+ > Mg2+ > K+ > NH4+ and > HCO3- > SO42- > Cl- > F- > PO43- , with concentrations varying between 0 to 60 mg/l. Heavy metal concentrations were relatively weak, dominated by Fe > Mn > As > Cd > Zn > Se. The main hydrochemical facies types revealed primarily 52% Ca-Na-HCO3 and 48% Ca-Mg-HCO3. Base on Gibbs diagram and relative ion ratios, the hydrochemical characteristics are derived from weathering of silicate rocks and atmospheric source. The influence of anthropogenic factors including agro-industrial activities on the hydrochemical characteristics was less marked. The chemical composition of the water samples was compared with the drinking water standards and only the concentration of Fe was above the WHO guide limits in a single sample at Passi. The evaluation of the water quality for irrigation showed that 95% of water samples are suitable for irrigation in almost all soil types. According to the water quality index (HPI, HEI and Cd), this water is considered of excellent quality for consumption. The results provide a preliminary database for sustainable management of water resource in the Mungo River basin.

湘江流域化工园区土壤与地下水重金属污染特征及相关性分析

目前针对化工园区的土壤重金属污染研究较多,但对其地下水重金属污染研究较少,特别是将土壤与地下水重金属污染相关联的研究更是寥寥无几。本论文针对湖南省湘江流域化工园区土壤与地下水中铅、铊、镉、汞、砷5种重金属污染特征,运用单因子指数法和内梅罗综合污染指数法进行评价分析,对地下水污染因子进行评价与相关性分析,找到化工园区土壤与地下水重金属污染相关性。因此,以某一区域为代表将土壤与地下水重金属污染进行相关性分析,可为化工园区的土壤与地下水重金属污染的监管与防治提供重要指导作用。

黄河流域典型铅锌冶炼企业重金属废水管控与碳排放协同研究

黄河流域作为国家生态安全的重要屏障,重金属污染一直以来备受关注.为提升重金属重点排放源铅锌冶炼行业废水排放管控水平,本文聚焦黄河流域中上游典型地区某铅锌冶炼企业,研究了不同产污环节排放废水中重点重金属排放特征及达标情况,并从行业绿色低碳发展方面测算了不同冶炼工艺流程碳排放强度、不同产污环节排放废水处理过程碳排放强度.结果表明:(1)采用氧化法+硫化钠除汞+石灰中和+生物制剂法+除铊稳定剂的组合处理工艺,污酸废水中总铅、总镉、总汞和总砷的排放浓度均可稳定达到《铅、锌工业污染物排放标准》(GB 25466-2010)特别排放限值要求,以处理后各重金属日最大检出浓度的90%分位数作为参比浓度,该处理工艺对总铅、总镉、总汞的去除率分别为98.2%、99.8%、99.9%.(2)铅锌冶炼企业污酸车间地面冲洗水应全部纳入污酸车间污水处理系统进行集中处理,避免铅、镉、汞、铊等重金属废水稀释排放,长期汇入黄河干流富集造成潜在环境风险.(3)锌冶炼过程重金属主要富存于固相颗粒和液相颗粒中,污酸废水(废气洗涤制酸废水)中总铅、总镉、总汞、总砷产污系数分别为4.83、4.33、7.02、0.01 g/t(以产品计),较实际流向废气中相应重金属产污系数低10^(3)量级.(4)鉴于污酸废水处理碳排放强度约为一般性生产废水的7.93倍,建议加强评估并推广应用2022年《国家先进污染防治技术目录(水污染防治领域)》提出的有色冶炼烟气洗涤污酸废水治理与资源化利用技术,研究提出基于资源化利用途径的污酸废水排放控制要求.(5)湿法炼锌工艺碳排放强度为3.08 t/t(冶炼1 t锌的CO_(2)排放量),相对属于绿色低碳冶炼工艺.研究显示,黄河流域中上游部分典型铅锌冶炼企业已采用相对绿色低碳冶炼工艺,鉴于黄河流域的国家战略定位,需进一步提升末端重金属废水风险管控和减污降碳协同治理力度,引领沿黄冶炼产业高质量发展.

珠江流域沉积物重金属污染特征、生态风险及来源解析

沉积物中重金属的富集威胁着珠江流域水环境的安全。研究珠江流域沉积物中重金属污染状况可以为流域沉积物重金属污染防治和水环境科学管理提供支撑。收集了2009-2022年发表的珠江流域沉积物中重金属(As、Cd、Pb、Cr、Cu和Zn)含量的数据,运用数理统计分析、相关性分析和正交矩阵分解模型(PMF)探讨了珠江流域沉积物中重金属的分布特征和污染来源,采用地累积指数和潜在生态风险指数法对重金属污染程度和生态风险进行了评价。结果表明,珠江流域沉积物中As、Cd、Pb、Cr、Cu和Zn平均含量分别为49.29、2.76、63.97、67.44、48.72和186.60mg∙kg^(-1),其中As、Cd、Pb和Zn超过了中国南方水系沉积物均值,而Cu和Cr接近中国南方水系沉积物均值。珠江流域沉积物中Cd和As污染最为严重,其中Cd主要为偏中度中度污染,As主要为轻度偏中度污染,其余重金属主要为轻度无污染。沉积物重金属单因子危害指数排序为:Cd>As>Pb>Cu>Zn>Cr。Cd在整个珠江流域内都表现出较为严重的危害程度,贡献了生态风险指数的70.73%~93.73%;As在西江、南北盘江和珠江三角洲危害程度均为中等;其余重金属Pb、Cr、Cu和Zn危害程度均为轻微。PMF解析结果表明,沉积物中重金属主要来源为矿业活动和农业活动的复合污染源、燃煤和工业活动污染源、大气沉降和交通污染源以及自然源,贡献分别为21%、17%、35%和27%,其中前三者均属于人为来源,贡献累计可达73%。Cd和As主要受到矿业活动、工业活动和农业活动的影响,Pb主要来源于交通污染和矿业活动,Cr主要为自然源,而Cu和Zn来源比较复杂,受到4种来源的综合影响。

广西思的河流域重金属污染物溶质运移模拟

为评价广西阳朔县思的河流域矿区的重金属污染情况,将流域水文模型ArcSWAT与地下水模型(groundwater modeling system,GMS)中MT3DMS溶质运移模块相结合,定量分析污染物锌和镉的迁移过程,为进一步的治理措施提供参考依据。结果表明:采用ArcSWAT和GMS可以更准确地确定垂向入渗量,从而准确进行地下水数值模拟。在没有防治措施的情况下,矿井废水对地下水环境造成较大的污染威胁:尾砂矿矿洞出水口水样中锌和镉的含量分别为18.62 mg/L和0.096 mg/L,是流域重金属污染的源头。模拟期20 a内,锌和镉的污染晕分别在16 d和44 d之后到达河流,前端最远距离污染晕中心分别为2303.75 m和1887.04 m,两端最长处为3159.57 m和2478.57 m,最宽处分别为1533.54 m和1128.36 m。锌和镉进入流域的质量分别为3512.44 g和18.15 g,流出流域的质量为1640.49 g和8.47 g,残留在流域的比例分别为53.28%和53.33%。根据已有研究结果表明,龙葵对镉具有较强的富集能力,在植物体中的最高富集量为1084.4 mg/kg,并对锌具有较强的耐性,富集量也超过1000 mg/kg。因此,设置一个模拟情景对尾矿库生态修复工程进行评价。以尾矿积水塘中锌含量0.284 mg/L和镉含量0.002 mg/L为替代污染源强,模拟期内,锌沿河谷方向的迁移速度由94.38 m/a降低至80.78 m/a,最大污染晕面积由3.80×10^(6)m^(2)缩小至2.50×10^(6)m^(2);镉的迁移速度由86.09 m/a降低至69.13 m/a,最大污染晕面积由1.67×10^(6)m^(2)缩小至1.29×10^(6)m^(2),说明生态修复工程取得较好效果,建议继续投入建设。根据模拟预测结果,建议在矿洞出水口修建防渗帷幕等防治措施,划分污染防治区,并加强地下水水质监测,同时制定地下水风险事故应急预案,避免污染进一步加剧。

苏南太湖流域农田土壤重金属输入输出清单构建及风险预警

为指导产地环境管理策略、巩固污染防治成果,以公开数据为基础构建了苏南太湖流域农田土壤重金属的输入输出清单,探究了土壤中八大重金属元素(As、Cd、Cr、Cu、Hg、Ni、Pb和Zn)的累积现状并预测了未来发展趋势.其中,输入途径主要包括大气沉降、畜禽粪便、灌溉水和化肥农药施用,输出途径主要包括作物收获和土壤渗流.结果表明,As、Cd、Cu、Cr和Hg元素主要通过灌溉用水输入农田,Ni主要通过大气沉降、化肥施用和灌溉水输入农田,Pb和Zn主要通过大气沉降进入农田;As、Cr、Cu、Hg和Pb主要通过土壤渗流输出农田,Cd和Zn主要通过作物收获输出农田.Cd是苏南太湖流域农田土壤中最需关注的重金属元素,在短期内其可能达到风险阈值,其余重金属元素均存在不同程度累积但远未达到风险阈值.

大清河流域下游沉积物重金属污染优控源解析

为探讨重金属不同污染源对生态和人体健康风险影响,本文以大清河流域下游为研究对象,采集并测定36个沉积物样品重金属Cu、Pb、Ni和Cr的含量,采用传统分析法量化重金属污染程度,利用正定矩阵因子分析法(PMF)对沉积物重金属污染来源进行分析.同时,在PMF源解析的基础上,结合重金属毒性和环境背景值等因素,运用PMF与潜在生态风险指数模型(ERI)、人体健康风险评估模型(HHRA)相结合的方法定量解析污染源对生态环境风险和人体健康风险的贡献率.单因子污染指数结果表明,以河北省土壤重金属本底值为标准值,研究区4种重金属Pb、Ni、Cu和Cr均为轻微污染.PMF解析表明,重金属污染源有工业源(43.26%)>农业-交通源(34.97%)>交通-自然源(21.77%).污染源生态风险评估模型显示,交通-自然源(39.21%)>农业-交通源(34.07%)>工业源(26.72%),交通-自然源为潜在生态风险优控源;污染源健康风险评估模型显示,工业源(43.98%)>农业-交通源(26.90%)>交通-自然源(29.12%),工业源为人体健康风险优控源,且Cr为人体健康风险优控污染物.

巢湖北岸烔炀河流域池塘沉积物中重金属污染特征

在巢湖北岸烔炀河流域,选择不同利用类型的池塘钻取了沉积物柱状样,分析了沉积物重金属元素浓度,并剖析了重金属在水平、垂向上的分布特征和污染程度。结果表明,池塘表层沉积物中Cr、As、Hg、Cd、Cu、Pb、Ni、Zn浓度分别为56.5~91.0、6.4~10.1、0.06~0.11、0.10~0.25、18.07~28.77、11.58~17.60、15.94~19.0、42.26~68.07 mg/kg;垂向上随着沉积物深度增加,重金属浓度总体呈下降趋势。烔炀镇老镇区池塘(S1)表层沉积物中重金属浓度高于其他池塘。烔炀河流域池塘沉积物中重金属Cr、Hg、Cu、Zn、As等5种重金属元素具有同源性,受成土母质影响,而Ni、Pb、Cd 3种重金属受人类活动影响;池塘表层沉积物重金属综合潜在生态风险指数处于轻微生态风险。

钱塘江流域下游城市河道沉积物重金属污染评价

为了解钱塘江流域下游河道沉积物中重金属的污染情况,本文以钱塘江流域下游城市河道(杭州下沙段)为研究区域,选择3处代表点位(1号为工业区、2号为湿地区、3号为生活区)采集沉积物检测其中重金属镉(Cd)、铜(Cu)、铬(Cr)、锰(Mn)浓度,并运用潜在生态危害指数法和污染负荷指数法对其污染程度进行评价。潜在生态危害指数法评价结果表明,大多数重金属污染处于低潜在生态风险等级,但Cd在1号点位和2号点位达到较高潜在生态风险,3个点位重金属综合污染均处于低潜在生态风险状态,但2号点位综合污染指数接近中等潜在风险。污染负荷指数法评价结果也表明,Cd在1号点位和2号点位污染程度较高,均为重度污染状态,2号点位多种重金属综合污染达到中度污染等级。评价结果表明:钱塘江流域下游城市河道重金属污染不容乐观,其中Cd是对河道污染较严重的元素,需要广泛关注和有效控制。

黄河流域渭河支流泾河(崆峒段)河流表层沉积物重金属溯源解析

河流沉积物重金属污染问题日益突出,严重威胁流域生态系统健康。以黄河流域泾河崆峒段为研究区,采集91个河流表层沉积物样品,测定并分析沉积物As、Cd、Cr、Cu、Hg、Ni、Pb和Zn共8项重金属元素含量及其空间分布特征。采用地累积指数(I_(geo))和污染负荷指数(PLI)系统量化重金属污染特征,并联合应用自组织神经网络(SOM)模型、相关性分析和正定矩阵因子分解(PMF)模型定量解析沉积物重金属污染来源及其贡献率。结果表明:泾河崆峒段河流表层沉积物重金属含量的平均值高低依次为Cr(65.66 mg/kg)>Zn(55.63 mg/kg)>Ni(21.78 mg/kg)>Pb(17.50 mg/kg)>Cu(14.07 mg/kg)>As(10.94 mg/kg)>Cd(0.19 mg/kg)>Hg(0.032 mg/kg)。除Cd和Hg外,As、Cr、Cu、Ni、Pb和Zn含量的均值均低于甘肃省土壤背景值和黄土高原土壤背景值,且As、Cd和Cr含量的均值分别是中国水系沉积物背景值的1.22、1.46和1.22倍。沉积物重金属含量空间分布具有明显的差异性,所有元素高含量和污染相对较重的区域均分布于人类活动强烈和入河口周边流域,且Hg的空间异质性最强。Cd是泾河崆峒段亟需关注的首要污染元素,Hg、Pb、Cr和Zn存在局部污染,Cu、Ni和As为清洁无污染。沉积物重金属的富集可能受污水交通源、农业源、金属冶炼加工源、电镀制造工业源和自然源的共同影响,贡献率依次为33.33%、27.21%、11.02%、15.49%和12.95%。