Zinc, lead and cadmium speciation in Dnieper water-bodies

Data on the concentrations and movements of Zn, Pb and Cd in Dnieper reservoirs and the Dnieper‐Bug estuary are considered. There is a clear trend of increasing concentrations, often two‐ to fourfold, of these materials from the 1960s to the end of the 1980s. Large increases may be explained as the result of increased human impact on the water‐bodies and also because of reduced water discharge in the Dnieper River (discharge has been reduced by nearly 10 km³ in recent years). At present, the average concentrations of Zn, Pb and Cd in Dnieper water‐bodies are 35.0–50.0, 15.0–18.0 and 0.5–1.8 μg L^–1, respectively. Anodic stripping voltammetry, membrane filtration, ion‐exchange and gel permeation chromatography on neutral sephadexes were methods used for analysis. The influence of adsorption and complexation processes on the mobility of Zn, Pb and Cd, and the ratio of their forms were compared. Ratios of free metal ions to ions bound in complexes with natural organic ligands were studied. The binding of metals in complexes with dissolved organic matter (DOM), or their adsorption onto suspended particles, were major processes reducing the concentration of free ions in their most toxic form. The percentage of Zn, Pb, and Cd free ions in the total balance of dissolved forms was no more than 3.6–4.8, 0.2–0.6 and 7.2–9.5%, respectively. The molecular‐weight distribution of organic metal complexes and their chemical nature, as well as the potential for complexing of DOM were investigated. Most Zn, Pb and Cd was found as complex compounds with DOM of different chemical natures and molecular weights. Humic substances, particularly fulvic acids, played a major role in the migration of the metals. These ligands bind from 40 to 80% of metals in the composition of organic complexes. Metal complex compounds of relatively low molecular weight (< 5000 Da) predominated in organic complexes of Zn (38–50%), Pb (38–52%) and Cd (22–47%). The role of inorganic ligands in complexation in surface waters was less important.     

Comparative spatial metal concentrations and partitioning in bottom sediments of two tropical freshwater lake basins,Kenya

Metal concentrations in the water, sediments and biota in alkaline, near neutral water tropical freshwater lake basins were determined and a comparative analysis made on the spatial and accumulated trace metal concentrations, and geochemical partitioning of iron (Fe), manganese (Mn), copper (Cu), chromium (Cr), zinc (Zn), nickel (Ni), cadmium (Cd) and lead (Pb) in bottom lake sediments. Variable accumulated levels were found in the analysed sediments and aquatic biological tissues. Metal partitioning data in the present study from the two areas exhibits similar trends in magnitude. The residual fractions retained relatively higher amounts of metals. Relatively higher contents of Pb, Cr and Cu were found in Lake Victoria sediments. Cd, Ni, Mn and Pb are of concern because a higher percentage of these metals were retained in the more bioavailable fractions in Lake Naivasha. Total levels of sediment mercury were comparable for the two lake basins. Metals were found in significant levels in the tissues of aquatic organisms, highlighting the potential risks to other levels within the aquatic food chain. Although the exposure risk was not evaluated, it is important to continue monitoring these elements in fish, as sediments were found to contain considerable quantities of the metals. Numerous sediment extraction techniques data applied for evaluating metal partitioning in sediments cannot be compared because of the use of different methods. Nevertheless, the information is still useful in differentiating and understanding pollution loads from natural versus anthropogenic sources and their associated risks.     

武汉东湖水生植物重金属分布现状研究

在武汉东湖采集9种水生植物及其对应水样、根区沉积物样,采用微波消解—ICP-MS(Inductively coupled plasma mass spectrometry,电感耦合等离子体质谱)测定其重金属(Cd ,Zn, As,Cu ,Co ,Pb, Mn, Cr, Ni)的含量,分析了9种重金属在植物体内的分布现状及各部位对重金属的富集能力。结果表明水生植物对各种重金属的吸收状况呈Mn>Zn>Pb>Cu>Ni>Cr>As>Co>Cd的一致性,不同植物各部位对重金属的富集能力表现为根>茎>叶。水生植物对重金属的富集能力表现为沉水植物>浮水植物>挺水植物。金鱼藻、青萍和水葫芦对重金属富集系数较大,可作为水体修复植物,净化被重金属Mn,Zn,Cd复合污染的水体。     

汉江中下游水体重金属时空分布及污染评价

为探明汉江中下游水体中重金属的污染状况,分别于2019年6月(丰水期)和2020年1月(枯水期)在汉江中下游选取20个监测断面采集水样,监测水体中Cu、Zn、Pb、Fe、Mn、As、Se和Cd 8种重金属的含量,分析汉江中下游水体中重金属污染的时空分布特征,并对水体重金属污染状况进行评价。结果表明:汉江中下游水体重金属污染以Fe、Mn为主,其他6种重金属浓度均满足地表水Ⅱ类水标准。汉江中下游水体中Fe和Mn含量沿程波动较大,二者变化规律基本一致。Fe和Mn含量最大值在支流竹皮河,其中Fe浓度超标4.63倍,Mn超标13%;此外,位于汉川市的S17断面Fe元素含量超标3.89倍。结合历史数据分析,发现近年来汉江中下游水体重金属含量总体呈上升趋势。评价结果表明,汉江中下游大部分水体水质良好,钟祥市和汉川市是汉江中下游重金属污染相对较重的两个城市,支流竹皮河的水体重金属污染问题需引起重视。     

Inorganic Chemistry of Particulate Matter from the Nearshore Zone of Lake Michigan

Particulate matter from a nearshore region of southeastern Lake Michigan serves as a sink for trace metals and a conveyor of trace metals to the sediments. Fe, K, Mg, and Mn are always more concentrated in the hypolimnion than in the epilimnion, and Ca, Cr, Cu, Na, Sr, Zn, and total P are generally more concentrated in the hypolimnion than in the epilimnion. Enrichment of these metals in the hypolimnion particulates is attributed to sediment resuspension. Comparison of trace metal concentrations in the particulates with those in phytoplankton and zooplankton indicates that the plankton are not a significant contributor to the trace metal particulate chemistry of this nearshore region. Significant fractions (33% to nearly 100%) of total Cr, Cu, Fe, Mn, and Zn concentrations in the water column are associated with particulates.During the warmer months, calcium carbonate precipitates. Particulate chemistry changes little with the CaCO₃ formation, with the exception of an increased amount of calcium. Variations in the concentrations of trace metals are controlled either by both dolomite and hydrated manganese oxides or by an unknown phase believed to be organic in nature.     

Distribution and removal efficiency of heavy metals in two constructed wetlands treating landfill leachate

The results of heavy metals (Fe, Mn, Zn, Ni, Cu, Cr, Pb, Cd) removal and partitioning between aqueous and solid phases at two treatment wetlands (TWs) treating municipal landfill leachates are presented. One of the TWs is a surface flow facility consisting of 10 ponds. The other TW is a newly constructed pilot-scale facility consisting of three beds with alternately vertical and horizontal subsurface flow. The metals concentrations were analysed in leachate (both TWs) and bottom sediments (surface flow TW). Very high (90.9-99.9%) removal rates of metals were observed in a mature surface flow TW. The effectiveness of metals removal in a newly constructed pilot-scale sub-surface flow wetland were considerably lower (range 0-73%). This is attributed to young age of the TW, different hydraulic conditions (sub-surface flow system with much shorter retention time, unoxic conditions) and presence of metallic complexes with refractory organic matter.     

Variations in trace elements in bottom sediments of major rivers in Lake Victoria's basin, Kenya

River sediments collected between March 1994 and January 1995 were analysed for iron (Fe), manganese (Mn), zinc (Zn), lead (Pb), copper (Cu), chromium (Cr), aluminium (Al) and cadmium (Cd) in the less than 63 μm grain‐size fraction. The river sediments were characterized by a sandy texture, with a relatively low organic matter (as percentage loss on ignition), ranging 3.5–9.6%. The metal mean range values in μg/g dry weight for the river sediments were: Mn (836–2.10 × 10⁴), Fe (1.09 × 10⁴–9.22 × 10⁴), Al (2.86 × 10³–7.77 × 10³), Zn (34–130), Cu (11–78), Cr (not detected ND–125); Pb (ND–100) and Cd (ND). Temporal variations were significant for Zn, Cr and Pb. There were no significant longitudinal differences in all the elements in rivers Nyando, Nzoia, Yala and Sondu‐Miriu, apart from sediment Fe contents. Relatively high sediment Fe, Mn, Zn, Cr and Al were observed in river Kasat. River Kasat was considered polluted with respect to Mn, Zn and Cr, which were comparatively higher than unpolluted sediments and geochemical background values. This supports similar results on surface water trace element levels. Most of the rivers drain an area of relatively similar lithological characteristics. Therefore, apart from the direct waste input into Kasat river from municipal and industrial sources, lack of specific point sources indicate lithological metal origins with localized variations. A final comparative evaluation of the river sediments’ trace metal pollution was made from the study results. The data is vital for pollution management of the lake as information about metal loadings into the lake ecosystem is lacking.     

Accumulation and Transport of Sediment Metals by the Vertically Migrating Opossum Shrimp,Mysis relicta

This study examined the accumulation of metals (Al, As, Cd, Cu, Cr, Fe, Ni, V, and Zn) in the opossum shrimp Mysis relicta from sediments to understand the contribution of sediment metals to overall body burden metal contents. Metal biota-sediment accumulation factors, tissue depuration ratios, and sediment metal assimilation efficiencies were calculated to examine the extent to which mysids accumulate metals from sediments contained within their guts. Results were then used to estimate the concentrations of metals transported to the water column and to fish because of mysid diel vertical migration. Results showed that Al, Cr, Fe, and V were readily depurated (34 to 73% of total body burden) and were not preferentially accumulated in mysid tissues (Biota Sediment Accumulation Factor, BSAF < 0.009). In comparison, As, Cd, Cu, and Zn were not readily depurated (9 to 26% of total body burden) and were more readily accumulated in mysid tissues (BSAF > 0.037). Nickel shows an intermediate behavior for depuration and accumulation. Calculations suggest that following 12 hours depuration through vertical migration, about 1.57 μg sediment/mysid (0.05% of dry weight of M. relicta) remained as gut contents. As a result, 16 to 50% of the Al, Cr, Fe, Ni, and V and 1.0 to 5.5% of the As, Cd, Cu, and Zn mysid body burden metal content transported to the water column was attributed to sediment in the gut. These results indicate that trace metals (As, Cd, Cu, and Zn) ingested from sediments are poorly accumulated in mysids (calculated AEs ranged from 0.07 for Cr to -11 for Cu) and metals transported by mysids to fish in the water column are primarily associated with mysid tissues.     

Distribution of Major and Trace Elements in Sediments and Pore Water of Lake Erie

Concentration profiles of major and trace elements were determined in sediment cores from the Central Basin of Lake Erie. The concentrations of trace elements (As, Cd, Cr, Cu, Hg, Mn, Ni, Pb, and Zn) in the sediments were greatest at approximately 18 cm sediment depth, corresponding to the early 1960s. The concentrations of all elements in the sediments have considerably decreased in the last decade. However, the concentrations of Hg, Pb, and Cd are still about 10, 5, and 4 times greater, respec, than those in the pre-industrial sediments. The profiles of dissolved concentrations of the trace ele in pore water were characterized by maxima below the sediment-water interface, dropping off rapidly within the zone of reduced sediments. Concentrations of dissolved trace elements below the sediment-water interface are about one order of magnitude greater than those in the lake water. Conservative estimates of benthic fluxes ranged from 0.04 /μg/cm².y to 194 /μg/cm².y for Cd and Fe, respectively. Upward diffusive remobilization from sediments to lake water is a significant transport process in the Central Basin of Lake Erie and may play an important role in the transport of trace elements from the sediments.     

Sedimentology and Geochemistry of Modern Sediments in the Kingston Basin of Lake Ontario

Accumulation of Recent fine sediment is limited to deep water areas in the Kingston basin and thicknesses of more than 50 cm are found only in the St. Lawrence trough; elsewhere, sands and silty sands are largely composed of reworked material. Local sources provide little input of fine sediment to the Kingston basin. Statistical relationships derived from geochemical analyses indicate several forms of association between heavy metals and organic carbon, sulphides, clays, hydrous Fe and Mn oxides, and carbonates. A comparison between Kingston and Niagara sediments shows that the combined effects of riverine and lacustrine erosion have resulted in a generally greater content of carbonates in the Niagara sediments. The content of Fe (which is partly influenced by redox potential) is highest, however, in sediment of the Kingston basin, where higher P values are also associated with an increased clay content. Differences in the concentrations of heavy metals in Lake Ontario, except for Hg, Co, Cu, and Zn, are largely explained by variations in silt and clay contents. Contaminant loadings from the Niagara River are largely responsible for the anomalously high concentrations of Hg and, to a lesser extent, Cu and Zn. Cobalt occurs at higher concentrations in the sediments of eastern Lake Ontario, where its presence is thought to reflect glacial dispersal patterns.     

Spatial and seasonal variations and ecotoxicological significance of sediment trace metal concentrations in Kebir-Rhumel basin (Northeast of Algeria)

This study sought to assess sediment contamination by trace metals (cadmium, chromium, cobalt, copper, manganese, nickel, lead and zinc), to localize contaminated sites and to identify environmental risk for aquatic organisms in Wadis of Kebir Rhumel basin in the Northeast of Algeria. Water and surficial sediments (0-5 cm) were sampled in winter, spring, summer and autumn from 37 sites along permanent Wadis of the Kebir Rhumel basin. Sediment trace metal contents were measured by Flame Atomic Absorption Spectroscopy. Trace metals median concentrations in sediments followed a decreasing order: Mn > Zn > Pb > Cr > Cu > Ni > Co > Cd. Extreme values (dry weights) of the trace metals are as follows: 0.6-3.4 microg/g for Cd, 10-216 microg/g for Cr, 9-446 microg/g for Cu, 3-20 microg/g for Co, 105-576 microg/g for Mn, 10-46 microg/g for Ni, 11-167 microg/g for Pb, and 38-641 microg/g for Zn. According to world natural concentrations, all sediments collected were considered as contaminated by one or more elements. Comparing measured concentrations with American guidelines (Threshold Effect Level: TEL and Probable Effect Level: PEL) showed that biological effects could be occasionally observed for cadmium, chromium, lead and nickel levels but frequently observed for copper and zinc levels. Sediment quality was shown to be excellent for cobalt and manganese but medium to bad for cadmium, chromium, copper, lead, nickel and zinc regardless of sites.     

Historical Records of Metal Pollution in Sediments of Toronto and Hamilton Harbours

The sediments of Hamilton and Toronto Harbours contain some of the oldest records of metal pollution in the Great Lakes basin. The fluxes of Cd, Cr, Cu, Ni, Pb, Zn, Fe, and Mn into the two harbours have been estimated from the analyses of core samples dated by the Pb-210 technique. The contrasting metal levels in the two harbour sediments are viewed in relation to the differences in the disposal strategies of the dredged spoils and the sources of metal pollution in the harbours. The Zn and Fe concentrations of 5 to 8 mg g^?1 and 10 to 13 % dry wt. in Hamilton Harbour sediments, which are among the highest recorded in any harbour, can be related to effluent discharges from the large local iron and steel plants. An inventory of the sources and sinks of pollutant metals in Hamilton Bay shows a substantive export of the metals to Lake Ontario.     

新疆巩乃斯河水中微量重金属元素的特征分析

对河流中微量重金属元素含量和来源的鉴别是准确、有效控制和预防污染的基本前提。通过对巩乃斯河水样进行分析,初步探讨了河流重金属元素的含量及来源。结果表明:水体中重金属元素Pb、Cr、Cu、Fe等的含量因采样断面的不同而相差悬殊,所测重金属的含量都符合国家地表水环境质量标准中Ⅰ类水标准。通过主成分分析发现河流中金属元素分为2个主要来源:第一主成分为矿物岩石的自然风化、侵蚀过程及工农业排污,其贡献率为63.43%;第二主成分为河流沉积物中金属的迁移、转化,其贡献率为26.11%。其中Pb、Cr、Cu、Fe和Ni主要受第一主成分控制;Mn和Ni主要受第二主成分控制;Cd则是受第一主成分和第二主成分共同支配。     

再生水回灌条件下地下水重金属污染特征

为了探讨再生水回灌条件下的地下水中重金属Fe、Mn、Pb、Se、Sr、Zn含量变化情况,在郑州回灌试验场采集并分析了再生水、河水、土壤水和地下水样品(共106个),研究了土壤水和地下水中重金属在再生水回灌过程中的变化情况。结果表明:地下水中Fe、Mn、Sr背景含量较大;回灌1 a后,Fe、Sr含量有所减小,但Mn、Pb、Se、Zn含量有所增大;再生水回灌引起的重金属含量增大的范围为地面以下15.0～20.0 m;引起地下水中重金属含量变化的原因除再生水的回灌以外,还有场地土壤和地下水中较高的重金属背景。     

长江源区主要河流表层沉积物及沿岸土壤重金属分布特征及来源

采用电感耦合等离子体质谱仪和原子荧光分光光度计测定了长江源区主要河流沉积物及周边土壤中14种重金属的含量,并采用富集因子法评价了长江源区主要河流沉积物及土壤中重金属富集程度,同时分析了河流沉积物及沿岸土壤中重金属分布特征及来源。研究结果表明:长江源区主要河流表层沉积物中,除Ni、Pb、Cd、Hg四种重金属外,其他元素含量均低于中国沉积物的平均含量;沉积物中Hg、Ni和Cd存在一定富集;与长江源区其他河流沉积物中重金属相比,沱沱河Cd含量相对较高,楚玛尔河重金属含量均相对较低,而通天河Hg和Fe含量相对较高;沉积物中重金属主要受自然因素影响。土壤中Ni、Pb、Cd、Ti略高于青海省土壤背景值,但重金属富集程度均较低;与长江源区其他河流沿岸土壤中重金属相比,当曲Cr、Ni、Cu含量相对较高,沱沱河Pb、Cd、Sb和Tl含量相对较高,而通天河V含量相对较高;重金属主要受自然因素影响,但部分重金属可能受交通因素影响。研究成果可为长江源区生态环境保护提供基础支撑。     

阳宗海表层沉积物中的重金属生态风险评估

对从阳宗海湖底表层采集的25组沉积物样品中的10种重金属质量比进行分析,结果表明,Ti、Mn、Zn、V、Cr、Cu、Ni、Co、Pb和As的质量比平均值均超过了当地土壤背景值。而重金属系统聚类分析表明,Zn、Cr、Pb、As高度相关,其污染主要由于人类活动造成;Ti、Mn、V、Cu、Ni、Co的分布特征相似,其污染原因以岩石风化等自然因素为主。单因子富集系数评价表明,阳宗海10种重金属均达到了中度富集程度,其中As、Cu、Cr富集程度较为突出。用Hakanson潜在生态风险指数法评价阳宗海表层沉积物中重金属的生态风险,结果表明,阳宗海表层沉积物中重金属的生态风险总体属轻微程度,阳宗海南岸局部区域达到中等生态风险程度。几种重金属对阳宗海生态风险的贡献由大到小依次为As、Cu、Co、Ni、Pb、Cr、V、Zn、Mn、Ti,其中,As是阳宗海最突出的生态风险因子。     

Heavy metal displacement in EDTA-assisted phytoremediation of biosolids soil.

Chelating agents are added to soil to solubilise the metals for enhanced phytoextraction. Yet no studies follow the displacement and leaching of heavy metals in soil with biosolids following solubilisation with chelates. The objective of this work was to determine the mobility of heavy metals in biosolids in a soil from a sludge farm that had received biosolids for 25 years. The soil was placed in columns in a greenhouse. Columns either had a plant (poplar) or no plant. After the poplar seedlings had grown for 144 d, the tetrasodium salt of the chelating agent EDTA was irrigated onto the surface of the soil at a rate of 1 g per kg of soil. Drainage water was analysed for three toxic heavy metals and four essential heavy metals. Without EDTA, concentrations of the seven heavy metals in the leachate from columns with or without plants were low or below detection limits. With or without plants, the EDTA mobilised all heavy metals and increased their concentration in drainage water. Without plants, the concentrations of Cd, Cu, Fe, and Zn in the leachate from columns with EDTA were above drinking-water standards. The presence of poplar plants in the soil reduced the concentrations of Cu, Fe, and Zn in the leachate so it fell within drinking-water standards. Concentrations of Cd and Pb in the leachate remained above drinking-water standards with or without plants.     

引滦入津工程黎河河道表层沉积物重金属形态及风险分析

对引滦入津工程黎河段表层沉积物和两岸尾矿中重金属特征进行研究。结果表明:受两岸尾矿砂影响,黎河河道表层沉积物的矿物组成及重金属特征与尾矿砂相一致,重金属含量依次为FeMnZnPbCuCd。重金属形态分析表明:Fe、Mn、Cu、Zn残渣态占绝对优势,Pb以可交换态和残渣态为主,Cd仅有可交换态和碳酸盐结合态。采用风险评价准则法(RAC)和平均沉积物质量基准系数法(SQG-Q)评价,结果均表明表层沉积物中Pb和Cd对环境具有非常高风险,其潜在的毒性风险应引起重视。     

大燕河沉积物重金属污染特征及生态风险分析

为了解大燕河表层沉积物重金属污染特征及潜在生态风险,对大燕河干流和支流沉积物重金属污染物进行了分析,并采用Hakanson生态危害指数法进行评价。结果表明,大燕河干流沉积物重金属含量明显高于支流,重金属含量高于广东省土壤背景值,Cu、Cd、Zn、Pb、Hg超出了土壤环境质量Ⅰ级标准。沉积物中重金属Cu、Cd的富集系数明显高于其他重金属,不同采样点重金属超出背景值的程度具有明显的差异性,呈现干流高于支流,下游高于上游的特征。沉积物中重金属具有极强的生态危害,各种重金属造成的平均生态危害程度由大到小依次为:CdHgCuAsPbZnNiCr,其潜在生态风险应引起足够的重视。     

Assessment of heavy metal contamination in coastal lake sediments associated with urbanization: Southern Kerala,India

The study of the spatiotemporal variation of heavy metals in lake sediments is of great importance because heavy metals can result in toxic effects on aquatic biota through bioaccumulation. This study was undertaken to evaluate the degree of heavy metal contamination in the lacustrine sediments and the corresponding environmental deterioration in a tropical, urban, coastal lake (Akkulam–Veli), located in Kerala, India. The spatiotemporal variations of the cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), manganese (Mn), nickel (Ni) and zinc (Zn) concentrations in the lake sediments, as well as various indices of anthropogenic contamination, including Contamination Factor (CF), Pollution Load Index and Geoaccumulation Index (Igeo), were used to assess the degree of contamination. This study indicated contamination of the lake sediments with Cu, Pb and Zn. Urban domestic sewage and land run‐off are the major drivers of the heavy metal loads to the lake. During the pre‐monsoon, sediment contamination occurs in the upstream portion of Akkulam Lake because of a high clay content in the sediments. During the monsoon period, Akkulam Lake and the upstream portion of Veli Lake exhibit sediment contamination owing to high silt content. Domestic sewage is the main source of copper and zinc to the lake. Sewage bypass into the drains in the lake basin is largely responsible for the copper and zinc sediment contamination. High traffic levels and wastewater discharges from service stations/workshops are the main cause of the Pb loads entering the lake. Rubber particles of vehicle tires contain zinc and copper pigments that can accumulate on the surface of busy streets, entering the drains during rainfall events. Based on these study results, the accumulation of copper, zinc and lead in lake sediment can be controlled to a great extent by restricting the above‐noted activities. As the sediment content of lead, zinc and copper is confined to the clay fraction during the non‐rainy season and to the silt fraction during other seasons, lake restoration work should largely incorporate treating the clay and silt fractions, respectively, during both the non‐rainy season and rainy season.