Bioaccumulation of heavy metals in the lotus root of rural ponds in the middle reaches of the Yangtze River

Purpose

The subject of this study is the sediment and wild lotus plants in unmanaged ponds, near Yichang City, contaminated by heavy metals. The objective is to determine the extent and frequency of heavy metal accumulation by lotus root in the ponds of rural areas and its significance to food safety and human health.

Materials and methods

The study area is located in the middle reaches of Yangtze River. The 11 sampling sites selected (Z1–Z11) were unmanaged ponds, and the lotus root samples were from wild plants. The lotus root and soil samples were processed using wet digestion, according to the national standard method; we tested concentration of heavy metal (Pb, Cd, Cr, As, Cu, and Zn). Both a single-factor index and an integrated pollution index were used to assess the heavy metal pollution of soil and wild lotus root. Correlation was used to examine the relationship of lotus root concentration to sediment concentration for each heavy metal.

Results and discussion

Cadmium (Cd) and arsenic (As) in both soil and pond sediment exceeded standards. The maximum single pollution index (SPI) for Cd and As was 1.16 and 1.15, respectively. The maximum integrated pollution index (IPI) for heavy metals was 2.17 for soil and 2.10 for sediment (moderate pollution). The heavy metal content in some samples of lotus root exceeded the national food standard and pose a health risk. The significant correlations of heavy metal concentrations (Pb, Cd, and As) in pond sediment with those in the surrounding soil show that the ponds act as sinks for agricultural nonpoint source pollution (NPS). The heavy metal concentrations in the peel of the edible tuber were 1.3～9.0 times higher than those in the inner flesh.

Conclusions

While Cd, Pb, and As concentrations in the sediment did not violate soil standards, concentrations in the lotus root did violate food standards. This species could be proposed as a suitable heavy metal bioindicator for the early stages of pollution from agricultural NPS.

     

北京城市流域底泥重金属形态特征及其生态风险评价

为了解北京城市流域底泥重金属污染现状及其生态风险,研究分别在北京市永定河流域、潮白河流域、温榆河流域、拒马河流域和泃河流域五大河系（北京段）共设置84个检测样点,采集底泥样品,利用ICP-MS分析法和BCR连续提取法测定北京城市流域底泥中铜（Cu）、锌（Zn）、铬（Cr）、镉（Cd）、镍（Ni）和砷（As）6种主要重金属的含量,分析其分布特征及养分变化,同时运用潜在生态危害指数法和地累积指数法综合评价流域底泥中重金属的生态风险。结果表明:（1）以北京土壤质量标准为北京市参比值,北京流域中下游底泥富营养化严重,重金属富集强弱依次为Cd > （Cr,As,Zn） > （Cu,Ni）;（2）底泥重金属潜在生态危害评价,其危害程度依次为Cd > （Cr,As,Zn） > （Cu,Ni）,其中五大河流下游潜在生态风险较大,生态风险最大的是拒马河水域;（3）地累积指数法进行污染评价,北京河流污染程度依次为下游 > 中游 > 下游,底泥中污染最大的重金属为Cd,其次为Cr,As和Zn,污染较小的为Cu和Ni。综上所述,北京污染较大的河流依次是拒马河、永定河、潮白河、温榆河和泃河,特别是河流下游区域底泥重金属累积较多,潜在生态危害最大。     

The Relationship between Topsoil and Stream Sediment Heavy Metal Concentrations and Acidification

Critical loads of acidity have been used by the UNECE Convention on Long Range Transboundary Air Pollution for the development of protocols to control the emissions of acidifying pollutants. Since soil acidity has an effect on the mobilisation of heavy metals in the environment, it is important to understand the relationships between acidity and heavy metal pollution. This paper examines the relationships between soil acidification and heavy metal (cadmium, copper, lead and zinc) concentrations in topsoils and in stream sediments. It makes use of published heavy metal data and two indices of acidification: soil pH and soil acidity critical loads. For cadmium and zinc, a general increase in the ratio of stream sediment to toposil metal concentrations is seen with a decrease in soil pH and soil acidity critical loads. This demonstrates that where soils are more acidic and acid sensitive the metal concentration in the stream sediments is greater relative to that in the topsoil, suggesting mobilisation of these metals under acid conditions. Results for copper are similar but the relationship weaker. However, for lead the ratios tend to decrease with a decrease in pH and critical loads suggesting that where soils are more acid, lead remains in the soil rather than being mobilised into streams and precipitating onto stream sediments. This reflects the association between soil lead concentrations and soil organic matter content, which tends to be greater in acidic, peaty soils.     

拉林河流域土壤重金属污染特征及来源解析

该文选取拉林河流域表层土壤为研究对象,通过对土壤重金属的含量和空间分布分析、污染评价、以及潜在生态风险评价,了解土壤重金属的分布特征和污染现状,并利用正定矩阵因子分解法（PMF）探索土壤重金属污染的来源。结果表明,表层土壤中Cr、As、Pb、Cu、Zn、Ni、Mn、V的平均含量均低于背景值,Co和Se略微高于背景值,部分土壤样点Cd和Ni超过国家土壤环境质量标准的二级标准。研究区土壤污染的主要金属元素为Cd和Hg,地累积指数表明受到污染的样品比例分别达到45.1%和37.0%,其潜在生态危害指数平均值分别为49.83和70.29。根据PMF计算结果,拉林河流域表层土壤重金属累积主要受自然源、农药肥料源、工业排放源的影响。其中,自然本底对研究区土壤中重金属的影响最大,贡献率为38.0%,其次是农药和肥料施用,贡献率为32.6%,燃煤和工业排放源的贡献率稍低,为29.4%。     

宝鸡市王家崖水库沉积物重金属含量及潜在生态风险评价

利用X-Ray荧光光谱仪对宝鸡市王家崖水库表层沉积物中的As,Co,Cr,Cu,Ni,Mn,Pb,V和Zn共9种重金属元素含量进行了测定,分析了这几种元素含量的分布特征,并采用潜在生态风险指数法对重金属生态危害程度进行了评价。测定结果表明,9种重金属的含量平均值均高于陕西省土壤背景值,是陕西省土壤背景值的1.5～1.9倍,其中Cu的累积程度最高,Zn的累积程度最低;各重金属元素具有相似的水平分布特征,高值区位于水库中游,低值区位于水库上游。潜在生态风险评价表明,研究区重金属元素综合生态风险程度属于中度,采样点位5（中游）综合生态风险最高,采样点位8（上游）综合生态风险最低;各元素生态危害程度大小顺序为：As〉Cu〉Ni〉Co〉Pb〉V〉Mn〉Cr〉Zn,其中As具有中度生态危害,其余各元素均为轻度生态危害。     

Contribution of Oil Industry Activities to Environmental Loads of Heavy Metals in the Tabasco Lowlands, Mexico

In Tabasco the petroleum industry pollutes soil recurrently by oil spills. We analysed Pb, V, Ni and Cr concentrations in water samples, and total metal contents and metal fractions in soil samples of contaminated and non-contaminated soils and in sediments. Besides, we determined Eh, pH, DOC and major ions in water and Eh, pH, C_org in soils and sediments. Sediments contained considerably larger heavy metal (HM) concentrations than soils. Local background concentrations of V, Ni and Cr in soils are larger than global means and oil spillages have not added these metals in quantities that exceed the natural variation. Spillage of formation water increases Pb concentrations in soils, particularly in mobile fractions. The contribution of the oil industry to HM loads is diluted by large fluvial water and sediment discharges and difficult to assess by comparison of total metal contents. Therefore, easily mobile metal fractions are much better indicators.     

丹河水系表层沉积物重金属污染及生态风险评价

采用原子吸收分光光度法和原子荧光光谱法,测定了丹河水系干流及主要支流表层沉积物中重金属（Mn、Zn、Cu、Pb、Cd、Cr、Hg、As）的含量,同时用沉积物质量基准法（SQG）和Hakanson潜在生态风险指数法,对重金属的毒性效应、污染程度及潜在生态风险进行了评价,并分析了重金属的主要来源。结果表明,丹河水系表层沉积物中Mn、Zn、Cu、Pb、Cd、Cr、Hg、As的平均含量分别为115.1、18.78、8.46、6.49、2.85、60.6、0.047、14.22mg·kg-1。Cd、As和Cr的含量介于最低效应水平（LE-L）与严重效应水平（SE-L）之间。根据SQG,丹河表层沉积物中重金属含量处于中度污染水平,可能会对河流生物产生一定的毒性效应,而Pb、Cu、Zn则尚无毒性效应。除了As和Cr之外,其他重金属元素之间均呈现较明显的正相关,表明在沉积物中这些重金属的含量具有共同的变化趋势,且具有一定的同源性。工业排污是造成丹河水质恶化的主要原因之一,也是重金属的主要来源。以山西省土壤背景值为参比进行Hakanson潜在生态风险指数评价发现,丹河水系表层沉积物呈现由强至极强的生态风险,其中Cd生态风险最大,Hg、As次之。对单个重金属的潜在生态风险系数和多个重金属的潜在生态风险指数进行分析显示,生态风险较大的样点是高平市、巴公河和水东。研究结果旨在得到单一污染物的环境影响和多种污染物的综合效应的评价结果,为丹河水系沉积物及水体重金属污染防治和决策管理提供科学依据。     

Urban soil pollution in Damascus,Syria: concentrations and patterns of heavy metals in the soils of the Damascus Ghouta

The objective of the study was to assess the extent and severity of heavy metal contamination of arable soils of the Damascus Ghouta, an area with intensive agricultural production. We examined the present degree and spatial distribution of heavy metal concentrations in 51 soil profiles and in 22 topsoil samples in the Damascus Ghouta. The soils were digested with aqua regia for heavy metal analysis. Pb, Cu and Zn concentrations in the topsoils exhibited anthropogenic increased values. The major sources for the heavy metal contamination in Damascus city are most possibly emissions from vehicles. These emissions transported by air and sewage water together with household and industrial sewage effluents have been considered to be responsible for the increased heavy metal concentrations found in the soils of the central Barada area. However, the values were in most cases below tolerable values of soil for agricultural use. Cr concentrations up to 1800 mg kg⁻¹ were found near a tannery industrial estate. Concerning the health risk of the population bioavailability and mobility of heavy metals seems to be of minor importance, based on the soil properties found in the study area. However, direct ingestion of soil, e.g., by children and inhalation of dust may contribute largely to the accumulation of heavy metal in human and livestock.     

Spatial and Temporal Heavy Metal Concentration (Cu,Pb, Zn,Hg, Fe,Mn, Hg) in Sediments of the Mar Piccolo in Taranto (Ionian Sea,Italy)

The Mar Piccolo (surface area of 20.72 km²) is located in the Northern area of the Taranto town (Ionian Sea, Italy). It is an inner, semi-enclosed basin with lagoon features connected with the Mar Grande through two channels which are very important for water exchange. Mar Piccolo basin is subjected to urbanization, industry, agriculture, aquaculture and commercial fishing. Hence, it is important to have a temporal picture both of heavy metal content and of organic carbon and their distribution (hydrophobic fraction, hydrophilic fraction, humic compounds) to check the progress of pollution in time. Three sediment cores collected on the basis of the pollution sources have been analyzed. Both heavy metal and organic carbon concentrations underline the fact that the anthropogenic input is different in the three sites, and that in time the amount of pollutants coming into the Mar Piccolo have changed in different ways. The high amount of organic hydrophilic compounds present in sediments, both due to the small water depth and to the high accumulation rate, make the sediment site high in oxygen consumption due to a considerable chemical and biochemical transformations of organic matter.     

Seasonal Variation of NOx Loss Processes Coupled to the HNO3 Formation in a Daytime Urban Atmosphere: A Model Study

Heavy metal concentrations of the acid-soluble fraction in sediment core samples from Nagaike, a reservoir in Osaka City, Japan, were measured by ICP-MS following the microwave extraction method. Spiked peaks for several metals in the sediment core samples were observed around 1960. The results of correlation coefficient study and cluster analysis of heavy metal concentrations in the sediment core samples showed that some metals, such as Cr, Cd, Ni and Cu, in the period of the spiked peak were derived from the different emission sources from other periods. These metals are often used for metal plating, and it was concluded that the spiked peaks were caused by illegal effluent from the metal plating industry. The load amounts of heavy metals by illegal dumping were calculated and the magnitude of the pollution was estimated.     

Use of regulatory documents for assessing the contamination of soils with heavy metals

The chronological review and analysis of the existing regulatory documents relevant to the assessment of soil contamination with heavy metals have been presented. Attention has been given to the incorrect use of the term “total heavy metal content” and the method of its determination in a 5 M nitric acid solution recommended by some regulatory documents. The maximum permissible concentrations (MPCs) and tentatively permissible concentrations (TPCTPCs) for the total heavy metal contents are based on the above method; therefore, the conventional methods of determining the true total contents of heavy metals overestimate the degree of contamination. To avoid confusion, it has been proposed to call the content of a heavy metal in a 5 M nitric acid solution the “pseudototal” content and to compare the experimental results with the MPC or TPCTPC values only if the methods recommended by the regulatory documents were used.     

环境物质磁性对重金属污染的指示作用研究进展

重金属污染并通过食物链对人体健康的危害已成为环境科学研究的重点,通过对土壤、沉积物及大气颗粒物的磁性测量,以监测环境中重金属污染的程度、来源和范围是国内外新近发展的新技术。本文着重阐述了环境物质磁测的基本原理和磁性参数,土壤、沉积物和大气颗粒物的磁性特征及其对重金属污染的指示作用,并对应用环境物质磁性监测重金属污染的前景进行了讨论。     

Response of ammonia oxidizing microbes to the stresses of arsenic and copper in two acidic alfisols

Soil pollution by elevated heavy metals exhibits adverse effects on soil microorganisms. Ammonia oxidizing bacteria and ammonia oxidizing archaea perform ammonia oxidative processes in acidic soils. However, influence of heavy metal stress on soil ammonia oxidizers distribution and diversity is inadequately addressed. This study investigated the responses of ammonia oxidizing bacteria and archaea to heavy metals, Cu and As during short-term laboratory experiment. Two different acidic alfisols named as Rayka and Hangzhou spiked with different concentrations of As, Cu and As + Cu were incubated for 10 weeks. Significant reduction in copy numbers of archaeal-16S rRNA, bacterial-16S rRNA and functional amoA genes was observed along elevated heavy metal concentrations. Ammonia oxidizing archaea was found to be more abundant than ammonia oxidizing bacteria in all the heavy metal treatments. The potential nitrification rate significantly decreased with increasing As and Cu concentrations in the two soils examined. Denaturing gradient gel electrophoresis analysis revealed no apparent community shift for ammonia oxidizing archaea even at higher concentrations of As and Cu. Phylogenetic analysis of archaeal amoA gene from 4 clone libraries indicated that all the archaeal amoA sequences were placed within 3 distinct clusters from soil and sediment group 1.1b of Thaumarchaeota. Our results could be useful for the better understanding of the ecological effects of heavy metals on the abundance and diversity of soil ammonia oxidizers.     

Potential of Aquatic Macrophytes as Bioindicators of Heavy Metal Pollution in Urban Stormwater Runoff

The concentrations of heavy metals in water, sediments, soil, roots, and shoots of five aquatic macrophytes species (Oenanthe sp., Juncus sp., Typha sp., Callitriche sp.1, and Callitriche sp.2) collected from a detention pond receiving stormwater runoff coming from a highway were measured to ascertain whether plants organs are characterized by differential accumulations and to evaluate the potential of the plant species as bioindicators of heavy metal pollution in urban stormwater runoff. Heavy metals considered for water and sediment analysis were Cd, Cr, Cu, Ni, Pb, Zn, and As. Heavy metals considered for plant and soil analysis were Cd, Ni, and Zn. The metal concentrations in water, sediments, plants, and corresponding soil showed that the studied site is contaminated by heavy metals, probably due to the road traffic. Results also showed that plant roots had higher metal content than aboveground tissues. The floating plants displayed higher metal accumulation than the three other rooted plants. Heavy metal concentrations measured in the organs of the rooted plants increased when metal concentrations measured in the soil increased. The highest metal bioconcentration factors (BCF) were obtained for cadmium and nickel accumulation by Typha sp. (BCF = 1.3 and 0.8, respectively) and zinc accumulation by Juncus sp. (BCF = 4.8). Our results underline the potential use of such plant species for heavy metal biomonitoring in water, sediments, and soil.     

嘉陵江李子口小流域侵蚀产沙模型初探

到目前为止,国内外对土壤侵蚀产沙模型已经进行了大量的研究,建立了大量的土壤侵蚀产沙模型,从嘉陵江流域、李子口小流域的基本情况（尤其是水土流失现状）入手,结合长江流域侵蚀产沙模型研究情况,初步探讨了李子口小流域侵蚀产沙模型。     

Sediment toxicity and heavy metals in eleven lime reference lakes of Sweden

Sediments from an eutrophic reference lake (L. HjÄlmaren) and eleven oligotrophic Swedish lakes were analyzed for heavy metals (Cd, Cr, Cu, Hg, Ni, Pb, and Zn) and tested for whole sediment toxicity to Daphnia magna. Whole sediment toxicity, expressed as 48-hr EC50 on a wet weight basis in reconstituted dilution water, ranged from 2.8% (most toxic) to >32% (least toxic). Correlations between bulk sediment heavy metal concentrations and toxicity were significant (P≤0.05) for Hg, Pb, and Zn. However, a causal connection between the concentrations of these metals and toxicity was not supported by the results from metal-spiked sediment toxicity tests. In addition sediment toxicity was not affected by the addition of EDTA, which is a strong chelator known to reduce metal toxicity. After storage for several months test sediments either remained nontoxic, toxic, or increased in toxicity. These results illustrate some of the difficulties in the interpretation of bulk sediment chemistry data and the release of toxic chemicals from sediment samples, highlighting the effect of sediment storage on toxicity.     

北京顺义区土壤重金属分布与环境质量评价

在北京顺义区采集了412份土壤表层样品,分析了其中7种重金属元素（Cu、Zn、Cr、Pb、Cd、As和Hg）的全量,采用单因子指数和内梅罗指数对土壤环境质量进行评价。结果表明,土样中As、Cd、Cr、Hg、Cu、Pb和Zn含量平均值分别为7.85、0.136、61.47、0.073、22.43、20.38mg.kg-1和69.75mg.kg-1,As、Cd、Cr、Cu和Zn含量平均值超过了北京地区环境背景值,但所有元素含量的平均值均未超出土壤环境质量一级标准。土壤中各重金属元素含量Shapiro-Wilk检验和相关性检验结果表明,研究区土壤中重金属Cr呈正态分布,Cd、Cr、Cu、Pb元素与As元素相关性显著。土壤各元素单因子污染指数排序为Zn〉Cr〉Cd〉Cu〉Pb〉As〉Hg,内梅罗综合污染指数平均值为0.745,达到了土壤环境质量评价分级标准Ⅱ级,污染等级为＂警戒线＂级;菜地、果园、荒地、林地、苗圃、设施农业用地和水浇地的土壤内梅罗指数分别为0.809、0.765、0.720、0.669、0.781、0.786和0.729,表现为菜地〉设施农业〉苗圃〉果园〉水浇地〉荒地〉林地。土壤环境质量总体安全,部分地区土壤重金属污染处于警戒水平。     

Geochemical Mobility and Bioavailability of Heavy Metals in a Lake Affected by Acid Mine Drainage: Lake Hope, Vinton County, Ohio

Sandy Run (Vinton County, southeastern Ohio, USA) is a stream receiving acid mine drainage (AMD) from an abandoned coal mine complex. This stream has been dammed to form Lake Hope. The heavy metal composition of waters (benthic and pore), sediments, and macroinvertebrates in the lake reservoir sediments were analyzed. Lake waters contained Mn as the heavy metal present in higher concentrations followed by Fe, Al, and Zn. Depletion of Fe and Al occurred from precipitation of less soluble Fe and Al oxides and hydroxides along Sandy Run before entering the lake, producing a high Mn water input into the reservoir. Concentrations of heavy metals in the sediments increased toward the dam area. Sequential extraction of metals in the sediments showed that the highest fractions of metals corresponded to the detrital fraction or eroded material from the watershed and metals associated with iron and manganese hydroxides. Heavy metals in the organic sediment fraction were low. Heavy metals from the AMD source, as well as sediments rich in heavy metals eroded from the watershed, were transported to the downstream dam area and stored at the bottom, producing the observed chemistry. Heavy metals in benthic waters also were sourced from the diffusion of ions from sediments and lake waters as variation in pH and redox conditions determined the flux at the sediment–water interface. Metal concentrations were measured within two deposit feeders, oligochaetes and chironomids, and compared to trends in physical metal concentration across the lake. For the four heavy metals with higher concentration in both benthic animals, the concentrations followed the trend: Fe?>?Al?>?Mn?>?Zn, which were similar to the bioavailable metals in the sediments rather than the pore or the benthic water where Mn was the most abundant heavy metal. Ingestion of sediment, not exposure to pore or benthic waters, appeared to be the main transfer mechanism for metals into the biota. Trends and patterns in animal metal concentrations across the lake were probably a complex process controlled by metabolic needs and metallic regulation and tolerance. Even when Mn was the highest concentration heavy metal in the pore waters, it was the lowest to bioconcentrate in the organisms. In comparison, Cd, the lowest concentration metal in the sediments, presented one of the highest bioaccumulation factors.     

Heavy metal contamination of urban topsoils in a typical region of Loess Plateau,China

Purpose

Heavy metals pollution of city soil has become a serious environmental issue. Attention has been given to the issue of soil contamination in big cities, but little research has been done in the Loess Plateau, which is the largest loess deposition area in the world. The aim of this study was to assess the contamination of topsoil.

Materials and methods

Forty soil samples were collected from different districts and sieved through nylon sieves. The coarse particles (2 mm) were used to determine pH and electrical conductivity using a suspension of 1:5 soil to deionized water. The fine particles (150 μm) were used to determine soil organic matter and selected heavy metals. Metals were measured in digested solutions by a flame atomic absorption spectrophotometer.

Results and discussion

The mean concentrations of heavy metals in urban soils in the study area are significantly lower than the mean concentrations across China. The integrated pollution index was determined to be 1.13, indicating moderate pollution. Weathering of parent material, the use of pesticide and fertilizer, discharge of waste from traffic, wastes from commodities and industry, and coal combustion are considered to be the main sources of heavy metal pollution in the study area.

Conclusions

The results indicate that, at least in the study area, land use greatly influences the soil quality and heavy metal contents in urban topsoils. Soil backfill may change heavy metal contents to some extent. Deep digging and backfill can be effectively used for the remediation of heavy metal contaminated soil and sediments.     

径流与施肥对流域入河重金属污染负荷的控制

[目的]农田重金属随降雨径流进入河湖,导致水体污染,对水体生态环境安全和人畜饮水健康构成重大威胁.目前对施肥与土壤重金属污染的关系研究较多,但很少把农田面源施肥与河湖水体中重金属污染相关联.了解农田施肥对入河重金属污染负荷的影响,对河湖水体重金属污染防控具有重要意义.因此,本研究通过测定农业小流域典型重金属入河污染负荷...