Changes in Al,Mn and Fe from sediments and aquatic plants after lake drawdown

Lake drawdown is often practiced during the winter season, causing freezing and/or drying of the sediments in order to retard subsequent rooted aquatic plant growth. In both lake and jar experiments, Zn and Mn levels in tissues of Elodea canadensis and seeded aquatic plants were elevated when grown on softwater sediments (pH 6.4) exposed to winter drawdown conditions, compared to plants grown on unexposed sediment. Dry weight production was likewise reduced by half. Sediment exchangeable acidity, and extractable Al, Zn and Mn were higher after exposure, and sediment Zn and Mn levels were highly correlated to growth (negatively) and tissue content (positively) of rooted aquatic plants. There were no consistent changes in metal concentrations of the overlying water after reflooding. It is proposed that plant growth inhibition upon reflooding is chemically mediated by increased root-available metal concentrations, found after sediment exposure and the associated oxidation of organic materials, metals, and reduced S, with release of H⁺ and a temporary drop in pH.     

云南滇池沉积物中重金属的形态分布特征

Fractionation of heavy metals in sediments can help in understanding potential hazards of heavy metals. The present study analyzed total concentrations and fractions of selected heavy metals （Cd, Cr, Cu, Pb, and Zn） in surface sediments from Dianchi Lake, Yunnan Province, China, as well as factors that may affect distributions of the various heavy metal fractions. Total concentrations of the heavy metals decreased in the order Zn 〉 Cu 〉 Pb 〉 Cr 〉 Cd. These heavy metals, except Cr, were much higher than their background levels, indicating that Dianchi Lake was polluted by Cd, Zn, Pb, and Cu. Cadmium occurred mainly as the non-residual fraction （sum of the HOAc-soluble, reducible, and oxidizable fractions） （97.6%）, and Zn （55.7%） was also predominantly found in the non-residual fraction. In contrast, most of the Cr （88.5%）, Pb （81.8%）, and Cu （59.2%） occurred in the residual fraction. Correlation analysis showed that total heavy metal concentrations, organic matter and reducible Fe were the main factors affecting the distributions of the various heavy metal fractions. In the Walhai section of Dianchi Lake （comprising 97% of the lake area）, the concentrations of Cd, Zn, Pb, and Cu in the non-residual fraction were significantly lower （P ≤ 0.01 or 0.05） than those of the Caohal section （3% of the lake area）. This indicated that potential heavy metal hazards in the Caohai section were greater than the Waihai section.     

Trace metals in Valencia lake (Venezuela) sediments

An exploratory study of the trace metals Cd, Cu, Mn, Ni, Pb, and Zn in sediments of lake Valencia (Venezuela), South America, 10° 10′N, 68°68′W, gave the following results: (A) Total amounts of Cu, Ni, Pb, and Zn were within the normal range reported by the literature. (B) No consistent pattern of variation with depth was found. A and B could be taken as lack of evidence for contamination by Cu, Ni, Pb, and Zn of the studied sediments. Absence of Cu, Ni, Pb, and Zn pollution after more than 40 yr of anthropogenic discharges on this lake, was attributed mainly to the exploratory nature (limited sampling) of this work, together with some possible dilution effects due to the high CaCO₃ content of these lake sediments. (C) Manganese was above normal values in most samples, but in absence of known anthropogenic sources of this metal, the results found could not be clearly ascribed to metal pollution. (D) Cadmium showed enrichment factors of 10 to 30 indicating pollution of the lake sediments by this metal (probably by urban effluents, runoff, and electroplating industries). (E) The proportion of exchangeable metals was nil in most cases. Exceptions (Ni and Mn) had very low exchangeable fractions (<1.22%). (F) The most abundant fraction (except for Mn) was the residual one (59.7–97.8% of total metal). Other fractions (carbonates, oxides, and organic) showed intermediate values. The general pattern was that the bulk of trace metals studied were present in non-mobile, slightly or non-reactive, poorly or non-available forms.     

Trace metals in fish exposed to asbestos rich sediments

Chrysotile asbestos fibers which contain high levels of Ni, Cr, Co, and Mn were introduced into the Sumas River by a landslide. The pH in the streamwater decreased with increasing distance from the landslide input source and in the process the trace metals in the asbestos rich sediments get leached. The findings from this study show that some of the trace metals such as Mn and Ni are elevated in several fish species. The Mn levels in fish muscle tissue and whole fish were found to be significantly higher than levels reported in the literature. Similarly Ni levels in whole fish were high. Threespine stickleback were found to have the highest Mn and Ni levels. Besides the elevated metal levels we have so far observed no other abnormalities in fishes of the system.     

Potential phytotoxicity of diquat accumulated by aquatic plants and sediments

The adsorption and desorption of Reglone A^R to freshwater algae, Myriophyllum spicatum and a soil-sand mixture, singly and in combination was examined to investigate the potential for phytotoxicity of diquat residues in aquatic sediments. The diquat adsorption capacity of the aquatic plants ranged from 0.6 to 2.4 mg diquat g dry wt^?1. Forty to seventy percent of the adsorbed diquat could be desorbed with 5 M ammonium chloride. The adsorption capacity of the soil system was about 2.5 mg diquat g dry wt^?1 and approximately 35% of this diquat could be desorbed. Reglone^R inhibited the growth of blue-green algae (Anabaena flos-aquae and Anacystis nidulans) at concentrations greater than 0.03 ppm. Eukaryotic algae were less sensitive, growth of Navicula pelliculosa was inhibited at concentrations exceeding 0.3 ppm and Chlorella vulgaris was unaffected by 3 ppm Reglone. In the presence of soil, growth inhibition by Reglone was eliminated. Reglone was added to a water-soil mixture system at levels up to 334 ppm to simulate chronic usage. Anabaena flos-aquae or Lemna sp. were used to bioassay the availability of the diquat adsorbed to this soil system. Significant growth inhibition of both bioassay plants was observed in soil treated with 33.4 ppm Reglone and the 334 ppm treatment was lethal. These experiments suggest that residual phytotoxicity becomes apparent in this soil system at about 7% of the diquat adsorption capacity. The Reglone adsorption-desorption isotherm of a natural, organic lake sediment was measured to predict the number of Reglone treatments at the recommended application rate before residual phytotoxicity would become apparent.     

Hydropower reservoirs enhanced the accumulation of heavy metals towards surface sediments and aggravated ecological risks in Jiulong River Basin,China

Journal of Soils and Sediments - In complex watersheds with multiple types of waterbodies, the effect of river damming on the distribution pattern of heavy metals in sediments and their potential...     

基于Copula函数的湘江流域气象干旱向水文干旱传播特性

水文干旱的发生往往与气象干旱的发生密切相关,因此揭示两者间的响应关系对干旱预警及水资源管理具有极其重要意义。该研究以湘江流域为研究对象,采用标准化降水指数(standard precipitation index,SPI)和标准化径流指数(standard runoff index,SRI)分别表征气象干旱和水文干旱,采用皮尔逊相关系数确定干旱响应时间,并结合游程理论识别、融合和剔除干旱事件,分析湘江流域上、中、下游不同季节干旱的趋势性及周期性,最后建立基于Copula函数耦合贝叶斯网络模型的气象-水文干旱特征响应概率曲线。结果表明:湘江流域气象干旱到水文干旱的传播时间为2个月,阈值组合[0.5、0、-0.5]相较于组合[0、-0.3、-0.5]识别得到的干旱事件更优;下游发生水文干旱的情况最为严重,中游气象干旱最为严重,整体上水文干旱发生历时和烈度的最大值均大于气象干旱;流域整体有湿润化趋势,但是在夏季和秋季,存在干旱化的趋势;干湿变化存在几个较为明显的震荡周期,分别为3～5、6～10和18～21 a;对于联合分布函数,除了上游和下游气象-水文干旱烈度的最优联合分布为Gumbel C...     

Origin,retention and release of trace metals from sediments of the river seine

Metallic contents (Fe, Mn, Pb, Cu, Cd, Zn, Cr) of sediments were measured in 14 sites in the River Seine (France) along 110 km; in three sites surrounding the sewage treatment plant at Achères, vertical profiles were established from cores and dialysis cells, and interface exchanges have been studied. Metal contamination increases downstream, except for Pb for which contamination is higher immediately downstream of stormdrains (up to 130 mg kg^?1); that confirms its urban origin. Upstream of Achères, metallic contamination increases with depth while downstream, contribution to sediments of suspended matter from the treatment plant, loaded with organic matter, alters the behaviour of metals within the first ten centimeters. A strong link between particulate organic carbon (POC), polycyclic aromatic hydrocarbons (PAH), polychlorobiphenyls (PCB) and metal contents has been established. The organic matter brought down by the treatment plant effluents induces a specific diagenesis downstream leading to metal release in summer as attested by a 30% metal contents decrease in sediments. Calculation of molecular diffusion fluxes shows that in september, the release phenomenon is ending.     

Trace metals concentrations in marine organisms from the coastal areas of Bahrain,Arabian Gulf

A total of 162 fish and shellfish samples representing important species have been collected from different coastal areas of Bahrain in the Arabian Gulf, and analyzed for lead, cadmium, mercury, and arsenic using electrothermal atomic absorption spectrophotometric method. The dverall mean levels for Pb, Cd, Hg and As in fish samples were 0.132, 0.032, 0.084 and 1.7 µg g^?1 wet weight, respectively, whereas for shellfish they were 0.149, 0.045, 0.042 and 3.61 µg g^?1 wet weight. These values indicate higher levels of metals in shellfish when compared with fish, except for mercury, and reveal that generally the levels of metals in these organisms are lower than existing guidelines, except for arsenic. The provisional tolerable weekly intake of Pb, Cd, Hg and As through fish was estimated to be 0.7, 0.17, 0.45 and 9 µg kg^?1 bodyweight per week, respectively. Our results did not reveal a clear pattern regarding variations of metals concentration between areas and species.     

Trace metals in roof runoff

In this paper we present the concentration of heavy metals (Cd, Cu, Pb, Zn) in runoff from five different roofs (tar felt, pantiles, asbestos cement, Zn sheet, gravel) during two rainfall events. The heavy metal load of roof runoff is assessed and the different processes influencing the fate of heavy metals on roof surfaces and in roof runoff are discussed. The extent of contamination with heavy metals of runoff from different roofing material has the following sequence: zinc sheet>tar felt>pantiles>asbestos cement>gravel. The hazard of infiltration of roof runoff with respect to heavy metals is discussed by comparison with concentrations in rain.     

Trace metals in two garden products derived from sewage sludge

Abstract

Yields were decreased in soybean (Glycine max L. C.V. Hawkeye), mint (Mentha viridis L. ), and barley (Hordeum vulgare L. C.V. Atlas 57) when grown in 50% Yolo loam soil and 50% of either of two commercial garden sewage sludge products. The trace elements Zn, Cu, Mn, and B were elevated in plants grown with the high‐level amendments. No Cd and little Ni were detected in shoots.     

Distribution and risk assessment of heavy metals in overlying water,porewater, and sediments of Yongding River in a coal mine brownfield

Journal of Soils and Sediments - Heavy metals from coal mines migrate into rivers and cause a severe impact on the health of local residents utilizing these rivers as a water source. However,...     

Heavy metal and chlorinated hydrocarbon contamination of selected aquatic sediments from the Berlin area

Sediments from the Berlin area were analysed for heavy metals and chlorinated hydrocarbons. the sedimentological and hydrogeological aspects of the Holocene sediments are discussed and an adapted sampling device for muds with a high water content is described. the contamination of surface sediments and dated cores is shown back in the 19th century; the hydrological influences on the degree of contamination and potential threats to groundwater and, via remobilisation, to surface waters are considered. It is concluded that the sediments of the Berlin area are highly contaminated.     

Trace Elements in Paddy Soils from the Central Region of the Mekong River,Laos

Extract

Laos (14–22.5°N and 100–107.5°E) is a land-locked country located in the Indo-China Peninsula, adjacent to Vietnam, Cambodia, Thailand, Myanmar, and China. The total area of the country is 236,800 km² and about 70% of the land is occupied by mountains. Paddy fields are distributed in flood plains along the Mekong River and its tributaries and in valley bottom plains dissected by small rivers. The climate is dominated by tropical monsoon.     

Trace metals in precipitation in Sweden

Trace metals (Cd, Cu, Fe, Mn, Pb, and Zn) concentrations in atmospheric precipitation have been routinely monitored in Sweden since the autumn of 1983. Concentrations are highest in southern Sweden and decrease northward. It is postulated that the long range transport of anthropogenic pollutants from the rest of Europe is the major source of Cd, Pb, and Zn in precipitation. Evidence for this hypothesis is that enrichment factors indicate anthropogenic origin, and Swedish atmospheric emissions of Zn and Cd are 2 to 3 times smaller than deposition fluxes. Also, Cd, Pb, and Zn concentrations are correlated in both space and time and are also well correlated with exSO₄ ⁺, a substance known to be of anthropogenic origin transported long distances.     

1951-2011年湘江径流泥沙演变过程与特征分析

根据湘江主要控制站1951-2011年长时间序列径流与泥沙资料,运用Mann-Kendall非参数检验法、小波分析法和均值差异T检验法等,揭示了湘江年径流量和年输沙量演变特征与规律,并分析了其驱动因素。结果表明:(1)径流量呈微弱增加趋势,而输沙量下降趋势明显; (2)时间序列上径流量未发生突变,而输沙量在1997年发生了突变,表现为1997年后有显著下降趋势; (3)小波分析表明径流量和输沙量均存在20和7 a的周期性变化规律; (4) 60 a来湘江年径流量可以分为1951-1954和1992-2002年两个多水期,1955-1991和2003-2011年两个少水期。径流泥沙集中度与集中期分析表明输沙量年内分配不均匀性更为明显,输沙主要集中在每年6月; (5)年输沙量显著减少主要是水利工程拦沙和水土保持工程措施所致。     

Distinguishing regional and local sources of pollution by trace metals and magnetic particles in fluvial sediments of the Morava River, Czech Republic

Purpose

Regional contamination of southern Moravia (SE part of the Czech Republic) by trace metals and magnetic particles during the twentieth century was quantified in fluvial sediments of the Morava River. The influence of local pollution sources on regional contamination of the river sediments and the effect of sampling site heterogeneity were studied in sediment profiles with different lithologies.

Materials and methods

Hundreds of sediment samples were obtained from regulated channel banks and naturally inundated floodplains and proxy elemental analyses were carried out by energy dispersive X-ray fluorescence spectroscopy (ED XRF) and further calibrated by inductively coupled plasma mass spectrometry (ICP MS). Magnetic susceptibility was determined as a proxy for industrial contamination. The age model for the floodplain sediments was established from ¹³⁷Cs and ²¹⁰Pb dating. Trace metal contamination was assessed by establishing the lithological background values from floodplain profiles and calculating enrichment factors (EF) of trace metals (i.e. Pb, Zn, Cu) and magnetic susceptibility for the entire study area.

Results and discussion

Channel sediments are unsuitable for the reconstruction of historical regional contamination due to their lithological heterogeneity and the “chaotic” influence of local sources of contamination, as well as the possibility of geochemical mobility of pollutants. On the other hand, sediments from regulated river banks qualitatively reflected the actual, local contamination of the river system.

Conclusions

This approach allowed us to distinguish the influence of local sources of contamination by comparison with more spatially averaged contamination signals from distal floodplain profiles. The studied area is weakly contaminated (EF ～1–2), while individual sediment strata from regulated channel banks reflect local sources of contamination and contain up to several times higher concentrations of trace metals.     

中国五个典型城市污水厂污泥中重金属的形态分布研究

Metal content and bioavailability are often the limiting factors for application of sewage sludge in agricultural fields. Sewage sludge samples were collected from five typical urban wastewater treatment plants in China to investigate their contents and distribution of various chemical fractions of Cu, Zn, Ni, Cr, Pb and Mo by using the BCR （Community Bureau of Reference） sequential extraction procedure. The sludges contained considerable amounts of organic matter （31.8%- 48.0%）, total N （16.3-26.4 g kg^-1） and total P （15.1-23.9 g kg^-1）, indicating high potential agricultural benefits of their practical applications. However, total Zn and Ni contents in the sludge exceeded the values permitted in China＇s control standards for pollutants in sludges from agricultural use （GB 4284-1984）. The residual fraction was the predominant fraction for Mo, Ni and Cr, the oxidizable fraction was the primary fraction for Cu and Pb, and the exchangeable and reducible fractions were principal for Zn. The distribution of different chemical fractions among the sludge samples refiected differences in their physicochemical properties, especially pH. The sludge pH was negatively correlated with the percentages of reducible fraction of Cu and exchangeable fraction of Zn. The sludges from these plants might not be suitable for agricultural applications due to their high contents of Zn, Ni and Cr, as well as high potential of mobility and bioavailability of Zn.     

Silver and other metals in some aquatic bryophytes from streams in the lead mining district of Mid-Wales,Great Britain

A reconnaissance survey was made of trace metals in surface waters and three aquatic bryophytes (Scapania undulata,Hygrohypnum luridum andPolytrichum commune) in the mid-Wales Ag-Pb mining district. This area is contaminated by heavy metals from past mining. Elevated levels of Ag, Cd, Cu, Pb, and Zn were found in water and plant tissue. All the plants accumulated Ag and the other metals butScapania appears the most suitable as a plant monitor of Ag-polluted waters.