MELIMEX,an experimental heavy metal pollution study: Particle size distributions in limno-corrals

The particle size distributions in three limno-corrals, located in Baldeggersee, Switzerland, have been determined by means of a Zeiss Micro-Videomat image analyzer as a function of depth and time. The distributions were measured biweekly over a period of 1 year at depths of 0 m, 2.5 m, 5 m, 7.5 m and 10 m (=above bottom). Two of the limno-corrals were charged with heavy metals, whereas the third was uncharged and served as a reference. The shape of the distributions as well as the particle concentrations in the uncharged container did not differ from the ones in the charged limno-corrals. The distributions were found to be self-preserving and independent on heavy metal load, time, depth and particle concentrations. As an average, the dependence of the distributions on the particle diameter was found to be ?1.5 to ?2.5.     

MELIMEX,an experimental heavy metal pollution study: Regulation of trace metal concentrations in limno-corrals

In three limno-corrals of the MELIMEX project the transport paths of the trace metals Cu, Zn, Cd, Hg and Pb and the reaction of the systems on increased metal loads were investigated. The metal balances lead to the conclusion that the biomass is the main factor responsible for the regulation of trace metal concentration. The observed sequence of relative residence times of the trace metals can be described with a steady-state model. Additional metal load decreases the ability of the limnic system to lower the metal concentration. The production of phytoplankton and its assimilation capacity for metals are reduced leading to relatively higher metal concentrations in the lake.     

MELIMEX,an experimental heavy metal pollution study: Effects of increased heavy metal loads on phytoplankton communities

Long-term impacts of increased metal loading (Hg, Cu, Cd, Zn and Pb) on phytoplankton communities of large limno-corrals (diameter 12 m, depth 10 m) were studied. Increased metal concentrations initially lowered phytoplankton biomass, as well as species number and photosynthetic activity of phytoplankton. They caused changes in metal speciation and shifts in phytoplankton community structure, favoring less susceptible species. Although adaptation was not sufficient to completely prevent the metal-induced depression of photosynthesis, due to depressed zooplankton grazing, at the end of the experiment even higher phytoplankton densities were observed in the metal-loaded corrals than in the control.     

MELIMEX,an experimental heavy metal pollution study: Behaviour of heavy metals in an aquatic food chain

Phytoplankton, periphyton and zooplankton samples, chironomid andSialis sp. larvae, and fry of trout and bream collected from unpolluted and artificially metal-polluted limno-corrals were analyzed for mercury, copper, cadmium, zinc and lead. The results indicate that these metals are not accumulated through the food chain and suggest that increased metal concentrations in the environment favor the growth of phytoplankton organisms with a low metal sorption capacity.     

MELIMEX,an experimental heavy metal pollution study: Vertical mixing in a large limno-corral

In a limno-corral (diameter 12 m, depth to sediments 10 m), located in Baldeggersee (Switzerland), vertical mixing has been measured during more than one year and compared to the conditions in the open lake (maximum depth 65 m, surface area 5.3 km²). The temperature method by McEwen and Hutchinson yields K_z values between 5×10⁻² cm²s⁻¹ at the upper boundary of the thermocline and 2×10⁻³ cm²s⁻¹ at the bottom, a value near the molecular diffusion of heat at 4°C (1.36×10⁻³ cm²s⁻¹). K_z calculated from profiles of excess radon-222 generally agree with those from the temperature data. Compared to the open lake, the corral has a more shallow epilimnion. However, during calm meteorological conditions, vertical mixing in the upper 10 m is similar outside and inside the corral. Supported by the Swiss National Science Foundation within the framework for its National Research Program on ‘Lake Currents.’     

MELIMEX,an experimental heavy metal pollution study: Effects of increased heavy metal load on crustacea plankton

The crustacea plankton of three artificial model lakes in Lake Baldegg was observed during 15 months. Two were loaded continuously with low concentrations of five heavy metals (Hg, Cu, Cd, Zn, Pb). It was attempted to explain the significant lower abundances of the loaded limno-corrals. The results suggest that the decrease was not, or only partially, caused by the lower food supply in the loaded limnocorrals, but directly by the heavy metals. Accompaning laboratory tests show significantly increased egg-development-times for two species of those animals from the loaded limno-corrals. Two other species show a decrease of the egg production/♀. It cannot be determined if increased mortality of particular animal stages was caused by heavy metals.

---

Résumé On a observé pendant 15 mois les crustacés planctoniques des trois modèles de lac installés dans le lac de Baldegg. Dans deux de ceux-ci, une charge constante de cinq métaux lourds (Hg, Cu, Cd, Zn, Pb) de faible concentration a été maintenue. On a essayé d'expliquer la faible concentration significative de plancton dans les bassins limnologiques chargés. Les résultats montrent que la diminution n'était que partiellement ou pas du tout causée par le faible approvisionnement en nourriture dans les bassins chargés, mais directement par les métaux lourds. Les tests de laboratoire montrent significativement l'augmentation du temps de développement des œufs pour deux espèces animales des bassins chargés. Deux autres espèces montrent une diminution de la production d'œufs/♀. On ne peut pas déterminer l'augmentation de la mortalité des animaux causée par les métaux lourds à des stades particuliers de développement.

     

MELIMEX,an experimental heavy metal pollution study: Chemical speciation and biological availability of copper in lake water

The chemical speciation of dissolved copper was investigated in waters from the limno-corrals of the MELIMEX project and compared with speciation data from other Swiss lakes. Copper is complexed primarily by organic ligands having molecular sizes between 10⁴ and 10³ daltons. The mean concentration of the ligands is approximately 5×10⁻⁷ mole/mg DOC. The conditional stability constants (pH=8.8) are about 10¹¹. An increased metal load did not induce an increase of binding ligands. A comparison of calculated Cu²⁺ concentration with corresponding copper contents in the biomass leads to the conclusion that organic ligands and pH are the most important factors in deciding the biological availability of copper. However the sorption capacity of the biomass depends as well on the variety of plankton species.     

MELIMEX,an experimental heavy metal pollution study: Effects of increased heavy metal load on uptake of glucose by natural planctonic communities

Glucose uptake in lake water samples has been determined with short-time¹⁴C-experiments at different additions of the single heavy metals Cu⁺⁺, Zn⁺⁺, Cd⁺⁺, Pb⁺⁺, Hg⁺⁺ and at different additions of a combination of all metals. The degree of a metal induced inhibition of glucose uptake varied from lake to lake and from season to season, whereby the addition of legally tolerated concentrations of 10 μg Cu/l and 200 μg Zn/l inhibited glucose uptake in most samples significantly, as well as the simultaneous addition of all metals. The legally tolerated limit of 1 μg Hg/l inhibited glucose uptake in Lake Lucerne samples almost completely, showed however no effect in samples of Lake Baldegg. The equimolar toxicity sequence of heavy metals for heterotrophic microorganisms has been determined as: Hg>Cu>Cd>(Zn. Pb). Glucose uptake of plankton sampled from metal polluted limno-corrals was less inhibited than that of the control plankton, when heavy metals were added to the samples singly or in combination. It is assumed that this effect is due to the natural selection of more resistant plankton species.     

Sedimentation and chronology of heavy metal pollution in Oslo harbor, Norway

Stratigraphic profiles of Cu, Cd and Hg in ten sediment cores from the Oslo harbor, Norway, combined with results of radiometric dating demonstrate that pollution by these metals peaked between 1940 and 1970. Dating results indicate that Hg discharges peaked between 1940 and 1950, Cd reached maximum ca. 1955-1960, and Cu has the highest concentration in sediment interval corresponding to ca. 1970. Geochemical profiles and maxima of Cu, Cd and Hg concentrations can be used as chronostratigraphic markers for sediment cores from the Oslo harbor. Acoustic backscatter and sediment core data indicate that propeller wash affects the seabed in the Oslo harbor. The propeller-induced turbulence causes erosion, and in places exposes and remobilizes contaminated sediments that accumulated in the harbor during previous decades. Such re-exposure of contaminated sediments could be detrimental to local ecosystems and offset remediation efforts, warranting further impact studies and potential mitigation strategies to prevent redistribution.     

Emergent effects of heavy metal pollution at a population level: Littorina brevicula a study case

Changes in genetic variability and allele frequency can be responses from natural populations when encountering a novel contaminated environment. The genetic diversity and population structuring of natural populations of the gastropod Littorina brevicula from heavy-metal polluted and unpolluted environments along the southeast coast of Korea were examined using two mtDNA markers, cyt b and ND6. This study applied a nested clade analysis to test the existence of structuring association of haplotype distribution with environments (polluted and unpolluted). No genetic differences within cyt b mtDNA were detected between environments. On the other hand, differences in population haplotype diversity and structuring were found within ND6 mtDNA between polluted and unpolluted environments. The ND6-mtDNA haplotype (=genetic) diversity was significant lower in polluted environments. This decreased genetic diversity along with differences in the haplotype distribution within heavy-metal polluted environments compared to those unpolluted ones stand out as emergent effects from pollution at a population level. In this study, we propose the use of different approaches, such as the NCA, that takes into account the rare haplotypes, when assessing the effects of pollution on population genetic structuring.     

Eutrophication and heavy metal pollution in the Flensburg Fjord: A reassessment after 30 years

A study of surface sediment organic matter and heavy metal content (e.g. Cu, Zn, Pb and Sn) was carried out in 2006 to assess changes in eutrophication and pollution in the periodically anoxic Flensburg Fjord since 1972. Low hydrodynamic activity together with sewage discharges and high primary production in the inner fjord promote the enrichment of present day surface sediments in organic matter and metals in contrast to the outer fjord. However, heavy metal contents in the fjord are typical for the western Baltic Sea, although they are higher than in the preindustrial period.Although the anthropogenic nutrient load has substantially decreased since the 1970s, sediments from the inner fjord contain more organic material in 2006 than in 1972 resulting from still high levels of primary production supported by internal nutrient loading. Of the heavy metals measured, a decrease in Pb content since the 1970s is distinct, which is explained by the banning on gasoline lead. Taken together, these results suggest that the amelioration of environmental conditions needs time but is indeed related to reduced anthropogenic inputs.     

Assessment of heavy metal pollution in surface sediments of the Bayan Lepas area,Penang, Malaysia

This study aimed to evaluate the spatial and temporal distribution of heavy metals (Cd, Cr, Cu, Co, Fe, Pb, Ni, V, and Zn) in the sediments of Bayan Lepas Free Industrial Zone of Penang, Malaysia. Ten sampling stations were selected and sediment samples were collected during low tide (2012 ? 2013). Metals were analyzed and the spatial distribution of metals were evaluated based on GIS mapping. According to interim sediment quality guidelines (ISQG), metal contents ranged from below low level to above high level at different stations. Based on the geoaccumulation index (I_geo) of sediment, sampling stations were categorized from unpolluted to strongly polluted. The enrichment factor (EF) of metals in the sediment varied between no enrichment to extremely high enrichment. The potential ecological risk index (RI) indicated Bayan Lepas FIZ was at low risk.     

40 年来江苏石梁河水库重金属污染的沉积记录

根据石梁河水库沉积物粒度和重金属元素(Cu,Cr,Zn,As和Pb)含量的分析,结合137Cs放射性比活度精确定年,研究了石梁河水库沉积速率和重金属的污染变化特征,并利用地累积指数法评价了重金属的污染程度.结果表明:石梁河水库 40年来平均淤积速率为3.85cm/a,Cu,Cr和zn地累积指数一直小于1,处于轻微污染;As污染水平变化较大.现处于低水平的轻度污染;Pb污染水平自柱底始持续恶化,目前地累积指数大于1,且有污染加剧趋势.     

Integration of magnetism and heavy metal chemistry of soils to quantify the environmental pollution in Kathmandu, Nepal

Abstract Soil profiles of the Kathmandu urban area exhibit significant variations in magnetic susceptibility (χ) and saturation isothermal remanence (SIRM), which can be used to discriminate environmental pollution. Magnetic susceptibility can be used to delineate soil intervals by depth into normal (< 10^?7 m³/kg), moderately enhanced (10^?7–< 10^?6 m³/kg) and highly enhanced (≥ 10^?6 m³/kg). Soils far from roads and industrial sites commonly fall into the ‘normal’ category. Close to a road corridor, soils at depths of several centimeters have the highest χ, which remains high within the upper 20 cm interval, and decreases with depth through ‘moderately magnetic’ to ‘normal’ at approximately 30–40 cm. Soils in the upper parts of profiles in urban recreational parks have moderate χ. Soil SIRM has three components of distinct median acquisition fields (B_1/2): soft (30–50 mT, magnetite‐like phase), intermediate (120–180 mT, probably maghemite or soft coercivity hematite) and hard (550–600 mT, hematite). Close to the daylight surface, SIRM is dominated by a soft component, implying that urban pollution results in enrichment by a magnetite‐like phase. Atomic absorption spectrometry of soils from several profiles for heavy metals reveals remarkable variability (ratio of maximum to minimum contents) of Cu (16.3), Zn (14.8) and Pb (9.3). At Rani Pokhari, several metals are well correlated with χ, as shown by a linear relationship between the logarithmic values. At Ratna Park, however, both χ and SIRM show significant positive correlation with Zn, Pb and Cu, but poor and even negative correlation with Fe (Mn), Cr, Ni and Co. Such differences result from a variety of geogenic, pedogenic, biogenic and man‐made factors, which vary in time and space. Nevertheless, for soil profiles affected by pollution (basically traffic‐related), χ exhibits a significant linear relationship with a pollution index based on the contents of some urban elements (Cu, Pb, Zn), and therefore it serves as an effective parameter for quantifying the urban pollution.     

Assessment of heavy metal pollution in Xuzhou urban topsoils by magnetic susceptibility measurements

The concentrations of four selected heavy metals (Pb, Zn, Ni and Cr) were measured on 167 topsoil samples collected from the city of Xuzhou, China via inductively coupled plasma mass spectroscopy (ICP-MS). It was found that Pb and Zn were principally derived from anthropogenic inputs whereas Cr and Ni distributions were mainly controlled by parent materials. The spatial distribution patterns of Pb, and Zn were similar to that from low field magnetic susceptibility (χlf), suggesting interaction among them. Two threshold values for magnetic susceptibility and frequency-dependent susceptibility percentage (χfd) were applied to discriminate between polluted and unpolluted samples according to their magnetic susceptibility, resulting in 109 samples populating the “polluted” subset. The Pb and Zn concentrations of the “polluted” subset were statistically significantly higher than those measured in the “unpolluted” one. The heavy metal concentrations were also investigated varying the magnetic susceptibility thresholds to change the “polluted” subset.     

Statistical and spatial assessment of soil heavy metal contamination in areas of poorly recorded, complex sources of pollution

The assessment of soil heavy metal contamination and the quantification of its sources and spatial extent represent a serious challenge to the environmental scientists and engineers. To date, statistical and spatial analysis tools have been used successfully to assess the amount and spatial distribution of soil contamination. However, these techniques require vast amounts of samples and a good historical record of the study area. Furthermore, they cannot be applied in cases of complex or poorly recorded contamination and provide only a qualitative assessment of the pollution sources. The author has developed a methodology that combines statistical and geostatistical analysis tools with geographic information systems for the quantitative and spatial assessment of contamination sources. This paper focuses on the techniques that may be employed to explore the structure of a soil data set. Soil contamination data from Lavrio old mine site in Greece were used to illustrate the methodology. Through the research, it was found that principal component and factor analysis tools delineate the principal processes that drive pollution distribution. However, the spatial assessment and quantification of multiple pollution sources cannot be resolved. This aspect is explored in detail in the second paper of the series, focusing on the exploitation of principal component and factor analysis results as inputs for canonical correlation, geostatistical analysis and geographic information systems tools.     

云南阳宗海沉积物重金属污染时空特征及潜在生态风险

分析了阳宗海柱状及表层沉积物中Al、Fe、Mn、Zn、Cr、Co、Ni、Cu、As、Cd、Pb等金属元素的含量,结合沉积年代学,研究了沉积物重金属污染的时空变化和潜在生态风险特征.结果表明,表层沉积物中重金属含量具有一定的空间差异性,As、Cd、Cu、Pb和Zn在中东部湖区含量较高,而Cr、Co、Ni含量高值位于南、北湖区的近岸区域;柱状沉积物中,1990s之前As、Cd、Cu、Pb和Zn含量较为稳定,1990s中后期以来,其含量逐渐增加,并在2009-2010年前后达到最大值,此后逐渐下降;而柱状沉积物中Cr、Co、Ni含量变化趋势与Al、Fe相似,总体上由下向上逐渐降低,这主要与沉积物质地(粒度)逐渐变粗有关.重金属富集系数表明,阳宗海沉积物中主要污染元素为As、Cd、Cu、Pb和Zn,1990s中后期污染程度快速增加,2009-2010年前后达到峰值,此后污染程度逐渐降低;表层沉积物中Cu为未污染至"弱"污染水平;Zn、Pb为"弱-中等"污染水平,As为"中等-强"污染水平,Cd为"弱-强"污染水平,中东部湖区污染程度高于其他湖区,这可能与该湖区缺少入湖径流、自然碎屑物质沉积速率较低以及砷污染事件等人为源的重金属贡献影响更为显著有关.生态风险评价结果表明,在2002-2010年前后沉积物重金属达到"中等-强"潜在生态危害,主要贡献因子是Cd和As,近年来其生态风险等级逐渐降低;表层沉积物中重金属在中东部湖区具有"中等"程度潜在生态危害,而其他湖区表层沉积物重金属具有较低程度的潜在生态风险.