Incorporation of Heavy Metals Bioavailability into Risk Characterization

The bioavailability of field‐aged Cd and Cu was calculated, and compared to the total concentrations determined by acid digestion. Only 0.60–4.15% for Cd and 0.59–9.43% for Cu were found to be bioavailable when determined by stomach‐phase extraction. The incorporation of bioavailability reduced more than 90% of the calculated risk of the metals at the site of study. It should be noted that such a reduction may not be generalized and the site‐specific bioavailability needs to be determined case by case.     

武汉东湖沉积物中重金属生物有效性研究

沉积物中的酸挥发性硫化物(AVS)是预测厌氧沉积物中重金属生物有效性的重要参数,SEM/AVS大于1时沉积物中重金属具有潜在生物毒性,小于1时则无生物有效性. 本文研究了东湖三个不同污染负荷的站点的同步提取金属SEM(Cu, Zn, Pb, Cd, Ni, Co, Ag, Cr)和SEM/AVS的深度分布,研究表明东湖沉积物中主要重金属是Zn, Cr和Cu,约占SEM总量的90%. I站、II站沉积物中AVS是重金属生物有效性的主控因子之一,对重金属的深度分布影响较大,重金属不具有生物有效性;III站沉积物中AVS对重金属的深度分布影响较小,重金属具有潜在的生物毒性. 相关分析表明,I站、II站沉积物中Cr、Ni、Ag、Cd与AVS在P<0.05有显著性相关,AVS对这些金属的深度分布具有更强的控制作用;虽然两站沉积物中Cr的含量差别不大,东湖I站沉积物中Cr/AVS比值(0.02)显著高于II站(0.003),沉积物中Cr与硫化物的结合主要是受还原反应的影响.     

南四湖表层底泥重金属污染及其风险性评价

通过对南四湖表层底泥中的重金属元素浓度分析,揭示出南四湖不同湖区重金属污染物空间分布特征.利用潜在生态风险指数(RI)和地质积累指数(Igeo)两种指标相结合的方法对表层底泥中重金属污染程度进行评价.结果表明,南四湖上级湖的重金属污染主要以汞为主,并依据潜在生态风险指数将南四湖上级湖分为三个生态风险功能区: 昭阳湖轻污染区;独山湖中等污染区和南阳湖重污染区.     

Demobilization of Heavy Metals from Mine Waters

The present study elucidates the remediation of mine waters by means of geochemical barriers („active barriers“). Active barrier systems (ABS) are developed, which can prevent heavy metal dispersion by introducing the barrier into the mine. Therefore, low‐cost materials are investigated which can remove contaminants by chemical, and/or physical mechanisms from water. The materials investigated are industrial by‐products (e.g. fly ash, red mud, scale arrears), natural wastes (e.g. tree bark), and relatively cheap natural products (bentonite, zeolites). Red mud and fly ash show the best results for the removal of Zn, Cd, Ni, and Mn from model water. Cd seems to have the strongest binding of the investigated metals on the sorption sites. The main mechanisms of metal removal from solution in this case are sorption and precipitation. Both materials have very good sorption and acid neutralization capacities (ANC), but ANC seems to be the determining factor.     

Size Fractions of Heavy Metals in Waters

The heavy metal content of river water samples with 12 and 15 mg/l dry matter of seston is increased to 400 … 3900μg/l by the addition of inorganic heavy metal salts, and after three days the distribution of the heavy metals is determined by fractional filtration (8, 3, 1.2, 0.8, 0.65, 0.45 and 0.22 μm pore size). More than 80% of Ni, Co and Mn are found in the fraction <0.22 μm, 60% of Pb and Cu in >8 μm as well as 40 and 25%, resp., in <0.22 μm, Cd, Cr and Zn are found in all fractions, 60 … 80% being in the fraction <0.22 μm, 90% of Fe occurring in the fraction >8 μm. The influence of specific parameters of water quality as pH-value and seston concentration on the distribution requires further investigations.     

Uptake of Heavy Metals by Cladophora glomerata

The influence of the duration of exposure on the accumulation of Pb, Cu, Cd, Cr, Co Zn and Ni by Cladophora glomerata was studied in short-term batch experiments. It was determined that the uptake of heavy metals differs not only in the rate of uptake but also in the maximum cumulation attained. The highest uptake after exposure for 6 h to an initial concentration of 200 μg/l occurred with chromium — 168 μg/g, the minimum uptake occurred with cobalt — 86.9 μg/g. Also the rate of uptake differed significantly. After the exposure period of 15 min 120.7 μg/g of chromium was taken up and, in contrast, only 7.6 μg/g of nickel was taken up after the same exposure period.     

Changes in Phytoplankton Production after the Introduction of Heavy Metals into Ecosystem with Subsequent Cleaning by Humic Sorbent

Water Resources - The paper presents the results of experiments with mesomodeling of water pollution in a lowland freshwater body by a mixture of salts of heavy metals (Cd, Zn, Cu). The response of...     

Heavy Metals in the Ivan'kovo Reservoir Bottom Sediments

Spatial and temporal variability of heavy metals concentrations in the Ivan'kovo Reservoir bottom sediments was studied. It was found that for the period of 1983–1998, their content largely decreased in many sections of the reservoir, with the exception of individual deep-water channel stretches and certain bays. The character of vertical distribution of microelements in the bottom sediments is shown to be related to the level of contamination and character and rate of water exchange in the reservoir.     

Characterization and Application of Dried Plants to Remove Heavy Metals,Nitrate, and Phosphate Ions from Industrial Wastewaters

Low cost adsorbents were prepared from dried plants for the removal of heavy metals, nitrate, and phosphate ions from industrial wastewaters. The efficiency of these adsorbents was investigated using batch adsorption technique at room temperature. The dried plant particles were characterized by N₂ at 77 K adsorption, scanning electron microscopy, energy dispersive X‐ray spectroscopy, Fourier transform infrared spectroscopy, and phytochemical screening. The adsorption experiments showed that the microparticles of the dried plants presented a good adsorption of heavy metals, phosphate, and nitrate ions from real wastewaters. This adsorption increased with increasing contact time. The equilibrium time was found to be 30 min for heavy metals and nitrate ions and 240 min for phosphate ions. After the adsorption process, the Pb(II) concentrations, as well as those of Cd(II), Cu(II), and Zn(II) were below the European drinking water norms concentrations. The percentage removal of heavy metals, nitrates, and phosphates from industrial wastewaters by dried plants was ～94% for Cd²⁺, ～92% for Cu²⁺, ～99% for Pb²⁺, ～97% for Zn²⁺, ～100% for ${\rm NO}_{{\rm 3}}^{{-} } $ and ～77% for ${\rm PO}_{{\rm 4}}^{3{-} } $ ions. It is proved that dried plants can be one alternative source for low cost absorbents to remove heavy metals, nitrate, and phosphate ions from municipal and industrial wastewaters.     

Biogeochemical Indicators of Aquatic Ecosystem Pollution by Heavy Metals

The present-day environmental state of some artificial (Irkutsk, Bratsk, and Novosibirsk reservoirs) and natural (lakes in Altai Territory and Yamal-Nenets Autonomous Okrug and the Tom River) water bodies in Western and Eastern Siberia was evaluated using biogeochemical indicators. The biogeochemical approach is presented as the best for establishing zones of risk and environmental disaster, since biogeochemical cycles play important role in aquatic ecosystems and unite all their blocks as a result of biogenic migration of chemical elements. Aquatic ecosystems transformed under anthropogenic impact are recognized and local sources of water pollution are identified.     

Distribution of Heavy Metals in Lake Seliger Bottom Deposits

The distribution of some microelements in the surface and stratified layers of bottom sediments in Lake Seliger is studied. Data on the bottom deposit pollution by heavy metals is used to determine the anthropogenic load on the lake ecosystem. Cd, Zn, and Pb are shown to rapidly accumulate in thick (>1 m) bottom deposits that have formed during the period of lake existence. The concentrations of Cd and Zn are shown to correlate with the organic matter in thick bottom deposits.