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221.
Piyal Aravinna Amarasooriya Pitawala Sudharma K. Yatigammana 《Journal of environmental science and health. Part. B》2017,52(1):37-47
Pesticides applied on agricultural lands reach groundwater by leaching, and move to offsite water bodies by direct runoff, erosion and spray drift. Therefore, an assessment of the mobility of pesticides in water resources is important to safeguard such resources. Mobility of pesticides on agricultural lands of Mahaweli river basin in Sri Lanka has not been reported to date. In this context, the mobility potential of 32 pesticides on surface water and groundwater was assessed by widely used pesticide risk indicators, such as Attenuation Factor (AF) index and the Pesticide Impact Rating Index (PIRI) with some modifications. Four surface water bodies having greater than 20% land use of the catchment under agriculture, and shallow groundwater table at 3.0 m depth were selected for the risk assessment. According to AF, carbofuran, quinclorac and thiamethoxam are three most leachable pesticides having AF values 1.44 × 10?2, 1.87 × 10?3 and 5.70 × 10?4, respectively. Using PIRI, offsite movement of pesticides by direct runoff was found to be greater than with the erosion of soil particles for the study area. Carbofuran and quinclorac are most mobile pesticides by direct runoff with runoff fractions of 0.01 and 0.08, respectively, at the studied area. Thiamethoxam and novaluron are the most mobile pesticides by erosion with erosion factions of 1.02 × 10?4 and 1.05 × 10?4, respectively. Expected pesticide residue levels in both surface and groundwater were predicted to remain below the USEPA health advisory levels, except for carbofuran, indicating that pesticide pollution is unlikely to exceed the available health guidelines in the Mahaweli river basin in Sri Lanka. 相似文献
222.
采用二次酸浸出的方法回收镍钴湿法冶金工业污泥中的有价金属。先采用水和硫酸作为浸出剂浸出Mg和Na,最佳工艺条件为浸出液的pH 7.5、浸出时间5 min、浸出剂体积与干污泥质量的比(ω)为10 mL/g。再采用硫酸作为浸出剂、焦亚硫酸钠作为还原剂进行二次酸浸,在硫酸与污泥质量比为1.3、焦亚硫酸钠与污泥质量比为0.3、ω为5 mL/g、浸出温度85℃、浸出时间20 min的最佳工艺条件下,Co、Ni、Cu、Mn和Zn的浸出率分别达92.45%、93.48%、89.52%、97.78%和94.79%。经XRD表征,浸出后污泥中未见原污泥中的矿物相,说明原污泥中的矿物几乎全部被溶解。 相似文献
223.
废锂电池中含有的Co、Ni和Cu等金属具有回收价值,Fe的存在降低了有价金属的回收效率。为去除废锂电池硫酸浸出液中的Fe,采用黄钠铁矾法分别以氯酸钠和过氧化氢作为氧化剂氧化除Fe,并优化了过氧化氢作为氧化剂的除Fe工艺参数。实验结果表明:过氧化氢作为氧化剂的除Fe效果好于氯酸钠;在n(H2O2)∶n(Fe)=0.5、初始溶液pH为1.8、终点pH为2.5、反应时间为2.0 h、搅拌速率为500 r/min的最佳工艺条件下,初始ρ(Fe)为0.212g/L的硫酸浸出液经除Fe处理后ρ(Fe)小于0.004 g/L,Fe去除率达98.0%,Co、Ni和Cu的损失率分别为1.04%、2.17%和1.41%。 相似文献
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226.
露天存放的铅锌尾矿受到自身酸化和酸雨的双重影响,从而加剧尾矿对环境的影响。因此,研究尾矿在酸性条件下的重金属行为及其植物毒性,对植物在铅锌尾矿地的自然定居有非常重要的意义。将铅锌尾矿砂装柱,用pH2~7溶液淋溶50天的结果表明,酸度的提高可以显著地增加尾矿砂中重金属(Pb、Zn、Cu和Cd)的溶出。而随着时间的延长,Zn的溶出量明显增高,Pb和Cu的溶出则逐渐降低。在pH值<3时,Cd的溶出逐渐升高,pH值>3时,Cd的溶出也呈下降趋势。酸度对重金属溶出的影响由大至小依次为Zn>Cd>Cu>Pb。渗滤液对植物的毒性随着起始淋溶酸度的提高与时间的推移而加剧 相似文献
227.
Bradley C. Paul Gurdeep Singh Steven Esling S. Chaturvedula H. Paudel 《Environmental monitoring and assessment》1998,50(1):1-13
A sulfate-rich flue gas desulfurization scrubber sludge was used as a substitute backfill material in reclamation of an abandoned coal strip mine. The site was surrounded by monitor wells and the material was characterized for leaching behavior using open column experiments. A drain was placed directly beneath the 45 000 ton fill to enable sampling before dilution or attenuation. The column studies indicated that the scrubber sludge would adsorb manganese, iron, aluminium, cobalt, nickel, thallium and zinc contaminants from the water. Changes in pH appear inadequate to explain the removal by precipitation. The groundwater cleaning phenomenon has been confirmed on a field scale by the drain samples. Boron and molybdenum leach from the fly ash was used to fix the scrubber sludge and serve as marker elements enabling calibration of the dispersivity in computer models of the groundwater system at the site. The leachate front appears to be diluted by a factor of 8 : 1 within the first 15 meters. Since boron and molybdenum release are associated only with the first flush, environmental impacts will be minimal. Columns appear to create a time compression effect on the duration of leaching phenomenon. The effect for this site appears to be at least 5 : 1. The columns were effective in predicting which elements would leach or adsorb in the field and in predicting the actual source concentrations. Other shake tests such as the TCLP and the ASTM shake test were found to be less effective at predicting which elements would leach and were not helpful in predicting field concentrations. 相似文献
228.
通过对"浮选+氰化浸出"工艺回收锑锍渣中金的试验研究,确锍渣中金的综合回收率可达80%-85%,既减少了污染,又回收了有价资源,有明显的经济和环境效益. 相似文献
229.
采用穿透渗漏实验方法研究了经水泥固化的重金属废物的长期渗漏行为。用由Pb^2+、Zn^2+、Cu^2+、Ni^2+和Cr^6+5种重金属组成的合成废物样品进行2组实验。实验研究了渗漏实验液流速、PH的变化和金属渗漏能力对固体废物长期渗漏行为的影响。 相似文献
230.
An approach is developed to simulate leaching of a dissolved chemical constituent in the vadose zone of an aquifer. Specifically,
nitrate loading at the water table for different water table depths, for a range of aquifer permeability values, and for different
cases of heterogeneity of the aquifer, are considered. Models from the literature are first used to derive soil–water characteristic
curves (water retention and hydraulic conductivity) from a grain size distribution curve for unsaturated conditions. Given
infiltration from the surface, the initial conditions for the chemical concentration, and the water content profile, leaching
of the chemical in the vadose zone is simulated as a function of both time and depth. The methodology is illustrated for a
permeable aquifer. Simulations are undertaken using a finite element code for saturated and unsaturated flow. Different scenarios
are simulated depending on the heterogeneity of the aquifer and the depth of the water table. Modeling results show that in
the example case studied, nitrate concentration loading at the water table does not depend strongly on the position of the
water table, but rather on the material properties of the aquifer. The contribution of this endeavor resides in the methodology
which allows a prediction of nitrate leaching using only the grain size property of the aquifer. It allows practitioners to
obtain a first assessment of leaching with limited data. 相似文献