Recovery of precious metals by an electrochemical deposition method

Conversion of soluble precious metals into a solid form for further reuse was studied by using an electrochemical deposition approach. It was found that the metal recovery followed a first-order reaction kinetics. The distance between the electrodes had no much impact on the recovery, while higher mixing led to faster kinetics. The presence of humic acid (HA) with lower concentration (<20mg l (-1)) did not have impact on the recovery. When its concentration was increased to 50 mg l (-1), it decreased the metal reduction. Presence of ethylene diamine tetraacetic acid (EDTA) and ionic strength slightly reduced the copper recovery rate. Around 50% removal of for HA and EDTA was achieved. In the competing environment, metal recovery was in the following order: silver>lead>copper. X-ray photoelectron spectroscopic and scanning electronic microscopic analysis of the reduced metals demonstrated that the depositions were composed of mainly elemental metals together with their oxides which were due to the oxidation.     

基于"3S"技术的城郊森林公园土地利用问题分析——以武汉市马鞍山森林公园为例

近年来城郊森林公园发展很快,然而城郊型森林公园的土地利用问题的研究却很少。分析了城郊森林公园土地利用的特点,并以武汉市马鞍山森林公园为例,借助3S技术,以1989年、1995年、1998年、2005年遥感影像为主要数据源,分析了马鞍山森林公园土地的现状、变化及存在的问题,并提出了建议。     

Effect of 17beta-estradiol on the reproduction of Japanese medaka (Oryzias latipes)

Estrogenic compounds such as 17beta-estradiol (E2) and its analogs are present in the aquatic environment and can adversely affect the reproductive systems of aquatic organisms. Although E2 has been detected at a maximum concentration of 64 ng/l in effluents of sewage treatment works (STWs), few reports address the associated effects on reproduction in fish. Therefore, we exposed adult medaka (Oryzias latipes) to mean measured E2 concentrations of 29.3, 55.7, 116, 227, and 463 ng/l for 21 d and assessed the effects on the egg number and fertility of paired medaka during the exposure period. In addition, we determined the hepatic vitellogenin (Vtg) concentration and histologically assessed the gonads of these fish. The number of egg produced and fertility of the paired medaka exposed to 463 ng/l E2 were significantly less compared with those of the control fish. Males in all treatment groups had developed testis-ova. Males treated with E2 concentrations = 55.7 ng/l contained relating great concentrations of hepatic Vtg. Therefore, although only the greatest E2 concentration tested in our study affected fecundity and fertility, effects of E2 were observed on induction of Vtg and testis-ova in male medaka exposed to environmentally relevant concentrations of E2.     

A new fossil mustelid from the Miocene of South Dakota,USA

A skull from the Barstovian of South Dakota has typical leptarctine characteristics, including robust zygomatic arches, double sagittal crests, grooves on the lingual side of the lower canines, and bony projections from the tympanic bullae. The robust mandibles and expanded masseteric fossa of this specimen indicate that it had large jaw muscles. Dental morphology and other characters lead us to agree with earlier suggestions that Hypsoparia is a valid genus. The morphology of Hypsoparia suggests that leptarctines were more herbivorous than most other Carnivora.     

单扫描极谱法测定废水中微量苯胺

在稀盐酸介质中 ,苯胺与亚硝酸钠反应生成重氮盐 ,其盐与亚硫酸钠、甲醛的反应产物在 - 0 .72V (vs·SCE)左右产生灵敏的二阶导数极谱波。苯胺浓度在 1 .0 0× 1 0 - 6 ～ 2 .5× 1 0 - 4mol·L- 1 范围与峰电流 (iP’’)呈线性关系 ,相关系数 0 .9996。本法可用于废水中微量苯胺的测定。     

Derivation of 137Cs deposition density from measurements of 137Cs inventories in undisturbed soils

The 137Cs inventories in undisturbed soils were measured for 292 locations across the territory of Vietnam. The logarithmic inventory values were regressed against characteristics of sampling sites, such as geographical coordinates, annual rainfall and physico-chemical parameters of soil. The regression model containing latitude and annual rainfall as determinants could explain 76% of the variations in logarithmic inventory values across the territory. The model part was interpreted as the logarithmic 137Cs deposition density. At the 95% confidence level, 137Cs deposition density could be predicted by the model within +/- 7% relative uncertainty. The latitude mean 137Cs deposition density increases northward from 237 Bq m(-2) to 1097 Bq m(-2), while the corresponding values derived from the UNSCEAR (1969) global pattern are 300 Bq m(-2) and 600 Bq m(-2). High 137Cs inputs were found in high-rainfall areas in northern and central parts of the territory.     

建筑施工行业特种作业人员安全职业能力倾向研究

职业能力倾向对长期从事职业活动的安全性起着决定性影响。本文通过人员访谈法调查了建筑施工现场145名特种作业人员,并咨询建筑特种作业领域相关专家35名,最终确认了对建筑施工行业特种作业人员安全职业能力倾向最重要的5个影响因素(准确性、注意力、判断力、快速反应能力、稳定性),它们在对特种作业人员的安全职业能力倾向的控制和支配过程中发挥主要作用。     

重金属复合污染下草本植物两两组合水培的富集特性

为了探明草本植物两两组合培养对其重金属富集特性的影响,寻求修复V、Pb、Cd、Cr复合污染的最佳草本植物组合模式,在V、Pb、Cd、Cr 4种重金属〔ρ分别为14.0、0.8、6.0、4.0 mg/L〕共存的水培条件下,研究蒌蒿(Artemisia selengensis turcz)、三叶草(Trifolium repens)、鱼腥草(Houttuynia cordata)和紫花苜蓿(Medicago sativa) 4种草本植物两两组合培养时的重金属富集特性,以及对植物生物量、重金属富集量和转运系数的影响. 结果表明:4种草本植物两两组合培养会在不同程度上影响植物的重金属富集特性,在重金属富集能力方面,蒌蒿、鱼腥草和紫花苜蓿分别与三叶草组合培养时,其地上部分w(Cr)分别比单独培养时提高约157%、303%、639%;两两组合培养时,紫花苜蓿可促进蒌蒿、鱼腥草和三叶草对Pb的吸收. 在重金属转移能力方面,效果最突出的是“三叶草‖紫花苜蓿”组合模式,其中三叶草对V、Pb、Cd、Cr 4种重金属的转运系数分别是单独培养时的1.19、2.52、22.60和1.67倍;对不同组合模式下植物地上部分重金属提取量的分析结果显示,“三叶草‖紫花苜蓿”组合模式对V、Pb、Cd、Cr 4种重金属的提取量均较高,分别为1 555、1 688、473、482 mg/kg,表明该组合模式能够有效缓解地表径流对附近土壤造成的叠加污染. 因此,水培条件下不同草本植物两两组合培养会改变植物的重金属富集特性,并且与植物种类有关.      

超滤和活性炭组合工艺流程位置的优化试验研究

以集成膜工艺处理回用钢铁废水现场试验为背景,介绍了超滤、活性炭于不同位置的预处理效果差异,分析了超滤、活性炭于工艺流程不同位置对CODCr去除效果、出水SDI15及超滤稳定运行工况的差异及原因,提出了两者组合工艺用于反渗透预处理的建议和进一步研究方向。     

Impacts of Bakken Shale Oil Development on Regional Water Uses and Supply

The Bakken shale play in western North Dakota is one of the largest unconventional oilfields in the United States, but published research about impacts on the region's water resources is rare. In this study, besides examining North Dakota water management policies and activities, we also analyzed three datasets: the Bakken horizontal well completion data (2008‐2014), North Dakota permitted water consumption data (2000‐2014), and groundwater level and streamflow observations in western North Dakota (2000‐2014). We found from 2008 to 2014, the annual total industrial water uses for Bakken shale oil development ranged between 0.5 and 10% of statewide total consumptive water use. The percentage increases were between 3.0 and 40% within the Bakken oil production region. The increased population of temporary oilfield service workers contributed additional domestic water use, which was equivalent to ~15% of annual industrial water use for the shale oil development in the Bakken. Despite being in a semiarid region, the impact of Bakken development on regional water supply was limited because the water in the Bakken was adaptively managed and the region received on average over 20% more precipitation than normal during 2008‐2014. Of the 15 glaciofluvial aquifers under study, 12 have seen water levels increasing or unchanged and the water levels for the remaining 3 aquifers have decreased.