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351.
Environmental contamination due to uncontrolled e-waste recycling activities is drawing increasing attention in the world. Extraction of these metals with biodegradable chelant [S,S]-ethylenediaminedisuccinic acid (EDDS) and the factors influencing extraction efficacy were investigated in the present study. Results showed that the addition of EDDS at low pH (5.5) produced higher metal extraction than that at high pH (8.0) solution. Metal speciation analysis indicated that Cu was completely complexed with EDDS at different pH conditions with various amounts of EDDS applied. For Pb and Zn, at low EDDS dose of 0.304 mol/kg soil, they were present as Pb- and Zn-EDDS. However, at high EDDS dose of 1.26 mol/kg soil, most of Pb was bound with dissolved organic matter. Ca and Al were found to be strong competitors for trace metals to EDDS at low application dose and low pH condition. 相似文献
352.
慢生型花生根瘤菌16S rRNA分析 总被引:5,自引:0,他引:5
以21株分离自四川,云南不同花生产区的慢性型花生根瘤菌和6株参比菌株为材料,进行了16SrDNAPCR-RFLP,结果除证实了慢性型花生根瘤菌同慢生型大豆根瘤菌(Bradyrhizobiumjaponicum)高度的遗传相似性外,还发现了一些菌株同Bradyrhizoibiumliaoningensis和Bradyrhizobiumelkanii有较高的遗传相似性,菌株Spr1-2的16SrRNA 相似文献
353.
Zhongwei Guo Yiming Li Xiangming Xiao Lin Zhang Yaling Gan 《Ecological applications》2007,17(6):1557-1562
Globally, particularly in developing countries, hydroelectricity production and economic growth occur together with ecosystem/biodiversity conservation in watersheds. There is a relationship between hydroelectricity production and ecosystem/biodiversity conservation in watersheds, centering on the supply and demand for ecosystem services of river water flow regulation and sediment retention. Here we show that, in the upper reach of the Yangtze River, hydroelectricity production of Three Gorges Hydroelectric Power Plant can form a beneficial relationship with forest conservation through the paid use (compensating residents for their cooperation in the conservation) of ecosystem services launched by the National Natural Forest Protection Project. This interaction can provide additional incentives to encourage local communities' long-term cooperation in conserving and protecting the restored forest ecosystems. Hydroelectricity plants also obtain benefits from this interaction. The industrialization of ecosystem services supply provides an operational framework for this beneficial interaction. Sustainable forest ecosystem conservation will require developing new institutions and policies and must involve local communities in the conservation and protection of their local forests. 相似文献
354.
珠江三角洲地区大气中有机氯农药的被动采样观测 总被引:8,自引:0,他引:8
利用PUF被动采样装置,对珠江三角洲地区大气中有机氯农药(OCPs)进行监测.结果显示,广东省大气中有机氯农药主要是滴滴涕(DDTs)、六六六(HCH)及氯丹(Chlordane),其中DDTs约占总OCPs的54.5%;香港大气中农药残留主要是氯丹和DDTs,氯丹约占总含量的51.3%.珠三角地区大气中有机氯农药空间分布差异明显(580-5500pg·m-3),香港平均浓度远远低于广东省.另外,广东省仍有工业DDT在使用,造成广东省大气中有"新"的工业DDT输入;而三氯杀螨醇是香港大气中DDT高含量的重要来源;广东省和香港HCH主要源于林丹使用的残留,香港的Eastern及Tsuen Wan源于工业六六六使用的残留;珠江三角洲所有采样点的HCB含量较低,大气中HCB少量残留可能是HCB作为药物中间体的化学合成及HCB在大气中长距离传输的结果. 相似文献
355.
沉积物中多环芳烃和有机氯农药定量分析的质量保证和质量控制 总被引:118,自引:8,他引:118
以美国EPA为方法为基础,进行了沉积物中多环芳烃和有机氯农药分析的质量保证和质量控制实验,采用回收率指示物控制回收率,用内标法定量。结果表明多环芳烃的指示物回收率为50.67-97.33%,目标化合物的回收率为58.67-96.33%,方法检测限为3.30-9.26μg.kg^-1。 相似文献
356.
温度和pH值对活性污泥法脱氮除磷的影响 总被引:8,自引:2,他引:8
温度和pH值是影响污水脱氮除磷效果的2个重要因素.试验采用连续搅拌槽式反应器(continuous stirred tank reactor,CSTR),通过对不同温度和pH值条件下的硝化、反硝化、释磷和吸磷反应速率的测定,总结出温度和pH值对活性污泥生化反应速率的影响规律.试验表明,硝化和反硝化速率随温度的升高而加快.在5℃和33℃时,硝化速率分别为0.01 kg NH4 -N/(kg VSS·d)和0.28 kg NH4 -N/(kg VSS·d);在5℃和30℃时,反硝化速率分别为0.097 kg NO3--N/(kg VSS·d)和0.476 kg NO3--N/(kg VSS·d);但温度对吸磷和释磷速率的影响不大.pH值对硝化、反硝化、吸磷和释磷速率均有显著影响,在pH值为7.74时,硝化速率为0.095 kg NO3--N/(kg VSS·d);而在pH值为4.9和10.08时,硝化速率仅为0.005 kg NO3--N/(kg VSS·d)和0.006 kg NO3--N/(kg VSS·d).在pH值为7.85时,反硝化速率达到最大值0.36 kg NO3--N/(kg VSS·d);而在偏酸性和碱性条件下,反硝化速率显著下降. 相似文献
357.
废弃线路板的粉碎和所含金属组分的高效解离是后续分选回收的前提条件。本研究分别使用乙二胺等10种溶剂浸泡废弃线路板,比较对线路板中铜箔与基板间剥离强度的影响,从而筛选出4种有代表性的溶剂,即溶剂D、溶剂F、丙酮和水, 比较废弃线路板经化学溶胀后的单体解离度和获得一定粒径分布的颗粒所需的破碎时间。研究结果表明,化学溶胀后破碎能大幅提高金属的单体解离度,浸泡效果的优良排序为:溶剂D>溶剂F>丙酮>水;浸泡时间越长,浸泡温度越高,对剥离强度的降低越有利;使用溶剂D在150℃、3 h或140℃、5 h的工艺下浸泡废弃线路板,可以使铜箔与基板自动脱落。研究结果为后续的分选提供了便利的条件。 相似文献
358.
城市污水厂二级处理出水深度处理组合工艺研究 总被引:2,自引:0,他引:2
为了研究臭氧-曝气生物滤池二级处理出水深度处理组合工艺的处理效果,采用臭氧-曝气生物滤池(biological aerated filter, BAF)组合工艺对城市污水处理厂二级生化处理出水进行深度处理。结果表明,组合工艺对造成水中色度的主要物质腐植酸和富里酸类有机物和嗅味物质中的二甲基三硫和二甲基异莰醇(MIB)能够进行有效去除。臭氧氧化能够显著提高后续BAF单元对CODMn的去除。在进水CODMn6~8 mg/L、色度为25~30度、浊度约为8 NTU的条件下,当臭氧投加量为5~6 mg/L、BAF的水力停留时间为1~1.5 h时,出水CODMn< 5 mg/L、色度<5度、浊度<1 NTU,出水水质可满足生产工艺对回用水的水质要求。 相似文献
359.
Polycyclic aromatic hydrocarbon (PAH) deposition to and exchange at the air-water interface of Luhu, an urban lake in Guangzhou, China 总被引:3,自引:0,他引:3
Urban lakes are vulnerable to the accumulation of semivolatile organic compounds, such as PAHs from wet and dry atmospheric deposition. Little was reported on the seasonal patterns of atmospheric deposition of PAHs under Asian monsoon climate. Bulk (dry + wet) particle deposition, air-water diffusion exchange, and vapour wet deposition of PAHs in a small urban lake in Guangzhou were estimated based on a year-round monitoring. The total PAH particle deposition fluxes observed were 0.44-3.46 μg m−2 day−1. The mean air-water diffusive exchange flux was 20.7 μg m−2 day−1. The vapour deposition fluxes of PAHs ranged 0.15-8.26 μg m−2 day−1. Remarkable seasonal variations of particulate PAH deposition, air-water exchange fluxes and vapour wet deposition were influenced by seasonal changes in meteorological parameters. The deposition fluxes were predominantly controlled by the precipitation intensity in wet season whereas by atmospheric concentration in dry season. 相似文献
360.
Accumulation of lead, zinc, copper and cadmium by 12 wetland plant species thriving in metal-contaminated sites in China 总被引:32,自引:0,他引:32
The concentrations of lead, zinc, copper and cadmium accumulated by 12 emergent-rooted wetland plant species including different populations of Leersia hexandra, Juncus effusus and Equisetum ramosisti were investigated in field conditions of China. The results showed that metal accumulation by wetland plants differed among species, populations and tissues. Populations grown in substrata with elevated metals contained significantly higher metals in plants. Metals accumulated by wetland plants were mostly distributed in root tissues, suggesting that an exclusion strategy for metal tolerance widely exists in them. That some species/populations could accumulate relatively high metal concentrations (far above the toxic concentration to plants) in their shoots indicates that internal detoxification metal tolerance mechanism(s) are also included. The factors affecting metal accumulation by wetland plants include metal concentrations, pH, and nutrient status in substrata. Mostly concentrations of Pb and Cu in both aboveground and underground tissues of the plants were significantly positively related to their total and/or DTPA-extractable fractions in substrata while negatively to soil N and P, respectively. The potential use of these wetland plants in phytoremediation is also discussed. 相似文献