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991.
Through short-term exposure (7-d exposure), long-term exposure (16-d exposure) and exposure-recovery (7-d exposure + 9-d recovery), the bioaccumulation and distribution of La and Ce and their effects on growth of wheat seedlings were studied. Addition of La (0.5-25 mg/l) and Ce (0.5-25 mg/l) to the culture medium individually and in combination inhibited primary root elongation, reduced the dry weight of roots and shoots and the content of mineral elements (Ca, Mg, K, Cu, Zn). The damage increased with an increase in the concentrations of La and Ce in culture medium. Relative damage ratio increased with an increase in concentrations of La and Ce in the culture medium and with exposure time. Comparing exposure-recovery groups with long-term exposure groups, primary root lengths, dry weight of roots and shoots and the content of five mineral elements were higher. The accumulation of La and Ce in the seedlings was positively correlated with the concentrations of La and Ce in the culture medium and with exposure time. Bioaccumulation factors of La and Ce in roots were much higher than those of shoots. The uptake rates of La and Ce by the plants were much higher than the translocation rates from roots to shoots. The accumulation and distribution of La and Ce in the seedlings in exposure-recovery groups showed that there was very little excretion through metabolism during the recovery period, but redistribution occurred throughout the whole plant. No apparent selective uptake was found between La and Ce by the plants when they were applied in combination. 相似文献
992.
近年来,重庆市将次级河流综合整治工作作为一项“重过程、重民生、重实效”的系统工程来抓,次级河流整治取得明显成效.但也面临一些问题,如污水处理基础设施仍不完善,农村面源污染局面未根本扭转,水污染防治长效管理机制不健全等.在此基础上提出以下建议,一是加强流域规划控制和管理;二是统筹实施次级河流整治项目;三是建立完善跨界河流上、下游联动工作机制;四是探索建立生态补偿机制. 相似文献
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Tao Huang Qiang Guo Hui Tian Xiaoxuan Mao Zhongyuan Ding Gan Zhang Jun Li Jianmin Ma Hong Gao 《Environmental science and pollution research international》2014,21(9):6124-6135
Thirty-two topsoil samples were collected to analyze the residue levels of organochlorine pesticides (OCPs) in topsoil of arid and semiarid areas of northwest China in 2011. Results showed that DDTs were the dominant contaminants with a mean concentration of 12.52 ng/g. The spatial distribution characteristics indicated that α-hexachlorocyclohexanes (HCHs) were mainly used in rural sites, whereas hexachlorobenzene (HCB) and endosulfan were detected mostly in urban areas. DDTs, heptachlor, and chlordane were found almost equally in both urban and rural areas. Source identification revealed that the current levels of HCHs in soils were attributable to the residues from their historical use and fresh usage of lindane (γ-HCH). DDTs were mainly from historical use and fresh usage of dicofol, and HCB was emitted from the chemical industry. It was also found that the current soil levels of heptachlor were mainly from its historical usage, endosulfan from fresh input, and chlordane from long-range atmospheric transport, respectively. The noncarcinogenic health risk assessment with a model was also conducted using USEPA standards for adults and children. Results indicated that health risk under nondietary exposure to OCPs decreased in the sequence of ΣDDT?>?ΣHCH?>?HCB?>?Σheptachlor?>?Σendosulfan?>?Σchlordane. According to the reference dose from the USEPA, the health risk under nondietary exposure to OCPs in the soil samples was at a relatively safe level. 相似文献
996.
Chao Xu Jinghui Ding Jiguo Qiu Yun Ma 《Journal of environmental science and health. Part. B》2013,48(11):960-966
A highly effective acetochlor-degrading bacterial strain (D-12) was isolated from the soil of a pesticide factory. The strain was identified as Achromobacter sp. based on its 16S rRNA gene sequence. The strain D-12 optimally degrades acetochlor at a pH of 7.0 and a temperature of 30°C in a mineral salts medium (MSM). Approximately 95% of acetochlor was degraded by the stain treated at a concentration of 10 mg L?1 after 5 days of incubation. A chiral high performance liquid chromatography (HPLC) system was used to study the enantioselectivity during the process. However, no obvious enantioselective biodegradation was observed. The primary biodegradation acetochlor products were identified by high-performance liquid chromatography-mass spectroscopy (HPLC-MS) and gas chromatography-mass spectrometry (GC-MS). The results indicated that the strain D-12 could be applied in the bioremediation of an acetochlor-polluted environment. 相似文献
997.
废水吸附法除磷的研究进展 总被引:7,自引:0,他引:7
本文叙述了利用吸附原理进行废水除磷的研究进展。吸附法除磷的研究主要表现在吸附材料的研究方面 ,基于应用场合的差异 ,包括廉价的天然材料、工业废渣及其改性物、传统的活性氧化铝及其改性物、其他多孔物质及人工合成的高效吸附剂等。人工合成高效吸附剂由于磷吸附容量大 ,其相关研究成为近年来的重要发展方向 相似文献
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环境污染应急处置是指在已经对污染物种类、浓度、污染范围及其危害程度做出判断的基础上,为尽快地消除污染物,限制污染范围扩大,以及减轻和消除污染危害所采取的一切措施。本文从水、大气、土壤3个方面介绍了由危险化学品引发的环境污染应急处置。 相似文献
1000.
稻田表面流去除鱼塘养殖水中的氮、磷效果试验研究 总被引:1,自引:0,他引:1
池塘水质对水产养殖非常重要,本研究的目的在于探索稻田面流净化池塘养殖水质的技术途径。在养殖池塘旁稻田内布置9个小区,进行田间面流试验,取水样进行分析。结果表明:在1.5—6.0m^3/h(相应的平均流速为7.5~30m/h)的水力负荷下,鱼池水经稻田表面流处理后可得到一定净化;N、P的去除率与稻田表面流的流量(流速)有关,随流量增大呈减小趋势;在抽穗一扬花期稻田可有效减少养殖水的氮磷含量,在拔节期一孕穗期可显著减少NOf—N含量,有利改善池塘养殖环境。 相似文献