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821.
822.
农药毒死蜱的生态风险及其微生物修复技术研究进展 总被引:11,自引:0,他引:11
毒死蜱是替代甲胺磷和对硫磷等高毒农药的高效有机磷杀虫剂,在世界范围得到广泛使用.但是,环境毒理学研究发现,毒死蜱对生态环境具有潜在的危险性,甚至被认为具有干扰内分泌的功能,许多国家对毒死蜱在农产品中的残留量有严格的规定.因此,深入研究毒死蜱的生态风险问题是当务之急.对国内外关于毒死蜱的残留活性、生态毒理、降解机制以及生物修复等方面的研究进行了综述,以期对毒死蜱的合理管理和使用提供科学依据. 相似文献
823.
824.
膨润土对Pb2+、Cu2+、Cr3+的吸附动力学及等温线研究 总被引:1,自引:0,他引:1
研究所用膨润土的主要成分为SiO2和Al2O3,属于Ca基膨润土,BET表面积为50.83 m2/g.在恒温及恒定pH条件下,用静态吸附法研究了膨润土对Pb2 、Cu2 、Cr3 的吸附特性,结果表明其较好地符合Lagergten二级吸附速率方程,对这3种离子的吸附速率为Pb2 >Cu2 >Cr3 .利用3种等温线方程对吸附过程进行拟合,发现利用Langmuir吸附等温方程计算的值与膨润土吸附Pb2 、Cu2 、Cr3 试验数据最为吻合.膨润土对3种金属离子的平衡吸附量为Cr3 >Cu2 >Pb2 . 相似文献
825.
826.
Recolonization and succession of marine macrobenthos in organic-enriched sediment deposited from fish farms 总被引:5,自引:0,他引:5
High organic loading deposited on the sea bottom by marine fish farming activities often eliminates benthic organisms in the vicinity. In this study, organic-enriched sediment collected underneath a fish farm was defaunated, placed in settling trays and exposed to the subtidal area of a clean site of similar hydrography. Trays were sampled monthly for a consecutive period of 5 months, and recolonization and successional patterns of macrobenthos were studied using univariate and multivariate statistics. Recolonization occurred rapidly, and averages of 144 animals/tray and 26 species/tray were recorded within the first month. Molluscs accounted for 49% of species and polychaetes for 77% of abundance during the first month of recolonization. Temporal changes in abundance, diversity and species composition found in subsequent months resembled spatial changes of benthic community along a decreasing pollution gradient generalised by Pearson and Rosenberg (1978, Oceanography & Marine Biology Annual Review 16, 229-311). Abundance reached a peak after 3 months (434 animals/tray) and then declined. Species number also increased, peaked after 4 months (47 species/tray), and was followed by a decrease. The polychaete Prionospio malmgreni succeeded Pseudopolydora paucibranchiata as the dominant species after the first month, reached a peak (194 animals/tray) after 3 months, then declined sharply. The rapid recolonization and succession of the macrobenthic community on organic-enriched sediment suggested that present fish farming methods are unlikely to have a long-term impact on benthic communities once farming activities are reduced/ceased. 相似文献
827.
Biodegradation of 2,4,6-trichlorophenol in the presence of primary substrate by immobilized pure culture bacteria 总被引:8,自引:0,他引:8
In this study, pure strains that are capable of utilizing 2,4,6-trichlorophenol have been isolated from the mixed culture grown on substrates containing chlorophenolic compounds. Studies have been carried out on the capability of these isolated pure strains in suspended and immobilized forms to decompose 2,4,6-trichlorophenol. Additionally, the influence of primary substrates (e.g., phenol, 2-chlorophenol, 3-chlorophenol, 4-chlorophenol, 2,4-dichlorophenol) on the decomposition of 2,4,6-trichlorophenol by the isolated pure strains grown in immobilized form is also investigated. The results are: Through bacterial isolation and identification, three pure strains have been obtained: Pseudomonas spp. strain 01, Pseudomonas spp. strain 02 and Agrobacterium spp. Whether in suspended or immobilized forms, all strains have poor removal efficiencies of 2,4,6-trichlorophenol. However, addition of 200 mg/l phenol will enable the immobilized Pseudomonas spp. strain 01, and Pseudomonas spp. strain 02 to achieve 65% and 48% removal of 2,4,6-trichlorophenol, respectively. Addition of phenol will assist the immobilized Pseudomonas spp. strain 02 in achieving removal of 2,4,6-trichlorophenol but the removal efficiency is not good if the phenol concentration is too low. The optimum phenol concentration should be between 200 and 400 mg/l. 相似文献
828.
829.
Effects of heavy metals on growth and arsenic accumulation in the arsenic hyperaccumulator Pteris vittata L 总被引:9,自引:0,他引:9
Fayiga AO Ma LQ Cao X Rathinasabapathi B 《Environmental pollution (Barking, Essex : 1987)》2004,132(2):289-296
The effects of Cd, Ni, Pb, and Zn on arsenic accumulation by the arsenic hyperaccumulator Pteris vittata were investigated in a greenhouse study. P. vittata was grown for 8 weeks in an arsenic-contaminated soil (131 mg As kg(-1)), which was spiked with 50 or 200 mg kg(-1) Cd, Ni, Pb, or Zn (as nitrates). P. vittata was effective in taking up arsenic (up to 4100 mg kg(-1)) and transporting it to the fronds, but little of the metals. Arsenic bioconcentration factors ranged from 14 to 36 and transfer factors ranged from 16 to 56 in the presence of the metals, both of which were reduced with increasing metal concentration. Fern biomass increased as much as 12 times compared to the original dry weight after 8 weeks of growth (up to 19 g per plant). Greater concentrations of Cd, Ni, and Pb resulted in greater catalase activity in the plant. Most of the arsenic in the plant was present as arsenite, the reduced form, indicating little impact of the metals on plant arsenic reduction. This research demonstrates the capability of P. vittata in hyperaccumulating arsenic from soils in the presence of heavy metals. 相似文献
830.
接种厌氧消化污泥EGSB反应器的快速启动 总被引:1,自引:0,他引:1
对接种市政消化污泥的EGSB反应器的启动进行实验研究以寻求快速启动EGSB反应器的有效方法。接种厌氧消化污泥EGSB反应器的成功启动仅需要46d。在整个启动期保持适当的液体上升流速是非常重要的。启动初期,高液体上升流速能够将悬浮污泥冲出反应器,使适合聚集的微生物留在反应器内。接下来需要降低进水流量和液体上升流速以利于构建稳定的微生态系统,使高活性颗粒污泥尽快形成。然后适当提高液体上升流速能保持污水与微生物的良好接触,促进颗粒污泥内外高效传质,形成更加稳定高效的微生物群落结构。为尽快形成高活性颗粒污泥,保证产甲烷菌的最佳营养需求是关键,可通过考虑进水基质、微量营养元素和硫化物来提高其活性。 相似文献