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171.
Survey of heavy metal pollution and assessment of agricultural soil in Yangzhong district, Jiangsu Province, China 总被引:37,自引:0,他引:37
We investigated concentrations of Hg, Cd, Pb, Zn, Cu, As, Ni, and Cr in samples of soil, cereal, and vegetables from Yangzhong district, China. Compared to subsoils, the sampled topsoils are enriched in Hg, Cd, Cu, Pb, Zn, and As. High levels of Cd and Hg are observed in most agricultural soils. Concentrations of Cr and Ni show little spatial variation, and high Cu, Pb, and Zn contents correspond well to areas of urban development. High As contents are primarily recorded at the two ends of the sampled alluvion. The contents of Cd, Hg, and total organic carbon (TOC) increase gradually to maximum values in the upper parts of soil profiles, while Cr and Ni occur in low concentrations within sampled profiles. As, Pb, Cu, and Zn show patterns of slight enrichment within the surface layer. Compared to data obtained in 1990, Cd and Hg show increased concentrations in 2005; this is attributed to the long-term use of agrochemicals. Cr and Ni contents remained steady over this interval because they are derived from the weathering of parent material and subsequent pedogenesis. The measured As, Cu, Pb, and Zn contents show slight increases over time due to atmospheric deposition of material sourced from urban anthropogenic activity. Low concentrations of heavy metals are recorded in vegetables and cereals because the subalkaline environment of the soil limits their mobility. Although the heavy metal concentrations measured in this study do not pose a serious health risk, they do affect the quality of agricultural products. 相似文献
172.
Response of microcystis to copper stress: do phenotypes of microcystis make a difference in stress tolerance? 总被引:2,自引:0,他引:2
To elucidate the role of phenotype in stress-tolerant bloom-forming cyanobacterium Microcystis, two phenotypes of M. aeruginosa - unicellular and colonial strains were selected to investigate how they responded to copper stress. Flow cytometry (FCM) examination indicated that the percents of viable cells in unicellular and colonial Microcystis were 1.92-2.83% and 72.3-97.51%, respectively, under 0.25 mgl(-1) copper sulfate treatment for 24h. Upon exposure to 0.25 mgl(-1) copper sulfate, the activities of antioxidative enzyme, such as superoxide dismutase (SOD) and catalase (CAT), were significantly increased in colonial Microcystis compared to unicellular Microcystis. Meanwhile, the values of the photosynthetic parameters (F(v)/F(m), ETR(max), and oxygen evolution rate) decreased more rapidly in unicellular Microcystis than in colonial Microcystis. The results indicate that colonial Microcystis has a higher endurance to copper than unicellular Microcystis. This suggests that the efficient treatment concentration of copper sulfate as algaecides will be dependent on the phenotypes of Microcystis. 相似文献
173.
In this paper, we addressed the utilization of photochemical method as an innovative technology for the destruction and removal of two potent greenhouse gases, SF(6) and SF(5)CF(3). The destruction and removal efficiency (DRE) of the process was determined as a function of excitation wavelength, irradiation time, initial ratio of acetone to SF(5)X (X represented F or CF(3)), initial SF(5)X concentration, additive oxygen and water vapor concentration. A complete removal was achieved by a radiation period of 55min and 120min for SF(6)-CH(3)COCH(3) system and SF(5)CF(3)-CH(3)COCH(3) system respectively under 184.9nm irradiation. Extra addition of water vapor can enhance DRE by approximately 6% points in both systems. Further studies with GC/MS and FT-IR proved that no hazardous products such as S(2)F(10), SO(2)F(2), SOF(2), SOF(4) were generated in this process. 相似文献
174.
A full-scale sequencing batch reactor (SBR) system was evaluated for its ability to remove carbon and nitrogen from swine wastewater. The SBR was operated on four, six-hour cycles each day, with each cycle consisting of 4.5 hours of "React," 0.75 hours of "Settling", 0.75 hours for "Draw" and "Fill." Within each cycle, an amount of wastewater equivalent to about 5% of the reactor volume (5,500 litres) was removed and added. The SBR system was able to remove 82% of biochemical oxygen demand (BOD) and more than 75% of nitrogen. Even though the SBR effluent, with an average effluent BOD5 of about 588 mg L(-1), did not meet the discharge criteria, it enabled a reduction of the land base required for land application of swine wastewater by about 75%. Results indicated that the SBR system was a viable method for the treatment of swine wastewater. 相似文献
175.
176.
建立了大型模拟填埋试验装置,研究了渗滤液回流对不同填埋结构甲烷变化规律的影响.每周对填埋气体中甲烷浓度进行监测.结果表明:厌氧填埋中回流操作使甲烷浓度峰值提前了147 d,峰值为59.6%(体积分数,下同);准好氧填埋中回流操作使甲烷浓度峰值提前259 d,峰值为44.7%.回流操作使甲烷产气高峰提前,增加产气量,加快填埋垃圾稳定,减轻渗滤液污染.厌氧填埋中进行回流操作有利于甲烷的回收利用;准好氧填埋结构可有效减少甲烷的排放,减小对环境的危害.稳定期的垃圾填埋体进行回流产生一定的甲烷,但浓度较低,最高仅26.0%,没有利用价值. 相似文献
177.
178.
重金属污染土壤接种丛枝菌根真菌对蚕豆毒性的影响 总被引:5,自引:1,他引:5
采用盆栽实验的方法,研究了重金属(包括Cu、Zn、Pb和Cd)复合污染和接种丛枝菌根真菌(arbuscular mycorrhizal fungi,AMF)Glomus mosseae对蚕豆(Vicia faba)生长及DNA损伤的影响.结果表明,虽然接种菌根真菌对蚕豆生物量的影响并不显著,但是却显著影响植物对重金属的吸收,接种菌根真菌对蚕豆吸收4种重金属元素的作用有差异.采用单细胞凝胶电泳(single cell gel electrophoresis,SCGE)法研究接种菌根真菌对蚕豆叶片的DNA损伤的影响,与重金属吸收的结果相吻合.结果表明,接种处理可显著增加蚕豆叶片的DNA损伤程度,这与接种处理可提高植物的重金属吸收相一致. 相似文献
179.
利用透射电子显微镜观察分析白腐真菌(黄孢原毛平革菌)在处理染料废水活性艳红X-3B过程中,染料和盐度对黄孢原毛平革菌的细胞结构产生的毒性作用.结果表明:活性艳红X-3B染料对黄孢原毛平革菌产生生物毒性作用,且随着染料浓度的增加,细胞受损伤程度不断加深.加入100 mg/L的染料活性艳红X-3B后,黄孢原毛平革菌菌丝细胞形态发生变化,出现质壁分离现象;染料浓度进一步加大,菌丝细胞超微结构受到损伤逐渐严重.染料废水中的盐度对黄孢原毛平革菌细胞也会造成损伤,且损伤程度随盐度增大而增大.NaCl浓度为3 g/L时,菌丝细胞发生质壁分离;而当NaCl加入量高于8 g/L时,细胞膜受损,线粒体、细胞核呈现空泡化,表现为受到不可逆的损伤.染料和盐双因子对黄孢原毛平革菌细胞的损伤效应表现为其损伤程度与单因子作用一致,且染料的影响作用占主导. 相似文献
180.