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991.
垃圾渗滤液对地下水污染的PRB原位处理技术 总被引:34,自引:0,他引:34
以被垃圾渗滤液污染的地下水为研究对象,分别用零价铁、零价铁和活性炭、零价铁和沸石的混合物作为反应介质,设计了3种地下可渗透反应器(PRB),分别为反应器A、B和C,对PRB技术治理污染地下水的可行性和有效性进行实验模拟研究.反应器的设计充分考虑了反应器的渗透能力与周围地层介质渗透能力的关系.实验结果表明:反应器A、B、C对COD的去除率分别达到80%、90%、70%以上,BOD5/COD值由0.32分别升高至0.781、0.728、0.716,总氮从50mg/L都降到10mg/L以下,NH4+的去除率达到78%~91%.反应器C中的沸石对重金属和硬度表现出良好的去除效果,其中Mn、Zn离子和硬度的去除率分别达到90%、80%和81%,说明PRB技术治理渗滤液污染的地下水是可行的. 相似文献
992.
环境信息公开作为信息化时代环境治理的新型武器,对我国这样一个具有特殊财政体制和政治激励模式的发展中国家而言,其在污染防治攻坚战中的效果有待深入探究。本文基于城市污染源监管信息公开指数(PITI),以2008—2016年120个城市数据为样本,采用动态面板数据模型和系统GMM估计方法,实证检验了环境信息公开的污染减排效应,并重点分析了不同城市区位和城市规模下存在的异质性效应。结果表明:环境信息公开有助于污染防治,改善环境质量,还能有效缓解财政分权引致的环境污染问题。环境信息公开对污染排放的抑制作用呈现“马太效应”,对东、中、西部地区和大、中、小城市的影响均依次递减。对东、中部地区和大、中型城市,其治污效应较显著,而在西部地区和小城市尚不见效。积极推动全面环境信息公开,构建环境多元共治的长效机制,是决胜污染防治攻坚战的关键所在。 相似文献
993.
Nitrification in natural waters with high suspended-solid content--a study for the Yellow River 总被引:8,自引:0,他引:8
In this research, the mechanism regarding the effects of suspended solids on nitrification in freshwater systems with high solid contents was examined. Experimental studies were conducted for natural water of the Yellow River under laboratory conditions. Nitrification kinetics was investigated in water systems with various levels of suspended-solid contents. The associated mechanisms were analyzed through investigation of the adsorption-desorption of ammonium nitrogen, the process of bacteria growth, and the feature of nitrification kinetics. The results indicated that the presence of suspended solids could accelerate the nitrification process. The nitrification rate would increase non-linearly with the increase of suspended-solid content. When the initial concentration of ammonia nitrogen was 12.70 mg/l in the water system, the ratios of half-time duration for nitrification would be 1.88:1.23:1 under suspended-solid contents of 0, 1.84 and 5.00 g/l, respectively. When the initial concentration of ammonia nitrogen was around 1.0 mg/l in the water system, the nitrification rates in systems with suspended-solid contents of 1.81 and 3.42 g/l would then be approximately 9 and 12 times that without suspended solids, respectively. The populations of nitrifying bacteria would rise with increasing suspended-solid content. The existence of suspended solids would increase the contact chances between bacteria and nitrogen, resulting in accelerated nitrification processes; this was manifested by the increased K(4) (tau(max)/K(S)) along with the raised suspended-solid contents while fitting nitrification kinetics with the growth-based logistic model. Since the amount of ammonium nitrogen adsorbed on suspended-solid surface was non-linearly proportional to the suspended-solid content, the nitrification rate was also non-linearly proportional to the suspended-solid content. 相似文献
994.
以钛酸四丁酯为原料,空心微珠为载体,采用溶胶凝胶法制备TiO2/beads光催化剂载体,然后浸渍法制备出H4SiW12O40/TiO2/beads表面负载修饰型复合光催化剂,并运用SEM、XRD、FT-IR和DRS对催化剂进行表征和分析。研究了H4SiW12O40/TiO2/beads对亚甲基蓝降解的光催化活性,考察了光强度、pH值、曝气量、底物浓度和催化剂用量等对催化效率的影响。实验结果表明,在中性条件下,H4SiW12O40/TiO2/beads催化剂的投加量为0.25 g/L,浓度为7.5 mg/L的亚甲基蓝溶液在250 W的紫外灯和600 W的可见光灯下光照60 min降解率分别可达到94.5%和55%。 相似文献
995.
Shan Y Feng Z Izuta T Aoki M Totsuka T 《Environmental pollution (Barking, Essex : 1987)》1996,91(3):355-361
The seedlings of Pinus armandi Franch. were exposed to ozone (O(3)) at 300 ppb for 8 h a day, 6 days a week, and simulated acid rain of pH 3.0 or 2.3, 6 times a week, alone or in combination, for 14 weeks from 15 June to 20 September 1993. The control seedlings were exposed to charcoal-filtered air and simulated rain of pH 6.8 during the same period. Significant interactive effects of O(3) and simulated acid rain on whole plant net photosynthetic rate were observed, but not on other determined parameters. The exposure of the seedlings to O(3) caused the reductions in the dry weight growth, root dry weight relative to the whole plant dry weight, net photosynthetic rate, transpiration rate in light, water-use efficiency and root respiration activity, and increases in shoot/root ratio, and leaf dry weight relative to the whole plant dry weight without an appearance of acute visible foliar injury, but did not affect the dark respiration rate and transpiration rate in the darkness. The decreased net photosynthetic rate was considered to be the major cause for the growth reduction of the seedlings exposed to O(3). On the other hand, the exposure of the seedlings to simulated acid rain reduced the net photosynthetic rate per unit chlorophyll a + b content, but did not induce the significant change in other determined parameters. 相似文献
996.
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999.
A survey was done in 15 typical villages, 150 soil and 86 vegetable plant samples were taken in Jiaxin prefecture of the Taihu Lake region, northern Zhejian province. Results indicate that after 15–20 years land use changed from the paddy rice–wheat (or oilseed rape) double cropping system, to a continuous vegetable land has caused soil quality dramatic change. (1) Acidification: average soil pH was 5.4; about 61% of total samples were pH < 5.5. It was 0.9 units lower than 10 years ago with same upland vegetable cultivation and was 1.2 units lower than soil pH of paddy rice–wheat (or oilseed rape) rotation. (2) Fertilizer salt accumulation: the average salt content was 0.28%, among these about 36.2% of the total samples contained more than 0.3%. (3) Nitrate N and available phosphorus (P) over accumulation: on average it was 279 mg NO3-N/kg, and 45–115 mg P/kg. Nitrate N four times higher and available P 4–10 times more than it is in present paddy rice–wheat rotation soils respectively. This has caused wide concern because of possible groundwater and well drinking water pollution by leached nitrate N and the P losses to water by runoff from vegetable lands induce surface water eutrophication. 相似文献
1000.
Heavy metal concentrations in soils and plant accumulation in a restored manganese mineland in Guangxi, South China 总被引:19,自引:0,他引:19
Heavy metal contamination of metal-mined soils is a widespread problem in China. In the restored (over 20 years) Lipu manganese mineland, 36 plant species from 22 families were found colonizing, some of which were planted agronomic ones. Heavy metal concentrations in tailings were very high. Minesoils were basically unpolluted, but soils in the remaining mining area and in the vicinity of tailings dumps were polluted by Cd and Mn. Measurements of metal contents in dominant plants showed they were close to those of other mineland plants. Plants tended to have a higher Cd accumulation (as reflected by Biological Accumulation Coefficient) from soil, but have a higher Mn translocation (as indicated by Biological Transfer Coefficient) to aboveground parts. The Chinese chestnut and sugarcane cultivated on the reclaimed mineland were not safe for human consumption, and this agricultural restoration pattern should be carefully reconsidered. 相似文献