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181.
新型阳离子聚合物治理煤泥水的应用研究 总被引:4,自引:0,他引:4
研究了聚季铵盐丙烯配角安接枝共聚物PQAAM在煤泥水治理中的絮凝沉降作用。通过不同特性粘度和不同阳离子度的PQAAM絮凝性能比较试验,PQAAM分别加入HPAM、PAM和PQAAM、PAS、PACL的絮凝沉降试验,结果表明该絮凝剂是一种质量优良的新型高效的阳离子絮剂,对煤泥水治理和环境保护有着广泛的应用前景。 相似文献
182.
铬渣的细菌解毒实验研究 总被引:1,自引:0,他引:1
采用从铬渣堆埋场附近的污泥中分离到的高效还原Cr(Ⅵ)的Ch-1菌进行细菌浸出的摇瓶实验,分别考察了不同液固比,温度,初始pH值情况下浸出液的pH值变化,Cr(Ⅵ)浓度变化及浸出过程铬渣中六价铬的浸出率变化和最终渣浸出毒性.实验结果表明,在细菌的作用下,浸出液Cr(Ⅵ)浓度均能解毒为0ppm,同时,浸出液pH值降低到8~9之间, 细菌浸出渣毒性降低到0.05ppm以下,远低于GB5085.3-1996危险废物浸出毒性鉴别标准1.5ppm.同时,渣中的Cr(Ⅵ)也大部分被有效浸出后还原为Cr(Ⅲ) 沉淀.特别是在液固比10:1,温度28℃,初始pH=10.0的条件下,铬渣中六价铬浸出率达到了95.43%,同时浸出液pH值=8.20,Cr(Ⅵ)浓度为0ppm,浸出渣浸出毒性0.007 ppm,均达到国家排放标准,取得了较好的解毒效果. 相似文献
183.
184.
Optimum Nitrogen Use and Reduced Nitrogen Loss for Production of Rice and Wheat in the Yangtse Delta Region 总被引:1,自引:0,他引:1
A long-term field and lysimeter experiment under different amount of fertilizer-N application was conducted to explore the optimal N application rates for a high productive rice–wheat system and less N leaching loss in the Yangtse Delta region. In this region excessive applications of N fertilizer for the rice–wheat production has resulted in reduced N recovery rates and environment pollution. Initial results of the field experiments showed that the optimal N application rate increased with the yield. On the two major paddy soils (Hydromorphic paddy soil and Gleyed paddy soil) of the region, the optimal N application rate was 225–270 kg N hm–2 for rice and 180–225 kg N hm–2 for wheat, separately. This has resulted in the highest number of effective ears and Spikelets per unit area, and hence high yield. Nitrogen leaching in the form of NO
3
–
-N occurs mainly in the wheat-growing season and in the ponding and seedling periods of the paddy field. Its concentration in the leachate increased with the N application rate in the lysimeter experiment. When the application rate reached 225 kg N hm–2, the concentration rose to 5.4–21.3 mgN l–1 in the leachate during the wheat-growing season. About 60% of the leachate samples determined contained NO
3
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-N beyond the criterion (NO
3
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-N 10 mg l–1) for N pollution. In the field experiment, when the N application rate was in the range of 270–315 kg hm–2, the NO
3
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-N concentration in the leachate during the wheat-growing season ranged from 1.9 to 11.0 mg l–1. About 20% of the leachate samples reached close to, and 10% exceeded, the criterion for N pollution. Long-term accumulation of NO
3
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-N from leaching will no doubt constitute a potential risk of N contamination of the groundwater in the Yangtse Delta Region. 相似文献
185.
The coastal city of Tel Aviv was founded at the beginning of the 20th century. The number of its inhabitants and its water consumption increased rapidly. This study analyses a 15-year record (1934-1948) of pre-industrial development of groundwater chemistry in the urban area. Archive data on concentrations of major ions, dissolved gases (CO2 and O2), organic matter, and pH were available for each half-year during the period of 1934-1948. The major factors causing changes in the chemistry of groundwater flowing in three sandy sub-aquifers have been seawater encroachment due to overpumping, and infiltration of effluents from pit-latrine collectors. Influence of these factors decreases with depth. Landward-penetrating seawater passed through clayey coastal sediments, interbedded among sands and calcareous sandstones, and spread into the Kurkar Group aquifer. This has led to exchange of sodium (dominant in seawater) with calcium adsorbed on clay particles, enriching groundwater with calcium. Intensity of cation exchange decreases inland and with depth. Infiltration of pit-latrine effluents has introduced large amounts of ammonium into the unsaturated zone. Its rapid oxidation in unsaturated sediments has caused massive nitrate production, accompanied by pore-water acidification. This process induces dissolution of vadose carbonate, resulting in enrichment of groundwater recharge in calcium. Anthropogenically induced dissolution of calcite in the unsaturated zone has been the major factor for the increase of Ca2+ concentration in groundwater, accounting for about 80% of this increase. In the interface zone, an additional 20% of calcium has been supplied by cation exchange. Owing to pH increase caused by denitrification in the aquifer, Ca(2+)-rich waters supersaturated with calcite could be formed, especially in the capillary fringe of the uppermost sub-aquifer, which could induce calcite precipitation and ultimately lead to the cementation of sandy aquifers. Urban development has caused drastic changes in the gas content in the unsaturated zone and in groundwater. Carbon dioxide was intensively generated by nitrification-denitrification processes, by hydration of urea, to a lesser degree by oxidation of organic matter, and probably by anoxic biodegradation of organics. Between 1934 and 1948, concentrations of CO2 in unsaturated sediment air rose from 3.2% to 7.6%. In the unsaturated zone, oxygen consumption for oxidation of ammonium and organic matter lowered O2 concentrations in sediment air to unusually low values of 3.9-12.9%. Nitrification in the urban unsaturated zone could thus serve as a pump, sucking in atmospheric oxygen at a rate of about 0.3-0.5 g m-2 day-1. The extreme concentrations of CO2 and O2 in unsaturated sediments have been preserved due to production and consumption of gas under conditions of diminishing areas open to the atmosphere, uncovered by buildings and by roads. 相似文献
186.
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188.
应用GLEAMS模型评估我国东南地区农业小流域硝态氦的渗漏淋失 总被引:3,自引:0,他引:3
应用GLEAMS模型估算我国东南亚热带地区农业小流域硝态氮的渗漏淋失。在五川流域8种不同土地利用方式的农田中埋设渗漏监测装置,每月采集水样分析硝态氮含量。用2002年4—12月作物生长季节的实测数据进行模型校验的结果表明,模型对水稻田除外的其他土地利用方式下硝态氮渗漏淋失模拟效果较好。五川流域2002年硝态氮淋失模拟计算结果表明,不同土地利用方式下硝态氮淋失时空差异显著,全年渗漏量(以氮计)为4.64~38.39kg·hm^-2,流域面积加权平均为29.99kg·hm^-2。甘蔗地、香蕉地和蔬菜地的年硝态氮渗漏量最高。渗漏峰值一般出现在7—8月。降雨、土地利用和化肥施用等人类活动是影响硝态氮渗漏淋失的主要因素。 相似文献
189.
上海郊区旱作农田氮素流失研究 总被引:3,自引:0,他引:3
通过测坑和大田小区试验,研究了上海郊区旱作农田氮素降雨径流和降雨渗漏流失的特征、相关因素和流失负荷。结果表明:平水年重质土麦地总氮流失负荷为18. 38 kg·hm-2,其中降雨径流总氮流失负荷为4. 4kg·hm-2,渗漏为13. 98kg·hm-2;菜地总氮流失量为55. 65kg·hm-2,其中降雨径流总氮流失负荷为21. 6kg·hm-2,渗漏为34. 05kg·hm-2;旱田氮素流失以硝态氮为主,占总氮90%左右。施用有机肥可较大幅度地减少旱田的氮素渗漏流失。 相似文献
190.