【作者】 高增文；

【导师】 郑西来；

【作者基本信息】 中国海洋大学 ， 环境工程， 2008， 博士

【摘要】 田庄水库位于鲁中南山区鲁山山脉之间,是典型的山区水库,也是淄博沂源县潜在的大型饮用水源地,但由于受氮肥生产与氮肥使用的长期影响,水库氮素严重超标,大大影响了水体的使用功能。随着工农业生产的迅速发展及人口的快速增长,沂源县水资源的供需矛盾日益突出。因此,迫切需要开展田庄水库氮污染行为与控制技术研究,从而为水污染的预防与治理提供科学的依据。本文在区域自然环境概况调查基础上,通过河流水质、水量调查,淋滤试验、粉煤灰氮素含量测定,沉积物氮素释放试验、沉积物孔隙水分析等方法确定了田庄水库各主要污染源的氮素负荷;另外,通过沸石覆盖、砂覆盖及无覆盖情况下的对比试验,测定覆盖层-水界面氨氮浓度、上覆水混合浓度、孔隙水氨氮浓度,结合界面释放通量、覆盖层理论穿透时间计算等手段综合评价沸石覆盖对抑制沉积物氨氮释放的有效性;最后,通过建立平面二维模型,就多污染源影响下不同水文年水库氮素分布及沉积物局部覆盖、粉煤灰堆移除、面源控制等对改善水库水质的效果进行了预测。取得了一些新的认识和结论:⑴田庄水库是一个常对流水库,硝氮与氨氮浓度高;受氨氮超标影响,田庄水库属于劣Ⅴ类水体。⑵沉积物是上覆水氨氮的重要来源,释放通量在80-175mg/(m~2·d)之间;沉积物表层发生的反硝化作用是水库硝氮重要的去除途径,扩散通量约40mg/(m~2·d)。⑶农业面源负荷(604.8t/a)占田庄水库硝氮总负荷的96.9%,是最大的硝氮来源;内源负荷(128.8t/a)占氨氮总负荷的76.0%,是氨氮的最大来源。⑷各水文年水库氮素模拟结果表明,氨氮只有在丰水年丰水期能够达到《地表水环境质量标准》III类标准要求,枯水年枯水期超标最严重,超标倍数为1.00-1.67倍;同一水文年枯水期的氨氮浓度比丰水期高1.30-1.50mg/L;田庄水库中硝氮浓度在5.00-8.00mg/L之间,不同水文年的同期浓度相差不大。⑸库岸粉煤灰的堆放对其周边水域硝氮浓度影响较大,粉煤灰移除前后,浓度相差0.20-0.50mg/L,粉煤灰应从水库岸边清除;治理面源污染是降低水库硝氮浓度的关键,面源负荷减少30%后,硝氮的模拟浓度比控制前降低了20%左右。⑹同一种覆盖材料的穿透时间与覆盖层厚度平方成正比,沸石覆盖层的穿透时间明显长于砂覆盖层;同一种覆盖材料的稳态释放通量与覆盖层厚度成反比;15cm厚沸石+15cm厚砂构成的复合覆盖层对沉积物中氨氮释放的抑制效果将优于50cm砂覆盖层。⑺取水口区沉积物沸石覆盖对改善出水水质的效果显著,各水文年丰水期氨氮浓度都满足III类标准;沉积物氨氮释放量需要减少80%,水库中氨氮才能全面达标。更多还原

【Abstract】 The Tianzhuang Reservoir is a typical mountainous reservoir, which is situated in the mountain area of central south of Shandong province. It is also the potential water source for Yiyuan County. But the nitrogen in the reservoir water has exceeded the environmental quality standards for surface water under the influences of production and use of nitrogen fertilizer. With the development of agriculture and industry and population growth, the contradiction between water demand and water supply are being aggravating. Therefore, it is urgent to study the behaviors and controls of nitrogen pollution in the Tianzhuang Reservoir in order to provide the foundation for the prevention and treatment of the water pollution.Based on the natural environment investigation in the area of the Tianzhuang Reservoir, the nitrogen loadings were determined through the monitor of water quality and water quantity of the inflows, the experiments of leaching and nitrogen release from the sediments, and the nitrogen analysis in the porewaters in surface sediment. In addition, the feasibility of sediments capping by natural zeolite to prevent the ammonium release were assessed via the comparison experiments; In these experiments the ammonium in water near the capping-water interface and in overlying water were monitored; The interfacial flux of ammonium and the time of ammonium breakthrough the capping layer were also calculated. At last, a plane 2D flow-water quality was developed to simulate the spatial-temporal distribution of nitrogen in the Tianzhuang Reservoir. The treatment effects of local sediment capping by zeolite, the fly ash move and agricultural diffuse control were also predicted. The major conclusions can be summarized as follows.⑴The Tianzhuang Reservoir is a polymictic revervoir. The concentrations of nitrate nitrogen and ammonium nitrogen are higher than the normal levels of the Chinese reservoirs. The water quality of the Tianzhuang Reservoir is inferior to class Ⅴ(GB3838-2002) under the influence of exceeding standard of ammonium nitrogen.⑵The release flux of ammonium nitrogen from sediments ranges from 80 to 175 mg/ (m2·d), and the sediments are the important source for ammonium nitrogen of the reservoir. The influx of nitrate nitrogen is about 40mg/(m2·d), and the denitrification in surface sediments is the most thorough pathway for nitrogen removal.⑶Agriculture diffuse is the largest source of nitrate nitrogen, which (604.8t/a)accounts for 96.9% of the total loadings. The sediments are the largest source (128.8t/a) of ammonium nitrogen, which occupies 76.0% of the total loadings.⑷The results of water quality simulation indicate that the concentrations of nitrate nitrogen range from 5.00 to 8.00 mg/L, and the concentrations in the same period of different hydrological years are close. Ammonium can be up to the standard only in wet period of wet years. Ammonium in dry period of dry years is below the standard seriously, and its exceeding criterion multiple is in the range of 1.00-1.67. The ammonium concentrations in dry period are higher 1.30-1.50 mg/L than values in the wet period of the same hydrological year.⑸The leachates from fly ash at the north bank of the Tianzhuang Reservoir influence the quality of ambient water. The concentration difference of nitrate nitrogen in the ambient water can be up to 0.20-0.50 mg/L between before and after the fly ash removal. The control of agricultural diffuse is the key factor to improve the water quality with respect to nitrate. The concentration of nitrate nitrogen will decrease about 20% if the loadings of agricultural diffuse decrease 30%.⑹The breakthrough time of ammonium through the same capping material is positive to the square of the layer thickness. The breakthrough time through zeolite- capping is longer than the time through sandy layer remarkably. The steady release flux of ammonium from the sediments is negative to the thickness of capping layer. The complex capping of 15 cm zeolite layer and 15 cm sand layer is more effective than the 50 cm sand layer.⑺The water quality with regard to ammonium will improve obviously after the sediments in intake area are capped by zeolite, and the ammonium nitrogen can be up to the standard in wet periods of all hydrological years. Ammonium nitrogen of the water in every part of the reservoir may be up to the standard when the internal loadings are decreased 80%.更多还原