【作者】 李琼；

【导师】 华珞； 马义兵；

【作者基本信息】 首都师范大学 ， 自然地理学， 2012， 博士

【摘要】 城市污泥是污水处理厂在废水处理过程中所产生的沉淀物质,是由有机残片、细菌菌体、无机颗粒及胶体等组成的极其复杂的非均质体。随着我国城市化进程的加快和污水处理率的提高,城市污泥的产生量也在急剧增加,急需无害化处理和资源化处置,综合比较各种污泥处置方式,污泥农用是一种经济有效的方法之一。我国在建立基于污泥农用研究的污染物的数据库方面的科学积累严重不足；对污泥农用后的环境效应进行风险评价方面的研究还较为薄弱；缺少长期定位田间试验的数据和结果；另外,由于城市污泥农用引起的氮、磷对土壤的污染风险也没有通过长期田间试验研究来进行分析和评价；以上问题皆是当前迫切需要解决的课题。本研究针对我国城市污泥的合理施用及我国污泥农用标准的制定中尚须解决的问题,通过代表性的石灰性土田间试验,研究施用污泥对土壤环境质量及作物生长的影响,确定污泥的安全、适宜用量,评估污泥施用的环境和农业风险,为污泥农用的可行性研究提供科学依据；通过对污泥农用的痕量元素土壤—植物间的转移系数的采集及数据库的建立,探讨了物种敏感性分布法在农用污泥中镉的阈值与风险评价研究中的应用,为城市污泥安全合理农用和我国污泥农用标准的制定提供理论依据和数据基础。本研究主要获得以下研究结果：以北京为例,研究了城市污泥中养分和痕量元素的动态变化,其结果显示北京市污泥呈高氮磷、低钾的特点,养分、有机质含量及pH均符合农业行业有机肥料标准(NY525-2002)。北京市污泥中Zn、Cu、Cr、Pb、Ni、As、Hg、Cd的含量平均值依次为1075、96、78、39、33、13.6、10、1.6mg kg-1,污泥痕量元素Cr、Cu、Cd、Ni、Pb和As的含量都远低于农用泥质标准(CJ/T 309-2009),但Zn含量接近A级污泥限值(1500 mgkg-1),Hg含量高于A级污泥限值(3 mg kg-1)。北京市污泥中的风险元素是Zn和Hg,特别是Hg,是中国城市污泥中Hg平均含量的3.6倍,北京市污泥农用要注意Hg的污染。选用山东德州田间位点进行了为期5年的污泥农用田间试验,研究结果显示施加污泥处理增加小麦、玉米籽粒中总氮(TN)、总磷(TP)含量,且施加污泥处理的作物产量维持在一个较高水平,其效果如同施加氮肥、鸡粪的处理；根据污泥施用后的小麦、玉米的籽粒产量效应函数得出小麦、玉米当年的最佳施肥量为18t ha1yr-1。在小麦-玉米轮作系统中,基于作物对氮的需求施用污泥到土壤中会导致土壤磷的累积,土壤中施加可溶性磷肥与施加污泥在土壤有效磷(Olsen-P)的累积方面有相似的趋势；在小麦-玉米轮作的石灰性土壤中,在施用78.6-1274千克污泥磷范围内,建立了以土壤起始的Olsen-P浓度、污泥磷的施用量、作物产量、土壤pH和耕作时间为参数的模型来预测土壤Olsen-P的浓度和磷的累积速率。德州石灰性土壤经过5年的污泥施加,耕层(0-20 cm)土壤中所有8种痕量元素含量均显著性的增加,尤其是Zn、Cu、Cd和Hg四种元素；而鸡粪处理的土壤中痕量元素含量则没有显著变化；土壤中Zn、Cu、Cd、Hg的含量(mgkg-1)与土壤中污泥施加量(t ha-1)之间存在着显著的线性回归关系,土壤中每年每公顷增施1吨污泥,土壤中Zn、Cu、Cd,Hg含量分别增加1.10、0.128、0.00099、0.0062 mg kg-1；按照农用泥质标准(CJ/T309-2009)每年施用7.5 t ha-1污泥的情况下,土壤中Hg含量达到土壤环境质量二级标准(GB15618—1995)所需要的年限为最短(18年),其次是Zn(30年),其它痕量元素所需年限较长(>30年)。施用污泥处理显著增加了小麦和玉米籽粒中Zn的含量。小麦和玉米籽粒中除Cr、Pb个别处理超过国家食品卫生标准(GB 2762-2005)外,其他元素含量均达标。小麦、玉米籽粒对痕量元素的BCF均小于0.5,小麦籽粒对痕量元素的BCF大小顺序为：Zn＞Cu＞Cd＞Cr、Hg＞Pb＞Ni＞As;玉米籽粒对痕量元素的BCF大小顺序为：Zn＞Cu＞Cd＞Cr＞Pb＞Hg＞Ni＞As。利用转移系数和物种敏感性分布研究了农用污泥中镉的阈值,研究结果显示土壤镉阈值(HC5值)主要受土壤pH和有机碳含量(OC)的影响,pH是最主要的影响因子,可控制HC5值变异的62.7%,OC可控制HC5值变异的25.2%。通过土壤镉HC5值与土壤pH和OC的关系建立的预测模型能较好地预测不同类型土壤中的镉阈值,为土壤镉生态环境质量标准的制定和执行提供科学基础。基于土壤总镉含量限制的污泥农用风险评价模型的建立较好地控制不同类型土壤中的施加污泥的总量及污泥的总镉含量限制,为城市污泥安全合理农用提供理论依据。本文的创新点：在我国首次利用长期定位田间试验研究了污泥农用对小麦-玉米轮作体系的影响,利用量化模型研究了污泥养分元素和重金属元素在土壤与植物体系中的积累及转运规律；基于污泥农用的Cd的BCF数据,构建了Cd在不同类型土壤中的SSD曲线,探讨SSD法在农用污泥中Cd的环境风险评价研究中的应用,并提出了污泥中痕量元素首要控制因素,限量标准和使用年限,为污泥资源化利用提供了可靠的依据。更多还原

【Abstract】 Biosolids, as the sediment of the sewage treatment plant wastewater treatment process, which is complex non-homogeneous body composed of organic debris, bacteria, inorganic particles and colloidal. Along with the acceleration of urbanization and improvement of the sewage treatment rate in China, biosolids production is increasing dramatically and in urgent need for harmless treatment and resource disposal. Comprehensive comparison of various kinds of biosolids disposal, biosolids agricultural utilization is a kind of economic and effective method. In our country, toxicology database based on the pollutants of biosolids agricultural utilization is absent. The rsearch on risk assessment of environmental effects caused biosolids agricultural application is also relatively weak. The laboratory experimental protocols are known to lead to several artefacts, so it is important that research on the control standards of bioslids agricultural application under field conditions should be undertaken. Morever, the soil pollution risk caused by nitrogen, phosphorus accumulation in bioioslids agricultural application be evaluated for lack of a long-term field experiment research. Therefore, it is an important and urgent task to research the above issues under field conditions.A field experiment was designed for the rational application biosolids and control standards of bioslids agricultural application. The biosolids added to a calcareous field soil was studied in order to assess the effects of biosolids agricultural application on soil quality and crop growth, and to determine the safety amount of the applied biosolids. The field experimental results were analyzed for assessing the environmental and agricultural risk of biosolids application in order to supply scientific basis for the feasibility of biosolids agricultural application. Bioaccomulation factors of trace elements for bioslids agricultural application were collected to extablish database and conbined with species sensitivity distribution to develope the cadmium criteria in soils and biosolids in order to provide a scientific basis for the rational application biosolids and control standards of bioslids agricultural application. The main results and conclusions are as follows:First, the dynamic changes of nutrients and trace elements in bioslids from Beijing were studied, and the results showed that the biosolids presents the characteristics of high nitrogen, phosphorus contents, and low potassium contents. Also the contents of nutrients and organic matter, pH in biosolids can meet the organic fertilizer standards of agricultural industry (NY525-2002). The mean concentrations of Zn, Cu, Cr, Pb, Cd, Ni, As, Hg and Cd in biosolids from Beijing sludge disposal plant are 1075,96,78,39,33,13.6,10 and 1.6 mg g-1, respectively. The contents of trace elements such as Cr, Cu, Cd, Ni, Pb, and As are much lower than the control standards for biosolids agricultural use (CJ/T309-2009), however, the contents of Zn were close to limits for the class A biosolids (1500 mg kg-1), Hg contents were over the limits for class A biosolids (3 mg kg-1). Zn and Hg in biosolids in Beijing are the elements of high risk for soil environmental quality, especially for Hg, which is 3.6 times of the average content in biosolids Hg of Chinese urban, so that Beijing biosolids are applied to agricultural field should pay attention to biosolids Hg pollution.The field experiment was carried out for five years in Dezhou, Shandong province. The results showed that the contents of TN and TP for wheat and maize grain were significantly increased by biosolids treatment. Crop yields by biosolids treatment maintain at a high level. biosolids can be a replacement for a part of nitrogen fertilizer or chicken manure. The optimum biosolids application rates was 18 t ha-1 yr-1, which derived from the wheat and maize grain yield effect functions by biosolids application.In wheat-maize rotation system, application of biosolids to agricultural soils based on the N requirement of crops will oversupply P. A similar trend of Olsen-P accumulation was found in soils treated with soluble P fertilizers only or with biosolids P as well, which provides evidence that the behaviour of biosolids P in field soils is similar to that of inorganic P fertilizers. In soils with the range of 78.6-2097 kg P ha-1 added by biosolids, the concentrations of Olsen-P in soils with wheat-maize rotation systems and the P accumulation rates could be predicted by a model that depended upon the initial concentration of Olsen-P in the soil, P input rate, crop yield, soil pH, and cultivation time.All of the eight kinds of trace elements were significantly increased in the plough layer (0-20cm) of Dezhou calcareous soil after biosolids application for five years, especially of Zn, Cu, Cd and Hg, and there were no significant changes in trace elements of soils applied with chicken manure. There was a significant linear relationship between the concentrations (mg kg-1) of Zn, Cu, Cd and Hg in plough layer soils and the biosolids application rates (kg ha-1); the increased concentration of Zn, Cu, Cd and Hg in plough layer soil were 1.10,0.128,0.00099, 0.0062 mg kg-1, respectively, when biosolids of 1 t ha-1 per year was added to the soil. According to the accumulation rates of different trace elements and the control standards for biosolids agricultural use (CJ/T309-2009), soil Hg content was up to the soil environmental quality standards (GB15618-1995) required the shortest time (18 years), followed by Zn (30 years), and other trace elements required more time (＞30 years).The contents of Zn in wheat and corn grains were significantly increased by biosolids applied. The contents of all trace elements except Cr and Pb in wheat and corn grains were under the national food hygiene standards (GB 2762-2005). The bioaccumulation factor (BCF) of all trace elements for wheat and maize grains were less than 0.5, the BCF of trace elements for wheat grains were in the order:Zn＞Cd＞Cu＞Cr, Hg＞Pb＞Ni＞As; the BCF of trace elements for wheat grains were in the order:Zn＞Cu＞Cd＞Cr＞Pb＞Hg＞Ni＞As.The cadmium of concentration in soils which prevents 95% plant edibile parts in safety (HC5) was mainly affected by soil pH and OC. Meanwhile, soil pH is the most important predictor for HC5, which explains 62.7% of variances while soil OC explains 25.2% of variances.The prediction model was set up by the relationship between soil pH, OC value and cadmium HC5 can well predict the cadmium threshold values in different soil types, which supplies a scientific basis for formulation and implementation the environmental quality standard of soil cadmium. The model for biosolids agricultural application based on the limits of soil total cadmium content can well control the amount of biosolids applied and the cadmium content of biosolids in different types of soil, which provide the theory basis for the safety and rational of biosolids agricultural application.Main innovative points:using a five-year continuous field experiment to investigate the feasibility of biosolids application to agricultural soils in a wheat-maize rotation system; the accumulation of the nutrient elements and trace elements in soils after biosolids application was quantified; the BCF values of trace elements in soil-plant systems integrated with species sensitivity distribution (SSD) were used for derivation of cadmium thresholds in soils and biosolids when biosolids were applied to soils; and finally the feasibility with cautions for biosolids application in agriculture was presented.更多还原