污泥土地利用研究II. 连续化学提取法研究施污泥土壤重金属的有效性和环境风险

本文采用连续化学提取法研究了施用污泥土壤中重金属的形态分配及有效性。铜和锌在2种土壤上施用污泥前、后的形态分配都有所差异,铜在河湖相水稻土上以可氧化态为主;红壤性水稻土可氧化态和可还原态含量都较高。锌在河湖相水稻土以可还原态为主,在红壤性水稻土以醋酸溶解态为主。两种土壤上,铜和锌的3种不同形态含量与污泥施用量之间都有很好的相关性。连续提取对于研究重金属的形态分配比单独提取更有价值。     

污泥土地施用研究I.施用污泥土壤中重金属的化学浸提性研究

本研究了施用污泥的太湖水稻土和江西第四纪红壤性水稻土中重金属的化学提取性。结果表明，随着污泥施用量的增加，土壤中Ｃｕ，Ｚｎ，Ｃｄ的醋酸，醋酸铵，ＥＤＴＡ３种提取形态的浓度都明显增加，有很好的相关性，各提取态浓度在各施用量之间存在显差异。污泥施用没有增加Ｐｂ含量，这可能与污泥本身含Ｐｂ量低有关。     

施用污泥的土壤重金属元素有效性的影响因素

污泥农用是解决城市污泥出路较为合理的途径,但由于含较高量的重金属,它的应用受到限制,研究发现,进入土壤的重金属在不同的土壤类型不同的土上,形态分布各不相同,而不同形态的重金属对植物的有效性和毒性也不相同,本文试图对土壤中影响重金属形态分布的因素及机制作一综述。     

香港土壤研究Ⅶ.BCR提取法研究重金属的形态及其潜在环境风险

基于类型土壤的重金属元素形态分析研究相对较少,本研究以香港地区7个亚纲的土壤剖面为例,利用欧共体参比司(BCR)制定的三步连续提取法研究了类型土壤中重金属Cd、Cu、Pb和Zn的化学形态及其潜在环境风险。结果表明,Pb、Cd和Zn元素除残留态外,HOAc溶解态的比例也相对较高,但不同类型的土壤有所差别,而Cu元素则以残留态和可氧化态为主。在这7种类型土壤中,正常潜育土和湿润淋溶土中的重金属潜在环境风险相对较高,而在这4种重金属元素中,又以Pb元素的潜在环境风险最大。     

污泥与施污土壤重金属生物活性及生态风险评价

将城市污泥以不同质量比施于土壤中构成污泥混合土壤,研究各污泥配比土壤中重金属的生物活性,并采用三种重金属评价方法(地累积指数法、潜在生态风险指数法、综合毒性指数模型)和黑麦草对重金属的吸收富集效果来对施污土壤中重金属具有的生态风险性进行评价。结果表明:污泥的添加使土壤中生物活性态Cd、Cu和Zn含量显著增加,对三种重金属具有活化作用,但对Pb却起到钝化作用。生态风险评价结果表明:污泥的添加使土壤中Pb呈现无污染和低生态风险;Cu和Zn呈现中度污染和低生态风险;Cd达到强度污染和重度生态风险,重金属潜在生态风险(RI)总体处于强度生态风险水平。当污泥添加比例大于6:10(污泥S3处理)时,施污土壤中重金属的综合毒性指数高于土壤对照。黑麦草对Cd、Pb、Cu和Zn的富集浓度与施污土壤中对应重金属的生物活性态含量存在显著正幂指数关系,同时黑麦草对施污土壤中Cd、Cu和Pb的富集能力大小与地累积指数法和潜在生态风险指数法对三种重金属具有的生态风险性的评价结果具有一致性。     

连续提取法区分土壤重金属元素形态的研究及其应用

用连续提取法研究土壤中重金属的存在形态在土壤化学、植物营养和环境科学领域均具有重大意义，许多研究者对之进行了广泛深入的研究，近年来这方面的工作进展较快，本文对近年来国内外就土壤中重金属元素的形态区分方法及其应用作一简要综述。     

污泥中重金属的环境活性及生态风险评估

研究了湖南省长沙市、株洲市和常德市10个污水处理厂剩余污泥中As,Cd,Cu,Ni,Pb,Zn的含量和形态特征,并利用潜在生态危害指数法对污泥农用过程中重金属的生态风险进行了综合评价。结果表明,城市污泥中富含有机质及N,P,K等养分,然而,污泥表现为以Cd为主的多金属污染,不能直接农用。污泥中Cd含量为1.43～260mg/kg,以可还原态为主,占全量比例高于28.9%;As,Pb的可还原态,Ni,Zn的酸可溶态和可还原态,Cu可还原态和氧化态所占比例较高,表明污泥中重金属的潜在环境活性较高。风险指数评价结果表明,污泥中Cd和As是潜在的强生态风险元素;以工业废水处理为主的污水处理厂污泥重金属单因子生态风险相对较高,且综合潜在生态风险严重。     

城市污泥与湖泊底泥土地利用对土壤-植物系统中养分及重金属Cd、Pb的影响

采用田间小区试验，探讨了城市污泥与湖泊底泥土地利用对土壤-植物系统中养分及重金属Cd、Pb的影响。结果表明，城市污泥与湖泊底泥能有效增加土壤养分含量；重金属Cd、Pb仅累积在土壤耕层，难以向下迁移；随施用量的增加，小麦籽粒产量及其对养分的吸收量均随之增加，但仍有大量养分存留在土壤中；植株对重金属的富集顺序表现为根系〉茎叶〉籽粒，Cd〉Pb，其中，籽粒中重金属Cd、Pb含量均未超出我国食品中重金属限量的卫生标准；如果该污泥、底泥分别以100，200t／hm^2的施用量施入土壤，可以连续施月5a和6a     

长江三角洲地区污水污泥与健康安全风险研究 Ⅲ. 苏、杭二城市污水污泥所施土壤中Cu和Zn的释放动态及其环境风险

未经处理的污泥农业利用后,不仅会增加土壤中污染物的含量,而且会威胁人类和其他生物的健康。室内培养试验结果表明,污泥中的重金属进入土壤后,表现出先释放,后固定的变化趋势,而且随培养时间的增加,施污泥土壤中EDTA和CaCl2提取态Cu和Zn含量逐渐增加,150d时其含量达到最高。与对照处理相比,施污泥土壤中EDTA提取态Cu和Zn含量分别增加了21.4mgkg-1和26.1mgkg-1,而CaCl2提取态Cu和Zn含量分别增加了0.10mgkg-1和3.37mgkg-1。重金属不合格的污泥农业利用存在一定程度的重金属污染风险,且其风险大小与土壤类型、污泥种类和培养时间及污泥的土壤施用量等因素密切相关。选择适宜的土壤类型、污泥种类、施用时间及控制污泥施用量等,能够在一定程度上降低污泥中重金属农业利用的环境风险。     

污泥土地利用研究：—Ⅴ．高铜污泥

本采用田间小区试验方法研究了高铜污泥对辣椒生长、Vc含量和重金属含量的影响。结果表明，污泥施用量在3．75和7．5t/hm^时，辣椒各个生长指标都有所增加，有些指标都有所增加，有些指标甚至优于施用化肥处理。污泥施用对辣椒果实Vc含量没有明显降低的趋势，污泥施用未显地增加辣椒植株和果实对铜、锌、镉和镍的吸收。     

污泥土地利用研究：Ⅲ、富锌污泥

西通过温室盆栽试验方法研究不同富锌污泥施用方法对水稻生长及其重金属含量的影响，结果表明，污泥施用主要通过增加水稻分蘖来促进水稻生长从而提高产量。污泥的施用显提高了水稻茎叶和籽粒中锌的含量。     

污泥土地利用研究：Ⅳ、无锡污泥与香港碱化污泥的肥效比较

本通过盆栽试验研究了污泥施用对青菜和番茄生长的影响，试验表明，污泥施用可显促进青菜和番茄的生长，但和长在酸酸性红壤和太源水稻土上两种蔬菜对污泥施用的响应不同，香港碱性污泥产品对青菜在酸性红壤上的增产效果优于无锡污染；无锡污泥随施用量增加产量有所增加：太湖水稻土上无锡污泥的肥效优于香港碱性污泥产品。污泥施用不仅对当茬蔬菜增产明显，对后茬蔬菜也有增产效应。     

污泥的土地利用及其环境影响

本介绍了目前国内外污水污泥处置与利用的现状和趋势；重点综述了污泥土地利用的途径利益，风险，管理以有我国近十年来研究进展；认为将稳定化，无害化，资源化处理的污泥作为一种有机肥料或土壤改良剂进行土壤利用，将成为我国污泥处置与利用方面很有应用前景的一种途径，但有必要开展污泥土地利用后污染物的环境行为，影响评价，控制管理等方面的长期研究。     

Modification of soil porosity after application of sewage sludge

The effect of the application of sewage sludge on soil porosity over 28 months is discussed here. Anaerobic sludges of urban refuse waters were applied on a degraded limestone soil in a mining land by two ways. First, a previous mixture of sludge and soil was carried out; this was then applied to the target land. Second, a direct application of sludge to soil and tilling. Porosity and pore morphology were measured on thin sections prepared from undisturbed soil samples. Data were obtained from backscattered electron images and image-processing computer equipment. The application of sludge induced an increase of both soil fine microporosity (φ<50 μm) and coarse microporosity (φ>50 μm). However, this effect showed transient, since no significant differences were reported in relation to the control plot after one year from application. The incorporation of sludge and developed vegetation modified coarse micropore irregularity and orientation. On the other hand, fine micropore morphology remains unchanged.     

Effects of sewage sludge application method on corn production

Abstract

A study was conducted to determine the effects of land application of municipal sewage sludge to agricultural land in Upper Cumberland Region of the Tennessee valley. Treatments included single and annual applications of sewage sludge both surface applied and injected into the soil. The primary objective of the study was to determine the effects of different land application methods of sewage sludge on corn grain yields. Other objectives were to determine the plant availability and migration of sludge Cu and Zn, and to determine organic N mineralization rates based on corn yield and leaf N content. Application of sewage sludge positively affected corn grain yields due to increased availability of N, and in drought years soil moisture. Yield and leaf N content data suggest that organic N mineralization rates near 50% in the year of application and 30% in the second year. Application of sewage sludge resulted in a greater increase in availability of Cu at the soil surface as compared to Zn, however neither Cu or Zn leached from the surface of the soil.     

Soil biochemical activities and the geometric mean of enzyme activities after application of sewage sludge and sewage sludge biochar to soil

There is a need to improve the way in which wastes, such as sewage sludges, are managed and a potential way to proceed would be to transform them into biochar. On the other hand, there is a growing interest in the use of soil biochemical properties as indicators of soil quality because they are sensitive to alterations in soil management. Thus, we have studied the effect of a biochar obtained from sewage sludge on soil biochemical properties in an organic soil using two doses of biochar and comparing these results with the control soil and with soils amended with the same two doses of unpyrolyzed sewage sludge. Microbial biomass C, soil respiration, net N mineralization and several enzyme activities (dehydrogenase, β-glucosidase, phosphomoesterase and arylsulphatase) were monitored. The geometric mean of enzyme activities (GMea) was used as a soil quality index. Individual biochemical properties showed a different response to the treatments, while GMea showed an increase in the quality of soils amended with the high biochar dose and a decrease in those amended with a high sewage sludge dose. The geometric mean of enzyme activities was a suitable index to condense the whole set of soil enzyme values in a single numerical value, which was sensitive to management practices.     

Bacterial leaching of heavy metals from sewage sludge for agricultural application

Bacterial leaching of heavy metals from sewage sludge was studied to assess the potential of agricultural application of the decontaminated sludge. Experiments were conducted in both batch processes (at 28 ?C) and continuous process (at 30 ?C) using a culture of Thiobacillus ferrooxidans and a mixted culture of Thiobacillus ferrooxidans and Thiobacillus thiooxidans. Reagent grade ferrous sulfate, spent ferrous sulfate and pyrite were used as the energy substrates. A first order kinetic model of Cu solubilization was proposed. It was shown that the processes in the continuously stirred tank reactor (CSTR) and the air lift reactor (ALR) with 20% cell recycling were more efficient than the others for metal solubilization due to a relatively large bacterial population.