土壤有机质对疏水性有机污染物的非线性吸附及其影响因素

土壤有机质(SOM)是土壤的重要组成部分,它对疏水性有机污染物(HOCs)的吸附作用对污染物在环境中的迁移转化有着至关重要的影响。近年来的一些研究表明,HOCs在SOM上的吸附行为并不严格地符合传统的线性分配模型。本文综述了近年来一些学者提出的SOM对HOCs的非线性吸附作用的机制及其影响因素,认为SOM的组成和结构均对HOCs的吸附有着重要的影响。SOM吸附在土壤矿物表面后,其结构或各组分的比例发生了改变,从而对其本身的吸附作用产生影响。溶液的化学环境(主要是阳离子)会对SOM的结构和吸附作用产生影响,特别是当溶液中存在一些过渡金属(如,铜或银)的离子时,共吸附的金属离子可能会与多环芳烃类分子形成阳离子-π键的作用,从而促进多环芳烃类物质在SOM上的吸附。     

土壤/沉积物中天然有机质对疏水性有机污染物的吸附作用

通过对土壤/沉积物中天然有机质的组成分析,阐述了天然有机物在吸附疏水性有机污染物过程中所起的重要作用,其中包括可溶性有机质的增溶作用和不溶性有机质的吸附作用。本文着重探讨了天然有机质结构的异质性对吸附作用的影响,导致吸附等温线的非线性,从而从土壤/沉积物有机质的微观结构上进一步解释了非线性吸附机理。     

堆肥化过程中有机污染物生物降解的研究进展

简介了卤代烃、多环芳烃、农药类及石油烃类等几种有机污染物在堆肥过程中的生物降解及其机理研究进展,并指出今后应重点加强高效降解微生物的分离培养、基因工程菌的开发、表面活性剂对生物降解的强化作用以及适合有机污染物降解的堆肥条件和有机污染物在堆制过程中降解的中间产物及终产物等方面研究。     

城市污泥堆肥过程中有机污染物的变化

根据国内外研究资料，综述了城市污染在堆肥处理过程中氯代酚（CPs)、PCDD/Fs、多环芳烃（PAHs)类、氯苯类（PCBs、CBs)等有机污染物的变化，提出将城市污泥进行堆肥处理，可以不同程度降解其中各种有机污染物，达到农用的目的。有机污染物降解的效果与其种类和性质、污泥的性质、环境因素（包括微生物类型和数量、C／N比、水分含量、温度、通气状况）等有关。     

土壤中有机污染物的老化及其环境意义

持久性有机污染物随着在土壤中时间的延长,其生物有效性和毒性会逐渐下降的现象被称为老化。老化对有机污染物的有效性和行为归趋有着重要的影响。本文对国外有关老化对有机污染物生物有效性和可浸提性的影响,老化的机理和影响因素,以及老化后有机污染物生物有效性评价方法的研究作了概述。指出老化作为土壤对有机污染物修复的一种自然修复过程,可降低有机污染物的潜在环境风险,具有重要的环境意义。     

蚯蚓对农村有机生活垃圾分解处理的研究

本文以农村有机生活垃圾为研究对象,根据蚯蚓的生活习性设计了4个不同组分的试验基质,这些基质的主要成分为厨余垃圾,辅料为猪粪、牛粪和土壤。本试验引进＂大平二号＂赤子爱胜蚓（Eisenia foetida）在室内进行盆养试验,同时以未放养蚯蚓处理的试验基质作为对照,培养周期为5周。研究表明,蚯蚓分解新鲜有机生活垃圾的效果最好,其生物降解率达到75.688%,该试样中蚯蚓日增重倍数和日增值倍数也最大。经蚯蚓处理后的各基质肥效都有所增加,试验样基质中有机碳、氮磷含量相对于对照样都有所升高,试验样中碱解氮含量是对照样的3倍左右。新鲜有机生活垃圾基质C/N比最大,其速效磷含量也为最大值。同时,蚯蚓还对各基质的重金属有富集作用,其富集效果都在48%左右。各组之间的试验结果大多存在显著性差异（P〈0.05）。     

菌根真菌对有机污染物的降解研究

菌根作为真菌与植物的结合体,有着独特的酶途径,可以降解不能被细菌单独转化的有机物,不仅能从微生物修复角度影响有机物降解,还能从植物修复角度影响有机物的降解。本文综述了近年来菌根真菌对土壤中的石油类、农药、氯代芳香烃类及酞酸脂类污染物的降解研究进展,探讨了菌根降解污染物的内在可能机理,其中包括酶的作用、根际的作用及土壤中其他微生物对降解的贡献。综合菌根真菌在生物修复中的优点,认为其在生物修复中具有良好的应用前景。     

洪水对河流底泥有机污染物分布的影响

文章结合我国１９９８ 年遭受特大洪水灾害的情况,介绍了美国密西西比河洪水对底泥有机污染物分布影响的研究成果。结果表明洪水前后所有底泥样品中都存在粪醇、多环芳烃（ 包括芘） 、直链烷基苯磺酸盐、多氯联苯和有机氯农药等污染物,浓度一般小于１ ｍｇ／ｋｇ ,其中上游浓度最高。洪水前后各种污染物浓度变化较大。洪水发生后,上游段底泥中芘和多氯联苯的浓度降低而粪醇浓度升高,这表明城市和农业水域中的污染底泥被洪水冲刷至河内并稀释或覆盖原来的底泥。并列举了这一成果给予我们的启示。     

生物质炭对有机污染物的吸附及机理研究进展

生物质炭是一种利用废弃生物质材料在缺氧或厌氧环境中热化学转换制备的多孔级富碳固体材料。因其吸附能力强,制备原料来源广泛,生产成本低且环境友好等优点受到学术界越来越多的关注。探究生物质炭对有机污染物的吸附机理和规律,对于评估其环境行为和应用价值至关重要。着重综述了目前研究报道的生物质炭吸附有机污染物的吸附机理,包括分配作用、表面吸附作用和孔隙截留等。一般低温生物质炭对非极性有机物的吸附机制以分配作用为主,这种非竞争性吸附机理可以解释高浓度有机污染物在生物质炭上的吸附过程。表面吸附是一种非线性竞争性吸附作用,是有机污染物在生物质炭表面有效吸附位点上形成静电作用或通过氢键、离子建、π-π相互作用等结合的过程。孔隙截留是另一种生物质炭固定有机污染物的微观机制,有机污染物在孔隙内部的分配和吸附也是生物质炭吸附能力的重要体现。而在实际复杂的污染环境中,各类生物质炭对有机污染物的吸附过程需要多种机制共同解释。此外,本文对吸附机制的影响因素进行了分析和总结,生物质炭自身理化特性决定了其应用价值,生物质炭的性质与有机污染物的极性、芳香性和分子大小等相匹配才能更好地实现吸附固定,不同的吸附环境如吸附介质、p H和共存离子等也会对吸附机制和吸附效果产生影响。最后,文章进一步探讨了生物质炭吸附有机污染相关研究未来应着重解决的问题,以及生物质炭在有机污染土壤修复中的应用前景。     

有机污染物根际胁迫及根际修复研究进展

根际环境及根际微生物是植物降解有毒有害有机污染物的基础。污染土壤植物修复的纵深研究产生了根际修复新技术。通过总结近20年来有机污染物胁迫的根际效应的研究,探讨了有机物污染士壤根际修复的可能性,为加强有机污染物在环境中的迁移、调控研究及土壤有机物污染的原位修复提供有利信息。     

Effects of organic manure and NPK fertilization on earthworm activity in an Oxisol

The effects of fertilization with N, P, K, and organic manure (alone or in combination) on earthworm populations, biomass, and casting activity were measured in a cultivated soil (organic C 1.5%, annual rainfall 2000–2300 mm). These applications of fertilizer caused significant increases in earthworm numbers, biomass, and casts. N alone or in combination with P and K also influenced these earthworm parameters significantly. The inorganic NPK fertilizer in combination with organic manure had a significantly greater effect on earthworm activities than NPK fertilizer alone, and therefore the addition of organic matter appears advisable in order to obtain maximum benefits from NPK fertilizer in this soil.     

Accumulation of zinc and its effects on the growth, reproduction and life cycle of Drawida willsi (Oligochaeta), a dominant earthworm in Indian crop fields

 Accumulation of Zn and its effects on the growth, reproduction and life cycle of the earthworm Drawida willsi were determined. D. willsi did not reveal any significant changes in their mass at any of the concentrations of Zn (50, 200 and 400 mg kg^–1) compared to in untreated soils. The Zn concentrations in the exposed earthworms were significantly increased, but they were able to regulate their body content of Zn within a range of 116–125 mg kg^–1 (dry wt) in 200–400 mg kg^–1 Zn-treated soil. Reproduction was significantly reduced when the Zn concentration in soil exceeded 200 mg kg^–1. The drop in reproduction at elevated concentrations of Zn apparently resulted in a delay in completion of the life cycle and a decline in the total population. Received: 9 September 1998     

Heavy metal accumulation by two earthworm species and its relationship to total and DTPA-extractable metals in soils

The concentrations of Zn, Cd, Pb and Cu in earthworm tissues were compared with the total and DTPA-extractable contents of these heavy metals in contaminated soils. Samples were taken from a pasture polluted by waste from a metallurgic industry over 70 y ago. Three individuals of Aporrectodea caliginosa and Lumbricus rubellus and soil samples were collected at six points along a gradient of increasing pollution. Total metal contents of earthworms, soil, and metals extracted by DTPA from the soil were measured. Total heavy metal contents of the soils ranged from 165.7 to 1231.7 mg Zn kg⁻¹, 2.7 to 5.2 mg Cd kg⁻¹, 45.8 to 465.5 mg Pb kg⁻¹ and 30.0 to 107.5 mg Cu kg⁻¹. Their correlations with metals extracted by DTPA were highly significant. Contents of the metals in earthworm tissues were higher in A. caliginosa than in L. rubellus, with values ranging from 556 to 3381 mg Zn kg⁻¹, 11.6 to 102.9 mg Cd kg⁻¹, 1.9 to 182.8 mg Pb kg⁻¹ and 17.9 to 35.9 mg Cu kg⁻¹ in A. caliginosa, and from 667.9 to 2645 mg Zn kg⁻¹, 7.7 to 26.3 mg Cd kg⁻¹, 0.5 to 37.9 mg Pb kg⁻¹ and 16.0 to 37.6 mg Cu kg⁻¹ in L. rubellus, respectively. Correlations between body loads in earthworms with either total or DTPA-extractable contents of soil metals were significant, except for Cd in L. rubellus and Cu in A. caliginosa. Considering its simple analytical procedure, DTPA-extractable fraction may be preferable to total metal content as a predictor of bio-concentrations of heavy metals in earthworms. Biota-to-Soil Accumulation Factor (BSAF) of these four metals are Cd>Zn>Cu>Pb, with range of mean values between: Cd (6.18-17.02), Zn (1.95-7.91), Cu (0.27-0.89) and Pb (0.08-0.38) in A. caliginosa, and Cd (3.64-6.34), Zn (1.5-6.35), Cu (0.29-0.87) and Pb (0.04-0.13) in L. rubellus. The BSAF of Ca, Fe and Mn are Ca>Mn>Fe, with mean values of: Ca (0.46-1.31), Mn (0.041-0.111), Fe (0.017-0.07) in A. caliginosa and Ca (0.98-2.13), Mn (0.14-0.23), Fe (0.019-0.048) in L. rubellus, respectively. Results of principal component analysis showed that the two earthworm species differ in the pattern of metal bioaccumulation which is related to their ecological roles in contaminated soils.     

多种潮土有机质高光谱预测模型的对比分析

为了对比不同方法建模效果的差异,筛选潮土有机质高光谱最佳预测模型,该研究采集国家潮土土壤肥力与肥料效益长期监测站不同施肥处理耕层土样83份,采用25种光谱预处理方法(15种单一预处理方法,10种预处理方法相加算法)结合3种建模方法(多元线性回归、偏最小二乘回归、支持向量机回归),构建不同的潮土有机质高光谱预测模型。对比模型预测结果表明,最佳光谱建模方法是偏最小二乘回归法,该方法结合多种预处理方法均获得了较高的模型预测精度和可靠性,25个检验模型的平均决定系数、均方根误差值RMSEv和相对分析误差RPD值分别为0.913、1.264 g/kg和3.299。使用预处理方法相加算法能更好地提升模型精度,相比使用单一预处理方法,3种建模方法的检验模型平均决定系数分别提高了0.049、0.033和0.071,RMSEv分别降低了0.318、0.204和0.528 g/kg,RPD值分别提高了0.530、0.307和1.144。先用多元散射校正法再进行5个平滑点数的一阶导数预处理在3种建模方法中表现均较好(平均决定系数=0.934,平均RMSEv=1.17 g/kg,平均RPD=3.59),可作为潮土有机质预测模型的通用预处理方法。偏最小二乘回归模型结合最大值标准化预处理所建模型(决定系数=0.948,RMSEv=0.972 g/kg,RPD=4.276)精度高、可靠性强,且建模过程数据运算更为简便,是筛选出的最佳潮土有机质高光谱预测模型。该研究结果对潮土有机质高光谱预测建模有一定的指导作用,并为筛选最佳高光谱预测模型提供技术参考。     

Digestion and residue stabilization of bacterial and fungal cells,protein, peptidoglycan,and chitin by the geophagous earthworm Metaphire guillelmi

Microbial biomass is an important source of soil organic matter, which plays crucial roles in the maintenance of soil fertility and food security. However, the mineralization and transformation of microbial biomass by the dominant soil macrofauna earthworms are still unclear. We performed feeding trials with the geophagous earthworm Metaphire guillelmi using ¹⁴C-labelled bacteria (Escherichia coli and Bacillus megaterium) cells, fungal (Penicillium chrysogenum) cells, protein, peptidoglycan, and chitin. The mineralization rate of the microbial cells and cell components was significantly 1.2–4.0-fold higher in soil with the presence of M. guillelmi for seven days than in earthworm-free soil and 1–11-fold higher than in fresh earthworm cast material. When the earthworms were removed from the soil, the mineralization of the residual carbon of the microbial biomass was significantly lower than that in the earthworm-free soil, indicating that M. guillelmi affects the mineralization of the biomass in soil in two aspects: first stimulation and then reduction, which were attributed to the passage of the microbial biomass through the earthworm gut, and that the microorganisms in the cast could play only minor roles in the stimulated mineralization and residual stabilization of microbial biomass. Large amounts (8–29%) of radiolabel of the tested microbial biomass were assimilated in the earthworm tissue. Accumulation of fungal cells (11%) and cell wall component chitin (29%) in the tissue was significantly higher than that of bacterial cells (8%) and cell wall component peptidoglycan (15%). Feeding trails with ¹⁴C-lablled microbial cells and cell components provided direct evidence that microbial biomass is a food source for geophagous earthworm and fungal biomass is likely a more important food source for earthworms than bacterial biomass. Findings of this study have important implications for the roles of geophagous earthworms in the fate of microbial biomass in soil.     

三氯乙烯和三氯苯在水-玉米-空气系统中的传输过程研究

采用水培实验及光照培养箱培养方法,通过测量玉米木质部伤流液及露珠中三氯乙烯（TCE）和1,2,3-三氯苯（TCB）两种有机污染物的浓度,对比探讨了两种有机污染物在水-玉米-空气系统中的传输过程和机制。结果表明,露珠中TCE与TCB均主要来源于随水蒸气的叶面挥发过程;水培条件下TCB在玉米木质部伤流液中的浓度与根外部水溶液中TCB浓度呈正相关,而露珠中TCB浓度与外部水溶液浓度呈负相关,蒸腾流浓缩系数（TSCF）值由暴露时间决定。实验条件下,根外部溶液浓度较低时,露珠中TCB浓度远大于木质部伤流液中TCB浓度;而高浓度时,木质部伤流液中TCB浓度远大于露珠中浓度。露珠中TCE浓度远大于木质部伤流液中TCE浓度,且与根外部水溶液浓度呈正相关;而木质部伤流液中TCE浓度随营养液中TCE浓度增加而减小。     

Constructed wetlands for the treatment of organic pollutants

Background  Constructed wetlands (wetland treatment systems) are wetlands designed to improve water quality. They use the same processes that occur in natural wetlands but have the flexibility of being constructed. As in natural wetlands vegetation, soil and hydrology are the major components. Different soil types and plant species are used in constructed wetlands. Regarding hydrology surface flow and subsurface flow constructed wetlands are the main types. Subsurface flow constructed wetlands are further subdivided into horizontal or vertical flow. Many constructed wetlands deal with domestic wastewater where BOD and COD (Biochemical and Chemical Oxygen Demand respectively) are used as a sum parameter for organic matter. However, also special organic compounds can be removed. Objective  The objectives are to summarise the state-of-the-art on constructed wetlands for treatment of specific organic compounds, to the present the lack of knowledge, and to derive future research needs. Methods  Case studies in combination with a literature review are used to summarise the available knowledge on removal processes for specific organic compounds. Results and Discussion  Case studies are presented for the treatment of wastewaters contaminated with aromatic organic compounds, and sulphonated anthraquinones, olive mill wastewater, landfill leachate, and groundwater contaminated with hydrocarbons, cyanides, chlorinated volatile organics, and explosives. In general the removal efficiency for organic contaminants is high in all presented studies. Conclusion  Constructed wetlands are an effective and low cost way to treat water polluted with organic compounds. There is a lack of knowledge on the detailed removal pathways for most of the contaminants. Removal rates as well as optimal plant species are substance-specific, and also typically not available. If a constructed wetland provides different environmental conditions and uses different plant species the treatment efficiency can be improved. Recommendations and Outlook  There is a great need to lighten the black box ‘constructed wetland’ to obtain performance data for both microbial activity and the contribution of the plants to the overall removal process. Also genetic modified plants should be considered to enhance the treatment performance of constructed wetlands for specific compounds.     

Comparisons of earthworm populations and cast properties in conventional and organic arable rotations

Abstract. Earthworms influence a wide range of soil properties. They are affected by practices that perturb the soil or change organic inputs. This study compared populations in UK organic and conventional rotations differing in such practices. Three farm pairs, ranging from stockless to arable-grassland systems, were sampled on three occasions in each of two crop years. Additional farm pairs were sampled on a single occasion. Nine common earthworm species were grouped into three classes based on the depth ranges from which they were recovered. Cast and soil samples were taken from leys to compare aggregate stability, organic and nutrient content, and microbial biomass.   For similar rotation stages, populations of surface and shallow species classes were often larger in organic systems. In some comparisons the reverse was the case, particularly as the proportion of ley within each pair increased. System differences in biomass, but not abundance, could be attributed to the proportion of leys in rotations; individual earthworm weights were larger in conventional systems. Casts from both systems had markedly higher organic contents, stability, available P and K concentrations, and microbial biomass than underlying soil. This trend was more pronounced in conventional sites for nutrients and microbial biomass. Differences in populations and cast properties may have implications for soil fertility and wider ecosystem function.     

结合高光谱信息的土壤有机碳密度地统计模型

传统线性回归模型在借助光谱信息进行土壤属性预测时,通常忽略了土壤自身所具有的空间异质性和依赖性,并且未考虑模型残差的空间结构。针对以上不足,该文以江汉平原232个土壤样本为研究对象,以土壤反射光谱为辅助变量,采用偏最小二乘回归、普通克里格、协同克里格以及回归克里格分别构建土壤有机碳密度预测模型,选取决定系数(R~2)、均方根误差、标准差与预测均方根误差比(ratio of performance to deviation,RPD)对模型预测精度进行对比评价。结果显示,结合高光谱信息,且同时考虑残差空间结构的回归克里格模型表现优于其他模型,预测决定系数R~2为0.617,RPD为1.614。鉴于土壤光谱信息同时还具有测定简单、省时、无损等优点,因此土壤光谱是土壤有机碳密度空间插值的理想辅助因子。