采煤沉陷区土地利用格局动态及复垦对策

煤矿区人口资源经济协调发展是近几年社会各界关注的热点问题，其中采煤塌陷区土地急剧减少，人地矛盾日益尖锐。以山东邹城采矿塌陷区1988～2002年土地利用格局动态变化为例，分析了平原煤矿区土地利用变化的过程、演变规律及其生态修复措施，为合理利用土地，提高土地承载量提供科学依据。     

壳聚糖对土壤理化性状的影响

壳聚糖对土壤理化性状有较大的影响。当土壤中施入壳聚糖酸溶液后,土壤的团粒结构和渗透系数随壳聚糖施用量的增加而增加,而容重、CEC和pH则减小;在EC值上表现为先下降后上升的趋势。当壳聚糖施用量达到0.45‰[对干土平均质量(W/W)]后,土壤物理性状的变化趋于稳定。3种壳聚糖酸溶液处理的土壤物理性状的变化趋势一致,无明显差异。在壳聚糖酸溶液中,酸作为溶剂本身对土壤物理性状的影响不大。壳聚糖酸溶液对土壤化学性状的影响过程较复杂,表现出是由壳聚糖和酸对土壤共同作用的结果。溶剂酸是影响土壤pH主要因素,其酸性越强,壳聚糖酸溶液的酸性就越强,处理后土壤的pH就越小。土壤CEC、EC同时受壳聚糖用量和溶剂酸种类的影响。     

利用土壤改良剂固定污染土壤中铅、镉的研究进展

Since the inception of industrial revolution, metal refining plants using pyrometallurgical processes have generated the prodigious emissions of lead (Pb) and cadmium (Cd). As the core target of such pollutants, a large number of soils are nowadays contaminated over widespread areas, posing a great threat to public health worldwide. Unlike organic pollutants, Pb and Cd do not undergo chemical or microbial breakdown and stay likely in site for longer duration after their release. Immobilization is an in-situ remediation technique that uses cost-effective soil amendments to reduce Pb and Cd availability in the contaminated soils. The Pb and Cd contamination in the soil environment is reviewed with focus on source enrichment, speciation and associated health risks, and immobilization options using various soil amendments. Commonly applied and emerging cost-effective soil amendments for Pb and Cd immobilization include phosphate compounds, liming, animal manure, biosolids, metal oxides, and biochar. These immobilizing agents could reduce the transfer of metal pollutants or residues to food web (plant uptake and leaching to subsurface water) and their long-term sustainability in heavy metal fixation needs further assessment.     

Remediation of contaminated soil using soil washing and biopile methodologies at a field level

Background, Aims and Scope  An out-of-service oil distribution and storage station (ODSS), which operated from 1966 to 2000 in Mexico, is contaminated mainly by gasoline and diesel, showing the presence of methyl-tert-butyl-ether, benzene, toluene, ethyl benzene, and xylenes. Nine of the 16 polycyclic aromatic hydrocarbons were found, as well as Fe, Pb, V, and Zn. The health risk assessment suggested the necessity of reducing of three PAHs [benzo(a)anthracene, benzo(a)pyrene, and benzo-(b)fluoranthene], and vanadium. The aim of this work is to show that soil washing (on-site) and biopiles are excellent remediation methodologies to treat soils contaminated with petroleum derivates and metals. Applying them, it is possible to reach the goal value of 2,000 mg TPH/kg in a few months, as requested by Mexican legislation. Methods  More than 140 m³ were excavated from the ODSS. Three soil-washing dishes were built. 1540 m³ were treated by soil washing using a nonionic surfactant. A 100 m³ biopile was built to study the system capabilities in the biodegradation of around 4,500 mg/kg of TPH using the autochthonous microflora. Results and Discussion  The soil washing, average TPH-removal value was 83%, but values up to ca. 93% were observed. Removal values resulted in a function of the TPH initial values. Biopile (100 m³) worked during 66 days, reaching a TPH-removal value of 85%. At the end of the processes, no PAHs were detected. The contaminated soil was treated successfully, reaching the legislation limits (TPH values under 2,000 mg/kg, and a significant reduction in PAH concentrations). Conclusion and Recommendation  Both systems are suitable for remediation purposes, achieving high removal efficiencies at short and medium stages. It is highly recommended to proceed with soil washing studies, identifying new products, and mixtures, which could reduce costs and assure optimum operation.     

Interactions of clay minerals with Arthrobacter crystallopoietes: starvation, survival and 2-hydroxypyridine catabolism

For bacterial inoculants to be effective in soil remediation, the bacterial strain must be capable of overcoming any negative effects of soil minerals on cellular processes. One class of minerals commonly encountered by soil bacteria is clays. Thus, the effect of commonly occurring clay minerals in soils on starvation, survival and 2-hydroxypyridine catabolism by Arthrobacter crystallopoietes was evaluated. Stationary phase A. crystallopoietes cells were suspended in 0.03M, pH7.0, phosphate buffer containing no clay or amended with 0.2% (wt/vol) montmorillonite, sodium montmorillonite or kaolinite. Marked effects of clay minerals on both survival rates and catabolic rates of 2-hydroxypyridine were noted. For example, after 14 weeks starvation, 4.6% of the initial cell population was viable with no clay present, compared to 0.8% (montmorillonite), 22.1% (kaolinite) and 54.1% (sodium montmorillonite) in the presence of the clay minerals. Acclimated and nonacclimated cell populations were used to evaluate 2-hydroxypyridine catabolism. Induction of 2-hydroxypyridine metabolism occurred in the unacclimated cells following starvation. Differential impact of the clay minerals on unacclimated cells was detected. Montmorillonite enhanced the capacity for induction of 2-hydroxypyridine catabolism and its decomposition rate after 0–3 days starvation. For acclimated cells, clay did not affect the metabolic activity prior to starvation, but the presence of clay resulted in increased activity during starvation. For example, after 3 days starvation, a nearly two fold increase in metabolism was detected in the presence of clay minerals. These data suggest that some clay minerals in soil alter the survival time and metabolic activity of soil-amended bacteria, thereby affecting the potential for bioremediation success. Received: 1 March 1996     

表面活性剂对植物修复有机污染土壤的增效作用及原理

Phytoremediation is becoming a cost-effective technology for the in-situ clean up of sites polluted with hydrophobic organic contaminants （HOCs）. The major factors limiting phytoremediation are the mass transfer, rate of plant uptake, and microbial biodegradation of HOCs. This article discusses the potential of surfactants to enhance desorption, plant uptake, and biodegradation of HOCs in the contaminated sites. Positive effects of surfactants on phytoremediation have been recently observed in greenhouse studies. The presence of some nonionic surfactants including polyoxyethylene sorbltan monooleate （Tween 80） and polyoxyethylene（23）dodecanol （Brij35） at relatively low concentrations resulted in significant positive effects on phytoremediation for pyrene-contaminated soil. However, the anionic surfactant （sodium dodecyl sulfate, SDS） and the cationic surfactant （cetyltrimethylammonium bromide, CTMAB） were not useful because of their phytotoxicity or low efficiency for surfactant-enhanced phytoremediation （SEPR）. The mechanisms of SEPR for HOC-contaminated sites were evaluated by considering experimental observations. In view of concerns about the cost effectiveness and toxicity of surfactants to plants, more research is needed to enhance the use of SEPR technology.     

Incorporation of trace elements on iron-rich concretions around plant roots of tagus estuary salt marsh (portugal)

Objective

The concentration gradients of solid Al, Fe, Mn, Zn, Cd, Pb, Cr and Ni in freshly formed concretions and in older concretions preserved in the sediment were evaluated in a millimetre resolution scale. These results provide a better understanding of the complex biogeochemical processes in the root-sediment system and elucidate the potentialities of marshes in the restoration of contaminated aquatic systems.

Methods

Tens (soll das vielleicht tonnes/tons heißen) of freshly formed concretions and preserved concretions were collected in the Rosário salt marsh. Each tubular structure and involving sediments were scraped in concentric layers of 2-mm thickness to form two sets of composite samples. The elemental composition of concretion and sediment samples were determined by atomic absorption spectrometry.

Results and Discussion

The sediment involving the concretions contained ～0.5 mmol g^-1 Fe, but concentrations increased towards the root up to 3.4 mmol g^-1 in 3-mm interval. Manganese, Zn, Cd and Pb exhibited similar radial distribution in both preserved and freshly formed concretions indicating that these metals remain in those structures with the age. Chromium and Ni showed a different pattern being lower in concretions with respect to involving sediments, and consequently, concretions do not act as a barrier for these elements. The estimated amount of Zn (59 tons), Pb (5 tons) and Cd (0.4 tons) retained in the concretions all over the Rosario salt marsh highlights the importance of these structures in sequestering metals.

Conclusions and Outlook

The sequestering may be particularly relevant in salt marshes located near urban and industrial zones, being areas working as a natural remediation system and contributing for the detoxification of aquatic environments and the well-being of coastal resources.

     

关于生态修复若干概念与问题的讨论

开展生态修复研究与实践 ,应理清环境、生态、环境生态、生态恢复、生态建设、生态工程等与之相关的一些概念及科学内涵 ,避免概念上的混乱。我国的生态工程与国外的环境生态修复和生态恢复有较大差别 ,将生态学应用于农林水等生产领域 ,是我国生态工程研究与实践的突出特点。流域生态修复是今后生态修复的发展方向 ,水土保持工程是建设项目生态修复的主体 ;当前亟待开展生态修复机理、生态修复潜力、生态修复指标体系等方面的研究     

非政府组织在农村居民点用地整治运行现状及对策探讨——以石城县农村理事会为例

当前农村居民点用地整治主要依托新农村建设工作开展和进行,是新农村建设的核心内容。农村非政府组织新农村理事会在农村建设用地管理等农村公共事务中发挥着日益重要的作用。笔者以江西省赣州市石城县理事会为例,通过对3个行政村的理事会运行现状进行分析,总结了当前非政府组织在农村居民点用地整治运行现状和现实困难,针对性地提出了引导非政府组织在农村居民点用地整治中发挥积极作用的对策措施。     

巢湖流域农村面源污染特性及其综合整治措施

分析了巢湖流域农村面源污染现状,指出了农业面源污染的主要表现形式,从生活污水治理及沼气工程两方面探讨了流域污染综合整治措施,并阐述了巢湖流域整治后的经济效益和生态效益。