有机络合强化植物修复的环境风险研究I. EDTA对复合污染土壤中TOC和重金属动态变化的影响

采用盆栽试验研究了EDTA存在条件下的土壤溶液总有机碳(TOC)和重金属浓度的动态变化。结果表明,施用3 mmol/kg EDTA极显著地增加了土壤溶液中TOC的含量。土壤溶液TOC随培养时间呈指数曲线下降。在加入EDTA 52天后土壤溶液TOC仍然高于对照处理。施用EDTA大幅度地提高了土壤溶液Cu、Zn、Cd和Pb的浓度,这些重金属的浓度在一个月内迅速下降,以后趋向稳定。EDTA活化土壤重金属存在淋溶迁移的潜在环境风险。     

有机络合强化植物修复的环境风险研究：Ⅱ．不同质地对EDTA淋溶土壤中重金属的动态作用

通过土柱淋溶试验研究了EDTA对不同质地土壤中Cu,Zn,Cd,Pb淋溶作的影响及其动态特征。结果表明，土壤质地对EDTA淋溶重金属元素的行为有一定的影响。这些金属的淋失主要发生在淋溶初期，可能造成地下水污染的潜在风险。     

有机络合强化植物修复的环境风险研究II. 不同质地对EDTA淋溶土壤中重金属的动态作用

通过土柱淋溶试验研究了EDTA对不同质地土壤中Cu、Zn、Cd、Pb淋溶作用的影响及其动态特征。结果表明,土壤质地对EDTA淋溶重金属元素的行为有一定的影响,这些金属的淋失主要发生在淋溶初期,可能造成地下水污染的潜在风险。     

重金属污染土壤的植物强化修复研究进展

随着工农业生产的快速发展,土壤重金属污染日益严重,土壤重金属污染的高效快速修复技术备受关注。在各种土壤重金属污染修复技术中,植物修复技术因其清洁、简单、高效、低消耗等优点,得到人们的认可,具有良好的发展前景。论文综述了土壤重金属污染来源及现状,植物修复技术的基本原理及特点,植物强化修复技术的研究进展,分析了当前植物强化修复技术中存在的问题,并指明了植物强化修复技术的发展方向,以期为土壤重金属污染的快速、绿色修复提供理论依据。     

EDTA对土壤渗滤液中TOC和重金属动态变化的影响

通过盆栽试验研究了EDTA对土壤渗滤液中总有机碳(TOC)和重金属动态变化的影响.结果表明,施用EDTA极显著地增加了土壤渗滤液中TOC含量,土壤渗滤液中TOC含量随淋洗量呈指数曲线下降.在加入EDTA 48天后,土壤渗滤液中TOC含量仍然高于对照处理.施用EDTA大幅度地增加了土壤渗滤液中Cd、Ni的浓度,其浓度在1个月内迅速下降,以后趋于稳定.用EDTA强化重金属污染土壤的修复存在淋溶迁移的环境风险.防止因EDTA施用而引起地下水污染的关键时期在EDTA施入后的2周内.     

农艺措施强化重金属污染土壤的植物修复

作为植物修复强化技术,农艺措施可有效提高土壤重金属污染的修复效率。本文从土壤管理和植物管理两大方面综述了农艺措施强化重金属污染土壤植物修复的研究进展,重点讨论了施肥、蚯蚓强化以及植物栽培管理措施用于强化植物修复的基本原理与相关应用,并提出今后研究的方向。     

强化植物修复的螯合诱导技术及其环境风险

本文就运用螯合诱导技术强化植物修复金属污染土壤的理论基础、实践应用及环境风险等方面进行了分析和评价,认为螯合诱导-强化植物修复可成为一种有潜力的应用技术.     

镉污染土壤的植物修复及其EDTA调控研究：Ⅰ、镉对富集植物印度芥菜的毒性

本通过温控盆栽试验研究在10－190mg/kg共10个浓度梯度的Cd处理下，印度芥菜生长对Cd的响应，Cd在根与地上部的积累以及在Cd胁迫和毒害条件下对Ca和Zn吸收的影响，结果表明，Cd对印度芥菜生长的毒害浓度在各个生育期各有不同：幼功期与营养生长前期在70－110mg/kg左右；营养生长后期在110mg/kg以上；成熟期在150mg/kg左右。植物吸收的镉随土壤镉处理浓度的增加而增加，本试验中印度茶菜根和叶积累镉最高浓度分别为300和160mg/kg，在Cd胁迫下，印度芥菜吸收的Ca和Zn增加，在Cd毒害条件下，印度芥菜吸收的Ca和Zn下降。认为高浓度的Cd对印度芥菜生产有抑制，但印度芥菜对镉也表现出很强的耐性，这种耐性可与植物体内Cd和Ca，Zn之间的平衡有关。     

镉污染土壤的植物修复及其EDTA调控研究：Ⅱ．EDTA对镉的形态及其生物毒性的影响

本通过温室盆栽试验研究了10－200mg/kg共20个浓度梯度的Cd处理下，EDTA加入土壤后对Cd的形态及其生物毒性的影响，在获前一周加入EDTA，收获后测定植物根和地上部的生物量，以及H2O、NH4NO3和EDTA3种提取剂提取的Cd浓度。结果表明，EDTA加入土壤一周后，土壤水溶态Cd增加了400倍以上，交换态Cd增加了40倍以上，印度芥菜根和地上部的生长都受到抑制。可能的原因是EDTA增加了土壤中镉的移动性，提高了Cd对植物的毒性。     

重金属污染土壤的植物修复研究Ⅰ.金属富集植物Brassica juncea对铜、锌、镉、铅污染的响应

用来修复污染土壤的理想植物应具有高的生物量并能忍耐和积累污染物.印度芥菜(Brassica juncea)能富集多种重金属且生物量较大.本文研究了Zn、Cd、Cu、Pb 4种重金属对印度芥菜生长的影响,特别是重金属对印度芥菜地上部生物量的影响.结果表明,在含Cu 250 mg/kg、Pb 500mg/kg或Zn 500mg/kg的污染土壤上,印度芥菜能够忍耐,正常生长.印度芥菜在含Cd 200 mg/kg的土壤上发生镉毒而出现失绿黄化症状,Cd与中等浓度的Zn、Cu、Pb共存时毒害更为严重.这种植物适合Cu、Zn、Pb中等污染土壤的修复.     

丛枝菌根对矿区环境修复的生态效应

针对煤矿区生态环境修复过程中存在的主要问题,通过定位监测菌根的生态来探索菌根生物技术在矿区环境治理的效应与推广模式.菌根对植物生长具有明显的促进作用,接种菌根6个月后杨树和白蜡的胸周和株高分别较对照明显增加,菌根侵染率达到80%以上,菌根与植物共生作用好.接种菌根菌6个月后,菌根际菌丝长度远远高于对照,产生的孢子数量也明显增加,接种菌根菌对于降低煤矿区环境修复成本以及增加未来生态收益具有很大的潜力,维持了矿区生态系统的稳定.     

Compost-assisted phytoremediation of As-polluted soil

Journal of Soils and Sediments - The effect of organic matter on the As bioavailability in soils and thus on phytoremediation processes is still controversial. The objective of the present study...     

Aspects of phytoremediation of organic pollutants

Phytoremediation is a quite novel technique to clean polluted soils using plants. In theory, phytoremediation methods are cheap, are accepted by the public and, compared to physical or chemical approaches, are ecologically advantageous. Until today, however, there are only a few examples of successful applications. One reason is that the processes involved are complex, and a full clean up may require many years. Plants affect the water balance of a site, they change redox potential and pH, and stimulate microbial activity of the soil. These indirect influences may accelerate degradation in the root zone or reduce leaching of compounds to groundwater. Compounds taken up into plants may be metabolised, accumulated, or volatilised into air. Based on these processes, several phytoremediation methods have been developed: Phytoextraction, rhizofiltra-tion, phytostabilisation, rhizo and phytodegradation, pump and tree, land farming, phytovolatilisation, hydraulic control and more. Already in use are plants (and here willow, poplar and grass) for the degradation of petroleum products, aromatic hydrocarbons (BTEX), chlorinated solvents, explosives and cyanides. However, phytotoxicity and pollutant mass balances were rarely documented. Often, the success of the projects was not controlled, and only estimates can be made about the applicability and the potential of phytoremediation. This lack of experience about possibilities and limitations seems to be a hindrance for a broader use of these techniques.     

Short-term kinetic response of enhanced methane oxidation in landfill cover soils to environmental factors

 This paper aims at a better understanding of methane oxidation under conditions that are representative of landfill cover soils. The kinetics of methane oxidation were studied in landfill cover soils that had been exposed to high methane mixing ratios. This was done in batch experiments, under various environmental conditions. V _max increased exponentially with temperature in the range 5–35  °C, with a Q ₁₀ value of 2.8. K _m increased approximately linearly in this range from 1.2 μM to 7 μM. Consequently, the influence of temperature on methane consumption was more pronounced at high concentrations than at low concentrations. The inhibition by ammonium of methane consumption was much stronger after 6–7 months of exposure to high methane mixing ratios than after 5–7 weeks of exposure, indicating that there was a shift of dominating methanotrophic species in soils after long exposure times. Additions of nitrifying sludge or compost to soils initially inhibited methane oxidation, followed by a stimulation after a few days. Received: 19 May 2000     

Nitrogen isotope composition of organically and conventionally grown crops

Authentic samples of commercially produced organic and conventionally grown tomatoes, lettuces, and carrots were collected and analyzed for their delta15N composition in order to assemble datasets to establish if there are any systematic differences in nitrogen isotope composition due to the method of production. The tomato and lettuce datasets suggest that the different types of fertilizer commonly used in organic and conventional systems result in differences in the nitrogen isotope composition of these crops. A mean delta15N value of 8.1 per thousand was found for the organically grown tomatoes compared with a mean value of -0.1 per thousand for those grown conventionally. The organically grown lettuces had a mean value of 7.6 per thousand compared with a mean value of 2.9 per thousand for the conventionally grown lettuces. The mean value for organic carrots was not significantly different from the mean value for those grown conventionally. Overlap between the delta15N values of the organic and conventional datasets (for both tomatoes and lettuces) means that it is necessary to employ a statistical methodology to try and classify a randomly analyzed "off the shelf" sample as organic/conventional, and such an approach is demonstrated. Overall, the study suggests that nitrogen isotope analysis could be used to provide useful "intelligence" to help detect the substitution of certain organic crop types with their conventional counterparts. However, delta15N analysis of a "test sample" will not provide unequivocal evidence as to whether synthetic fertilizers have been used on the crop but could, for example, in a situation when there is suspicion that mislabeling of conventionally grown crops as "organic" is occurring, be used to provide supporting evidence.     

Production of organically bound selenium yeast by continuous fermentation

This paper describes a protocol for incorporation of sodium selenite or sodium selenate into Saccharomyces cerevisiae biomass by continuous fermentation in a medium with minimal sulfur and methionine concentrations. Selenium incorporation was followed by atomic absorption analysis and methylene blue reduction time (MBRT). Continuous fermentation at 0.2 h(-1) dilution rate and sodium selenite addition gradient up to 0.69 g/L of Na(2)SeO(3) yielded 1. 89 g/L of biomass with 1904 microg of selenium/g of dry biomass. However, MBRT was 0.1 min, which indicated that the majority of selenium was in the inorganic form. On the other hand, continuous fermentation at 0.2 h(-1) dilution rate and sodium selenate gradient up to 0.28 g/L of Na(2)SeO(4) yielded 0.76 g/L of dry biomass with 687 microg of selenium/g of dry biomass, and MBRT was 26 min, which indicated a high concentration of organically bound selenium. Overall, the results indicate a Se/S ratio of 3.9:1 and a dry biomass/Se ratio of 5.5:1 as optimal for continuous production of organically bound selenium.