The effects of inoculation of earthworms and arbuscular mycorrhiza separately, and in combination, on Cd uptake and growth of ryegrass were studied in soils contaminated with 0.5, 10, 20 mg of Cd kg-1 soil. Both earthworms and mycorrhiza were able to survive in all the treatments with added Cd. Earthworm activity signicantly increased mycorrhizal infection rate of root and ryegrass shoot biomass. Earthworm activity decreased soil pH by about 0.2 units, and enhanced root Cd concentration and ryegrass Cd uptake. Mycorrhiza inoculation increased shoot and root Cd concentration substantially, and at the highest dosage of 20 mg Cd kgK1 decreased biomass of ryegrass. Inoculation of both earthworms and mycorrhiza increased ryegrass shoot Cd uptake at low Cd concentrations (5 and 10 mg Cd kgK1 soil), when compared with inoculation of earthworms or mycorrhiza alone. In conclusion, earthworm, mycorrhiza and their interaction may have a potential role in elevating phytoextraction efciency in low to medium level metal contaminated soil.

Laboratory incubation experiments were conducted to examine the effect of earthworm (Pheretimasp.) activity on soil pH, zinc (Zn) fractionation and Nmineralization in three soils. No Zn uptake by earthworms was observed. Zinc addition decreased pH of red soil (soil 1) and hydragric paddy soil (soil 3) by 0.5 and 0.2 unit, respectively, but had no effect on alluvial soil (soil 2). The effect of Zn on soil pH was possibly due to a specific adsorption mechanism between Zn and oxides. Earthworm activity significantly decreased the pH of the red soil, a key factor affecting Zn solubility, but not of the other two soils. Earthworm activity significantly increased DTPA-Zn (DTPA-extractable) and OxFe-Zn (NH2OH-HCl-extractable) in the red soil, but had little effect on other fractions. In the alluvial soil, earthworm activity significantly increased OxFe-Zn but decreased organic-Zn (organic-associated Zn). In the hydragric paddy soil, earthworm activity significantly increased MgCl2-Zn (MgCl2-extractable) and organic-Zn. The level of CaCl2-extractable Zn in all three soils was not affected by earthworm activity. Nitrogen mineralized as a result of earthworm activity was equivalent to 110, 120 and 30 kg N ha–1 in soils 1, 2 and 3, respectively. Zinc added at rates less than 400 mg Zn kg–1 did not seem to affect the activity of N-mineralizing microorganisms. The present results indicated the possibility of increasing the metal bioavailability of relatively low level metal contaminated soils, with a higher organic matter content, by earthworm inoculation.

以褐土（Cinnamon soil）、潮棕壤（Aquic brown soil）和酸性棕壤（Acid brown soil）为供试土壤, 通过培养实验, 研究了土壤中重金属Zn、Pb对赤子爱胜蚓（Eisenia foetida）生长率的影响, 赤子爱胜蚓（Eisenia foetida）对不同土壤中有效态Zn、Pb含量的影响, 并与野生环境中生长的灰暗异唇蚓（Allolobaphora caliginosa）进行比较。结果表明：重金属的污染明显抑制了赤子爱胜蚓的生长；赤子爱胜蚓可以显著提高潮棕壤中DTPA-Pb的含量, 对DTPA-Zn的含量影响不大；加赤子爱胜蚓, 褐土中DTPA-Zn和Pb的含量显著高于加灰暗异唇蚓, 潮棕壤中DTPA-Zn的含量和酸性棕壤中大DTPA-Pb的含量则相反。

以江苏省国营大沙河果园为代表, 查明淮北黄泛沉积区果园土壤肥力现状。结果表明:土壤

以江苏省吴县市农地为例, 研究了高强度经济开发下土壤环境中重金属元素的变化。结果表明, 除Zn接近背景值外, Cu、Pb全量已超过背景值;工业快速发展地区土壤中Pb已显著高于农业环境;它们的有效态含量已达到丰富或过多的供应水平, 且工业环境中显著高于农业环境中;重金属元素的活化率显示工业发展对土壤环境重金属元素的强烈污染冲击。这种20～30a尺度的土壤环境变化对水环境及食物安全和环境安全的潜在影响必须引起科学家和决策者的密切注意。