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

以太湖地区3种对酸缓冲能力不同的水稻土（黄泥土、白土和鸟泥土）为供试土壤, 以不同pH值(pH为5.6, 4.0, 3.0, 2.0)的模拟酸雨淋溶, 研究模拟酸化条件下土壤酸碱缓冲能的变化。根据酸碱滴定曲线, 进行统计分析和数学拟合, 提出以酸碱滴定曲线拟合方程的斜率表征土壤酸缓冲能力的新方法。结果表明, 3种供试土壤酸碱的基础缓冲能力依次为黄泥土（β=3.25）、鸟泥土(3.00)、向土(1.58)；土壤酸碱滴定曲线在其突跃范围内, 加酸的量与pH早显著线性负相关：直线斜率6的绝对值用以定量土壤对酸碱缓冲能力, 6的绝对值越大, 土壤酸碱缓冲能力越差。K值用以定量说明土壤酸碱缓冲能力的变化, 当K>100%时, K值越大, 土壤酸缓冲能力降低越多当K<100%时, K值越小, 土壤酸碱缓冲能力增加越大；当K≈100%(≤±5%)时, 可视为土壤酸碱缓神能力无显著变化。因新方法的理论依据仍为酸碱滴定曲线的理论, 所以仅适用于反应动力学上较快的阳离子交换反应, 即土壤酸碱初级缓冲体系, 不适用于原生矿物的风化的土壤酸碱次级缓冲体系。其结果为研究土壤酸碱缓冲能力的变化, 乃至研究土壤环境质量变化提供了可靠的定量方法。

重金属污染土壤的植物修复技术是绿色生物技术, 该技术的应用受制于两个主要因素:超积累植物生物量小和土壤中重金属有效性低。本文在收集大量资料基础上, 论述了蚯蚓与重金属的相互关系:重金属对蚯蚓的毒理效应和蚯蚓对重金属的忍耐力。根据在重金属污染土壤中, 蚯蚓活动能提高植物生物量和土壤中的重金属的生物有效性, 论证了在重金属污染土壤植物修复技术中引入蚯蚓的可行性, 并指出引入蚯蚓的植物修复技术当前的研究热点及今后的研究方向。