[Transformation of Cu forms in Cynodon dactylon rhizosphere soil of copper tailings yard].

The study on the Cu forms in Cynodon dactylon rhizosphere soil of copper tailings yard in Tongling City, Anhui Province showed that among the test Cu forms, the amount of residual form occupied the majority, while that of exchangeable form was relatively low. Compared with non-rhizosphere soil, rhizosphere soil had a higher organic matter content but a lower pH. With the growth of C. dactylon, the contents of organically combined and exchangeable Cu in rhizosphere soil increased by 7.89% and 5%, respectively, while those of carbonate-combined and Fe-Mn oxides-combined Cu decreased. The growth of C. dactylon accelerated the transformation of Cu forms in rhizosphere soil, and decreased the rhizosphere soil Cu content through its absorption.

[Impact of Cu and Zn pollution on rape growth and soil enzyme activity].

A pot experiment was conducted to study the impact of Cu and Zn pollution on soil enzyme activities and rape seedlings growth. The results showed that Cu had a stronger inhibitory effect than Zn on soil urease activity, while Zn had more obvious impact on soil calatase activity. The damage on the growth and dry mass of rape was more serious under Cu than under Zn pollution. The inhibition of rape seedlings growth was mainly due to the inhibition of root growth and its material accumulation. Factor analysis indicated that root dry mass was more sensitive than other indices, which could be adopted to monitor soil Cu and Zn pollution.

Separate and combined effects of Cu and Cd on seedling growth and active oxygen metabolism system of Trifolium repens L.

Pot-culture experiments were used to examine the individual and combined effects of Cu and Cd pollutants on Trifolium repens L. seedlings, both on their growth and their active oxygen metabolism system, mainly superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) activities. The results showed that the negative action took place at low concentrations of Cu (less than 500 ppm) and Cd (less than 0.5 ppm), which had no obvious effects on the seedlings' growth. However, as the concentrations of Cu and Cd increased (500-3000 ppm and 0.5-50 ppm respectively), synergistic activities was observed, showing obvious negative effects (P less than 0.05). Compared with the control samples, the seedlings affected by Cu and Cd pollutants were shorter and smaller, their fresh/dry weight and content of soluble protein decreased drastically, their leaf electric conductivity increased, and the contents of their leaf pigments decreased. Chlorophyll a was more sensitive than chlorophyll b to Cu and Cd pollutants, and chlorophyll b was more sensitive than carotenoid. It was also shown that the active oxygen metabolism of T. repens seedlings was destroyed by high amounts of Cu and Cd, the balance of the anti-oxidase system was broken, and the CAT and SOD activities noticeably decreased while POD activity evidently increased. Cd had a more noticeable effect on seedling growth than Cu.

[Studies on the adaptation of five legumes species to copper tailings].

Pot experiments with five legumes were conducted in five different amendment substrates for the reclamation of copper tailings in Tongling, Anhui province. The five tested legumes species are Glycine max, Phaseolus angularis, P. calcaratus, P. radiatus, P. mininus. The results showed that the main factors to restrict growing of the vegetation are poor nutrient and high concentration of Cu. The seeds of the legumes species could germinate, but they germinated later in the substrates with higher proportion of copper tailings than in the substrates with lower proportion of copper tailings. After clipping, G. max, P. angularis, P. calcaratus, P. radiatus were alive all the time, but some of the other two legumes species were dead because of the their non-adaptation to the copper tailings. At the same amendment group, the chlorophyll contents of G. max and P. calcaratus were higher than that of other three experimental species on the 50th day. The height and the biomass of G. max and P. calcaratus were higher than that of other three experimental species on the 70th day too. According to the biological characteristics of the five species during the growth periods about indexes of the seeding survival, chlorophyll content, height and biomass, G. max and P. calcaratus are more adaptive and tolerant than the other legumes and the TA75 amendment approach is the more reasonable for the reclamation of copper tailings.