Variations in Uptake and Translocation of Copper, Chromium and Nickel Among Nineteen Wetland Plant Species

An experiment was carried out to investigate the variations in metal uptake and translocation among 19 wetland plant species in small-scale plots of constructed wetland using artificial wastewater containing 2.0 mg L^-1 copper （Cu）, 1.0 mg L^-1 chromium （Cr）, and 2.0 mg L^-1 nickel （Ni）. More than 97% of Cu, Cr, and Ni were removed from the wastewater by the wetland plant species. There were more than ]00-fold differences in the metal accumulation and more than ten-fold differences in the metal concentrations among the 19 plant species. These plants accumulated as high as 8.8% of Cu, 20.5% of Cr, and 14.4% of Ni when they were grown in the wetland soaked with the wastewater. Several plant species were found to be highly capable of accumulating one, two or all the three metals. The results indicated considerable variations in the metal removal abilities through phytoextraction among the 19 wetland plant species. It can be concluded that the selection of appropriate plant species in constructed wetland can be crucial for the improvement of metal removal efficiency of the wetland system.

Evaluation on Feed Factors Affecting the Dung Pollutants of Livestock and Poultry

The 30 pairs of feed and dung samples from the livestock and poultry farms with different scales were checked and analyzed. The results showed： a great linear relation existed between the feed factors and 7 pollutants such as ammonia nitrogen, phosphorus, copper, iron, arsenic, mercury, cadmium in livestock and poultry＇s dung. The main affecting factors of feed were respectively nitrogen, phosphorus, copper, and arsenic, which were totally feed ingredient elements. And it indicated that the dung pollutants such as nitrogen, phosphorus, copper, iron, arsenic, mercury, and cadmium could be regulated by controlling the feed ingredients. But the dung nitrogen did not have a linear relation with the feed factors. Reducing the nitrogen in feed did not mean the relative decrease of the dung nitrogen content. Feed consumption rate of unit weight did not have notable performances, and it did not show curve model after curve fitting method. The pollutant index of ammonia nitrogen, phosphorus, copper, and arsenic of the group whose feed consumption rate of unit weight was less than 20 g/kg·d was extremely remarkably lower than those of the 20 -30 g/kg·d group. The pollutant index of mercury, chromium, and cadmium showed the opposite performance. With the increase of feed consumption rate, each pollutant did not act in an increasing trend, of which the pollutant index of ammonia nitrogen and the general phosphorus presented a quadratic model trend. The feed consumption level of unit weight had an extremely remarkable effect on the pollution level rate and the eady warning level rate, showing the thrice model trend, of which the 20 -30 g/kg. d group was the maximal, respectively for 16.67% and 50%, which was the same with the above-mentioned law.