Xuemei Zhu

Effects of Zinc and Chromium Stresses on Heavy Metal Accumulation of Rice Roots at Different Growth Stages of Rice Plants

Pot experiments were conducted to reveal the discipline of the heavy metal accumulation of rice (Oryza sativa L.) roots at different growth stages of rice plants under zinc and chromium stresses, and provided the basis for safe production of rice grains. The results showed as follows: with increasing concentration of zinc in soil, the zinc content in rice roots increased at first and then decreased at different growth stages of rice plants. With increasing concentration of chromium in soil, the chromium content in rice roots increased at different stages of rice plants. The order of zinc content in rice roots was: tillering stage > filling stage > booting stage, and the order of chromium content was: booting stage > filling stage > tillering stage. Partial correlation analysis showed that: the correlation was achieved at a significant or very significant level between the zinc content in rice roots and zinc concentration in soil at different growth stages, and the correlation was achieved at a significant level about the chromium. The concentration of zinc and chromium in soil did not have compound effects to zinc content or chromium content in rice roots.

Effects of Pb and Zn Stresses on Protective Enzyme Activities of Pb Accumulator Plant Pseudostellaria maximowicziana(Franch.et Savat.) Pax

To understand the physiological and biochemical response of the lead-accumulator plant pseudostellaria maximowicziana (Franch.et Savat.) Pax to lead and zinc stresses, the pot experiment was used to study the protective enzymes (SOD, CAT and POD) activity and MDA content of pseudostellaria maximowicziana under lead and zinc stresses. The results showed as follows: with the increase of lead concentration, SOD activity of plants had a decreasing trend before increase, and with the increase of zinc concentration, SOD activity had an increasing trend. CAT activities of plants had a trend of increase and POD activities had a decreasing trend before with increase of lead and zinc concentrations increasing. However, with lead and zinc concentrations increasing, MDA contents of plants had a wavy trend. ANOVA showed that the differences of the three kinds of protective enzyme activities among the concentration of lead, lead-zinc interaction and MDA content were extremely significant. While those of SOD and CAT activities by zinc concentrations were extremely significant, and POD activity and MDA content were significant.

Eco-Physiological Responses of Rice (Oryza sativa L.) Roots to Zinc, Chromium Stress

The plant could adapt to heavy metal conditions in soil to some extent. To study the adaptation process of rice plants under zinc, chromium stress, the effects of zinc, chromium in the soil on metabolism of rice (Oryza sativa L.) roots were investigated by soil pot experiments at tillering, booting and filling stages of rice plants. In the experiment, with the augment of zinc or chromium concentrations, superoxide dismutase activity increased at both tillering and booting stages, and decreased at the filling stage, peroxidase activity increased at tillering stage, and decreased at booting and filling stages, and catalase activity decreased at the three growth stages. The increase of concentration of zinc or chromium augmented the content of soluble carbohydrate and the soluble protein content while reduced the content of soluble protein in rice roots at three growth stages. The growth of rice plants decreased with the increase of chromium and zinc concentration in soil, and the roots and shoot biomass and the rice grain weight reduced, but the root/shoot ratio (w/w) tended to increase with the augment of zinc or chromium concentration, which indicating that rice can improve its ecological adaptability under zinc or chromium stress.

Environmental Impacts of Milk Packaging Made from Polythene Using Life Cycle Assessment

Life Cycle Assessment (LCA) is induced to examine the environmental impacts in the life cycle of milk package from polythene, and to compare the environmental impacts from different plastic package waste treatments in this article. The data of the mass and energy fluxes and the environmental emissions are obtained from literatures and sites investigation. The application of LCA by using Eco-Indicator 99 has made possible the comparison of the environmental impacts of three treatments. The results of this LCA study are discussed and reveal that the environmental impacts of plastic package from raw materials supply period is highest, over 90.2% of total environmental impacts in its life cycle except treatment stage. The plastic package contributes more to Fossil fuels, Respiratory inorganics and Climate change. While the contribution of Carcinogens, Eco-toxicity, Acidification and Eutrophication is less. The environmental impacts from plastic package waste is highest in landfill treatment followed by incineration and recycling, which landfill and incineration can append 16.1% and 5.3% of additional environmental impacts respectively, compared to that before plastic package come into waste stream. In contrast, recycling can reduce 75.9% of environmental impacts more significantly.

Study on Fuzzy Evaluation of Packaging Rationality Based on Life Cycle Assessment

Based on the practicable of function, environment compatibility and economic applicability of packaging, and using life cycle assessment (LCA), the hierarchy structure of evaluation index system was established. Then weight of items in the evaluation system was given by the analytic hierarchy process (AHP). The fuzzy comprehensive evaluation was used for rationality evaluation of packaging. Furthermore, an example was analyzed for demonstration. The results showed that using LCA in rationality evaluation of packaging could comprehensively consider evaluate environmental, economic and functional factors. It was a comprehensive evaluation index system, and could get the objective and impartial results. For the strong social significance, it could provide direction for improvement assessment with this simple and practicable method even good maneuverability. It also showed the feasibility of rationality evaluation.

Effects of Zinc and Chromium Stresses on Quality of Rice Grain

To reveal the impact of zinc and chromium stresses on the quality of rice grain, a set of experiments were conducted where the quality of rice grain was studied across different concentrations of zinc and chromium in the soil. The results revealed many dependencies. For example, the changes in milling quality and the shape of rice grain were minimal. However, increasing concentrations of zinc and chromium in the soil both produced higher rates of chalky rice. Amylose content was found to increase at lower concentrations of zinc in the soil, yet higher concentrations of chromium also produced higher amylose content. The content of crude protein in rice grain showed an increasing trend with increasing concentrations of either zinc or chromium. Finally, a positive correlation was found between the concentration of zinc in the soil and the concentrations of both zinc and chromium in the rice grain. Whereas increasing concentrations of chromium in the soil yielded higher chromium content in the rice, but had no measurable impact on zinc content.