Jirong Shao

Pollution characteristics and risk assessment of human exposure to oral bioaccessibility of heavy metals via urban street dusts from different functional areas in Chengdu, China

Urban street dusts were collected in commercial area (CA), traffic area (TA), educational area (EA), residential area (RA) and parks area (PA) of Chengdu, China, to investigate the concentrations of heavy metals (Pb, Zn, Cu, Ni, Cd and Cr), and analyzed to evaluated possible sources and health risk assessment. The average concentrations (mg/kg) of Pb (82.3), Zn (296), Cu (100), Cd (1.66) and Cr (84.3) in urban street dusts were all higher than the local soil background values. The concentrations of heavy metals in each functional area could be classified as follows: CA>TA>RA>EA>PA. Principal component analysis and Cluster analysis showed mainly derived from the mixed sources of nature and traffic (51.7%). The results of health risk assessment showed no non-carcinogenic and carcinogenic risks of the metals for inhabitants. However, higher concentrations and oral bioaccessibility of the heavy metals in the dusts from CA and TA, indicating there was more health risks to the inhabitants in than that in other functional areas.

Characteristics and health risk assessment of heavy metals exposure via household dust from urban area in Chengdu, China.

To investigate the characteristics of heavy metals (Cr, Cd, Pb, Zn, Cu and Ni) in household dust in urban household environment of Chengdu, China, 90 household dust samples were collected from 6 districts of the city. The information of houses and residents were also recorded during dust sampling to identify the correlations between heavy metals in household dust and the house attributes. And also the principal component analysis and cluster analysis for sources and impactor factors. The concentrations of Pb (123mg·kg-1), Zn (675mg·kg-1), Cu (190mg·kg-1), Cr (82.7mg·kg-1), Cd (2.37mg·kg-1) and Ni (52.6mg·kg-1) in household dust are in low or moderate levels when compare with that from other counties or areas. The heavy metals of household dust samples from Chengdu is higher concentrations than that in the street dust from Chengdu, except for Cr. Statistical analysis result showed traffic sources and corrosion of alloys are important factors contributing to the rise concentrations of heavy metals in household dust. In addition, there is negative correlation (p<0.05) between the heavy metals concentrations and floor levels. The ingestion is the important pathway for Pb, Zn, Cu and Ni via household dust exposure to the residents, and the dermal contact was identified as a main route for Cr and Cd in household dust exposure to the residents. There are minor non-carcinogenic and carcinogenic risks from the heavy metals in household dust for the residents in Chengdu.

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.

Predicting soil erosion in sloping Hilly Areas of Central Sichuan based on SVM model

Based on Support Vector Machine (SVM) model, observational data from 1991 to 2000 of the six sloping runoff plots at Suining Soil and Water Conservation Experiment Station which located in Hilly Areas of Central Sichuan, China, were used for modeling and predicting the soil erosion. For modeling, five factors (rainfall, rainfall duration, rainfall intensity, vegetation coverage, slope), nine factors (five factors plus early rainfall, early rainfall duration, pre-rainfall intensity and time interval before and after the rain), ten factors (nine factors added to soil and water conservation measures) were as inputs to SVM model, respectively, and the erosion was as output. The results indicated that, the coefficients of efficiency of 5 factors and 9 factors on the soil erosion were 0.52 and 0.55, while that of 10 factors including soil and water conservation measures factor was 0.90. Compared with 5 and 9 factors, the model of 10 factors as input achieved a more satisfied prediction result and could be used for business forecasting. For a particular farming method, the values of soil and water conservation measures factor varied with the slopes, and the values of 15° were 1.46–2.03 times of those of 10°. For a certain farming method, the model with terrain, rainfall, rainfall and the vegetation coverage factors as input factors, could achieve a good effect.

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.

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.