[Distribution Characteristics and Health Risk Assessment of Heavy Metals in a Soil-Rice System in an E-waste Dismantling Area].

This study selected Guiyu Town, Guangdong Province as the research area, the content of 15 kinds of metals (As, Be, Cd, Co, Cr, Cu, Hg, Li, Mn, Ni, Sb, Sn, Pb, V, and Zn) in the soil was determined, and the content of heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn in the rice of this research area was identified. Multivariate statistical analysis and a human health risk assessment model were used to investigate the distribution characteristics and health risk of heavy metals in a soil-rice system. The results showed that Hg, Sb, and Sn in the surface soil surrounding the electronic waste dismantling area have obvious accumulation effect. The average content of Cd and Hg exceeds the Ⅱ standard limit of the "Environmental Quality Standard for Soil" (GB 156182-1995), and that Guiyu Town is more seriously polluted than Chendian Town and Simapu Town. The multivariate statistical analysis showed that Cu, Sb, Ni, Zn, Sn, Pb, and Hg originated from the surrounding electronic waste dismantling activities, Cd and Be originated from other man-made sources of pollution, and V, Li, Cr, Co, As, and Mn originated from natural sources. Heavy metal evaluation concentration in the soil-rice system by heavy metal migration accumulated in rice are in compliance with national food hygiene standards, and the enrichment ability is Cd > Zn > Cu > Ni > As > Cr > Hg > Pb. Soil heavy metal health risk assessment results showed that children are more susceptible to heavy metal pollution, and handling-oral ingestion is the main way of soil exposure risk. The non-carcinogenic risk and carcinogenic risk of heavy metals in the soil of each town are acceptable. The health risk in Guiyu Town through ingestion of rice is mainly from the elements that include As, Cr, Cu, and Ni.

[Seasonal Characteristics and Ecological Risk Assessment of Heavy Metals in PM10 Around Electroplating Plants].

PM10 samples were collected from 45 sites around the electroplating factories in five towns in Dongguan at different times during all four seasons in 2015. The contents of 12 heavy metals (HMs) from the PM10 samples were analyzed by ICP-MS. The seasonal and spatial distribution characteristics and the ecological risk were analyzed to provide a scientific foundation for the relevant department to make decisions regarding the environmental hazard, risk assessment and, pollution control. The results showed that PM10 concentrations in the towns were lower than national standard level-Ⅱ, and the air pollution was heavier in winter than summer. The HM concentrations were higher in autumn and winter, and As, Cd, and Cr concentrations were higher than national standard (GB3095-2012). The concentrations of HMs in Humen, Shatian, and Dalingshan were much higher. The results for the enrichment factor and the geoaccumulation index indicated that Cd, Sb, Hg, and Co were in the extreme degree of pollution category, Pb and Zn were in the slight to extreme degree of pollution category, and Ni, Cr, Mn, and V were described as uncontaminated. The average potential ecological risk assessment (RI) of the HMs from the PM10 samples was more than 600, which suggested an extremely serious ecological risk in the study area.

[Distribution Characteristics and Health Risk Assessment of Heavy Metals in Surface Water Around Electroplating Factories].

To investigate the distribution characteristics and the human health risks of heavy metals in surface water samples, 30 samples were collected around electroplating factories of Machong, Shatian, Humen, Changan and Dalingshan towns in Dongguan city, 8 heavy metals(As, Cd, Cr, Cu, Hg, Ni, Pb and Zn) contents were measured and analyzed by using multivariate statistical analysis method and human health risk assessment model. The results showed that the maximum concentrations of Cr, Pb and the average concentration of Hg exceeded Environmental Quality Standards for Surface Water(GB 3838-2002, Grade Ⅲ), the concentrations of Cr, Cu, Hg, Ni, Zn and Pb during rainy season were all higher than that those during dry season. Multivariate statistical analysis indicated that Cd, Cr, Cu, Ni and Zn mainly originated from the contaminated electroplating factories, Pb and Hg were mainly affected by the traffic sources, and As was significantly correlated with natural sources. Health risk assessment result of surface water indicated that heavy metal pollution would lead to high health risks especially for children, and the health risks of heavy metals through drinking pathway were 2-3 orders of magnitude higher than the values caused by dermal contact pathway. Moreover, carcinogenic risks caused by Cr and As were higher than the maximum allowance levels (5×10-5 a-1), and non-carcinogenic risks of the heavy metals (10-10-10-7 a-1) decreased in the order of Pb > Ni > Cu > Hg > Zn, which were 4-5 orders of magnitude lower than the maximum allowance levels.

[Effects of DMPP-compound fertilizer on greenhouse celery growth and nutritional quality].

A field study with greenhouse celery (Apium graveolens L. ) showed that compared with basal application of ordinary compound fertilizer, one-time basal application of DMPP-compound fertilizer ( ENTEC , 12-12-17) at the rates of 67. 5 kg N x hm(-2) and 54. 0 kg N x hm(-2) increased the yield by 5. 78% and 10. 14% , respectively. The application of ENTEC also improved the nutritional quality of edible parts, e. g. , the Vc, amino acid, soluble sugar, N and P contents increased, while nitrate content decreased. Compared with basal plus side dressing applications, appropriately reducing the application rate and times of ENTEChad more beneficial effects on celery yield and quality, and reduced the production costs. ENTEC could suppress the transformation of soil NH4+ -N to NO3 - -N effectively, and thus, its application could retain soil residual N more in NH4+ -N than in NO3- -N form after celery harvested, resulting in a reduction of nitrate leaching.