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A systematic investigation into total and bioaccessible heavy metal concentrations in rice grains harvested from heavy metal-contaminated regions was carried out to assess the potential health risk to local residents. Arsenic, Cr, Cu, Pb, and Zn concentrations were within acceptable levels while Cd and Ni concentrations appeared to be much higher than in other studies. The bioaccessibity of As, Cd, and Ni was high (>25%) and could be well predicted from their total concentrations. The noncarcinogenic risk posed by As and Cd was significant. The carcinogenic risk posed by all bioaccessible heavy metals at the fifth percentile was 10-fold higher than the acceptable level, and Cd and Ni were the major contributors. The contribution of each metal to the combined carcinogenic risk indicates that taking pertinent precautions for different types of cancer, aimed at individuals with different levels of exposure to heavy metals, will greatly reduce morbidity and mortality rates.

Significant attentions are rising for estrogenic compounds in environment, because their potential impacts on water ecosystem and human health. Estrogenic compounds (Estrone[E1], 17b-Estradiol[E2], Estriol[E3], 17a-Ethinylestradiol[EE2] and Bisphenol A [BPA]) in rivers of southern Jiangsu, China were investigated to realize their distributions and risks. The results showed E1, E2, E3 and BPA ranged from 1.96 to 143.29ng/L in rivers, with the detection rates from 12.5% to 100%. These estrogenic compounds in waters showed higher contents in winter than in spring and autumn. Levels of E1, E2 and E3 were higher in rivers nearby livestock breeding areas, while the concentrations of BPA were higher in the rivers nearby industrial areas. The risk assessment of estrogenic compounds were performed by the calculation of risk quotient (RQ) based on the predicted no effect concentration (PNEC), which was deduced through a species sensitivity distribution (SSD) model. The RQ values of E1, E2, E3 and BPA were 0.02∼1.87, 1.28∼23.22, 0.01∼0.80 and 0.03∼0.44 respectively. These results imply that harmful ecological effects might happen in some rivers. It indicates that different anthropogenic activities will lead to diverse inputs of estrogen compounds into rivers and pose different risks.

The source and temporal changesof mineralstransported by the world’slarge riversare important. In particular, clay minerals are important in evaluating the maturity of suspended sediments, weathering intensity, and source area. To examine seasonal changes in mineralogical compositions of the Changjiang River (CR), suspended particulate matter (SPM) samples were collected monthly for two hydrological cycles in Nanjing city and then were studied using X-ray diffraction (XRD), diffuse reflectance spectrophotometry (DRS), X-ray fluorescence spectrometry (XRF), and chemical analyses. The resultsindicate that the concentration of CR SPM rangesfrom 11.3 to 152 mg/L and ishighly correlated to the rate of water discharge, with a greater concentration in flood season and lower concentrations during the dry season. CaO, MgO, and Na2O increase with increasing discharge whereas Al2O3decreases sharply with increasing discharge. Dolomite, calcite, and plagioclase show strikingly similar seasonal variations and increase with increasing discharge with maximum concentrations in the flood season. In contrast, the clay mineral content exhibits the opposite trend with the lowest concentrationsin the flood season. Illite dominatesthe clay mineralsof the CR SPM, followed by chlorite, kaolinite, and smectite. Illite and kaolinite show distinctly seasonal variations; SPM contains more illite and less kaolinite during the flood season than during the dry season. The illite chemistry index and crystallinity, as well as kaolinite/illite ratio, all indicate intense physical erosion in the CR basin during the rainy season. Total iron (FeT) and highly reactive iron (FeHR) concentrations display slight seasonal changes with the smallest values observed during the flood season. Goethite is the dominant Fe oxide mineral phase in the CR SPM and hematite is a minor component, as revealed by DRS analyses. The FeTflux and FeHRflux are 2.786×106T/y and 1.196×106T/y, respectively.