[Temporal-spatial Variation and Source Identification of Hydro-chemical Characteristics in Shima River Catchment, Dongguan City].

Shima River catchment is of strategic importance to urban water supply in Dongjiang portable water source area. To investigate the hydro-chemical characteristics of Shima River, 39 river water samples were collected in February, June and November, 2012 to analyze the major ions (K+, Na+, Ca2+, Mg2+, Cl-, SO4(2-) , HCO3-) and nutritive salts (PO4(3-), NO3- and NH4+) and to discuss the temporal-spatial variation and controlling factors of hydro-chemical composition, relative sources identification of varied ions was performed as well. The results showed that the hydro-chemical composition exhibited significant differences in different periods.

[Temporal-spatial difference of ecotoxicity and heavy metals pollution in Shima catchment, Dongguan].

Shima River, a tributary of Dongjiang River, located in Dongguan City of Guangdong Province, has been seriously polluted in the last 30 years. Water samples were collected from the river and the aquifer and the soil samples were collected as well in the wet (June) and dry (February) season to investigate the temporal and spatial variations of water quality in terms of heavy metal concentrations and inhibition rate of the luminescent bacterium (Vibrio fischeri, LUMIStox 300). Heavy metal concentrations and inhibition rate in river water were found decreasing from the upstream to the downstream, with metal concentrations exceeding the national surface water quality standard (Class I) for all samples and a highest inhibition of 38.