The widespread contamination by heavy metals is of major concern because of their toxicity, persistence and bioaccumulative nature. Past studies indicated that anthropogenic activities have been changing metal concentrations in the Han River, leading to hazards on human and wildlife (Journal of Hazardous Materials. 181, 1051-1058 and 176, 579-588, 2010). Thus, it is urgent to determine the effects of land use change by human activities on trace metals in the fluvial system and estimate the contribution of possible sources of metals. Related research has been published in Journal of Hazardous Materials (doi:10.1016/j.jhazmat.2011.03.026) entitled “Response of dissolved trace metals to land use/land cover and their source apportionment using a receptor model in a subtropic river, China”.

In this study, Dr Siyue Li and Quanfa Zhang in the system ecology (Zhang’s Group) from Wuhan Botanical Garden, CAS conducted filed campaigns, lab analysis by ICP-AES (Inductively Coupled Plasma Atomic Emission Spectrometer), and Landsat TM and +ETM for land use/land cover composition, as well as FA-MLR (factor analysis-multiple linear regression) receptor model.

The results demonstrated that metal variables were better predicted by land use away from rivers than land use close to rivers. At the cathcmment scale, urban was a better predictor of metals, while at the buffer scale, vegetation and shrub were the better predictors in the snow melt and base flow periods, and bare land was the predictor in the high flow period. Furthermore, remarkably varied metals were predictable by landscape variables along river networks among water flow sesonality, which suggested that hydrological seasonality within the buffer zone had much higher explanative values to metals. However, almost similar metals were explained by land use in both subcatchment and buffer zone in the snow melt flow period. FA-MLR model provided apportionment of five sources to trace metals. It revealed that mining, fuel combustion and vehicle exhaust were among the major polluting sources responsible for metal concentrations in river water.

This paper provided fresh insights into the interactive influence of hydrology and landscape on metals using quantitative and qualitative analytic methods. This study also demonstrated the value of multivariate statistic techniques in identification and apportionment of pollution sources in river systems.