Spatial Distribution of Fe, Cu, Mn in the Surface Water System and Their Effects on Wetland Vegetation in the Pearl River Estuary of China

摘要

Water samples and vegetation data in 1 m × 1 m vegetation quads (vegetation density, biomass, and size were investigated) were collected from Panyu District and reclaimed regions with different reclamation histories in Nansha District throughout the Pearl River Estuary in August 2010. The spatial distribution characteristics of Fe, Cu, and Mn in the surface water system were measured based on ordinary Kriging method of ArcGis Geostatistical Analyst. Metal index (MI) was selected to assess the pollution levels and principal correlation analysis (PCA) was chose to interpret the effects of these heavy metals on vegetation. Results showed that (i) there were higher concentrations of Fe and Cu appearing in the up west than that in the other parts of the whole region, meanwhile, a similar spatial distribution was showed in Fe and Cu, which indicated the two kinds of metals came from the same pollution source; (ii) all the MI values exceeded class I level and the water quality in metal levels was over or equal to class III level in the whole research region, and worse water quality was presented in the middle west of Panyu District and in the old reclamation region in Nansha District due to the characteristic of the surface water system and the long-term tillage, respectively; (iii) the concentrations of Fe and Cu showed negative correlation with vegetation, and Mn nearly had no effects on vegetations, and 1/3 of all samples were seated in the higher coverage and lower pollution area, which belongs to the new reclamation in Nansha District.