Modelling the relationship between catchment attributes and wetland water quality in Japan

The influence of catchment attributes has been examined to find out whether variations in water quality indicators [electrical conductivity (EC), pH, turbidity, dissolved oxygen (DO), total dissolved solid (TDS), total nitrogen (TN), dissolved organic nitrogen (DON), dissolved inorganic nitrogen (DIN), temperature and nitrogen] could be explained by them for 24 wetlands in west Japan. Urban areas (%) were positively (P <= 0.05) correlated with EC (r=0.67), TDS (r=0.69), TN (r=0.92), DON (r=0.60), [NH4+] (r=0.47) and with [NO2-] (r=0.50). Forest areas (%) were inversely (P <= 0.05) correlated with EC (r=-0.62), TDS (r=-0.68), TN (r=-0.68) and [NH4+] (r=-0.55) and with DON (r=-0.43). Agricultural area (%) was positively (P <= 0.05) correlated with EC (r=0.40), TDS (r=0.45), TN (r=0.44) and [NH4+] (r=0.56) and with both areas (%) of grey lowland soil (r=0.60) and diluvial sand (r=0.58). Area (%) of regosol was positively correlated with DO (r=0.42) but inversely with DON (r=-0.44, P0.05). Rhyolite was positively (P0.05) correlated with the TN (r=0.46) but inversely with DON (r=-0.49) and [NH4+] (r=-0.47). Regression models were developed for the water quality indicators including EC (r(2)=0. 62), [NO2-] (r(2)=0.90), [NO3-] (r=0.52), TN (r=0.86), DIN (r(2)=0.74) and DON (r(2)=0.54) at 0.01 <= P <= 0.05. In the models, no significant contribution has been observed for catchment geometric features of the wetlands on water quality indicators. Copyright (c) 2014 John Wiley & Sons, Ltd.