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), [NH 4 + ] ( r  = 0.47) and with [NO 2 − ] ( 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 [NH 4 + ] ( 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 [NH 4 + ] ( 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, P  ≤ 0.05). Rhyolite was positively ( P  ≤ 0.05) correlated with the TN ( r  = 0.46) but inversely with DON ( r  = −0.49) and [NH 4 + ] ( r  = −0.47). Regression models were developed for the water quality indicators including EC ( r 2  = 0. 62),NO 2 −( r 2  = 0.90),[ NO 3 − ] ( 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 © 2014 John Wiley & Sons, Ltd.