The influence of irrigation with paper mill effluent on soil chemical properties of the heavily degraded coastal saline-alkaline wetlands in the Yellow River Delta The influence of irrigation with paper mill effluent on enzyme activity in the saline-alkaline lands of Yellow River Delta Effects of irrigation with paper mill effluent on growth and nutrient status of Populus tomentosa seedlings Responds of soil enzfyme activities of degraded coastal saline wetlands to irrigation with treated paper mill effluent