Effects of paper mill effluent, sludge and wheat straw residue on remediation of heavily degraded coastal saline wetlands in Yellow River Delta, China

This study investigated the effects of paper mill effluent, waste sludge, and wheat straw residue on remediation of heavily degraded coastal saline wetlands in the Yellow River Delta, China. Five treatments were employed, i.e., plowing (P); plowing plus paper mill effluent (PE); plowing plus paper mill effluent and sludge (PES); plowing plus paper mill effluent and wheat straw residue (PER); and plowing plus paper mill effluent, sludge and wheat straw residue (PESR). Effects of the five treatments on wetland remediation were evaluated in soil properties, including bulk density, total soluble salt, organic matter, alkali-hydrolyzable N, available P and available K, microbial biomass carbon, soil respiration, and enzyme activity. All the treatments improved soil properties. The most effective treatment was PERS which significantly improved all of the soil properties, compared to the controls. In general, the effects of different treatments were in the following order: PERS>;PER>;PES>;PE>;P. Besides soil nutrients, total soluble salt was another main factor that influenced soil microbial activities.