Spatial distribution of total halogenated organic compounds (TX), adsorbable organic halogens (AOX), and heavy metals in wetland soil irrigated with pulp and paper wastewater

Long-term irrigation using wastewater from paper industry may cause seriously problems to the receiving soil. This work surveyed and monitored the soil quality of a wastewater irrigation wetland system in Yancheng City, Jiangsu Province in China in 2014 and 2015. The wetland soil showed different soil properties and TX, AOX, heavy metal contents after long-term wastewater irrigation. Long-term irrigation also accumulated the heavy metals such as Cu, Cd, Zn, and Pb in the wetland soil. Compared to the control, TX in the irrigated soil increased by 47.7-69.8% (2014) and 61.5-83.1% (2015). AOX varied in concentration from 1.7 to 55.0 mg kg(-1) (2014) and 11.0 to 53.0 mg kg(-1) (2015). The long-term irrigation of wastewater to wetland systems caused the accumulations of heavy metals, TX, and AOX in the soil and the levels of accumulations were related to several factors including soil properties, wastewater quality, and irrigation time.