Investigation and assessment of heavy metal pollution in pond and river sedimentsin of the southern river network

The scaled development of livestock and poultry put substantial increasing wastes which brings serious pollution problems in the surrounding environment. The sediments of fish ponds and rivers were conducted to examine the environmental pollution in the Southern River Network region. This study showed that the concentration of organic matter（ OM），total nitrogen（ TN） and total phosphorus（ TP） in the sediments of rivers were about 2.0-10.0 times that of fish ponds. In addition，the average value of arsenic（ As） in the sediments of fish ponds and rivers were 70.06 mg/kg and 73.21 mg/kg，respectively. Furthermore，the vertical distribution pattern of Cr in the sediments was ranked in the order：0-10 cm ＞ 11-20 cm ＞ 21-30 cm ＞ 31-40 cm. And the average value of Cr in river sediments（ 133.66 mg/kg） was 2.5 times that of fish ponds（ 54.36 mg/kg）. The single pollution index（ Pi） and comprehensive pollution index（ Pm） of heavy metals in river sediments were higher than fishponds. Furthermore，the order of Pi of fishpond and river sediments was As ＞ Cr ＞ Cu ＞ Pb ＞ Zn. Correlation analysis of heavy metal and physical-chemical properties in different layers of sediment indicated that Cu，Pb and Zn-contaminated in sediment is mainly affected by OM，TN，and Total P. Therefore，livestock waste disposal is mainly based on absorption of fish ponds which will cause pollution problems such as nutrient salt and heavy metals in surrounding rivers.