Distribution of Carbon, Nitrogen and Phosphorus in Soil and Sediments of the Chenqiao Wetland and Pollution Evaluation of Sediments

Purpose To explore the nutrient status of soil and sediments and the pollution level of sediment in Chenqiao wetland.

Methods The non-water soil (mudflat area) and water sediment of Chenqiao wetland were collected respectively, which were analyzed for the content and stoichiometric characteristics of total nitrogen (TN), total phosphorus (TP), organic matter (OM), total inorganic nitrogen (TIN), ammonium nitrogen (NH₄⁺), nitrate nitrogen (NO₃⁻) and nitrite nitrogen (NO₂⁻). The comprehensive pollution index method and organic pollution index method were used to evaluate the pollution level of sediments.

Results 1) The contents of OM, TN, TP and TIN in sediments were much higher than those in soil. 2) The average values of C/N, C/P and N/P in soil were 25.31, 16.39 and 0.66, respectively; the average value of C/N in sediments was 18.08, and there were great differences in C/P and N/P between sample points. 3) The average values of TN, TP, OM of sediment samples were (1723.35±1562.50) mg/kg, (754.28±98.94) mg/kg and (5.00±4.26)%, respectively. Both the comprehensive pollution index and the organic pollution index were slight or severe pollution level.4) There was no correlation between TP and OM and various nitrogen indexes in study area (P>0.05), but there was a significant positive correlation between TN and OM (P<0.05).

Conclusion The contents of OM, nitrogen and phosphorus in the sediments of Chenqiao wetland are higher than those of soil, and the pollution level is higher in water sediment. The ecological environment of water is greatly affected by nitrogen. In the future, it is necessary to strengthen management and control the endogenous load of water.