【Title】Phosphorus Sorption-desorption Characteristics of Ditch Sediments from Different Land Uses in a Small Headwater Catchment in the Central Sichuan Basin of China
【Author】WANG Zhenhua1,2,3, HE Min1,4, WANG Tao1,2, ZHU Bo1,2*
【Addresses】1 Key Laboratory of Mountain Environment Evolvement and Regulation, Chinese Academy of Sciences, Chengdu 610041, China; 2 Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, China; 3 Department of Water Environment Research, Changjiang River Scientific Research Institute, Wuhan 430010, China; 4 Faculty of Forestry, Sichuan Agriculture University, Ya'an 625014, China
【Citation】WANG Zhenhua, HE Min, WANG Tao, ZHU Bo. Phosphorus Sorption-desorption Characteristics of Ditch Sediments from Different Land Uses in a Small Headwater Catchment in the Central Sichuan Basin of China. Journal Of Mountain Science(2012) 9(3): 441–450. DOI: 10.1007/s11629-009-2207-8
【Abstract】Investigation of phosphorus (P) sorption-desorption characteristics of drainage ditch sediments is important for better understanding on sediment P transport behaviors in ditches. Surface ditch sediment samples were collected from headwater sub-catchment of forestland, sloping cropland, paddy field, and residential area in a representative catchment in the central Sichuan Basin. These sediment samples were used for determination of P sorption-desorption characteristics by a batch equilibrium technique. Results showed that the maximum P sorption capacities (Qm) in the sediments ranged from 159.7 to 263.7 mg/kg, while higher Qm were observed in the ditch sediments from the paddy fields. The Qm was significantly and positively correlated with oxalate-extractable Fe and Al oxides (r=0.97 and 0.98, p < 0.01), clay fraction (r = 0.78, p < 0.05) and organic matter (r = 0.95, p < 0.01). Sediment pH, clay and organic matter influenced the P sorption through amorphous Fe and Al oxides. CaCO3 content was negatively correlated with the Qm (r = －0.83, p < 0.05), implying that saturated CaCO3 (> 50 g/kg) would not increase P sorption capacity in the ditch sediments. The ditch sediments featured a linear desorption curve, suggesting that P release risk would be enhanced with the increase of the P adsorption. The P desorption rate was positively correlated with Olsen P (r = 0.94, p < 0.01), but negatively related to the fine particle-size fractions (r = －0.92, p < 0.01), the sum of the amorphous Fe and Al oxides (r = －0.67, p < 0.05) and the P sorption capacity (r = -0.59, p < 0.05). The ditch sediments from residential area had a higher P release risk than that from the other ditches of forestland, sloping cropland and paddy field. The P sorption index (PSI) derived from single-point measurement was significantly correlated with the P sorption capacity (r = 0.99, p < 0.01), and could be used for estimating Qm as 1.64 times PSI plus 24.0 (Qm = 1.64 PSI + 24.0) for similar sediments with highly calcareous soils and sediments. Ditch cleaning and sediment removal for the ditch in residential area were recommended in this area to reduce the P release risk.
【Keywords】Ditch sediment; Phosphorus sorption-desorption; Sediment properties; Land use