Zhejiang North Sea Tu Soil Moisture Characteristics And Solute Transport Simulation Studies

Coastal soils are widely distributed in China and its comprehensive utilization is important for food safety and the growth of agricultural economic benefit. The study on physical property of soil water and solute movement, which are related to soil pollution and use of chemical fertilizer, takes a positive significance on further development of coastal soils. In the present paper, the physical property of soil water and solute movement of coastal soils was studied. Main results were showed as follows. The particle composition of coastal soils was mainly made up of coarse silt fraction which is characterized by relatively weak retention ability of water. The water retention capacity of each layer in soil profile showed that the layers of O~?O, 20?0, 4O梸6O, 60?0 cm had stronger water retention capacity than that of layer of 80條OO cm , while the difference among layers of O?0, 2O~?O, 4O~-~6O, 6O~?O cm was very low. The coastal embankment time also had an effect on the water retention capacity. Under low suction, the longer the embankment time was, the stronger the water retention ability of coastal soils, the higher the available water content. The relationship between water content and suction of coastal soils could be showed by logarithmic function model, power function model, index function model. According to the correlation coefficient, the logarithmic function model was better than another two model. The rate of infiltration of coastal soils decreased gradually with the increasing of infiltration time and finally reached a stable value. Under different water content . the change of water diffuse rate of coastal soils was enormous, 57 the biggest difference could reached over 1000 times. Water diffuse rate was the function of water content and increased with the increase of water content. The difference of bulk density of coastal soils took an effect on infiltration rate and diffuse rate. The infiltration rate and diffuse rate of coastal soils which bulk density was small were big. The water transmitting experiment of coastal soils showed that the saturated conductivity of different layers in soil profile were great, and the saturated conductivity of undisturbed soil was highly higher than that of disturbed soil. The saturated conductivity of coastal soils embanked earlier was lower than that of coastal soils embanked later. Under different water content, the unsaturated conductivity of coastal soils had a great change and the bulk density had an effect on unsaturated conductivity. The soil with a low bulk density had a high unsaturated conductivity. Chlorine ion moved in coastal soil was an inert ion. The distribution of CU in soil was definite and repeated, which is no relation with the time and velocity of infiltration. The concentration of infiltration solution and the texture of coastal soils had no apparent effect on solute movement synthetic dispersion coefficient (Dsh), while bulk density took an apparent effect on solute movement synthetic dispersion coefficient (Dsh). Synthetic dispersion coefficient (Dsh) of coastal soils increased as bulk density decreased.