Spatial And Temporal Distribution Of Total Phosphorus In The Sediments Of Wetland Of Reeds In Liao Estuary

Wetlands are unique ecosystems on earth, which are formed by interacting between land and water. As human beings unreasonably utilize the wetland resources and lack of protection methods for wetlands, wetland ecological destruction and pollution is more and more serious. Now, the eutrophication of wetland, which is in the international ecological environment and the frontier areas, is the focus of the concern. Sediments as wetlands pollution sinks, Due to the effect between the sediments and overlying water exchange, the sediment may again become a potential source of pollution water and diffusion pollution through the water to harm the survival environment of human beings. Shuangtai estuary wetland is one of the most typical wetland which is the best preserved of ecological characteristics area, and there are a lot of reeds in the area of reserve. The research of the sediment TP in time and space distribution aims to reveal the TP change of longitudinal distribution rules with the depth change which is in the sediment of the various development time (germination period, development period, reproductive period and maturity period). It also shows the transverse distribution rules and each function difference between TP content. The results are followings:(1) The TP content transfers from the surface to the deep and commonly focuses on the surface in terms of vertical distribution rules because of the impact of human activities. The TP content of Shuangtai estuary wetland sediment is gradually reduced with the increase of depth from surface to the bottom. The TP content in the depth of 0 to 30cm is more than the depth of 30cm to 50cm. All of the highest content of the TP is in the depth of 0 to 10cm. The reason is that it is caused TP enrichment in surface soil by surface runoff input, litter decomposition and wetlands sedimentation. TP content changes a lot and focuses on the surface because of the change of the Liaohe oilfield and human factors. TP content is low and is not affected by the depth in middle and lower sediment(30～50cm). From an overall perspective, the TP content is lowest in depth of 40cm to 50cm, and it shows that the wetland sediment in middle and lower has little influence. Meanwhile, due to the sea water effect, the TP content distribution near the river is more regular than distant the river.(2) In terms of lateral distribution, on the time scale, with the growth of reeds change, the transverse distribution of TP content present regular and seasonal dynamics trend, TP content is high in the sediments during plant dormancy period(December to next year April),Due to the large number of plants absorb phosphorus during reed germination period(April to May)which cause TP content in the sediment decreased. In the development of nutrition reed(May to July), due to upstream farmland fertilization, the nutrient along with runoff flows into the estuary wetlands resulting TP content increased in July. However, the reed grows vigorous in August, the reeds absorptive capacity are strengthening, TP content begins to decline in the sediments. With stopping drainage in September, a significant reduction in surface water, and farmed seafood(such as crabs, etc.)reach maturity, the amount of feed increased, so that TP content increased slightly. Reed reach maturity in October, water dried up, the seafood cultivation is over, and the human factors greatly reduced.TP content reaches the minimum in wetland sediment. Studies have shown that the TP in sediment fluctuated throughout the growing season. The overall trend is the germination period of TP in wetland sediment have shown a downward trend, TP content in wetland sediments period is generally increased first and then declined, the reproductive stages of TP content in wetland sediment is firstly increased and then decreased, the mature stage of TP content in wetland sediment is rendered as a slight upward trend. Among them, the highest content of TP occurs in June, and the lowest is October(3) During the reeds’growing period, TP content in sediment of the core area>TP content in sediment of the buffer area>TP content in sediment of the test area. From the northeast to southwest the TP content in the entire area presented increasing trend. This shows the upstream industry, agriculture, domestic sewage collected in the core area, the core area has been affected by the upstream in Shuangtai estuary wetland. At the same time due to the impact of surface runoff, TP content in sediment of far from the river is slightly higher than the area near the river, And TP content distribution is more regular than that in the area near the river.