The Geochemical And Mineral Research Of Surface Soil Of Coastal Wetland In Yellow River Delta

Yellow River Delta is the most complete, typical and youngest ecosystem ofwetland in the warm temperate zone of world, and it is a transit area that the differentkinds of birds can accomplish the big migrate around the west Pacific Ocean, so manybirds make here as their habitat and breeding place in winter. Yellow River Delta isrich in biological resources and is a international important wetland that need to beprotected. Modern Yellow River Delta is formed from the silting of Yellow River’ssediment more than one hundrand years, the different kinds of vegetations’ growingmakes the slowly evolution of the Yellow River Delta happen at the same time, alsomakes the soil formed gradually and the content of organic matter and nutrientelement increase continuously, and a comfortable habitat adape to the different kindsof creatures appears in the end. Recentaly,the fast development of industry andagriculture in Yellow River area have brought many pollutant in, the serious soilsalinization caused by the irrationally reclaim and till, the abuse of other chemicalfertilizer accelerate the evolution of the surface soil, the heavy evapotranspiration andsea tide effects change the mineral composition of soil to modern coastal wetland’ssurface soil and sediment of Yellow River Delta. Now, many researches concern onformation of soil, but lack of the research aim at the formation and evolution ofsurface soil in coastal wetland’s of Yellow River Delta. The research mainly focus onthe feature of the mineral composition, and the factors control the mineralcomposition. The research can’t only enlarge the recognition of the formation andevolution of soil, but also provide reliable scientific basis to environmental protection,administration and pollution regulation of Yellow River Delta’s coastal wetland.In the research, we have sampled219sample of surface soil and sediment, andutilize moden technic to analyze the mineral and element of samples, after collect and organize the data, compare them to the data of mineral and chemical composition ofYellow River, and link the environmental factors together to find theirinterrelationship, probe the formation and evolution of the coastal wetland’s surfacesoil and sediment after the sediment of Yellow River silt in Yellow River Delta.(1) Themineral composition of surface soil of Yellow River Delta is mainly quartz,feldspar, calcite and illite, the mineral composition of quartz and feldspar is close tothe sediment of Yellow River, which is the consequence inherit from quaternarysediment of Yellow River’s middle reaches area, it is in the situation that the mineralcomposition inherit from the sediment of Yellow River, however, Due to the exsit ofstrong infiltration and circumfluence, the content of calcite become higher, so the traitof carbonate mineral composition is high calcite content and low dolomite. The claymineral composition is mainly illite, chlorite take second place.(2)Most elements’ content of surface soil of Yellow River Delta are close to thesediment of Yellow River, which inherit the trait of element composition from thesediment of Yellow River. Due to the effect of sea water, some elements are broughtin, such as Na, Mg, which cause the surface soil can’t be indicated by the index ofchemical weathering very well. The elements of surface soil in upper delta plain aredivided into4categories, which is Terrigenous origin, biological source origin,marine origin and authigenic origin. The elements of surface sediment in shallow seaare divided into3categories, which is Terrigenous origin, marine origin andauthigenic origin.(3)The C:N of surface soil in Yellow River Delta is close to or even higher than50, suggest the surface soil organic carbon isn’t stable, organic carbon, P and N insurface soil of upper delta plain is higher than that in shallow sea. In the soil ofYellow River Delta, organic carbon have a good relativity with N, but absent the goodrelativity with P. Many nutrient element deposit in estuary zone, which also enhancethe content of Cu, Mn, Zn, N, S, Fe, Mg, Ca, K, Al and TC absorbed by the organiccarbon, which is the reason why organic carbon have a good relativity with these elements.(4) The REE in surface soil of Yellow River Delta is higher than that in thesediment of Yellow River, the different kinds of wetlands that coverd by differentvegetation have some differences in distrbutuin of REE. The wetlands covered bysea-blite is close to mudflats. The wetlands covered by reed is close to the wetlandscovered by Chinese tamarisk. LREE have significant difference, but the discrepancyof HREE is small, so there are more LREE join in eco-geochemical circle, HREE isnot active in ecosystem. Biological action is blossoming in Ecosystem of wetland, sothat the content of organic matter is high, which also make the average of δEu andδCe in surface soil of Yellow River Delta higher than that in sediment of YellowRiver.(5)The Yellow River Delta have a good ecological environment, don’t exist thepollution of heavy metal, surface soil can reach national primary standard of soil. Dueto the heavy metal come from land and sea water can clean it up, so heavy metal inshallow sea have lower content than in upper delta plain. According to the analyse ofheavy metal, it can be divided in three categories in the surface soil of the YellowRiver Delta, they are①Cd,Hg，②Cu,Pb,As，③Cr,Zn，apart from Hg, the other heavymetal have a good relativity with organic carbon.