Dajinshan Island Land Survey And Evaluation Of Soil Environment

During August2011to May2012, the research group has embarked onconducting a detailed investigation on the the terrestrial soil environment, naturalgeographical and biological resources for eight times to enter Dajinshan Island. Afterinvestigation and analysis of soil sample, this paper gets a more comprehensive graspof the Dajinshan Island land soil environment and its trends, providing a morescientific basis for the natural ecological protection and appropriate developmentand utilization of the Dajinshan Island.Based of GPS technology, using the grid method and serpentine samplingmethod, the paper acquires the first-hand information of the state of the land soilenvironment in the Dajinshan Island,with detailed distribution of the DajinshanIsland for four quarterly sampling and analysis. Single factor pollution index methodand potential ecological risk index method are used to evaluate the state of heavymetals pollution in soil environment of the Dajinshan Island. Finally, the paperanalyses the influence between the soil environment and vegetation/animal/plantresources and their correlation, combining the findings of the islands animal andplant resources. Then,it can be seen that the soil environment of the Dajinshan Island,on the overall, is more good soil moist, fertile soil, adequate nutrients and organicmatter content. Its alkali and heavy metalsbuffer performance better, but the soilacidic trace intensified. In addition, heavy metal pollution is not very serious, Cdcontent in soil slightly more than a standard (0.2mg/kg) in most of the region andindividual regions Pb content seriously.Specific research results are summarized asfollows:(1)Soil pH and buffering performanceThe mean of the soil pH in the Dajinshan Island is4.52, in a strongly acidic soilsrange (pH <5.0). Its more acidic of soil has deteriorated significantly higher than theJinshan District which mean soil pH is6.5±0.52. Huge loss of calcium, magnesium,potassium and other bases courses its soil base leaching strong and low acidbuffering capacity. On the same time, Soil organic matter of the Dajinshan Island cushions properties of alkali and heavy metals.(2)Soil bulk density and organic matterThe mean of soil bulk density is1.27, at the intersection of the secondclassification level(1.00-1.25) and the third level (1.25-1.35)in suitability soil bulkdensity. Soil organic matter content is area volatile for the range of2.02%-22.63%,mean8.96%, up to the first standard(>4%) of soil nutrients contents whichdeveloped in Chinas second national soil survey, and the change is not great,compared by the measured data of9.01%on2002. But its mean of soil organicmatter is significantly higher than the Chongming soil of (1.90±0.93)%and JinshanDistrict of (3.31±0.90)%.(3) Soil nutrientsThe total nitrogen content?of?the Dajinshan Island soil is in the range of1.06g/kg and11.67g/kg, mean4.52g/kg, with lower slightly than the measured data6.89g/kg in2002, but higher slightly than the Chongming soil total nitrogen (0.93±0.47g/kg) and Jinshan District of total soil nitrogen content (2.10±0.51g/kg). Soiltotal phosphorus and total potassium potassium content is relatively low. The annualmean is0.65g/kg and8.28g/kg respectively. According to Chinas soil nutrient gradingstandards (6class in all), the soil total phosphorus content of the Dajinshan Islandis distributed in class3(0.6-0.8g/kg), above the average level in our soil totalphosphorus content (0.44to0.85g/kg). Its total potassium distributed in class5(5-10g/kg), on the lower of national soil potassium content with mean (16.1g/kg) andon a lower level in the national soil content range (0.83to33.2g/kg).(4) Heavy metals in soilThe heavy metals in soil is elementary up to the first class soil standard. Amongthat, Cd is slightly contaminated and its samples exceeded the rate of85.4%;followed by Pb, exceeding the rate of26.8%; Zn and Cu is not exceeded. Thedistribution of heavy metals type in soil is a gaussian distribution, suggesting thatelements in the soil media are more evenly distributed. Judging from the variationcoefficient of the soil elements content, the size of the order is that Cd (0.346)<Zn(0.393)<Cu (0.423)<Pb (0.511). Addition to Pb, the other elements of the variation coefficient is <0.4.The area luffing smaller and distribution closer reflect thecharacteristics of the soil homogenization process in the formation of long-term role.Based on the first class of soil background values(Cd,0.2mg/kg), the four heavymetals potential ecological risk in this order: Cd (40.43)> Pb (4.65)> Cu (2.64)> Zn(0.79). Excepting to Cd, the potential ecological risk factor of the other heavy metalsis very small (<40),and can be classified as minor ecological harm. The potentialecological factor RI of the four heavy metals is36.85, less than minor ecological riskthresholds (50), classified as minor ecological harm.(5) soil correlation between soil environment and its vegetationThe paper collects soil sampling near landmark trees in the spring, analyses andcompares the similarities and differences between the soil environment nearby treesarea and other regional soil environment of the island. Find that the soil moisturecontent,organic matter and total potassium content near big tree are slightly higherthan the whole island area; pH, calcium and magnesium content is slightly lower; soilheavy metals content is more obvious differences and heavy metals copper (11.6mg/kg) and zinc (72.7mg/kg) of soil area near big trees was significantly lower than soilcopper (18.5mg/kg) and zinc content (78.1mg/kg) in the whole area of theDajinshan Island.