Deterioration And Microbial Indication Role Of Soil In Urban Green Space

The characteristics of soil quality deterioration and the distributions of Cu, Zn, Cd and Pb were analyzed for total concentration in urban green space, with sixty-four soil samples from nine functional areas of Tai'an city as research objects. The pollution indices were calculated to assess the pollution extent by adopting the Single Factor Index and Nemerow Multi-Factor Index Methods, and the microbial indexes indicative of heavy metals' was created by means of certain calculation. The results showed that: Compared with the natural vegetation soil and soil in croplands beside suburb, the soil of urban green space was dominated by sandy loam, silt loam and loamy sand. It had compaction widespread phenomenon with high bulk density and low specific gravity, and its porosity declined. The pH values of soil were obviously high as compared with natural soils, and dominated by saline-alkaline trends. The conductance increased. Soil organic matter and total nitrogen were low, but total phosphorus was a little higher than natural soils. Available nitrogen and available kalium was pretty much the same thing, but Available phosphorus was higher than natural soils. The analysis among different vegetation types of green space showed that: the surface of the soil: The soil texture of tree types' green space is better than lawns' and shrubs', and its had the lightest of compaction, but its salinity was the most serious; The soil nitrogen and organic matter of shrubs types' green space was minimum, but its available P and K was the highest; The content of soil organic matter of lawns types' green space was highest, but its compaction was the most serious, and had the lowest content of available K. And the phenomenon of enrichment was the most serious about total phosphorus. The soil texture was a gradual deterioration with using age increasing in urban green space, and the compaction was more severe, and the content of organic matter, nitrogen and available kalium was increasing. And the concentration of phosphorus and saline-alkaline trends were more clearly.The analysis among different function areas of green space showed that: commercial green space, beauty spot and residential green space were polluted serious by Cu, Zn, Cd and Pb. seedling production areas should also pay attention to the phenomenon of heavy metal pollution; The distribution of Pb and Cd in the old industrial areas is relatively high; Heavy metal pollution's value by the Single Factor Index Methods showed that, The four heavy metal pollution levels from heavy to light were that: Cd>Zn>Cu>Pb. The cadmium pollution was particularly serious, and had been a threat to human health, and the remaining heavy metals did not exceed two value standard of "The Technical Specification for soil Environ mental monitoring"; Heavy metal pollution's assessment by the Nemerow Multi-Factor Index Methods showed that, the level of pollution of soil in urban green space were in mildly and moderate pollution levels, which in the "moderately polluted" pollution level were industrial green space, commercial green space, beauty spot and residential green space. Seedling production green space and green space were close to the "moderately pollution" level; The analysis among different vegetation types of green space showed that: The content of Cu in shrubs types green space was the highest, but The content of Zn, Cd and Pb in tree types green space was the highest. The heavy metal pollution of soil was increasing with using age increasing in urban green space.The content the surface soil microbial C, N in industrial green space, the campus green space, roads green space of Tai-an urban were lower than the natural vegetation soil, and industrial green space>Campus green space>roads green space. The total number of bacteria and microorganisms in urban green space of different functional areas was in the same trend with the content of soil microbial C, N. While the highest number of fungi and actinomyces were roads green space and industrial green space respectively. The analysis among different vegetation types of green space showed that: The order of the content of soil microbial C, N was: lawns types' green space>shrubs types' green space>tree types' green space, The order of the content of bacteria and micro-organisms were: shrubs types' green space>lawns types' green space >tree types' green space; The soil microbial C, N content and the number of bacteria in the surface of urban green space were was increasing with using age increasing. The correlation analysis between metals and microbial index showed that: The heavy metals Cu was positively correlated with actinomyces and was a negative correlation with microbial biomass C, N and reached a significant level(p<0.05); The soil microbial biomass C was significantly negatively correlated with heavy metals Zn; And the number of fungi was negatively correlated with the soil heavy metals Cd and Pb, reaching significant levels(p<0.05) and very significant levels(p<0.01).