Taking a certain area in Sichuan Province as the object of this study, this paper adopts fuzzy mathematics method to make an evaluation on ecological risks of heavy metal in soil of this area. On calculation of factor...Taking a certain area in Sichuan Province as the object of this study, this paper adopts fuzzy mathematics method to make an evaluation on ecological risks of heavy metal in soil of this area. On calculation of factors’ weights, the traditional method of giving weight according to pollutants’ concentrations fails to consider the toxicity of heavy metals, and can’t reflect their actual ecological effect. With reference to the toxicity coefficient in potential ecological risk index evaluation, this article revises the traditional fuzzy mathematics evaluation model and puts forward a new method to calculate factors’ weight by incorporating toxicity levels in weight setting. The results of this study indicate: surface soil of this area was good in general, with 91.2% samples belonging to the first level, 7.77% samples belonging to the second level, and only 1.03% belonging to the third level. Compared with the results of the evaluation method of the reality content of soil, soil quality is better than the results of the quantitative evaluation, and is closer to the actual local conditions.展开更多
With the continuous development of society,the problem of the tourism also appears more outstanding.The article analyzed the relationship between ecotourism and recreation ecology on the basis of the understanding and...With the continuous development of society,the problem of the tourism also appears more outstanding.The article analyzed the relationship between ecotourism and recreation ecology on the basis of the understanding and researching,and put recreation ecology forward a deeper level of request.How to develop the tourism,including ecotourism,is the problem to be solved.Five research methods about recreation ecology were introduced,namely the field survey method,the positioning method,the ecological simulation method,the modern information technology method and the tourism evaluation and planning method,from the point of view of research methods to elaborate the present situation of recreation ecology at home and abroad.The relationship of recreation ecology and landscape ecology,landscape architecture,biological statistics and the potential were discussed at the end of the article.展开更多
Plant uptake factor （PUF）, single-variable regression of natural log-transformed concentrations in rice grain/vegetables versus natural log-transformed concentrations in soil and multiple-variable regression with so...Plant uptake factor （PUF）, single-variable regression of natural log-transformed concentrations in rice grain/vegetables versus natural log-transformed concentrations in soil and multiple-variable regression with soil concentrations and pH, was derived, validated and compared based on the paired crop and soil data collected from studies regarding As, Cd and Pb contaminated croplands in China. Results showed that the median value of PUF did not present deterministic prediction. But after natural logarithm transformation, the PUF followed Gaussian distribution which could be useful in risk assessment. The single-variable regression models were significant for As, Cd and Pb uptake both by rice and vegetables; however, the standard errors of all the regressions were comparatively large. Soil pH as a variable was generally significant but it only contributed positively to model fit for Cd uptake. After model comparison and selection, the upper 95% prediction limits of the multiple regression model for Cd uptake by rice was recommended to calculate screening value of Cd for paddy soil based on the limit for Cd concentration in rice grain.展开更多
文摘Taking a certain area in Sichuan Province as the object of this study, this paper adopts fuzzy mathematics method to make an evaluation on ecological risks of heavy metal in soil of this area. On calculation of factors’ weights, the traditional method of giving weight according to pollutants’ concentrations fails to consider the toxicity of heavy metals, and can’t reflect their actual ecological effect. With reference to the toxicity coefficient in potential ecological risk index evaluation, this article revises the traditional fuzzy mathematics evaluation model and puts forward a new method to calculate factors’ weight by incorporating toxicity levels in weight setting. The results of this study indicate: surface soil of this area was good in general, with 91.2% samples belonging to the first level, 7.77% samples belonging to the second level, and only 1.03% belonging to the third level. Compared with the results of the evaluation method of the reality content of soil, soil quality is better than the results of the quantitative evaluation, and is closer to the actual local conditions.
基金Supported by Key Program of National Natural Scientific Fund "Coordination Mechanism and Management of Guangxi Red Soil Fertility and Ecological Function"(U1033004)
文摘With the continuous development of society,the problem of the tourism also appears more outstanding.The article analyzed the relationship between ecotourism and recreation ecology on the basis of the understanding and researching,and put recreation ecology forward a deeper level of request.How to develop the tourism,including ecotourism,is the problem to be solved.Five research methods about recreation ecology were introduced,namely the field survey method,the positioning method,the ecological simulation method,the modern information technology method and the tourism evaluation and planning method,from the point of view of research methods to elaborate the present situation of recreation ecology at home and abroad.The relationship of recreation ecology and landscape ecology,landscape architecture,biological statistics and the potential were discussed at the end of the article.
基金supported by the Key Project of the National Natural Science Foundation of China (No.40432005)the Program of Knowledge Innovative Engineering of the Chinese Academy of Sciences (No.CXTD-Z2005-4)the Chinese Ministry of Science and Technology (No.2006DFA91940)
文摘Plant uptake factor （PUF）, single-variable regression of natural log-transformed concentrations in rice grain/vegetables versus natural log-transformed concentrations in soil and multiple-variable regression with soil concentrations and pH, was derived, validated and compared based on the paired crop and soil data collected from studies regarding As, Cd and Pb contaminated croplands in China. Results showed that the median value of PUF did not present deterministic prediction. But after natural logarithm transformation, the PUF followed Gaussian distribution which could be useful in risk assessment. The single-variable regression models were significant for As, Cd and Pb uptake both by rice and vegetables; however, the standard errors of all the regressions were comparatively large. Soil pH as a variable was generally significant but it only contributed positively to model fit for Cd uptake. After model comparison and selection, the upper 95% prediction limits of the multiple regression model for Cd uptake by rice was recommended to calculate screening value of Cd for paddy soil based on the limit for Cd concentration in rice grain.
