[Objectives] The research was conducted to study characteristics of bioavailable levels pollution of heavy metals in the surface soil of the lead-zinc mine in Changhua.[Methods] A total of 56 surface samples were coll...[Objectives] The research was conducted to study characteristics of bioavailable levels pollution of heavy metals in the surface soil of the lead-zinc mine in Changhua.[Methods] A total of 56 surface samples were collected from the 3 study zones （peripheral zone, reclamation zone and tailing zone） located at the lead-zine mine in Changhua. Based on total and bioavailable heavy metals （Pb, Zn, Cu and Cd） in soils, the correlation of total content with bioavailable content was analyzed, and their pollution characteristics were assessed by methods of single factor pollution index, Nemerow pollution index, geological accumulation index and potential ecological risk index.[Results] （i） The surface soils were polluted by Pb, Zn, Cu, Cd in different degrees, and the overall trend of the contents of the 4 heavy metals was in order of Cd 〉 Pb 〉 Zn 〉 Cu. The average excess multiple of heavy metals of total and bioavailable content in soils were in the order of peripheral zone 〉 tailing zone 〉 reclaimed zone, and their pollution degrees were tailing zone 〉 peripheral zone 〉 reclaimed zone. （ii） In general, the total and bioavailable contents of Pb, Zn, Cu, Cd showed a significant correlation, but were not correlated in each study zone. （iii） Pollution degrees of the study zones were in the order of tailing zone 〉 peripheral zone 〉 reclamation zone. The pollutions of heavy metals Pb and Cd were more serious, especially Cd reached high levels of pollution degree, and the pollution degrees of Zn, Cu were lighter. Contributors of ecological risk were mainly Cd, Pb and Cu, and the contribution of Cd achieved more than 90 %, making it the main source of pollution.[Conclusions] The results not only revealed the pollution status of heavy metals in the surface soil of the abandoned coal mine, but also could provide scientific guidance for reasonable utilization and ecological recovery of the land.展开更多
The dependability of world major soybean exporters was measured and its influencing factors were analyzed through constructing the export output elasticity indicator.It was found that since 2010,among the world major ...The dependability of world major soybean exporters was measured and its influencing factors were analyzed through constructing the export output elasticity indicator.It was found that since 2010,among the world major soybean exporters,the dependability of Brazil,India,Russia and Ukraine increased,the dependability of Argentina and Paraguay dropped,while that of Canada,the USA and Uruguay was basically stable.Among the influencing factors of the dependability,the increase in international soybean prices and abundance of cultivated land resources are helpful for increasing the dependability,while the increase of population and improvement of economic development will reduce the dependability.China should reduce its dependence on countries with low export dependability,and actively develop production cooperation with import source countries to promote their dependability.展开更多
基金Supported by the Natural Science Foundation of Hainan Province(411102)the Scientific Research Innovation Project for College Graduates of Hainan Normal University(Hsyx2015-33)the College Students Science and Technology Innovation Project in Hainan Province(cxcyxj2017016)
文摘[Objectives] The research was conducted to study characteristics of bioavailable levels pollution of heavy metals in the surface soil of the lead-zinc mine in Changhua.[Methods] A total of 56 surface samples were collected from the 3 study zones （peripheral zone, reclamation zone and tailing zone） located at the lead-zine mine in Changhua. Based on total and bioavailable heavy metals （Pb, Zn, Cu and Cd） in soils, the correlation of total content with bioavailable content was analyzed, and their pollution characteristics were assessed by methods of single factor pollution index, Nemerow pollution index, geological accumulation index and potential ecological risk index.[Results] （i） The surface soils were polluted by Pb, Zn, Cu, Cd in different degrees, and the overall trend of the contents of the 4 heavy metals was in order of Cd 〉 Pb 〉 Zn 〉 Cu. The average excess multiple of heavy metals of total and bioavailable content in soils were in the order of peripheral zone 〉 tailing zone 〉 reclaimed zone, and their pollution degrees were tailing zone 〉 peripheral zone 〉 reclaimed zone. （ii） In general, the total and bioavailable contents of Pb, Zn, Cu, Cd showed a significant correlation, but were not correlated in each study zone. （iii） Pollution degrees of the study zones were in the order of tailing zone 〉 peripheral zone 〉 reclamation zone. The pollutions of heavy metals Pb and Cd were more serious, especially Cd reached high levels of pollution degree, and the pollution degrees of Zn, Cu were lighter. Contributors of ecological risk were mainly Cd, Pb and Cu, and the contribution of Cd achieved more than 90 %, making it the main source of pollution.[Conclusions] The results not only revealed the pollution status of heavy metals in the surface soil of the abandoned coal mine, but also could provide scientific guidance for reasonable utilization and ecological recovery of the land.
基金2019 Youth Project for Humanities and Social Science Research of the Ministry of Education of China(19YJC790194)2019 General Project for Humanities and Social Science Research of Henan Provincial Department of Education(2019-ZZJH-328)+3 种基金2018 Science and Technology Innovation Fund Project of Henan Agricultural University(KJCX2018B02)2021 General Project for Humanities and Social Science Research of Henan Provincial Department of Education(2021-ZZJH-156)2019 General Project for the 13 th Five-Year Plan for Education Science of Henan Province(2019-JKGHYB-0032)Soft Science Research Project of Henan Province in 2021(212400410530).
文摘The dependability of world major soybean exporters was measured and its influencing factors were analyzed through constructing the export output elasticity indicator.It was found that since 2010,among the world major soybean exporters,the dependability of Brazil,India,Russia and Ukraine increased,the dependability of Argentina and Paraguay dropped,while that of Canada,the USA and Uruguay was basically stable.Among the influencing factors of the dependability,the increase in international soybean prices and abundance of cultivated land resources are helpful for increasing the dependability,while the increase of population and improvement of economic development will reduce the dependability.China should reduce its dependence on countries with low export dependability,and actively develop production cooperation with import source countries to promote their dependability.
