To illuminate the spatio-temporal variation characteristics and geochemical driving mechanism of soil pH in the Nenjiang River Basin,the National Multi-objective Regional Geochemical Survey data of topsoil,the Second ...To illuminate the spatio-temporal variation characteristics and geochemical driving mechanism of soil pH in the Nenjiang River Basin,the National Multi-objective Regional Geochemical Survey data of topsoil,the Second National Soil Survey data and Normalized Difference Vegetation Index(NDVI)were analyzed.The areas of neutral and alkaline soil decreased by 21100 km^(2)and 30500 km^(2),respectively,while that of strongly alkaline,extremely alkaline,and strongly acidic soil increased by 19600 km^(2),18200 km^(2),and 15500 km^(2),respectively,during the past 30 years.NDVI decreased with the increase of soil pH when soil pH>8.0,and it was reversed when soil pH<5.0.There were significant differences in soil pH with various surface cover types,which showed an ascending order:Arbor<reed<maize<rice<high and medium-covered meadow<low-covered meadow<Puccinellia.The weathering products of minerals rich in K_(2)O,Na_(2)O,CaO,and MgO entered into the low plain and were enriched in different parts by water transportation and lake deposition,while Fe and Al remained in the low hilly areas,which was the geochemical driving mechanism.The results of this study will provide scientific basis for making scientific and rational decisions on soil acidification and salinization.展开更多
This study uses paradata and survey data from the China Family Dynamic Survey to analyze the issue of response time in a questionnaire survey.The survey questions were classified into three levels and we compared the ...This study uses paradata and survey data from the China Family Dynamic Survey to analyze the issue of response time in a questionnaire survey.The survey questions were classified into three levels and we compared the inter-group differences of response time between four kinds of questions which included information inquiries,logical calculations,intimate information and logical judgments.We used OLS method to perform a regression analysis to identify the impediments to response time and discussed the roles played by the survey locale,and the characteristics of interviewees and those of interviewers.The major impediments that prolonged response time were factors that impeded comprehension of the survey.The impediments included the difficulties interviewees had understanding questions,questions that did not take into account the different cultural backgrounds of interviewees,the complexity of questionnaires,and the performance of interviewers.Finally,this paper puts forward some suggestions for questionnaire design and investigation processes to reduce impediments to comprehension and improve the ability of interviewers.展开更多
基金supported by China Geological Survey(DD20230554,DD20230089)the Strategic Priority Research Program of the Chinese Academy of Science(XDA28020302)the funding project of Northeast Geological S&T Innovation Center of China Geological Survey(QCJJ2022-40).
文摘To illuminate the spatio-temporal variation characteristics and geochemical driving mechanism of soil pH in the Nenjiang River Basin,the National Multi-objective Regional Geochemical Survey data of topsoil,the Second National Soil Survey data and Normalized Difference Vegetation Index(NDVI)were analyzed.The areas of neutral and alkaline soil decreased by 21100 km^(2)and 30500 km^(2),respectively,while that of strongly alkaline,extremely alkaline,and strongly acidic soil increased by 19600 km^(2),18200 km^(2),and 15500 km^(2),respectively,during the past 30 years.NDVI decreased with the increase of soil pH when soil pH>8.0,and it was reversed when soil pH<5.0.There were significant differences in soil pH with various surface cover types,which showed an ascending order:Arbor<reed<maize<rice<high and medium-covered meadow<low-covered meadow<Puccinellia.The weathering products of minerals rich in K_(2)O,Na_(2)O,CaO,and MgO entered into the low plain and were enriched in different parts by water transportation and lake deposition,while Fe and Al remained in the low hilly areas,which was the geochemical driving mechanism.The results of this study will provide scientific basis for making scientific and rational decisions on soil acidification and salinization.
基金funded by the China Social Science Foundation(Grant 16ZDA089)-Construction of China’s population data platform(1949-2015).
文摘This study uses paradata and survey data from the China Family Dynamic Survey to analyze the issue of response time in a questionnaire survey.The survey questions were classified into three levels and we compared the inter-group differences of response time between four kinds of questions which included information inquiries,logical calculations,intimate information and logical judgments.We used OLS method to perform a regression analysis to identify the impediments to response time and discussed the roles played by the survey locale,and the characteristics of interviewees and those of interviewers.The major impediments that prolonged response time were factors that impeded comprehension of the survey.The impediments included the difficulties interviewees had understanding questions,questions that did not take into account the different cultural backgrounds of interviewees,the complexity of questionnaires,and the performance of interviewers.Finally,this paper puts forward some suggestions for questionnaire design and investigation processes to reduce impediments to comprehension and improve the ability of interviewers.
