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The agricultural land use transition (ALUT) assessment can be a prominent tool for comprehensively implementing suitable agricultural land use and agricultural development in Senegal. Based on remote sensing and survey data, this investigation aimed to simultaneously assess the geographical dispersion of ALUT and its probable mechanisms and determine the agricultural land functions in the Thiès region. Through ArcGIS and ENVI software, the remote sensing data of 2000, 2010, and 2020, the transfer matrix method and a spatial index calculation were used to characterize the ALUT. Then, the mixed linear regression model was constructed to determine the relationship between ALUT and its potential driving factors. The main results show that ALUT was about −588.66 km2. Regarding spatial distribution, a positive net ALUT was experienced in the north-west department of Tivaouane; conversely, a negative transition was noted in the southern Mbour department. The agricultural land per capita (0.37 ha/per) and the per capita agricultural income (USD $167.18) were unsatisfactory, and only 59.49% of the respondents frequently used fertilizers for production. The linear regression model showed that rainfall variability, research and development, soil salinization, and land tenure were significant at 1% (p < 0.01) with agricultural land change, living security, and ecological functions. Parallelly, transportation facilities (p < 0.01) and agricultural investment (p < 0.01) were also significant with agricultural land morphology change, while population growth (p < 0.1) was only correlated with agricultural land morphology change. These factors reflect the farmer's income and often induce land abandonment and degradation of agricultural land. Consequentially, the ALUT in the Thiès region revealed several insights, such as the need to strengthen land use reforms and research and development. Therefore, agricultural land use is impacted by many fields that require an inter-discipline research method for practical and balanced use. Such endeavors could start with reconciling agricultural development and land conservation. [ABSTRACT FROM AUTHOR]

The agricultural land use transition (ALUT) assessment can be a prominent tool for comprehensively implementing suitable agricultural land use and agricultural development in Senegal. Based on remote sensing and survey data, this investigation aimed to simultaneously assess the geographical dispersion of ALUT and its probable mechanisms and determine the agricultural land functions in the Thiès region. Through ArcGIS and ENVI software, the remote sensing data of 2000, 2010, and 2020, the transfer matrix method and a spatial index calculation were used to characterize the ALUT. Then, the mixed linear regression model was constructed to determine the relationship between ALUT and its potential driving factors. The main results show that ALUT was about −588.66 km2. Regarding spatial distribution, a positive net ALUT was experienced in the north-west department of Tivaouane; conversely, a negative transition was noted in the southern Mbour department. The agricultural land per capita (0.37 ha/per) and the per capita agricultural income (USD $167.18) were unsatisfactory, and only 59.49% of the respondents frequently used fertilizers for production. The linear regression model showed that rainfall variability, research and development, soil salinization, and land tenure were significant at 1% (p < 0.01) with agricultural land change, living security, and ecological functions. Parallelly, transportation facilities (p < 0.01) and agricultural investment (p < 0.01) were also significant with agricultural land morphology change, while population growth (p < 0.1) was only correlated with agricultural land morphology change. These factors reflect the farmer’s income and often induce land abandonment and degradation of agricultural land. Consequentially, the ALUT in the Thiès region revealed several insights, such as the need to strengthen land use reforms and research and development. Therefore, agricultural land use is impacted by many fields that require an inter-discipline research method for practical and balanced use. Such endeavors could start with reconciling agricultural development and land conservation.

In this study we systematically reviewed 1203 research papers published between 2008 and 2018 in China and recorded related data on eight kinds of soil heavy metals (Cr, Pb, Cd, Hg, As, Cu, Zn, and Ni). Based on that, the pollution levels, ecological risk and health risk caused by soil heavy metals were evaluated and the pollution hot spots and potential driving factors of different heavy metals in different provinces were also identified. Results indicated accumulation of heavy metals in soils of most provinces in China compared with background values. Consistent with previous findings, the most prevalent polluted heavy metals were Cd and Hg. Polluted regions are mainly located in central, southern and southwestern China. Hunan, Guangxi, Yunnan, and Guangdong provinces were the most polluted provinces. For the potential health risk caused by heavy metals pollution, children are more likely confront with non-carcinogenic risk than adults and seniors. And children in Hunan and Guangxi province were experiencing relatively larger non-carcinogenic risk. In addition, children in part of provinces were undergoing potentially carcinogenic risks due to soil heavy metals exposure. Furthermore, in our study the 31 provinces in mainland China were divided into six subsets according to corresponding potential driving factors for heavy metal accumulation. Our study provide more comprehensive and updated information for contributing to better soil management, soil remediation, and soil contamination control in China. Image 1 • Cd and Hg were the most polluted heavy metals in soil across China. • The ER values for Cd in 30 provinces varied from moderate to very high risk. • Hunan, Guangxi, Yunnan and Guangdong were confirmed as priority control provinces. • Children are undergo larger health risk than adults and seniors in China. • Controlling factors of heavy metals accumulation in different provinces were mapped. [ABSTRACT FROM AUTHOR]