Bibliometrics of the nexus between food security and carbon emissions: hotspots and trends.

With the growth of global food demand, agricultural carbon emissions caused by agricultural production have become a major challenge in controlling global warming. However, a systematic and visual literature review of food security and carbon emissions (FSCE) is still lacking, and there is a lack of exploration on the balanced path between ensuring food security and realizing carbon emission reduction. Based on 872 articles related to FSCE in the Web of Science (WOS) core database, this paper used CiteSpace and VOSviewer bibliometric software to analyze the relevant research focus and trends. This study found that developed countries dominated the research in this field, and the quantity, quality, and intensity of their authors, institutions, and cooperation among countries are higher than those of developing countries. Although the intensity of interdisciplinary cooperation has increased, it remains at a low level. Since 2007, the number of papers published in this field has increased significantly, and the research perspectives have diversified. Moreover, the research theme continues to expand with the core of "food security," involving the impact of climate change, crop production and food security, soil carbon sequestration, and farmers' livelihood sustainability. In addition, food production, food transportation, and food loss reduction are key paths that need to be balanced to ensure global food security and realize carbon emission reduction, and how to promote "economic growth" under the constraints of FSCE will be a future research hotspot.

Combining habitat area and fragmentation change for ecological disturbance assessment in Jiangsu Province, China.

Understanding where and how human land use causes ecological consequences is essential for habitat conservation. However, the assessment of the ecological disturbance caused by human land use is usually shaped by the area change in ecological land. The comprehensive evaluation of ecological disturbance based on the losses and gains of ecological patches is neglected. This paper analyzed the land use change between agricultural land, construction land, and ecological land from 1995 to 2015 in Jiangsu Province of eastern China. The ecological disturbance was quantificationally evaluated by a proposed index that considered both the changes of habitat area and fragmentation caused by the losses and gains of ecological landscape patches. The findings showed that there was a slight increase in area of ecological land in Jiangsu Province; however, ecological fragmentation was becoming severe with the growth of human land use, which, in turn, resulted in increased ecological disturbance. The losses and gains in the area and fragmentation of ecological land were comprehensively reflected using the proposed ecological disturbance index. Negative ecological disturbance was more likely to be observed at the edge of the city centers, ecologically sensitive areas, and counties with low area ratios of ecological land. Ecological governance policies should be formulated and implemented based on quantity, quality, and spatial relationships between human land use and ecological disturbance.

Spatial imbalance and changes in supply and demand of ecosystem services in China.

Human activities and regional land development have caused intense interference to ecosystems. With rapid development of economy and urgent needs of life quality improvements in China, sustainable ecosystem management is crucial for national ecological civilization construction. However, few studies have focused on supply-demand patterns of ecosystem services on a national scale in China. The aim of this study was to analyze the spatial-temporal patterns and changes in the supply-demand of ecosystem services and to explore their interactive relationship in the context of economic development and urbanization drivers. The ecosystem services provision index (ESPI) and land development index (LDI) were proposed to indicate the supply and demand for ecosystem services. The results indicated that the Low supply-High demand (L-H) pattern accounted for 3.27% of the total land area in China and was mainly concentrated in developed regions and some capital cities, where 28.95% of the total population and 51.93% of the country's GDP was generated in 2015. The spatial imbalance in the supply-demand of ecosystem services was obvious. From 2000 to 2015, the imbalance was shrinking, and regions with negative changes in supply-demand patterns were declining. During 2000-2008, there was an obvious transformation from Low supply-Low demand (L-L) to High supply-Low demand (H-L), which accounted for 12.44% of the total land area due to Grain for Green and other ecological protection policies. The proportion of ecological land to total land area, vegetation cover and elevation were significantly correlated with the supply of ecosystem services. In the meantime, ESPI was negatively correlated with LDI in most regions in China. There were also regional differences in their relationships. The rapid economic growth and the intensive land development resulted in a more significant decrease in ESPI in the developed regions than that in the undeveloped North and Northeast China. The results of this study could contribute to sustainable ecosystem management and decision-making for Chinese ecological civilization construction.

Effects of bile salts and divalent cations on the adsorption of norfloxacin by agricultural soils.

The effects of bile salts (sodium cholate and sodium deoxycholate, 0-20 mmol/L), divalent cations (Ca(2+), Mg(2+), Cu(2+) and Zn(2+), 0-20 mmol/L) or pH (3.0-10.0) on the adsorption of norfloxacin by three selected soils (Paddy_H, Paddy_G and Red_J) were systematically studied. Soil adsorption of norfloxacin follows a pseudo second-order kinetics model, and the maximum adsorption capacity has been determined from the nonlinear fit of the Langmuir isotherm model to be 88.8, 88.1 and 63.0 µmol/g for the adsorption onto Paddy_H, Paddy_G and Red_J, respectively. The results indicate that norfloxacin has a high adsorption affinity for the agricultural soils tested and that the organic content of these soils have at least a slight influence on this adsorption. The adsorption of norfloxacin to soils was strongly dependent on pH and exhibited a maximum at approximately pH 6. The presence of divalent cations prominently suppressed the adsorption of norfloxacin by paddy soils, which followed an order of Cu(2+) > Mg(2+) > Ca(2+) > Zn(2+), and by red soil, which followed an order of Cu(2+) > Zn(2+) > Ca(2+) > Mg(2+). The adsorption of norfloxacin (by the soils studied) sharply decreased as the amount of bile salts was increased. For uncharged norfloxacin at environmentally relevant pH values, such factors as soil type, exogenous divalent cations and macromolecules significantly altered the environmental fate and transport of norfloxacin between aquatic and soil interfaces.

Simulating the conversion of rural settlements to town land based on multi-agent systems and cellular automata.

Rapid urbanization in China has triggered the conversion of land from rural to urban use, particularly the conversion of rural settlements to town land. This conversion is the result of the joint effects of the geographic environment and agents involving the government, investors, and farmers. To understand the dynamic interaction dominated by agents and to predict the future landscape of town expansion, a small town land-planning model is proposed based on the integration of multi-agent systems (MAS) and cellular automata (CA). The MAS-CA model links the decision-making behaviors of agents with the neighbor effect of CA. The interaction rules are projected by analyzing the preference conflicts among agents. To better illustrate the effects of the geographic environment, neighborhood, and agent behavior, a comparative analysis between the CA and MAS-CA models in three different towns is presented, revealing interesting patterns in terms of quantity, spatial characteristics, and the coordinating process. The simulation of rural settlements conversion to town land through modeling agent decision and human-environment interaction is very useful for understanding the mechanisms of rural-urban land-use change in developing countries. This process can assist town planners in formulating appropriate development plans.

Mapping of Cu and Pb contaminations in soil using combined geochemistry, topography, and remote sensing: a case study in the Le'an River floodplain, China.

Heavy metal pollution in soil is becoming a widely concerning environmental problem in China. The aim of this study is to integrate multiple sources of data, namely total Cu and Pb contents, digital elevation model (DEM) data, remote sensing image and interpreted land-use data, for mapping the spatial distribution of total Cu and Pb contamination in top soil along the Le'an River and its branches. Combined with geographical analyses and watershed delineation, the source and transportation route of pollutants are identified. Regions at high risk of Cu or Pb pollution are suggested. Results reveal that topography is the major factor that controls the spatial distribution of Cu and Pb. Watershed delineation shows evidence that the streamflow resulting from rainfall is the major carrier of metal pollutants.