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Biological disasters in farmland have become a serious threat to global sustainability. Quantitative studies on spatiotemporal change in regional intensity of biological disasters in farmland (RIBDF) are crucial for promoting sustainable intensification of farmland use and global food security. Many studies have revealed the impacts of natural environment on biological disasters in farmland. However, research on the impacts of farmers' activities on biological disasters remains very limited from the perspective of induced substitution in agricultural production. Based on the principle of induced substitution in agricultural production, a theoretical framework for the impacts of farmland use intensity (FUI), the occurrence intensity of biological disasters (OIBD), the natural loss intensity resulting from biological disasters (NLIBD), and the actual loss intensity controlled by human activities (ALIBD) on change in RIBDF was presented, and we therefore established an assessment model integrating these four key indices in this study. Taking Guangdong Province in China as the study area, this study analyzed the spatiotemporal changes in RIBDF from 1996 to 2017 and found that RIBDF increased overall with three change stages of slow growth, rapid growth, and decline at the provincial and regional levels. Moreover, the gravity center of RIBDF appeared to shift towards the coastal region in southwestern Guangdong at a speed of 18.20 km per year. The results reveal that the spatiotemporal change in RIBDF is determined by the key influencing factors including the substitution of chemical fertilizers for farmland and crop substitution. These findings suggest that it is necessary to expand the scale of farmland management and to encourage farmers to implement diversified cropping as well as chemical fertilizers reduction. The foremost contribution of this study is its exploration of an understanding of the linkage between farmland use activities characterized as induced substitution in agricultural production and biological disasters. Moreover, policy implications for sustainable intensification of farmland use were discussed based on these findings. [ABSTRACT FROM AUTHOR]

Cancer is a growing global health threat. Examining the determinants of cancer incidence can benefit for cancer treatment and prevention. Farmland transfer relates to the risk factors of esophageal cancer including environmental pollution, services access, and habits. This study characterizes the associations between farmland transfer and esophageal cancer incidence rate (ECI) that integrate mediated effect of pollution-related agricultural input intensity in Xiaoshan District, China. The state-space model is employed to quantify the relationships among farmland transfer, pollution-related agricultural input intensity, and ECI. The results showed that (1) Total effects of the proportion of transferred farmland (TFA) area cause a reduction in the ECI. Besides, the total positive effects of the proportion of transferred farmland cultivated non-grain crop (NGC) and proportion of farmland transferred to non-farmer users (NFU) show a downward trend. (2) The raise of TFA can result in the reduction of chemical fertilizer use intensity. Meanwhile, the raise of NGC and NFU can result in the growth of pollution-related agricultural input intensity. But these increasing effects generally show a downward trend. (3) Increasing chemical fertilizer use intensity and pesticide use intensity results in the rise of esophageal cancer incidence rate as a whole. (4) In general, farmland transfer has positive direct effects on esophageal cancer incidence rate. (5) The average proportions of mediated effects in all state-space models are larger than 10%. These findings can raise land reform policy designers' awareness of the risk of public health since the land transfer markets are emerging rapidly in land reform in many developing countries to improve agricultural production. [ABSTRACT FROM AUTHOR]

Although numerous studies have explored various impacts of Internet use, few have investigated the linkage between Internet use and chemical fertilizer use in developing economies. This study examines the influences of Internet use and related promotion policy on chemical fertilizer use based on a nationwide dataset including China's 7766 rural households. The baseline regression results show that Internet use reduced chemical fertilizer use significantly. The mechanism analysis unveils the mediation role of human capital; Internet use increased farmers' human capital and then reduced chemical fertilizer use. In addition, the difference-in-difference method is employed to examine the effects of Internet promotion policy and the findings reveal that the promotion policy could help reduce farmers' use of chemical fertilizer. Finally, both propensity score matching-DID model and a two-stage instrumental variable model are used to address potential endogeneity issues associated with Internet use, and results indicate that the empirical results are robust. Our findings suggest that improving the availability of broadband access in a rural area, promoting Internet-related training and education, and more government's investment in rural ICTs infrastructure can contribute to the reduction of chemical fertilizer use. [ABSTRACT FROM AUTHOR]

China promulgated the Air Pollution Prevention and Control Action Plan (the Action Plan) in 2013 and developed stringent control measures to mitigate fine particulate matter (PM2.5) pollution. Here, we investigated the PM2.5 chemical composition changes over eastern China associated with the Action Plan during 2013–2017 using satellite-based PM2.5 chemical composition data derived using CMAQ simulations and satellite inputs. The PM2.5 concentrations decreased considerably during this time as a result of the reductions in all chemical species in PM2.5. The population-weighted mean concentrations over eastern China decreased from 11.1 to 6.7 μg m-3 for S O 4 2 − , 13.8–13.1 μg m-3 for N O 3 − , 7.4–5.8 μg m-3 for N H 4 + , 9.9–8.4 μg m-3 for OM, 4.6–3.8 μg m-3 for BC and 12.9–9.6 μg m-3 for other species in PM2.5. S O 4 2 − had the largest reduction of 40%, while N O 3 − had the lowest reduction of 5%, resulting in a greater fraction of N O 3 − and a smaller fraction of S O 4 2 − in PM2.5. Among the three key regions, Beijing-Tianjin-Hebei had the largest reduction in PM2.5 and its chemical compositions. The decrease in SO4 2 concentrations was in line with the reduction of SO2 emissions, and the major driver of the SO2 emission reductions was the industrial sector. The decrease in N O 3 − concentrations was limited because the decrease in SO2 emissions and the stable NH3 emissions facilitated the formation of N O 3 − from HNO3, which partially offset the reduction in NOx emissions driven by the power sector. To mitigate PM2.5 pollution more effectively, future efforts are needed to reduce NH3 emissions. [ABSTRACT FROM AUTHOR]

Biochar is frequently applied for the reduction of mercury (Hg) migration in soil; however, most of the studies only focused on the adsorption capacity evaluation of fresh biochar. We investigated the Hg adsorption capacities of biochar prepared from wheat straw, corn straw, and sunflower seed shells. Biochar aging was simulated via natural aging, high-temperature aging, and freeze-thaw aging. The adsorption capacities of all the aged biochar were increased, and wheat straw biochar and seed shells biochar treated with high-temperature aging (wBC-Ha500 and sBC-Ha600) and corn straw biochar treated with freeze-thaw aging (cBC-Fta500) showed an observable improvement on the equilibrium adsorption amounts. The kinetics of the fresh biochar samples fitted the pseudo-first-order kinetic model and the pseudo-second-order kinetic model, while the kinetics of the aged biochar samples fitted the pseudo-second-order kinetic model. Biochar adsorption capacity increased with higher initial concentrations and increasing temperatures. Elemental analysis, Fourier-transform infrared spectroscopy (FT-IR) spectra, cation-exchange capacity (CEC), surface area (SA), zeta potential, and X-ray photoelectron spectroscopy (XPS) showed that the aging mechanism consisted of hydroxylation and carboxylation caused by the functional groups on the biochar surface. According to the different climatic zones in China, wheat straw biochar and seed shell biochar are suitable for the tropical zone and the subtropical zone, while corn straw biochar is more suitable for the cold and the mid-temperate zones. [ABSTRACT FROM AUTHOR]

The mechanisms underlying the retention of inorganicNin acidic forest soils in southern China are not well understood. Here, we simultaneously quantified the gross N transformation rates of various subtropical acidic forest soils located in southern China (southern soil) and those of temperate forest soils located in northern China (northern soil). We found that acidic southern soils had significantly higher gross rates ofN mineralization and significantly higher turnover rates but a much greater capacity for retaining inorganicN than northern soils. The rates of autotrophic nitrification and NH3 volatilization in acidic southern soils were significantly lower due to low soil pH. Meanwhile, the relatively higher rates of NO3 - immobilization into organic N in southern soils can counteract the effects of leaching, runoff, and denitrification. Taken together, these processes are responsible for the N enrichment of the humid subtropical forest soils in southern China. [ABSTRACT FROM AUTHOR]

Valency control of neptunium is an important issue in the partitioning of high level liquid waste (HLLW) from power-reactor spent fuel treatment. The redox behavior of neptunium in HLLW is quite different from that in nitric acid because of the effect of the large amount of ions in HLLW. In order to remove neptunium from HLLW, we studied the reduction of neptunium in synthetic HLLW (SHLLW) to maintain its valency at IV so that it can be extracted by TRPO extractant in the well developed Chinese TRPO process. Five different reductants were tested and the reduction behavior was investigated. The influence of some active elements in SHLLW was studied. The mechanism that the reductants react with neptunium through Fe element was supposed and proved by experiments. The reduction rate of Np(V) was highly enhanced by Fe element. Finally, a hybrid reductant was suggested and good reduction efficiency was obtained. [ABSTRACT FROM AUTHOR]

The diazotrophic communities in a rice paddy field were characterized by a molecular polyphasic approach including DNA/RNA-DGGE fingerprinting, real time RT-PCR analysis of nifH gene and the measurement of nitrogen fixation activities. The investigation was performed on a diurnal cycle and comparisons were made between bulk and rhizosphere / root soil as well as between fertilized / unfertilized soils. Real time RT-PCR showed no significant difference in the total quantity of nifH expression under the conditions investigated. The functional diversity and dynamics of the nifH gene expressing diazotroph community investigated using RT-PCR-DGGE revealed high diurnal variations, as well as variation between different soil types. Most of the sequence types recovered from the DGGE gels and clone libraries clustered within nifH Cluster I and III (65 different nifH sequences in total). Sequence types most similar to Azoarcus spp., Metylococcus spp., Rhizobium spp., Methylocystis spp., Desulfovibrio spp. , Geobacter spp. , Chlorobium spp., were abundant and indicate that these species may be responsible for the observed diurnal variation in the diazotrophic community structure in these rice field samples. Previously described diazotrophic cyanobacterial genera in rice fields, such as Nostoc and Cyanothece, were present in the samples but not detectable in RT-PCR assays. [ABSTRACT FROM AUTHOR]

In April and September of 2005, two sediment cores were collected from Lake Aha, which is polluted by the acid mine drainage of the mining industries. Sulfate-reducing bacteria (SRB) groups and their quantity were analyzed by using PCR and FISH (fluorescence in situ hybridization), respectively. The results showed that four SRB groups ( Desulfotomaculum, Desulfobulbus, Desulfococcus–Desulfonema–Desulfosarcina and Desulfovibrio–Desulfomicrobium) were detected in September, while only three SRB groups ( Desulfotomaculum, Desulfobulbus and Desulfococcus–Desulfonema–Desulfosarcina) were detected in April. Desulfovibrio–Desulfomicrobium was not detected and was expected to exist inactively, in April. Meanwhile, the distribution of every SRB group was wider in September than in April. The results indicated that different SRB groups had different vertical and temporal distribution. The vertical and temporal distribution of SRB was mainly in the upper sediments, and the number of SRB groups and quantity were larger in September than in April. It suggested that the environmental conditions of sediments in September were more suitable for SRB. [ABSTRACT FROM AUTHOR]