China’s rapid road infrastructure construction (RIC) occupies farmland and promotes the flow of rural development factors, which causes farmland use transition (FUT). Although prior research on RIC and their impact on FUT has attracted considerable attention, few studies have investigated the threshold effect of RIC on FUT. Threshold effect is the phenomenon that when the level of RIC reaches a certain critical value, the level of FUT changes abruptly. This paper uses China’s provincial panel data from 2004 to 2018 to evaluate FUT. We also consider the spatial spillover effect of RIC and construct a panel threshold regression model to assess the impact of RIC on FUT. The results demonstrate that, considering the spatial spillover effect, RIC significantly promotes FUT, and the threshold effect first rises and then falls. Also, the threshold effect of RIC on FUT also has significant regional heterogeneity. There is a significant single threshold effect for RIC in central and western China, with threshold values of 0.90 and 0.84, respectively, while the spatial lag of RIC in eastern China has a single threshold with a value of 1.10. Our research indicates that the Chinese central government should promote the synergistic increase in RIC and sustainable farmland use by improving the accessibility of road infrastructure and basing RIC planning on the actual development needs of the region.

A coupled methodology of nitrogen isotopes, hydrogeochemical characterization, multivariate statistical analysis, and SIAR Bayesian modeling has been employed to identify the sources of NO₃⁻ and N transformation processes in three alluvial aquifers (Schinos, Thiva, and Central Evia) located in central Greece where geogenic Cr(VI) co-occurs with agricultural activity and rural development. Hexavalent chromium concentrations exceed 50 μg/L in many sampling stations of the studied groundwater bodies, while nitrate contamination is evident in all three study areas with concentrations well over 50 mg/L. The mean δ¹⁵N-NO₃– and δ¹⁸Ο-NO₃⁻ values are 6.67 ± 1.77‰ and 2.68 ± 1.77‰ in C. Evia, 8.72 ± 4.74‰ and 3.96 ± 4.57‰ in Schinos and 4.44 ± 1.71‰ and 2.91 ± 1.02‰ in Thiva, respectively. Domestic sewage and N-bearing fertilizers are contributing in various degrees to the observed nitrification which is the dominant transformation process of N in the studied aquifers. Multivariate statistics indicated that the main processes identified in the study areas are salinization, silicate dissolution, and groundwater contamination due to fertilizer use. It is suggested that ultramafic rock–related alluvial aquifers must be closely monitored in terms of nutrient inputs as an effective measure for controlling Cr(VI) release in groundwater.

This study analyzes whether an optimal level of urbanization (UB) exists at which the newly industrialized countries (NIC) can reduce carbon dioxide emissions (CE). The results suggest that UB has a positive effect when it is lower than the threshold value. Whereas UB has a negative effect on CE when it is above the threshold value, identify an optimal level in the NIC countries for CE. Moreover, industrialization, economic growth, and energy consumption have a positive significant impact on CE while renewable energy has a negative effect. The study is useful for policymakers to realize optimal UB level to reduce CE. Moreover, the balanced developmental approach for the rural-urban areas and encouragement of internal migration to small cities will minimize the flow of migration to metropolitan cities. Sustainable economic development required continuous energy supply; thus, the event of low carbon energy is extremely vital. The development of low carbon energy is very important and policymakers should improve the structure of energy consumption.

Several studies were carried out and drought coexistence technologies were developed to deal with the problem of drought in semiarid regions, such as the construction of underground dams, which became a tool for rural development, mainly for family agriculture. However, there are still scarce informations regarding technical studies on the water security level of underground dams, especially about trace metal contamination due to the use and agricultural occupation of the soils downstream of the dams. In this work, the level of contamination of trace metals in waters of underground dams, during two hydrological years, was evaluated around of the sub-basin of the Cobras river, in the Rio Grande do Norte state, Brazil. The analysis of the results indicated that the water samples stored in the Alexandre and Ginaldo underground dams are within the permitted drinking patterns and did not suffer, on the other hand, any alteration in their quality that requires treatment for human consumption, fitting into Class 1. Most of the samples from the waters of the Boa Vista and Ademar dams are above the maximum allowable value for iron (Fe), lead (Pb), chromium (Cr), and nickel (Ni), requiring a differentiated treatment for human consumption, and can be classified as Class 2. The probable contamination of the waters stored in the underground dams may be of geological origin, since the largest accumulation of trace metals occurred in the lower area of the river course greater drained area, leading to believe that the metals come from the rock weathering that make up the geological framework of the region.

This paper reviews the ecological environment protection measures of Chinese rural hydropower development schemes. China’s rapid economic growth is making great energy demands and developing rural hydropower currently provides 30.4 GW annually. There is a conflict of interest between hydropower development and ecological and environmental protection. Potential problems include changes in hydrological condition, eutrophication, downstream nutrient reduction, sediment deposition, aquatic ecosystem alteration, and ecological water demand variation. Since most of the rural hydropower resources are located in ecologically fragile regions, it is significantly more important that ecological environment protection is being considered. As exploitation of rural hydropower has developed in China, ecological environment protection schemes had to adapt to changing boundary conditions. Due to improvements in environmental protection management, various environmental impact assessment methods have been applied including fuzzy analysis hierarchy process, ecological scheduling, pressure-state-response, and ecological environment evaluation index. The latter index can both qualitatively and quantitatively analyze ecological environment impacts and has become the most frequently used tool in the evaluation of rural hydropower exploitation. To rebalance the interests regarding energy generation and environmental protection, countermeasures originating from different aspects such as engineering design optimization, management improvement, and ecological restoration were recommended to promote ecological environment protection. The review concludes that by taking ecological environment protection into consideration in the whole rural hydropower plan, adopting ecological scheduling to guarantee river ecological water demand and implementing ecological restoration in watershed management are the most effective approaches in furthering sustainable development of rural hydropower.

The country’s advancement is fueled by regional growth. It frequently has many detrimental effects in its application, including contamination. Climate, notably temperature, is negatively impacted by the ensuing pollution. This study uses the Multiple Correspondence Analysis (MCA) method to measure the pollution index, followed by the instrumental variable (IV) method to calculate the effect of development on pollution and temperature. Rural data from Podes 2018 is among the data used in this investigation. The findings of this study show that developed and developing areas are where the negative pollution index forms the most frequently. The construction and the resulting pollution index have a negative impact on temperature. The development process should pay attention to environmental aspects to anticipate worse temperature changes in the coming period.

Many areas in the Southern African Development Community are data-poor and poorly accessible. Water quality assessment in these areas therefore has to rely on the limited available data, coupled with restricted field sampling. This paper documents the first evaluation of the main geochemical processes and impact of anthropogenic and natural sources of contamination on the groundwater quality of the aquifer system used for domestic and agricultural purposes in Limpopo National Park, Gaza Province, Southern Mozambique. Twenty-five groundwater and surface water samples were collected during two field campaigns, one in October 2016 (the end of the arid period) and the other in March 2017 (the end of the wet period). In the field, the researchers analysed chemical–physical parameters such as temperature, pH and EC. In the laboratory, the major ions (boron, Na⁺, Ca²⁺, K⁺, Mg²⁺) and anions (Cl⁻, SO₄²⁻, NO₃⁻, HCO₃⁻, CO₃²⁻) were determined, and almost all groundwater samples fall into the brackish water category. The B/Cl ratio and δ¹¹B concentrations were then measured to better understand the origin of these brackish waters. The direct relationship between boron and chlorine and δ¹¹B concentrations above 40‰ suggests the presence of fossil water in the aquifer. The groundwater in this area was found to be above the limits stated as desirable by the Department of Water and Sanitation (DWS) and the World Health Organisation for domestic and irrigation purposes. The suitability of the groundwater for drinking purposes was also evaluated, with the results indicating that it is not suitable. The values of the sodium absorption ratio, sodium percentage and electrical conductivity show that most of the groundwater samples are also not suitable for agricultural purposes. However, the surface waters have higher quality for both domestic and irrigation purposes. The water of Massingir Lake turns out to be the most suitable resource for a possible rural development plan for the area.