Environmental Development Centre

Agricultural activities are the second largest source of greenhouse gas emissions, and carbon emissions from agricultural land use (CEALU) have become a hot issue across the world. Although there are some studies on the impact of high-standard farmland construction policies on carbon emissions, they focus on quantitative analysis and do not give sufficient consideration to the relationship between HSFC and CEALU. Therefore, in this study, by relying on provincial panel data of China for the period 2005–2017, the effect of the high-standard basic farmland construction policy on carbon emissions from agricultural land use per unit area and its regional differences were quantitatively analyzed using the difference-in-difference (DID) model. The results showed that: (1) China’s CEALU per unit area presented a fluctuating upward change, but the growth rate slowed down during the period 2005–2017, from 392.58 kg/ha to 457.72 kg/ha, with an average annual growth rate of 1.31%; (2) the high-standard farmland construction (HSFC) policy led a significant carbon emission reduction effect in agricultural land use and reduced the CEALU per unit area by 10.80% on average. With the promotion of this policy, its carbon emission reduction effect in agricultural land use presented an overall increasing change; (3) the carbon emission reduction effect of the high-standard farmland construction policy in agricultural land use was significant in central China, but non-significant in eastern China and western China.

Although residential crowding has many well-being implications, its connection to mental health is yet to be widely examined. Using survey data from 1613 residents in Beijing, China, we find that living in a crowded place – measured by both square metres per person and persons per bedroom – is significantly associated with a higher risk of depression. We test for the mechanisms of such associations and find that the residential crowding–depression link arises through increased living space-specific stress rather than increased life stress. We also identify the following subgroups that have relatively stronger residential crowding–depression associations: females, those living with children, those not living with parents, and those living in non-market housing units. Our findings show that inequality in living space among urban residents not only is an important social justice issue but also has health implications.

Abstract China's migration boom has reshaped its domestic economic pattern and social structure, resulting in a typical urbanization model dominated by massive internal migration. By using the 1% National Population Sample Survey data in 2005 and 2015, this study depicts and analyses the spatial pattern of intercity migration in China and its changes using the Gini index, network analysis approach, and gravity model. Individual‐level data enable us to reveal that the distribution of migrants among destinations and origins has become considerably balanced over the decade, although destinations are markedly more concentrated than origins. The migration network is stable but also becomes significantly disperse owing to the increasing short‐distance and intra‐provincial migration. Even with a burgeoning railway system, migration distance generally matters more than before, particularly for migration from Central and Western China. The results provide new insights to universal migration theories and implications to regional development and population redistribution.

The low conductivity, structural degradation during cycling and severe capacity loss in the initial cycle make silicon difficult to meet the increasing demand in various aspects as one of the promising anodes material. Here we introduce a conductive three-dimensional structure to tackle these problems. The design of the electrode is achieved via plasma enhanced chemical vapor deposition (PECVD) of silicon nanoparticles onto three-dimensional nickel foam, forming a 3D conductive network. The three-dimensional networks provide abundant electrochemical activity sites and conductive transport paths. Besides, this design can significantly improve the energy density of the electrode since no binders or conductive agents are deposited. The initial columbic efficiency of Si anode is greatly improved by tuning the deposition time. A secondary phase of NiSi2 is found from XPS results which serves as an inactive buffer matrix in the composite. The anode with 40min deposition time achieves remarkable electrochemical performance as 84.84% initial columbic efficiency and 525.5mAh·g−1 specific capacity after the 100th cycles. This preferable performance is the result of enhanced physical and mechanical properties of the electrode with a 3D conductive structure.

A total of 110 topsoil samples and 61 crop samples along the Lantian-Yangdong Villages were collected in Shizhong, Longyan City. The total amount and speciation of heavy metals(Pb, Cd, As) in soil and crops were determined. The characteristics of the absorption of heavy metals by specific crops in the study area were analyzed, and a new method of risk assessment based on the heavy metal speciation and its bioavailability was established by statistical analysis. This new method was used to evaluate the soil ecological risk and to compare it with the traditional method of potential ecological risk index (RI). The results indicated that the Lantian-Yangdong Villages were located in an area where Pb, Cd, and As mainly originate from the natural soil parent material with weak human disturbance. There was no significant Pb or As pollution in the whole region. Cd was the main pollutant with low pollution intensity. Four types of biological components except for the residual form followed the order of Cd(53.28%) > Pb(43.28%) > As(30.71%). Correlation and regression analyses of total metal concentrations, heavy metal speciation, and crop uptake in the study area showed that the correlations between the total amount of heavy metals and the ion exchange state, carbonate state, and other active forms were low; the results even showed nonlinear relationships between those variables.The ion exchange state had the greatest effect on the absorption of Pb, Cd, and As by coix seed and rice. From the perspective of bioavailability, the new method based on the heavy metal speciation was more accurate than the traditional method based on the total amount of heavy metals.

At present, economic development has become a dominant factor in the promotion of urban renewal in China. This means that decision-makers often overlook the impact of the natural environment on the urban renewal of the region. This paper begins with a review of the literature concerning urban renewal and natural disaster vulnerability in order to discuss the mechanism of interaction between natural disasters and urban renewal. Then, an evaluation model of natural disaster vulnerability in urban areas is constructed, and a DEA model is used to assess the vulnerability of natural disasters in various regions of a city. Finally, using the idea of regional planning, this paper puts forward a method for urban renewal, taking natural disaster factors into consideration, and provides an important direction for urban renewal in order to realize the sustainable development of cities. The findings of this paper substantiate the phenomenon that, at this stage, urban renewal has brought many problems. Although urban renewal enhances the city's resilience to natural disasters, understanding how to assess the vulnerability of natural disasters in all regions of the city has been a challenge and should be part of an integrated planning approach. This paper puts forward the countermeasure of urban renewal against the background of natural disaster, from the perspective of sustainable development.