Rice husk and cotton straw were used to produce biochar under 300, 400, 500, 600, and 700 °C pyrolysis conditions, and the physicochemical properties of the obtained biochar samples were characterised. The effects of various adsorbent amounts, initial pH, and adsorption time on the Cd²⁺ adsorption performance were studied. The results showed that, at increasing pyrolysis temperatures, the biochar yield decreased, the ash content increased, the pH transitioned from acidic/neutral to basic/strongly basic, the biochar aromaticity gradually increased, and the biochar structure became more stable. In contrast, the hydrophilicity and polarity decreased, the specific surface area increased, and the number of oxygen-containing functional groups decreased. All these factors resulted in differences in the Cd²⁺ adsorption by the biochar samples. With increasing adsorbent content, the rate of Cd²⁺ adsorbed on the biochar gradually increased. The adsorption performance was optimal when the initial solution pH of the rice-husk and cotton-straw biochar samples was 5 and 6, respectively. The shortest time to achieve equilibrium was 30 min for rice-husk biochar, and 20 min for cotton-straw biochar. The Cd²⁺ adsorption data for both types of biochar were very well fitted with a pseudo-second-order kinetic model. Ion exchange and cation–π interactions may be the main factors influencing the Cd²⁺ adsorption by biochar. At the same time, the large specific surface area of biochar also plays a role in the Cd²⁺ adsorption.

Recovery efficiency of nitrogen fertilizers has always been an important issue, especially for N fertilizer recommendation rate in cropping systems. Based on the equilibrium of N in the soil–plant system, apparent accumulated N fertilizer recovery (NRE_ac) was determined for long-term (15-years) experiments in wheat (Triticum aestivum L.) and maize (Zea mays L.) rotations at five field sites with various soils and climate characteristics in China. The result showed that the frequency of cropping and the content of soil clay affected NRE_ac positively and negatively, respectively. In the absence of nutrient deficiencies and other soil constraints (from NPK (nitrogen, phosphorus and potassium) in S2-CP (site2-Changping) in Beijing, S3-ZZ (site3-Zhengzhou) in Henan province and S4-YL (site4-Yangling) in Shaanxi province), NRE_ac had a narrow range from 70% to 78% with the highest average of 75% in wheat and maize cropping system. Meanwhile, the value 75% of NER_ac is a rational value proved by 3414 experiments. Additionally, the nitrate-N approach suggested that nitrate-N could be utilized by subsequent crops, the amount of which is calculated by the equation −1.23 × [(NO₃⁻-N) − 87]. Furthermore, another simpler and feasible method was proposed to maintain basic soil fertility while achieving a rational grain yield and maintaining a safe environmental upper threshold of nitrate. The present study provided a suit of methods for N fertilizer recommendations for the optimization of N applications in wheat and maize cropping system in China.

In order to understand the regional non-point source pollution at different management level in Longgang District of Shenzhen City, the commercial and residential zone, the cultural and educational zone, the transportation zone, the industrial zone and the urban village were chosen as sampling sites. The surface street dust and rainfall runoff samples were collected after investigating the management levels and the correlation between the management level and street dust or rainfall runoff was analysed. The results showed that the street dust accumulation was the highest in the transportation zone (25 g/m²), which was at the lowest management level. However, the best-managed commercial and residential zone and the cultural and educational zone had a street dust accumulation of about 8 g/m², which was higher than those in the industrial area and urban village (3.5 g/m²). This may be due to the different size of the crowed flow. In each zone, the large-sized particles contribute a major proportion of the street dust. The N and P contents in the dust was highly correlated with the particle size, but showed no correlation with the management level. The correlation was also observed between the pollutant contents in rainfall runoff and the management level. The low-managed transport zone had the highest pollutant contents, with most of the indicators exceeded the values limited by the Environmental Quality Standard for Surface Water (GB 3838-2002, class V criteria)

Surface vegetation cover is a difficult problem in surface temperature inversion by thermal infrared remote sensing, thus this paper selected water body as the reference surface, measured surface temperature of five different vegetation landscape types (high tree, tree-shrub-grass, grass, shrub, and tree-grass) by using ground thermal infrared remote sensing instrument and analyzed the temperature difference along the Wenyu river. The results showed that there were seasonal differences of surface temperature among different vegetation landscape, the seasonal variation of shrub surface temperature was the most stable, but those of tree-shrub-grass was the most unstable; the directional difference of the surface temperature among vegetation landscape was influenced by the slope, given the consistent slope, the order of directional difference of surface temperature among vegetation landscape types was: tree-grass > high tress > tree-shrub-grass > shrub >grass; there was different respond relationship between surface temperature and vertical temperature among vegetation landscape, in which there was linear equation model (y = b₁x + b₀) for the two types of high-tree and shrub, Joe forest and shrub forest, “S” type curve model (y = exp (b₀ + b₁ / x)) for the three types of tree-grass, grass, and tree-shrub-grass.