Does soluble starch improve the removal of Cr(VI) by nZVI loaded on biochar?

A novel material that nano zero valent iron (nZVI) loaded on biochar with stable starch stabilization (nZVI/SS/BC) was synthesized and used for the removal of hexavalent chromium [Cr(VI)] in simulated wastewater. It was indicated that as the pyrolysis temperature of rice straw increased, the removal rate of Cr(VI) by nZVI/SS/BC first increased and then decreased. nZVI/SS/BC made from biochar pyrolyzed at 600 °C (nZVI/SS/BC600) had the highest removal efficiency and was suitable for a wide pH range (pH 2.1-10.0). The results showed that 99.67% of Cr(VI) was removed by nZVI/SS/BC600, an increase of 45.93% compared to the control group, which did not add soluble starch during synthesis. The pseudo-second-order model and the Langmuir model were more in line with reaction. The maximum adsorption capacity for Cr(VI) by nZVI/SS/BC600 was 122.86 mg·g-1. The properties of the material were analyzed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) mapping, Brunauer-Emmett-Teller (BET), Fourier-transform infrared (FTIR), and X-ray diffraction (XRD). The results showed that the nZVI particles were uniformly supported on the biochar, and the BET surface areas of nZVI/SS/BC was 40.4837 m2·g-1, an increase of 8.79 times compared with the control group. Mechanism studies showed that soluble starch reduced the formation of metal oxides, thereby improving the reducibility of the material, and co-precipitates were formed during the reaction. All results indicated that nZVI/SS/BC was a potential repair material that can effectively overcome the limitations of nZVI and achieve efficient and rapid repair of Cr(VI).

Configurational analysis of environmental information disclosure: Evidence from China's key pollutant-discharge listed companies.

The environmental information disclosure system is regarded as an important environmental management tool for supervising the environmental behavior of listed companies in China. To explore what drives the environmental information disclosure, a configurational analysis targeted at 264 China's key pollutant-discharge listed companies was studied by fuzzy-set qualitative comparative analysis (fs/QCA). The results showed that there were three types of paths to drive the environmental information disclosure: "Strict regulation - low resources - weak capability", "Strict regulation - low resources - strong capability" and "Strict regulation - high resources - strong capability", and that strict environmental regulation played a greatly significant role for promoting the environmental information disclosure level. The research provides a theoretical basis for the effectiveness of environmental regulation on environmental information disclosure, and it charts the future direction for environmental management in China.

Identifying important ecosystem service areas based on distributions of ecosystem services in the Beijing-Tianjin-Hebei region, China.

Water conservation, soil conservation, biodiversity importance, and sandstorm prevention are important ecosystem services (ES) and the core challenges to sustainable economic and societal development in the Beijing-Tianjin-Hebei (BTH) region. Using the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model and observation data, we identified high-value ES areas in the BTH region. The high-value ES areas were mainly found in the northern and southwestern parts of the region, like the Yanshan Mountain Range and the Taihang Mountain Range. The ecosystem in the northern mountains is dominated by forest and grassland, and generally provides more valuable ES than does the eastern agricultural plain. Greater species richness was mainly found in the northern mountains with low human activity intensity. Due to its proximity, the Yanshan Mountain Range is critical to the health of the local ecosystem of Beijing. High biodiversity was present in the vicinity of the national nature reserves. Compared with other regions of China, changes in the BTH region are highly intense. Reinforcement of biodiversity conservation and ecosystem restoration in areas with a high degree of ES in the BTH region are capable of effectively improving habitat quality and regional ES.

Chronic brain toxicity response of juvenile Chinese rare minnows (Gobiocypris rarus) to the neonicotinoid insecticides imidacloprid and nitenpyram.

Imidacloprid and nitenpyram are widely used neonicotinoid pesticides worldwide and were observed to adversely affect non-target aquatic organisms. In this study, the toxic effect of imidacloprid and nitenpyram on the brain of juvenile Chinese rare minnows (Gobiocypris rarus) was investigated by determining the oxidative stress, 8-hydroxy-2-deoxyguanosine (8-OHdG) content and acetylcholinesterase (AChE) activity. The superoxide dismutase (SOD) activities did not significantly change after long-term exposure to imidacloprid and nitenpyram. A noticeable increase of catalase (CAT) activities was observed on the brain tissues under 0.1 mg/L imidacloprid and under all nitenpyram treatments (p < 0.05). The malondialdehyde (MDA) content increased markedly under 2.0 mg/L imidacloprid and 0.1 mg/L nitenpyram treatments (p < 0.05). The glutathione (GSH) content in the brain significantly increased under 0.5 and 2.0 mg/L imidacloprid (p < 0.05). A significant decrease was observed in the mRNA levels of Cu/Zn-sod under 2.0 mg/L imidacloprid and those of cat under 0.1 and 0.5 mg/L nitenpyram (p < 0.05). The mRNA levels of gpx1 clearly decreased under 2.0 mg/L imidacloprid and under 0.1 mg/L nitenpyram (p < 0.05). The treatments of 0.1 and 0.5 mg/L nitenpyram decreased cat expression levels markedly (p < 0.05). 2.0 mg/L imidacloprid raised the 8-OHdG content. The AChE activities increased markedly under 0.5 and 2.0 mg/L imidacloprid while clearly decreasing under 2.0 mg/L nitenpyram (p < 0.05). Therefore, our results indicate that imidacloprid and nitenpyram might cause adverse effects on juvenile Chinese rare minnows brain. Notably, imidacloprid had greater impacts on juvenile rare minnows compared to nitenpyram.