The spread of antibiotic resistant bacteria (ARB) in the environment poses a potential threat to human health, and the reactivation of inactivated ARB accelerated the spread of ARB. However, little... Show moreThe spread of antibiotic resistant bacteria (ARB) in the environment poses a potential threat to human health, and the reactivation of inactivated ARB accelerated the spread of ARB. However, little is known about the reactivation of sunlight-inactivated ARB in natural waters. In this study, the reactivation of sunlight-inactivated ARB in dark conditions was investigated with tetracycline-resistant E. coli (Tc-AR E. coli) as a representative. Results showed that sunlight-inactivated Tc-AR E. coli underwent dark repair to regain tetracycline resistance with dark repair ratios increasing from (0.124 ± 0.012)‱ within 24 h dark treatment to (0.891 ± 0.033)‱ within 48 h. The presence of Suwannee River fulvic acid (SRFA) promoted the reactivation of sunlight-inactivated Tc-AR E. coli and tetracycline inhibited their reactivation. The reactivation of sunlight-inactivated Tc-AR E. coli is mainly attributed to the repair of the tetracycline-specific efflux pump in the cell membrane. Tc-AR E. coli in a viable but non-culturable (VBNC) state was observed and dominated the reactivation as the inactivated ARB remain present in the dark for more than 20 h. These results explained the reason for distribution difference of Tc-ARB at different depths in natural waters, which are of great significance for understanding the environmental behavior of ARB. Show less
Over the past decades, China's rice production area has experienced a substantial change in spatial distribution that has exacerbated national freshwater scarcity. To support the development of... Show moreOver the past decades, China's rice production area has experienced a substantial change in spatial distribution that has exacerbated national freshwater scarcity. To support the development of guidelines for sustainable water use in rice cropping, this study explores the potential for achieving a downscaled freshwater use boundary with high spatial resolution while maintaining China's current production levels. We found that, to operate within the boundary, which was defined using a water scarcity index, national irrigation water use for rice cropping should reduce by 10% in water-scarce regions, implying a 10% loss in national rice production without further intervention. However, using scenario analysis, we found that the production losses can be reduced to approximately 7% by closing yield gaps, and fully compensated by closing harvest area gaps in water-rich regions. The closing of both the yield and harvest area gaps allows an increase of 6.9 million metric tons of rice (3% of the national production). The water-rich regions which are suitable for double-rice systems show a high potential to increase rice production. The spatial redistribution of rice production under these scenarios resulted in a reduction in the national water-scarcity footprint related to rice cropping of 52-55%. These results demonstrate that, to reach the downscaled water use boundary, national redistribution of rice production is necessary and urgent. Our study provides detailed spatial information to support water and land use decisions. Show less
