A review of the occurrence, monitoring, and removal technologies for the remediation of per- and polyfluoroalkyl substances (PFAS) from landfill leachate.

Per- and polyfluoroalkyl substances (PFAS) are persistent organic pollutants (POPs) that pose significant environmental and human health risks. The presence of PFAS in landfill leachate is becoming an increasingly concerning issue. This article presents a comprehensive review of current knowledge and research gaps in monitoring and removing PFAS from landfill leachate. The focus is on evaluating the effectiveness and sustainability of existing removal technologies, and identifying areas where further research is needed. To achieve this goal, the paper examines the existing technologies for monitoring and treating PFAS in landfill leachate. The review emphasizes the importance of sample preparation techniques and quality assurance/quality control measures in ensuring accurate and reliable results. Then, this paper reviewed the existing technologies for removal and remediation of PFAS in landfill leachates, such as adsorption, membrane filtration, photocatalytic oxidation, electrocatalysis, biodegradation, and constructed wetlands. Additionally, the paper summarizes the factors that exhibit the performance of various treatment technologies: reaction time, experimental conditions, and removal rates. Furthermore, the paper evaluates the potential application of different remediation technologies (i.e., adsorption, membrane filtration, photocatalytic oxidation, electrocatalysis, biodegradation, and constructed wetlands, etc.) in treating landfill leachate containing PFAS and its precursors, such as fluorotelomeres like FTOH and FTSs. The review highlights the importance of considering economic, technical, and environmental factors when selecting control measures. Overall, this article aims to provide guidance for promoting environmental protection and sustainable development in the context of PFAS contamination in landfill leachate.

Further mitigating carbon footprint pressure in urban agglomeration by enhancing the spatial clustering.

The increasing environmental pressure of anthropogenic CO2 emissions is impeding the sustainability of urban agglomerations (UAs). Recent research has shown that the spatial clustering of UA elements reduces CO2 emissions but underestimates its impact on vegetation carbon sequestration. Using an extended IPAT equation analysis framework and the Logarithmic Mean Divisia Index decomposition approach, this study revealed the positive effects of the economy and population spatial clustering on carbon footprint pressure (CFP) mitigation. Specifically, improving economic spatial clustering mitigated the rise in UA's CFP caused by affluence and population growth. Furthermore, population clustering in core cities effectively mitigated CFP in neighboring cities. Additionally, we found that the efficiency improvement, i.e., the decrease in the ratio of carbon emissions and gross domestic product, should be the dominant driver of CFP mitigation, followed by improved vegetation carbon sequestration. However, these drivers have limited future potential. We believe that by improving UA's spatial clustering of the economy and population, future urban environmental pressures and climate risks will be mitigated.

Spatial-temporal evolution of pumped hydro energy storage potential on the Qinghai-Tibet Plateau and its future trend under global warming.

Global warming has brought extensive and far-reaching impacts on human life and production. A pumped hydro energy storage contributes to the large-scale development of renewable energy and serves as an important measure to mitigate climate change. Despite considerable efforts in estimating the potential of the pumped hydro energy storage, research gaps in response to global warming remain. In this regard, this study conducts a novel assessment of the pumped hydro energy storage's potential from a dynamic perspective, taking the Qinghai-Tibet Plateau as the study area. The spatiotemporal evolution of the pumped hydro energy storage's potential over the past few decades (the 1970s-2017) is analyzed, and its response to precipitation is identified innovatively. On this basis, the trend in the future period is further predicted for the first time, which is divided into near, short, medium, and long terms. Results show that the pumped hydro energy storage potential has a generally upward but not monotonic trend, decreasing from the 1970s to 1995 and then rising more dramatically, with slopes of 5548.5 ± 69.2 GWhyr-1 and -238.1 ± 90.4 GWhyr-1. In the majority (68.6 %) of lake basins (68.6 %), changes in precipitation positively contribute to the pumped hydro energy storage potential, resulting in a noticeable growth in the future. Under the representative concentration pathway of 8.5, the mean potential density is projected to rise by 23.4 %, 25.2 %, 28.3 %, and 30.6 % in the near, short, medium, and long terms, respectively. This result indicates that high-intensity greenhouse gas emissions under this scenario will lead to a greater potential for the pumped hydro energy storage in the future.

[Soil phosphorus forms and phosphorus solubilizing bacteria distribution after restoration from seriously burning in Greater Khingan Mountain areas, China]. / å¤§å ´å®‰å²­é‡åº¦ç«çƒ§è¿¹åœ°æ¢å¤åŽåœŸå£¤ç£·å½¢æ€ä¸Žè§£ç£·ç»†èŒåˆ†å¸ƒç‰¹å¾.

To understand the contents of various phosphorus forms, phosphorus solubilizing bacte-rial community structure and the relationship between them in soils after restoration from the seriously burning, we collected soil samples from artificial restoration (Pinus sylvestris var. mongolica plantation, Larix gmelinii plantation), artificial accelerated natural restoration (secondary forest) and natural restoration (natural secondary forest) stands in Greater Khingan Mountain area. Using methods of Sui et al. modified from Hedley phosphorus fractionation, we measured the contents of different phosphorus forms in rhizosphere soil and bulk soil (0-10, 10-20 cm). Abundances of phosphorus solubilizing bacteria were quantified by high-throughput sequencing method. The results showed that the contents of H2O-Pi, NaHCO3-Pi and NaHCO3-Poin 0-10 cm bulk soil and NaHCO3-Po in rhizosphere soil followed the order of L. gmelinii plantation : P. sylvestris var. mongolica plantation : natural secondary forest : secondary forest. The contents of H2O-Pi, NaHCO3-Pi, NaHCO3-Po in 10-20 cm bulk soil and H2O-Pi, NaHCO3-Pi in rhizosphere soil followed the order of L. gmelinii plantation : P. sylvestris var. mongolica plantation : secondary forest : natural secondary forest. The ratios of contents of H2O-Pi, NaHCO3-Pi and NaHCO3-Po in rhizosphere to those in bulk soil (R/S) were higher than 1 in all forest stands. The moderately labile NaOH-P included NaOH-Pi and NaOH-Po. The content of NaOH-P was in order of L. gmelinii plantation : natural secondary forest : secondary forest : P. sylvestris var. mongolica plantation in 0-10 cm layer of bulk and rhizosphere soil, and ranked as L. gmelinii plantation : P. sylvestris var. mongolica plantation : secondary forest : natural secondary forest in 10-20 cm layer of bulk soil. There was rhizosphere effect of NaOH-P in the soil. The stable HCl-P included HCl-Pi and HCl-Po. The content of HCl-P followed the order of L. gmelinii plantation : natural secondary forest : P. sylvestris var. mongolica plantation : secondary forest in 0-10 cm layer of bulk soil,and ranked as L. gmelinii plantation : P. sylvestris var. mongolica plantation : natural secondary forest : secondary forest in the 10-20 cm layer. The content of residual-P in the soil was not sensitive to restoration methods. Bradyrhizobium, Streptomyces, Burkholderia and Bacillus were the main phosphorus solubilizing bacteria across all forest stands. The abundances of phosphorus solubilizing bacteria in soil of L. gmelinii plantation and P. sylvestris var. mongolica plantation were significantly higher than that of secondary forest and natural secondary forest. Results of redundancy analysis showed that the correlation between phosphorus solubilizing bacteria and various phosphorus forms was different. Our results showed that artificial afforestation was more conducive in improving the availability of phosphorus in soil and the abundance of phosphorus solubilizing bacteria.