Spatial pattern of impervious surfaces and their impacts on land surface temperature in Beijing,China

Land surface temperature （LST）, which is heavily influenced by urban surface structures, is a significant parameter in urban environmental analysis. This study examined the effect impervious surfaces （IS） spatial patterns have on LST in Beijing, China. A classification and regression tree model （CART） was adopted to estimate IS as a continuous variable using Landsat images from two seasons combined with QuickBird. LST was retrieved from the Landsat Thematic Mapper （TM） image to examine the relationships between IS and LST. The results revealed that CART was capable of consistently predicting LST with acceptable accuracy （correlation coefficient of 0.94 and the average error of 8.59%）. Spatial patterns of IS exhibited changing gradients across the various urban-rural transects, with LST values showing a concentric shape that increased as you moved from the outskirts towards the downtown areas. Transect analysis also indicated that the changes in both IS and LST patterns were similar at various resolution levels, which suggests a distinct linear relationship between them. Results of correlation analysis further showed that IS tended to be positively correlated with LST, and that the correlation coefficients increased from 0.807 to 0.925 with increases in IS pixel size. The findings identified in this study provide a theoretical basis for improving urban planning efforts to lessen urban temperatures and thus dampen urban heat island effects.

Fundamentals and application in phytoremediation of an efficient arsenate reducing bacterium Pseudomonas putida ARS1

Arsenic is a ubiquitous environmental pollutant.Microbe-mediated arsenic biotransformations significantly infuence arsenic mobility and toxicity.Arsenic transformations by soil and aquatic organisms have been well documented,while little is known regarding effects due to endophytic bacteria.An endophyte Pseudomonas putida ARS1 was isolated from rice grown in arsenic contaminated soil.P.putida ARS1 shows high tolerance to arsenite(As(Ⅲ))and arsenate(As(V)),and exhibits efficient As(V)reduction and As(Ⅲ)effux activities.When exposed to 0.6 mg/L As(V),As(V)in the medium was completely converted to As(Ⅲ)by P.putida ARS1 within 4 hr.Genome sequencing showed that P.putida ARS1 has two chromosomal arsenic resistance gene clusters(arsRCBH)that contribute to efficient As(V)reduction and As(Ⅲ)effux,and result in high resistance to arsenicals.Wolffia globosa is a strong arsenic accumulator with high potential for arsenic phytoremediation,which takes up As(Ⅲ)more efficiently than As(V).Co-culture of P.putida ARS1 and W.globosa enhanced arsenic accumulation in W.globosa by 69%,and resulted in 91%removal of arsenic(at initial concentration of 0.6 mg/L As(V))from water within 3 days.This study provides a promising strategy for in situ arsenic phytoremediation through the cooperation of plant and endophytic bacterium.

Water Resource Monitoring Exploiting Sentinel-2 Satellite and Sentinel-2 Satellite Like Time Series;Application in Yangtze River Water Bodies

As part of the Dragon 4 project,the water extents of Wuchang and Shengjin lakes have been extracted from Sentinel-2 time series,using all exploitable images since the beginning of the acquisitions in 2015.The aim of the study is to assess the capability of the Sentinel-2 constellation and Landsat 8 over the Anhui region,especially the high temporal resolution.A total of 32 dates have been used and 10 Landsat 8 images(Libra)have been added to try to reduce the temporal gaps in the Sentinel-2 acquisitions caused by cloudy conditions.Extractions were done using a SERTIT-ICube automatized routine based on a supervised Maximum Likelihood Classification.These extractions allow to recreate the dynamic of the two lakes and show the drought and wet periods.During the 3 years interval,the surface peaks in July 2016 for both lakes.The lowest level appears at two different dates for each lake;in January 2018 for Wuchang,in February 2017 for Shengjin.Wuchang Lake surface area appears to be more variable than Shengjin Lake,with many local maximum and minimum between the end of 2017 and April 2018.In the case of Wuchang Lake,floating vegetation is a problem for automatic water surface area extraction.The lake is covered by vegetation during long periods of time and the water below can’t be detected by automatic radiometric means.Nevertheless,Sentinel-2 stays a pertinent and powerful tool for hydrological monitoring of lakes confirming the expectation from the remote sensing wetland community before launch.The presence of NIR and SWIR bands induces a strong discrimination between water and other classes,and the systematic acquisitions create dense time series,making analysis more consistent.It makes possible to sensor events occurring over short periods of time.Thanks to this a link can be done between endangered bird species,such as the Siberian Crane and the Lesser White-Fronted Goose and periodically flooded areas.These midterm results illustrated the pertinence and powerful of multi-source optical satellite data for environmental analysis.

Gut microbiota and transcriptome response of earthworms(Metaphire guillelmi)to polymyxin B exposure

Polymyxin B(PMB)has received widespread attention for its use as a last-line therapy against multidrug-resistant bacterial infection.However,the consequences of unintended PMB exposure on organisms in the surrounding environment remain inconclusive.Therefore,this study investigated the effects of soil PMB residue on the gut microbiota and transcriptome of earthworms(Metaphire guillelmi).The results indicated that the tested doses of PMB(0.01–100 mg/kg soil)did not significantly affect the richness and Shannon’s diversity index of the earthworm gut microbiota,but PMB altered its community structure and taxonomic composition.Moreover,PMB significantly affected Lysobacter,Aeromonas,and Sphingomonas in the soil microbiota,whereas Pseudomonas was significantly impacted the earthworm gut microbiota.Furthermore,active bacteria responded more significantly to PMB than the total microbial community.Bacterial genera such as Acinetobacter and Bacillus were highly correlated with differential expression of some genes,including up-regulated genes associated with folate biosynthesis,sulphur metabolism,and the IL-17 signalling pathway,and downregulated genes involved in vitamin digestion and absorption,salivary secretion,other types of O-glycan biosynthesis,and the NOD-like receptor signalling pathway.These results suggest that adaptation to PMB stress by earthworms involves changes in energy metabolism,their immune and digestive systems,as well as glycan biosynthesis.The study findings help elucidate the relationship between earthworms and their microbiota,while providing a reference for understanding the environmental risks of PMB.

Quantification of the redox properties of microplastics and their effect on arsenite oxidation

Microplastics have attracted global concern.The environmental-weathering processes control their fate,transport,transformation,and toxicity to wildlife and human health,but their impacts on biogeochemical redox processes remain largely unknown.Herein,multiple spectroscopic and electrochemical approaches in concert with wet-chemistry analyses were employed to characterize the redox properties of weathered microplastics.The spectroscopic results indicated that weathering of phenol-formaldehyde resins(PFs)by hydrogen peroxide(H2O2)led to a slight decrease in the content of phenol functional groups,accompanied by an increase in semiquinone radicals,quinone,and carboxylic groups.Electrochemical and wet-chemistry quantifications,coupled with microbial-chemical characterizations,demonstrated that the PFs exhibited appreciable electron-donating capacity(0.264-1.15 mmol e-g^(-1))and electron-accepting capacity(0.120-0.300 mmol e-g^(-1)).Specifically,the phenol groups and semiquinone radicals were responsible for the electron-donating capacity,whereas the quinone groups dominated the electron-accepting capacity.The reversible redox peaks in the cyclic voltammograms and the enhanced electron-donating capacity after accepting electrons from microbial reduction demonstrated the reversibility of the electron-donating and-accepting reactions.More importantly,the electron-donating phenol groups and weathering-induced semiquinone radicals were found to mediate the production of H2O2 from oxygen for arsenite oxidation.In addition to the H2O2-weathered PFs,the ozone-aged PF and polystyrene were also found to have electron-donating and arsenite-oxidation capacity.This study reports important redox properties of microplastics and their effect in mediating contaminant transformation.These findings will help to better understand the fate,transformation,and biogeochemical roles of microplastics on element cycling and contaminant fate.

Combined pollution of arsenic and Polymyxin B enhanced arsenic toxicity and enriched ARG abundance in soil and earthworm gut microbiotas

Polymyxin B(PMB)is considered as the last line of antibiotic defense available to humans.The environmental effects of the combined pollution with PMB and heavy metals and their interaction mechanisms are unclear.We explored the effects of the combined pollution with PMB and arsenic(As)on the microbial composition of the soil and in the earthworm gut,as well as the spread and transmission of antibiotic resistance genes(ARGs).The results showed that,compared with As alone,the combined addition of PMB and As could significantly increase the bioaccumulation factor and toxicity of As in earthworm tissues by 12.1%and 16.0%,respectively.PMB treatment could significantly increase the abundance of Actinobacteria in the earthworm gut(from 35.6%to 45.2%),and As stress could significantly increase the abundance of Proteobacteria(from 19.8%to 56.9%).PMB and As stress both could significantly increase the abundance of ARGs and mobile genetic elements(MGEs),which were positively correlated,indicating that ARGs might be horizontally transferred.The inactivation of antibiotics was the main resistance mechanism that microbes use to resist PMB and As stress.Network analysis showed that PMB and As might have antagonistic effects through competition with multi-drug resistant ARGs.The combined pollution by PMB and As significantly promoted the relative abundance of microbes carrying multi-drug resistant ARGs and MGEs,thereby increasing the risk of transmission of ARGs.This research advances the understanding of the interaction mechanism between antibiotics and heavy metals and provides new theoretical guidance for the environmental risk assessment and combined pollution management.

How to disentangle microbially functional complexity: an insight from the network analysis of C, N, P and S cycling genes

A complete ecosystem is also a complex network in which multifarious species interact with each other to achieve system-level functions, such as nutrient biogeochemistry (1)Microbial community is commonly considered as the primary driving force of ecosystem nutrient mobilization and metabolism, especially carbon (C), nitrogen (N), phosphorus (P), sulfur (S) and methane coupling process (2)The rise of metagenomics and high-throughput array (e.g. PhyloChip, GeoChip, etc.

Climate extremes and ozone pollution:a growing threat to China’s food security

Ensuring global food security requires a sound understanding of climate and environmental controls on crop productivity.The majority of existing assessments have focused on physical climate vari-ables(i.e.,mean temperature and precipitation),but less on the increasing climate extremes(e.g.,drought)and their interactions with increasing levels of tropospheric ozone(O3).Here we quantify the combined impacts of drought and O3 on China’s crop yield using a comprehensive,process-based agricultural eco-system model in conjunction with observational data.Our results indicate that climate change/variability and O3 together led to an annual mean reduction of crop yield by 10.0%or 55 million tons per year at the national level during 1981-2010.Crop yield shows a growing threat from severe episodic droughts and in-creasing O3 concentrations since 2000,with the largest crop yield losses occurring in northern China,causing serious concerns in food supply security in China.Our results imply that reducing tropospheric O3 levels is critical for securing crop production in coping with increasing frequency and severity of extreme climate events such as droughts.Improving air quality should be a core component of climate adaptation strategies.

Prevalent fecal contamination in drinking water resources and potential health risks in Swat, Pakistan

Fecal bacteria contaminate water resources and result in associated waterborne diseases.This study assessed drinking water quality and evaluated their potential health risks in Swat, Pakistan. Ground and surface drinking water were randomly collected from upstream to downstream in the River Swat watershed and analyzed for fecal contamination using fecal indicator bacteria（Escherichia coli） and physiochemical parameters（potential of hydrogen, turbidity, temperature, electrical conductivity, total dissolved solid, color, odor and taste）. The physiochemical parameters were within their safe limits except in a few locations, whereas, the fecal contaminations in drinking water resources exceeded the drinking water quality standards of Pakistan Environmental Protection Agency（Pak-EPA）,2008 and World Health Organization（WHO）, 2011. Multivariate and univariate analyses revealed that downstream urbanization trend, minimum distance between water sources and pit latrines/sewerage systems, raw sewage deep well injection and amplified urban,pastures and agricultural runoffs having human and animal excreta were the possible sources of contamination. The questionnaire survey revealed that majority of the local people using 10–20 years old drinking water supply schemes at the rate of 73% well supply,13% hand pump supply, 11% spring supply and 3% river/streams supply, which spreads high prevalence of water borne diseases including hepatitis, intestinal infections and diarrhea, dysentery, cholera, typhoid fever, jaundice and skin diseases in children followed by older and younger adults.

Silencing the silent pandemic:eliminating antimicrobial resistance by using bacteriophages

As a result of the global spread of antibiotic-resistant bacteria(ARB)and antibiotic resistance genes(ARGs)among humans,animals,and environments,antibiotic resistance has become a silent pandemic that threatens public health worldwide(Larsson and Flach,2022).

Identification of potential electrotrophic microbial community in paddy soils by enrichment of microbial electrolysis cell biocathodes

Electrotrophs are microbes that can receive electrons directly from cathode in a microbial electrolysis cell(MEC).They not only participate in organic biosynthesis,but also be crucial in cathode-based bioremediation.However,little is known about the electrotrophic community in paddy soils.Here,the putative electrotrophs were enriched by cathodes of MECs constructed from five paddy soils with various properties using bicarbonate as an electron acceptor,and identified by 16S rRNA-gene based Illumina sequencing.The electrons were gradually consumed on the cathodes,and 25%–45% of which were recovered to reduce bicarbonate to acetic acid during MEC operation.Firmicutes was the dominant bacterial phylum on the cathodes,and Bacillus genus within this phylum was greatly enriched and was the most abundant population among the detected putative electrotrophs for almost all soils.Furthermore,several other members of Firmicutes and Proteobacteria may also participate in electrotrophic process in different soils.Soil pH,amorphous iron and electrical conductivity significantly influenced the putative electrotrophic bacterial community,which explained about 33.5% of the community structural variation.This study provides a basis for understanding the microbial diversity of putative electrotrophs in paddy soils,and highlights the importance of soil properties in shaping the community of putative electrotrophs.

Microbial response to CaCO_3 application in an acid soil in southern China

Calcium carbonate(CaCO_3) application is widely used to ameliorate soil acidification. To counteract soil and bacterial community response to CaCO_3 application in an acidic paddy soil in southern China, a field experiment was conducted with four different dosages of CaCO_3 addition, 0, 2.25, 4.5 and 7.5 tons/ha, respectively. After one seasonal growth of rice, soil physicochemical properties, soil respiration and bacterial communities were investigated. Results showed that soil p H increased accordingly with increasing dose of CaCO_3 addition, and 7.5 tons/ha addition increased soil p H to neutral condition. Moderate dose of CaCO_3 application(4.5 tons/ha) significantly increased soil dissolved organic carbon(DOC) and dissolved organic nitrogen(DON) content, enhanced soil respiration, while the excessive CaCO_3 application(7.5 tons/ha) decreased these soil properties. High-throughput sequencing results illustrated that moderate dose of CaCO_3 application increased the richness and alpha diversity of soil bacterial community. Compared with control, the relative abundance of Anaerolineaceae family belonging to Chloroflexi phylum increased by 38.7%, 35.4% and 24.5% under 2.25, 4.5 and 7.5 tons/ha treatments, respectively.Redundancy analysis(RDA) showed that soil p H was the most important factor shaping soil bacterial community. The results of this study suggest that proper dose of CaCO_3 additions to acid paddy soil in southern China could have positive effects on soil properties and bacterial community.

Protecting global soil resources for ecosystem services

2015 is the International Year of Soils,as adopted by the United Nations,and reflects the global importance of soil resources in ecosystem sustainability.Soil is not only required for food production,but is also critical for biodiversity conservation and a broad range of ecosystem services.However,soil degradation and loss through anthropogenic activities is highly worrying and reaching a crisis point.Protecting the physical,chemical,and biological integrity of soil is,therefore,of vital importance in securing human and ecosystem health.