Climate warming greatly affects the frequency and intensity of flash droughts, which can cause huge damage to agriculture. It is important to understand the changing rules of future flash droughts and take precautionary measures in advance. Thus, we focused on the flash drought characteristic of the Jinghe River basin using variable infiltration capacity (VIC) model and four-model ensemble in the two representative concentration pathway scenarios. Four-model ensemble mean can well capture hydrological changes in the reference period. The heat wave flash drought (HWFD) and the precipitation deficit flash drought (PDFD) mainly occur in the northern during reference period. The HWFD and PDFD have shown a linear growth trend in the future and both shown higher growth rates in the RCP8.5 scenario. The frequency of occurrence (FOC) increments of flash droughts were relatively high in the southern Jinghe River basin. And the HWFD and the PDFD mainly occurred in May–September. Further results indicate that the contribution of the maximum temperature to HWFD was the biggest (greater than 0.7), followed by evapotranspiration (ET) and soil moisture (SM). The contribution of maximum temperature to PDFD was the biggest (greater than 0.5), followed by precipitation and ET. Global warming in the twenty-first century is likely to lead to intensification of flash droughts. Therefore, measures and suggestions were proposed to effectively respond to flash droughts in our study.

This study assessed the bacterial populations in a non-sanitary landfill around Guarani Aquifer recharge zone in Brazil. Samples from two different positions (sites 1 and 2) at three different depths were evaluated, totaling six solid waste samples; two samples from an impacted stream were also collected. 16S rRNA sequencing was performed using the Ion S5TM XL platform; 3113 operational taxonomic units (OTUs) and 52 phyla were identified. Proteobacteria (37%) and Firmicutes (28%) were the most abundant phyla in the landfill, whereas Proteobacteria (~ 50%) and Bacteroidetes (~ 10%) were more profuse in surface water samples. Canonical correlation analysis (CCA) enabled us to clearly separate the samples according to their spatial location (site 1 or 2) or environmental matrix (surface water or solid waste samples), showing that microbiological populations are strongly associated with site-specific conditions and the kind of environmental matrix they come from. Environmental factors that mostly influenced the microbial communities were organic matter, oxidation–reduction potential, moisture, alkalinity, nitrogen (TKN), sodium, potassium, and zinc. Exiguobacterium (phylum Firmicutes) was overwhelmingly dominant at site 1 and was associated with higher concentrations of organic matter and potassium. Differently, site 2 did not present such dominant genera and was more diverse having lower concentrations of organic matter and nutrients. Distinct environments co-exist inside the same waste deposit, including zones which are representative of active and closed landfills and the occurrence of considerable physicochemical and microbiological shifts within short distances. Those shifts indicate that microbial populations are well adapted to the heterogeneity typical of urban solid waste, which is possibly beneficial to contaminant degradation. Graphical abstract

Several epidemiological studies have investigated the adverse health effects of air pollution, but studies reporting its effects on allergic rhinitis (AR) are limited, especially in developing countries having the most severe pollution. Limited studies have been conducted in China, but their results were inconsistent. So, we conducted a time-series study to evaluate the acute effect of six air pollutants (fine particulate matter [PM₂.₅], particulate matter with diameter less than 10 μm [PM₁₀], sulfur dioxide [SO₂], nitrogen dioxide [NO₂], ozone [O₃], and carbon monoxide [CO]) on hospital outpatient visits for AR in Xinxiang, China from January 1, 2015, to December 31, 2018. An over-dispersed Poisson generalized additive model adjusting for weather conditions, long-term trends, and day of the week was used. In total, 14,965 AR outpatient records were collected during the study period. Results found that each 10 μg/m³ increase in PM₂.₅, PM₁₀, SO₂, NO₂, O₃, and CO corresponded to 0.70% (95% confidence interval 0.00–1.41%), 0.79% (0.35–1.23%), 3.43% (1.47–5.39%), 4.54% (3.01–6.08%), 0.97% (− 0.11–2.05%), and 0.07% (0.02–0.12%) increments in AR outpatients on the current day, respectively. In the stratification analyses, statistically stronger associations were observed with PM₂.₅, PM₁₀, SO₂, NO₂, and CO for AR outpatients < 15 years of age than in those 15–65 and ≥ 65 years of age, whereas the opposite result was found with O₃. Associations between PM₁₀, SO₂, NO₂, O₃, and AR outpatients were higher in the warm season than those in the cool season. This study suggests that exposure to PM₂.₅, PM₁₀, SO₂, NO₂, and CO was associated with increased AR risk and children younger than 15 years might be more vulnerable.

Agricultural soil is easily polluted by heavy metal and recently by metal-based nanoparticles, which has been synthesized in lab and discarded to environment. The uptake and accumulation of them by crops in polluted soil may pose high risks for human health. Here, we investigated the fate and the fixation effect of Fe₃O₄-GO nanocomposites (NCs) to lead ions in the soil-leek system during four harvest lifecycle. The results showed within 100 days, 600-mg/kg Fe₃O₄-GO significantly decreased Pb(II) concentrations in leaves by 37.89%, 39.10%, 73.86%, and 47.17% compared with controls. When Fe₃O₄-GO was added into Pb(II)-polluted soil, a significant fixation effect of Pb(II) was found, and the reduce percentages were 47.29%, 66.60%, 78.04%, and 39.16% for leaves, stem, storage roots, and absorbing roots compared with controls. The scanning electron microscope images showed that the overall appearance of Fe₃O₄-GO has not been destroyed during the interaction with soil. Graphical Abstract

The plasmid-borne mobilized colistin resistance genes (mcr-like) are related to resistance to polymyxins, which were reintroduced for the treatment of infections caused by multidrug-resistant pathogens. To analyze the presence of clinically relevant antimicrobial resistance genes (ARGs), including mcr-like genes and plasmids in a beach, sand samples from a public beach were collected. Fifty-seven amplicons from 22 ARGs [mcr-4, blaVIM, blaCTX₋M₋Gₚ₉, blaPER, blaCMY, qnrB, qnrS, oqxA, oqxB, sul1, sul2, sul3, floR, cmlA, tetA, tetB, tetC, aadA, ant(2″)-Ia, aph(3′)-Ib, aac(6′)-Ib, and mefAE] and 18 amplicons from seven plasmid families (IncFᵣₑₚB, IncFIA, IncHI1, IncFIB, IncY, IncN, and ColE-like) were detected. To the best of our knowledge, this is the first report of the mcr-4 gene in Brazil and the first report in the world of mcr-4 gene in a recreation area. This study calls attention to the presence of mcr-4 gene and contribute to the surveillance studies about the mcr-like genes.

To investigate the potential pollution risk of permeable brick paving systems in areas with high groundwater levels, a system was constructed by using ceramic permeable bricks as the surface and a Chinese character “well”-shaped frame as the base on the top of a 1.0 m clay layer. The concentrations of total suspended solids (TSS), total phosphorus (TP), ammonia nitrogen (NH₄⁺-N), total nitrogen (TN), chemical oxygen demand (COD), and heavy metals (Zn, Cu, and Pb) at different underground depths were measured, the potential pollution of the groundwater was assessed, and the effectiveness of the fillers inside the frame for improving the quality of the groundwater was discussed. The results showed that NH₄⁺-N and COD concentrations detected at the depth of 0.6 m were higher than that of the national standard for groundwater (GBT14848-2017), these two pollutants had the potential pollution risk. The pollution risk by heavy metals was comparatively low because most of the heavy metals were likely retained in the surface soil by adsorption, complexation, and precipitation, while the pollution risk by TSS and TP was negligible due to the good purification ability in the clay layer. The results suggest that the removal rates of TSS, TP, TN, COD, and heavy metals can be improved by appropriate fillers’ adjustment, such as iron filings, coal slag, or volcanic rocks. This research offers a new perspective on the potential risk of pollution and the governance of groundwater.

Medicinal and aromatic plants represent an outstanding source of green active ingredients for a broad range of real-world applications. In the present study, we investigated the insecticidal potential of the essential oils obtained from three medicinal and aromatic plants of economic importance in Algeria, Artemisia campestris, Pulicaria arabica, and Saccocalyx satureioides. Gas chromatography coupled with mass spectrometry (GC-MS) was used to study the essential oil chemical compositions. The three essential oils were tested against a mosquito vectoring filariasis and arboviruses, i.e., Culex quinquefasciatus, a fly pest acting also as pathogens vector, Musca domestica, and an agricultural moth pest, i.e., Spodoptera littoralis, using WHO and topical application methods, respectively. The essential oil from A. campestris, containing β-pinene (15.2%), α-pinene (11.2%), myrcene (10.3%), germacrene D (9.0%) (Z)-β-ocimene (8.1%) and γ-curcumene (6.4%), showed remarkable toxicity against C. quinquefasciatus (LC₅₀ of 45.8 mg L⁻¹) and moderate effects (LD₅₀ of 99.8 μg adult⁻¹) against M. domestica. Those from P. arabica and S. satureioides, containing epi-α-cadinol (23.9%), δ-cadinene (21.1%), α-cadinol (19.8%) and germacrene D-4-ol (8.4%), and thymol (25.6%), α-terpineol (24.6%), borneol (17.4%) and p-cymene (11.4%), respectively, were more active on S. littoralis showing LD₅₀ values of 68.9 and 61.2 μg larva⁻¹, respectively. Based on our results, the essential oil from A. campestris may be further considered a candidate ingredient for developing botanical larvicides.

The general toxicity assays for evaluating the risk of aquatic environment were commonly based on single-species test organism models. Thus, the lack and conflict of the different responses among species had hindered researchers to assess the real toxicity of a target toxicant. Therefore, the difference between the test species and their corresponding methodologies was investigated in this work and three species, Escherichia coli, Saccharomyces cerevisiae and Misgurnus anguillicaudatus (a fish), were chosen as the test organism for typical prokaryotes, eukaryotes, and vertebrates, respectively. More specifically, we investigated (i) the individual and combined toxicity of Cu²⁺ and Zn²⁺ by the three test organisms; (ii) the different evaluation manners for the test organisms, including IC₅₀ and toxic unit (TU) model for microorganisms by respiratory toxicity assay and enzyme-substrate assay, while survival time for fish; and (iii) the states of test organism, including suspended and immobilized states for microorganisms. The combined effects, including synergistic (Vt < Vp), antagonistic (Vt > Vp) and additive effects for the three species, were complex as that they were usually dose-dependent and could be changed by the different evaluation manners. The present work was useful for enriching of the associated theory and the insights from this work could open the way for further practical risk assessments.

Concentrations of the major ions (Ca²⁺, Mg²⁺, Na⁺, K⁺, NH₄⁺, Cl⁻, HCO₃⁻, SO₄²⁻ and NO₃⁻), pH and electrical conductivity (EC) values in the rainwater (RW) samples at 16 stations in Syria were determined for characterizing the principal factors affecting the chemical composition of precipitation (P) in this country. Collection of the RW samples was made on a monthly basis during the period (1989–2006). The volume-weighted mean (VWM) values calculated for the different parameters at all stations show VWM values of 6.84 and 96 μS/cm for pH and EC, respectively. The ionic trend of the VWM concentrations (μeq/L) in the RW samples of entire dataset follows the descending order: Ca²⁺ ≥ HCO₃⁻ > SO₄²⁻ > Mg²⁺ > Cl⁻ > Na⁺ > NO₃⁻ > K⁺ > NH₄⁺. The lowest pH and EC values were found for the southern mountainous stations, while the highest were reported for the interior inland stations, depending on the amount of carbonate dust present in the atmosphere. The major part of the RW salinity (> 70%) was due to Ca²⁺, HCO₃⁻ and SO₄²⁻ concentrations. The highest concentrations of Na⁺ and Cl⁻ were found for the Tartous coastal station, where the Na⁺/Cl⁻ ratio (0.84 ± 0.16) was remarkably very close to that of the Mediterranean Sea (MS) value (0.86), implying thus the sea spray effect. The highest NO₃⁻ concentrations (≈ 8–9 mg/L), with relatively high SO₄²⁻/NO₃⁻ ratios (> 2 ± 1), were found for the major cities (Damascus, Homs and Aleppo), implying hence the influence of intensive traffics and urban pollutions. The pH parameter was moderately linked with Ca²⁺ and HCO₃⁻ (R² ≈ 0.36), while EC was correlated with all ions, except NH₄⁺. This later ion was weakly correlated with NO₃⁻ (R² ≈ 0.23). Strong correlations were found between Ca²⁺ and SO₄²⁻ (R² ≈ 0.80) and between Cl⁻ and Na⁺ (R² ≈ 0.95). Ca²⁺ and Mg²⁺ ions were the most responsible for neutralizing the RW acidity. The role of K⁺ and NH₄⁺ as acidity neutralizers was small. By using the principal component analysis (PCA), five major factors, explaining ≈ 87% of the total variance, were suggested for the possible sources affecting the chemical composition of RW in this country. The factors are (1) crustal natural materials, (2) sea salts, (3) fossil fuel combustion, (4) rural activity, and (5) biomass burning.

Large-scale, inter-basin water diversion projects have been developed to relieve water scarcity crisis and water pollution problems. Environmental status and ecosystem impacts are largely unknown for the Wanjiazhai Yellow River Diversion Project (YRDP-WJZ), a water body critical in northern China. In the current study, twelve hydrochemical indices (including Mn, Cu, Zn, Hg, Pb, NH₃-N, COD-Mn, DO, BOD₅, COD, TP, and TN) were collected from 2008 to 2017 based on multiple analytical approaches to understand environmental status and ecological risks. Human health risk and threats to aquatic organisms from heavy metals were assessed. Heavy metals have no regular spatial distribution. Biochemical parameters and nutrients pollute seriously in midstream and downstream, respectively. Hydrochemical indices suggested high levels of pollution in the midstream section. Water quality improved downstream of the Fenhe Reservoir, but total nitrogen and total phosphorus in the downstream section increased in recent years. The Canadian Council of Ministers of the Environment Water Quality Index (CWQI) suggested midstream water quality was poor in general, and 80% of annual calculations had a marginal grade. For aquatic organisms, ecological risks of Cu and Zn were high. For local residents, drinking water was generally safe, but continued monitoring is critical due to ongoing threats to water quality in these areas.