A new sediment P release risk index (SPRRI) for “in-situ” phosphorus (P) release risk in lake sediment, is developed based on diffusive gradients in thin films (DGT) technique, DGT induced flux in sediments (DIFS) model and sediment properties. SPRRI includes three sub-indexes, which contain (1) the labile P pool size, (2) resupply constant (r) and desorption rate (Dspt rate) for P transfer and (3) the molar ratio between iron (Fe) in sequential extraction for sediment P by bicarbonate-dithionite (BD) and aluminum (Al) by NaOH (at 25 °C), i.e. BD(Fe)/Al[NaOH25] in sediment solid. The first sub-index considers P release from (i) sediment with NH₄Cl-P+BD-P pool, i.e. the loosely sorbed P (NH₄Cl-P) plus iron associated P (BD-P), or (ii) sediment with NH₄Cl-P pool, respectively. The second and third sub-indexes reflect kinetic P desorption and resupply ability of solid phase, and the effect of P sequestration by Al hydroxide on P release, in turn. The inner relationship between SPRRI and sub-indexes, and their effects on P release risk are elucidated. SPRRI can be used to evaluate sediment P reactivity by five release risk ranks. For Lake Dianchi (China), P transfer dynamics, labile P pool, resupply ability and Al-P in sediment, and “external P-loading” control and affect P release risk in different regions, which is reflected by the spatial distribution map for SPRRI. The present SPRRI can be applied for lakes with (1) pH range varying from moderate acidity to weak alkalinity in waterbody and (2) NH₄Cl-P or NH₄Cl-P+BD-P pool in sediment solid.

The ecological risk assessment (ERA) of polycyclic aromatic hydrocarbons (PAHs) is imperative due to their ubiquity and biological effects in aquatic organisms. We evaluated the seasonal levels and ERA of 16 priority PAHs in surface water, sediment and fish from four (4) anthropogenic-impacted zones of the Lagos lagoon, Nigeria. PAHs were analysed using GC-FID and standard guidelines were utilized for the ERA. Also, we developed a sediment to water-PAHs ratio and ranking of PAHs for the ERA. The dominant fish species were Sarotherodon melanotheron (Black-Jawed Tilapia), Gerres melanopterus (Gerres), Liza falcipinnis (Sicklefin Mullet) and Pseudotolithus elongatus (Bobo Croaker) at Ilaje, Iddo, Atlas cove and Apapa zones respectively. The range of sum PAHs was 195–1006 μg L⁻¹, 302–1290 μg kg⁻¹ and 8.80–26.1 μg kg⁻¹ in surface water, sediment and fish species respectively. Naphthalene was dominant in the surface water and sediment samples while 3-ring to 4-ring PAHs were predominant in fish species across the zones and seasons. The sediment to water-PAHs ratio was greater than 1 for sum PAHs and significantly higher (p < 0.05) in the wet season for specific PAHs across the zones and seasons. On the basis of the sediment PAHs level, Apapa zone was highly polluted with frequent biological effects while the other zones were moderately polluted with occasional biological effects across the zones and seasons. Fish species from all zones were minimally contaminated in both seasons except S. melanotheron which was not contaminated. The specific PAHs identified as ecological risk factors in the lagoon and ranking based on 50–75% recurrence in the ERA were; naphthalene, acenaphthene > acenaphthylene, fluorene, pyrene and benzo[a]anthracene. We recommend that the specific PAHs identified should form the basis for the establishment of environmental quality standards for individual PAHs in coastal waters based on the UN sustainable development goal 14 (life below water).

Tetraconazole, a chiral triazole fungicide, is widely used for the prevention of plant disease in wheat fields. However, the chirality of pesticides like tetraconazole can cause diverse biological responses. Therefore, it is important that research is conducted to investigate the enantioselective effects of chiral enantiomers in this regard. The absolute configurations of two tetraconazole enantiomers were initially confirmed by ECD (Electrostatic circular dichroism). The bioassay test showed that the fungicidal activity of (R)-(+)-tetraconazole against two pathogens (R. cerealis and F. graminearum) was approximately 1.49–1.98 times greater than that for (S)-(−)- tetraconazole. Following recovery experiments, a modified QuEchERS (Quick, easy, cheap, effective, rugged, safe) method was established using UPLC-MS/MS (ultra-performance liquid chromatography tandem mass spectrometry). The mean recoveries from plant and soil sample ranged from 78.9% to 100.5% with intraday relative standard (RSDᵣ) values of 0.8%–6.9% and interday relative standard (RSDR) values of 3.0%–5.2% respectively. The stereoselective degradation of tetraconazole in wheat meant that (S)-(−)-tetraconazole was more rapidly degraded than (R)-(+)-tetraconazole. Conversely, (R)-(+)-tetraconazole was preferentially degraded in wheat soil. These results will provide us with a greater understanding when assessing future environmental risk assessments and strategies that invoke pesticide reduction.

In this study, we present the development of a mobile system to measure real-world total respiratory tract deposition of inhaled ambient black carbon (BC). Such information can be used to supplement the existing knowledge on air pollution-related health effects, especially in the regions where the use of standard methods and intricate instrumentation is limited. The study is divided in two parts. Firstly, we present the design of portable system and methodology to evaluate the exhaled air BC content. We demonstrate that under real-world conditions, the proposed system exhibit negligible particle losses, and can additionally be used to determine the minute ventilation. Secondly, exemplary experimental data from the system is presented. A feasibility study was conducted in the city of La Paz, Bolivia. In a pilot experiment, we found that the cumulative total respiratory tract deposition dose over 1-h commuting trip would result in approximately 2.6 μg of BC. This is up to 5 times lower than the values obtained from conjectural approach (e.g. using physical parameters from previously reported worksheets). Measured total respiratory tract deposited BC fraction varied from 39% to 48% during walking and commuting inside a micro-bus, respectively.To the best of our knowledge, no studies focusing on experimental determination of real-world deposition dose of BC have been performed in developing regions. This can be especially important because the BC mass concentration is significant and determines a large fraction of particle mass concentration. In this work, we propose a potential method, recommendations, as well as the limitations in establishing an easy and relatively cheap way to estimate the respiratory tract deposition of BC.

Concentrations of unsubstituted and methylated polycyclic aromatic hydrocarbons (PAHs and Me-PAHs) were examined in road dusts from some representative areas with different land-use types in northern Vietnam, providing updated information about the occurrence, sources, and risks of these pollutants in Southeast Asian region. The Vietnamese road dusts were contaminated with low to moderate levels of PAHs and Me-PAHs as compared to those from other countries in the world. Concentrations of PAHs and Me-PAHs (Σ34PAHs) decreased in the order: urban (median 1800; range 1100–5500) ≈ industrial (1300; 550–10,000) > suburban (450; 310–1300) ≈ rural road dust (330; 210–2300 ng g⁻¹), suggesting an urban-rural declining trend and effects of urbanization-industrialization processes in PAH emission extent in Vietnam. The profiles and diagnostic ratios of PAHs and Me-PAHs in our samples revealed that these compounds were mainly derived from pyrogenic sources rather than petrogenic sources. Traffic emissions (e.g., vehicle exhaust, tire debris, and possible leaks of fuels, oils, and lubricants) were estimated as principal sources of PAHs and Me-PAHs, especially in the urban and industrial areas. Other pyrogenic sources (e.g., coal, wood, and biomass combustion) were also existed in the industrial, suburban, and rural areas, reflecting PAH origins from thermal industrial processes, open burning of agricultural by-products, and domestic energy utilization. Persons working outdoors and children in the urban and industrial areas were estimated to receive higher intake doses of PAHs and Me-PAHs, which were one to two orders of magnitude higher than those estimated for other groups. Except for potential cancer risk estimated for the occupational groups in the industrial area under the worst exposure scenarios, the non-cancer and cancer risk levels were generally acceptable; however, more comprehensive risk assessment considering other exposure pathways (e.g., inhalation and diet) is needed.

The extent of per- and polyfluoroalkyl substances (PFAS) in groundwater surrounding legacy landfills is currently poorly constrained. Seventeen PFAS were analysed in groundwater surrounding legacy landfills in a major Australian urban re-development precinct. Sampling locations (n = 13) included sites installed directly in waste material and down-gradient from landfills, some of which exhibited evidence of leachate contamination including elevated concentrations of ammonia-N (≤106 mg/L), bicarbonate (≤1,740 mg/L) and dissolved methane (≤10.4 mg/L). Between one and fourteen PFAS were detected at all sites and PFOS, PFHxS, PFOA and PFBS were detected in all samples. The sum of detected PFAS (∑₁₄PFAS) varied from 26 ng/L at an ambient background site to 5,200 ng/L near a potential industrial point-source. PFHxS had the highest median concentration (34 ng/L; range: 2.6–280 ng/L) followed by PFOS (26 ng/L; range: 1.3–4,800 ng/L), PFHxA (19 ng/L; range: <LOQ – 46 ng/L) and PFOA (12 ng/L; range: 1.7–74 ng/L). Positive correlations between ∑₁₄PFAS, PFOA and other perfluoroalkyl carboxylic acids (PFCAs) (e.g. PFHxA) with typical leachate indicators including ammonia-N and bicarbonate were observed. In contrast, no such correlations were found with perfluoroalkyl sulfonic acids (PFSAs) (e.g., PFOS and PFHxS). In addition, a strong positive linear correlation (R² = 0.69) was found between the proportion of PFOA in the sum of detected perfluorinated alkylated acids (PFOA/∑PFAA) and ammonia-N concentrations in groundwater. This is consistent with previous research showing relatively high PFOA/∑PFAA in municipal landfill leachates, and more conservative behaviour (e.g. less sorption and reactivity) of PFCAs during subsurface transport compared to PFSAs. PFOA/∑PFAA in groundwater may therefore be a useful indicator of municipal landfill-derived PFAA. One site with significantly elevated PFOS and PFHxS concentrations (4,800 and 280 ng/L, respectively) appears to be affected by point-source industrial contamination, as landfill leachate indicators were absent.

Coastal wetlands are widely recognized as atmospheric methane sources. However, recent field studies suggest that some coastal wetlands could also act as methane sinks, but the mechanism is not yet clear. Here, we investigated methane oxidation with different electron acceptors (i.e., oxygen, nitrate/nitrite, sulfate, Fe(III) and Mn(IV)) in four coastal wetlands in China using a combination of molecular biology methods and isotopic tracing technologies. The geochemical profiles and in situ Gibbs free energies suggest that there was significant nitrite-dependent anaerobic oxidation of methane (nitrite-AOM) in the sub-surface sediments; this was subsequently experimentally verified by both the microbial abundance and activity. Remarkably, the methanotrophic communities seemed to exist in the sediments as layered structures, and the surface aerobic methane-oxidizing bacteria were able to take up atmospheric methane at a rate of 0.10–0.18 nmol CH₄ day⁻¹ cm⁻², while most, if not all, sedimentary methane was being completely consumed by anaerobic methanotrophs (23–58% by methane oxidizers in phylum NC10). These results suggest that coastal methane sinks might be governed by diverse microbial communities where NC10 methane oxidizers contributed significantly. This finding helps to better understand and predict the coastal methane cycle and reduce uncertainties in the estimations of the global methane flux.

Freshwater environments are susceptible to possible contamination by residual antibiotics that are released through different sources, such as agricultural runoffs, sewage discharges and leaching from nearby farms. Freshwater environment can thus become reservoirs where an antibiotic impact microorganisms, and is an important public health concern. Degradation and dilution processes are fundamental for predicting the actual risk of antibiotic resistance dissemination from freshwater reservoirs. This study reviews major approaches for detecting and quantifying antibiotic resistance bacteria (ARBs) and genes (ARGs) in freshwater and their prevalence in these environments. Finally, the role of dilution, degradation, transmission and the persistence and fate of ARB/ARG in these environments are also reviewed. Culture-based single strain approaches and molecular techniques that include polymerase chain reaction (PCR), quantitative polymerase chain reaction (qPCR) and metagenomics are techniques for quantifying ARB and ARGs in freshwater environments. The level of ARBs is extremely high in most of the river systems (up to 98% of the total detected bacteria), followed by lakes (up to 77% of the total detected bacteria), compared to dam, pond, and spring (<1%). Of most concern is the occurrence of extended-spectrum β-lactamase producing Enterobacteriaceae, methicillin resistant Staphylococcus aureus (MRSA) and vancomycin resistant Enterococcus (VRE), which cause highly epidemic infections. Dilution and natural degradation do not completely eradicate ARBs and ARGs in the freshwater environment. Even if the ARBs in freshwater are effectively inactivated by sunlight, their ARG-containing DNA can still be intact and capable of transferring resistance to non-resistant strains. Antibiotic resistance persists and is preserved in freshwater bodies polluted with high concentrations of antibiotics. Direct transmission of indigenous freshwater ARBs to humans as well as their transitory insertion in the microbiota can occur. These findings are disturbing especially for people that rely on freshwater resources for drinking, crop irrigation, and food in form of fish.

In our study, Bufo gargarizans (B. gargarizans) larvae were exposed to control, 0.5, 5, 10 and 50 mg/L of NaF from Gs 26 to 42. At Gs 42, we evaluated the changes of liver histology and the mRNA levels of target genes in liver. In addition, we also examined the composition and content of fatty acids. Histological analysis revealed that fluoride caused liver injury, such as the increase of number of melanomacrophage centres, atrophy of nucleus, dilation of bile canaliculus, and decrease of quantity, degradation and deposition of lipid droplets. The results of RT-qPCR indicated that exposure to 5, 10 and 50 mg/L of NaF significantly decreased the transcript levels of genes related to fatty acid synthesis (FASN, FAE, MECR, KAR and TECR) in liver. Besides, mRNA expression of genes involved in fatty acid β-oxidation (ECHS1, HADHA, SCP2, CPT2, ACAA1 and ACAA2) and oxidative stress (SOD, GPx, MICU1 and HSP90) was significantly downregulated in 0.5, 5, 10 and 50 mg/L of NaF treatment groups. Also, in the relative expression of genes associated with synthesis and secretion of bile acid, BSEP significantly increased at 0.5, 5 and 50 mg/L of NaF while HSD3B7 significantly reduced in 0.5, 5, 10 and 50 mg/L of NaF. Finally, the fatty acid extraction and GC-MS analysis showed that the content of saturated fatty acids (SFAs) was decreased and the content of polyunsaturated fatty acids (PUFAs) was increased in all fluoride treatment groups. Taken together, the present results indicated that fluoride-induced the histological alterations of liver might be linked to the disorder of lipid metabolism, oxidative damage.

Microplastics (MPs), are tiny plastic fragments from 1 μm to 5 mm generally found in the aquatic environment which can be easily ingested by organisms and may cause chronic physical but also toxicological effects. Toxicological assays on fish cell lines are commonly used as an alternative tool to provide fast and reliable assessment of the toxic and ecotoxic properties of chemicals or mixtures. Rainbow trout liver cell line (RTLW-1) was used to evaluate the toxicity of pollutants sorbed to MPs sampled in sandy beaches from different islands around the world during the first Race for Water Odyssey in 2015. The collected MPs were analyzed for polymer composition and associated persistent organic pollutants: polycyclic aromatic hydrocarbons (PAHs), polychlorobiphenyls (PCBs) and dichlorodiphenyltrichloroethane (DDT). In addition, DMSO-extracts from virgin MPs, MPs artificially coated with B[a]P and environmental MPs were analyzed with different bioassays: MTT reduction assay (MTT), ethoxyresorufin-O-deethylase (EROD) assay and comet assay. Microplastics from sand beaches were dominated by polyethylene, followed by polypropylene fragments with variable proportions. Organic pollutants found on plastic from beach sampling was PAHs (2–71 ng g⁻¹). Samples from Bermuda (Somerset Long Bay) and Hawaii (Makapu'u) showed the highest concentration of PAHs and DDT respectively. No toxicity was observed for virgin microplastics. No cytotoxicity was observed on cells exposed to MP extract. However, EROD activity was induced and differently modulated depending on the MPs locations suggesting presence of different pollutants or additives in extract. DNA damage was observed after exposure to four microplastics samples on the six tested. Modification of EROD activity level and DNA damage rate highlight MPs extract toxicity on fish cell line.