Ambient ozone (O₃) concentrations have shown an upward trend in China and its health hazards have also been recognized in recent years. High-resolution exposure data based on statistical models are needed. Our study aimed to build high-performance random forest (RF) models based on training data from 2013 to 2017 in the Beijing-Tianjin-Hebei (BTH) region in China at a 0.01 ° × 0.01 ° resolution, and estimated daily maximum 8h average O₃ (O₃-8hmax) concentration, daily average O₃ (O₃-mean) concentration, and daily maximum 1h O₃ (O₃-1hmax) concentration from 2010 to 2017. Model features included meteorological variables, chemical transport model output variables, geographic variables, and population data. The test-R² of sample-based O₃-8hmax, O₃-mean and O₃-1hmax models were all greater than 0.80, while the R² of site-based and date-based model were 0.68–0.87. From 2010 to 2017, O₃-8hmax, O₃-mean, and O₃-1hmax concentrations in the BTH region increased by 4.18 μg/m³, 0.11 μg/m³, and 4.71 μg/m³, especially in more developed regions. Due to the influence of weather conditions, which showed high contribution to the model, the long-term spatial distribution of O₃ concentrations indicated a similar pattern as altitude, where high concentration levels were distributed in regions with higher altitude.

Economic development, population growth, industrialization, and urbanization dramatically increase urban water quality deterioration, and thereby endanger human life and health. However, there are not many efficient methods and techniques to monitor urban black and odorous water (BOW) pollution. Our research aims at identifying primary indicators of urban BOW through their spectral characteristics and differentiation. This research combined ground in-situ water quality data with ground hyperspectral data collected from main urban BOWs in Guangzhou, China, and integrated factorial data mining and machine learning techniques to investigate how to monitor urban BOW. Eight key water quality parameters at 52 sample sites were used to retrieve three latent dimensions of urban BOW quality by factorial data mining. The synchronically measured hyperspectral bands along with the band combinations were examined by the machine learning technique, Lasso regression, to identify the most correlated bands and band combinations, over which three multiple regression models were fitted against three latent water quality indicators to determine which spectral bands were highly sensitive to three dimensions of urban BOW pollution. The findings revealed that the many sensitive bands were concentrated in higher hyperspectral band ranges, which supported the unique contribution of hyperspectral data for monitoring water quality. In addition, this integrated data mining and machine learning approach overcame the limitations of conventional band selection, which focus on a limited number of band ratios, band differences, and reflectance bands in the lower range of infrared region. The outcome also indicated that the integration of dimensionality reduction with feature selection shows good potential for monitoring urban BOW. This new analysis framework can be used in urban BOW monitoring and provides scientific data for policymakers to monitor it.

The odor problems in river-type micro-polluted water matrixes are complicated compared to those in lakes and reservoirs. For example, the TY River in Jiangsu Province has been associated with complex odors, whereas the specific odor compounds were not clear. In this paper, a comprehensive study on characterizing the odors and odorants in source water from the TY River was conducted. Six odor types, including earthy, marshy, fishy, woody, medicinal, and chemical odors, were detected for the first time; correspondingly, thirty-three odor-causing compounds were identified. By means of evaluating odor activity values and reconstituting the identified odorants, 95, 93, 92, 90, 89 and 88% of the earthy, marshy, fishy, woody, medicinal and chemical odors in the source waters could be clarified. Geosmin and 2-methylisoborneol were associated with earthy odor, while amyl sulfide, dibutyl sulfide, propyl sulfide, dimethyl disulfide, dimethyl trisulfide and indole were related to marshy odor. The major woody and fishy odor compounds were vanillin, geraniol, β-cyclocitral and 2,4-decadienal, 2-octenal, respectively. Medicinal and chemical odors were mainly caused by 2-chlorophenol, 4-bromophenol, 2,6-dichlorophenol and naphthalene, and 1,4-dichlorobenzene, respectively. This is the first study in which six odor types and thirty-three odorants were identified simultaneously in a river-type micro-polluted water source, which can offer a reference for odor management in drinking water treatment plants.

Identifying the adverse impacts of pesticide exposure is essential to guide regulations that are protective of wildlife and human health. Within rice ecosystems, amphibians are valuable indicators because pesticide applications coincide with sensitive reproductive and developmental life stages. We conducted two experiments using wild cane toads (Rhinella marina) to test 1) whether environmentally relevant exposure to a commercial formulation of butachlor, an acetanilide herbicide used extensively in rice, affects amphibian development and 2) whether cane toad tadpoles are capable of acclimatizing to sub-lethal exposure. First, we exposed wild cane toads to 0.002, 0.02, or 0.2 mg/L of butachlor (Machete EC), during distinct development stages (as eggs and hatchlings, as tadpoles, or continuously) for 12 days. Next, we exposed a subset of animals from the first experiment to a second, lethal concentration and examined survivorship. We found that cane toads exposed to butachlor developed slower and weighed less than controls, and that development of the thyroid gland was affected: exposed individuals had smaller thyroid glands and thyrocyte cells, and more individual follicles. Analyses of the transcriptome revealed that butachlor exposure resulted in downregulation of transcripts related to metabolic processes, anatomic structure development, immune system function, and response to stress. Last, we observed evidence of acclimatization, where animals exposed to butachlor early in life performed better than naïve animals during a second exposure. Our findings indicate that the commercial formulation of butachlor, Machete EC, causes thyroid endocrine disruption in vertebrates, and suggest that exposure in lowland irrigated rice fields presents a concern for wildlife and human health. Furthermore, we establish that developmental assays with cane toads can be used to screen for adverse effects of pesticides in rice fields.

Water contamination caused by radionuclides is a major environmental issue. Uranium (U) belongs to the actinide group of elements. Hexavalent uranium (U(VI)) is radioactively and chemically harmful and highly mobile in the environment and wastewater stream. Therefore, developing highly efficient materials for minimizing the environmental impact of U(VI) is essential. To achieve this goal, we successfully synthesized a novel material, namely graphene oxide (GO)/hydroxyapatite (HAP), by directly assembling GO and HAP through a facile hydrothermal method, which exhibits effective U(VI) removal and immobilization. The GO/HAP composite has an outstanding sorption capacity for U(VI) (i.e., 373.00 mg/g) within 5 min at a pH of 3.0. The parameters from thermodynamic analysis indicated that the GO/HAP composite absorbed U(VI) through a process of spontaneous and exothermic adsorption. XPS, XRD, and FT-IR results revealed that the composite’s phosphate group was mainly responsible for U(VI) retention and incorporation. The GO/HAP composite’s enhanced U(VI) sorption capacity is most likely ascribed to the synergistic effect after functionalizing with nano HAP. The current findings may greatly facilitate the creation of rational design strategies to develop highly efficient materials that can treat radioactive wastewater.

Forchlorfenuron (CPPU) has been used worldwide, to boost size and improve quality of various agricultural products. CPPU and its metabolites are persistent and have been detected frequently in fruits, water, sediments, and organisms in aquatic systems. Although the public became aware of CPPU through the exploding watermelon scandal of 2011 in Zhenjiang, China, little was known of its potential effects on the environment and wildlife. In this study, adverse effects of CPPU on developmental angiogenesis and vasculature, which is vulnerable to insults of persistent toxicants, were studied in vivo in zebrafish embryos (Danio rerio). Exposure to 10 mg CPPU/L impaired survival and hatching, while development was hindered by exposure to 2.5 mg CPPU/L. Developing vascular structure, including common cardinal veins (CCVs), intersegmental vessels (ISVs) and sub-intestinal vessels (SIVs), were significantly restrained by exposure to CPPU, in a dose-dependent manner. Also, CPPU caused disorganization of the cytoskeleton. In human umbilical vein endothelial cells (HUVECs), CPPU inhibited proliferation, migration and formation of tubular-like structures in vitro. Results of Western blot analyses revealed that exposure to CPPU increased phosphorylation of FLT-1, but inhibited phosphorylation of FAK and its downstream MAPK pathway in HUVECs. In summary, CPPU elicited developmental toxicity to the developing endothelial system of zebrafish and HUVECs. This was do, at least in part due to inhibition of the FAK/MAPK signaling pathway rather than direct interaction with the VEGF receptor (VEGFR).

To characterize the emissions of polycyclic aromatic hydrocarbons (PAHs) from residential biomass burning and coal combustion in field environments, smoke samples were collected from the combustion of six types of biomass in heated kangs and four types of coal in traditional stoves and semi-gasifier stoves. The emission factors (EFs) of the total PAH were in the range of 84.5–344 mg/kg for biomass burning, with lower EFs for biomass with higher densities, and in the range of 38.0–206 mg/kg for coal combustion, with lower EFs for coals with higher maturity. Moreover, EFs were lower from high-density biomass fuels (wood trunk, 84.5 ± 11.3 mg/kg) than low-maturity coals (bituminous coal, 206 ± 16.5 mg/kg). Parent, oxygenated, alkylated, and nitrated PAHs accounted for 81.1%, 12.6%, 6.2%, and 0.1%, respectively, of the total-PAH EFs from biomass burning, and 84.7%, 13.8%, 1.4%, and 0.1%, respectively, of the total-PAH EFs from coal combustion. PAH source profiles differed negligibly between biomass fuels but differed significantly between bituminous coal and anthracite coal fuels. The characteristic species of sources were phenanthrene, 9-fluorenone, and 2-nitrobiphenyl for biomass burning, and were phenanthrene, benzo[ghi]perylene, 1,4-naphthoquinone, and 2-nitrobiphenyl for coal combustion. The ratios of benzo[b]fluoranthene/(benzo[b]fluoranthene + benzo[k]fluoranthene) were 0.40–0.45 for biomass burning and 0.89–0.91 for coal combustion, and these significantly different values constitute unique markers for distinguishing these fuels in source apportionment. Benzo[a]pyrene-equivalent factor emissions were 2.79–11.3 mg/kg for biomass and 7.49–41.9 mg/kg for coal, where parent PAHs contributed 92.0%–95.1% from biomass burning and 98.6%–98.8% from coal combustion. Total-PAH emissions from residential heating were 1552 t across Shaanxi province, to which wheat straw (445 t) in biomass burning and bituminous coal (438 t) in coal combustion were the highest contributors. Results from this study provide crucial knowledge for the source identification of PAHs as well as for the design of abatement strategies against pollutant emissions.

Scleractinian coral are experiencing global and regional stressors. Microplastics (<5 mm) are an additional stressor that may cause adverse effects on coral. Experiments were conducted to investigate ingestion size limits and retention times of microspheres in a two-day exposure as well as observing growth responses in a 12-week exposure in two Atlantic species, Pseudodiploria clivosa and Acropora cervicornis. In the two-day exposure, P. clivosa ingested a higher number of microspheres ranging in size from 425 μm–2.8 mm than A. cervicornis. Both species egested the majority of microspheres within 48 h of ingestion. In the long-term exposure, calcification and tissue surface area were negatively affected in the treatment group of both species. Exposure also negatively affected buoyant weight in A. cervicornis but not in P. clivosa. The results indicate that microplastics can affect growth responses, yet additional research is warranted to investigate potential synergistic impacts of microplastics and other stressors.

The widespread decline in oceanic dissolved oxygen (DO), known as deoxygenation, is a threat to many marine ecosystems, and fish are considered one of the more vulnerable marine organisms. While food intake and growth rates in some fish can be reduced under hypoxic conditions (DO ~ 60 μmol kg⁻¹), the dietary transfer of essential metals remains unclear. In this context, we investigated the influence of DO on the dietary acquisition of two essential metals (Zn and Mn) in the commercially important gilthead seabream (Sparus aurata) using radiotracer techniques. Fish were exposed to variable DO conditions (normoxia 100% DO, mild-hypoxia 60% DO, and hypoxia 30% DO), and fed a single radiolabeled food ration containing known activities of ⁵⁴Mn and ⁶⁵Zn. Depuration and assimilation mechanisms under these conditions were followed for 19 d. Based on whole body activity after the radio-feeding, food consumption tended to decrease with decreasing oxygen, which likely caused the significantly reduced growth (- 25%) observed at 30% DO after 19 d. While there was an apparent reduction in food consumption with decreasing DO, there was also significantly higher essential metal assimilation with hypoxic conditions. The proportion of ⁶⁵Zn remaining was significantly higher (~60%) at both low DO levels after 24 h and 19 d while ⁵⁴Mn was only significantly higher (27%) at the lowest DO after 19 d, revealing element specific effects. These results suggest that under hypoxic conditions, stressed teleost fish may allocate energy away from growth and towards other strategic processes that involve assimilation of essential metals.

Urban black-odor water (BOW) is a typical phenomenon seen in the urban water environment; it is caused by excessive pollution by organic matter and other pollutants, such as nitrogen and phosphorous. Chromophoric dissolved organic matter (CDOM) is a major optical fraction of dissolved organic matter. In this study, optical properties and components of CDOM were obtained from 178 river samples collected from five cities in China, the sample were investigated using absorption and fluorescence spectroscopy. The collected included 89 ordinary water (OW) samples, 63 mild BOW (MBOW), and 26 heavy BOW (HBOW) samples. Significant differences were found in the absorption spectra of the HBOW, MBOW, and OW samples, particularly in their optical parameters (the slope of the spectrum (S₂₇₅₋₂₉₅), and the ratio of two absorption coefficients of CDOM (E₂:E₃)). Additionally, the fluorescence intensity of the humic acid-like component (F₅) and soluble microbial by product-like component (F₄) obtained via the fluorescence regional integration (FRI) method were 3 and 4.2 times higher in HBOW than in OW, respectively; this could be used as an indicator to distinguish OW from BOW in urban rivers. The results obtained using the redundancy method and the strong negative correlation between F₄ and dissolved oxygen (DO) (r = − 0.56) suggested that the composition of CDOM could change significantly under different urban water environments (p < 0.01). Different correlations were also found between F₅, and a355, E₂:E₃, S₂₇₅₋₂₉₅ in different BOW levels, suggesting that the optical parameters of CDOM were mainly determined by the polluted organic matter originating from terrestrial sources with large molecular humic acid-like compounds; optical parameter a355 could distinguish BOW from OW. These findings are conducive in understanding the dynamics of organic matter pollution and to discover the composition and optical properties of the CDOM in urban BOW and OW, thereby providing an effective method for tracking the spatial characteristics of BOW in urban rivers using remote sensing technologies in areas with multiple sources of pollution.