Microalgae can excrete exopolymer substances (EPS) with a potential to form hetero-aggregates with microplastic particles. In this work, two freshwater (Microcystis panniformis and Scenedesmus sp.) and two marine (Tetraselmis sp. and Gloeocapsa sp.) EPS producing microalgae were exposed to different microplastics. In this study, the influence of the microplastic particles type, size and density in the production of EPS and hetero-aggregates potential was studied. Most microalgae contaminated with microplastics displayed a cell abundance decrease (of up to 42%) in the cultures. The results showed that the formed aggregates were composed of microalgae and EPS (homo-aggregates) or a combination of microalgae, EPS and microplastics (hetero-aggregates). The hetero-aggregation was dependent on the size and yield production of EPS, which was species specific. Microcystis panniformis and Scenedesmus sp. exhibited small EPS, with a higher propension to disaggregate, and consequently lower capabilities to aggregate microplastics. Tetraselmis sp. displayed a higher ability to aggregate both low and high-density microplastics, being partially limited by the size of the microplastics. Gloeocapsa sp. had an outstanding EPS production and presented excellent microplastic aggregation capabilities (adhered onto the surface and also incorporated into the EPS). The results highlight the potential of microalgae to produce EPS and flocculate microplastics, contributing to their vertical transport and consequent deposition. Thus, this work shows the potential of microalgae as biocompatible solutions to water microplastics treatment.

Swampy/septic odors are one of the most important odor types in drinking water. However, few studies have specifically focused on it compared to the extensive reported musty/earthy odor problems, even though the former is much more offensive. In this study, an investigation covering the odor characteristics, algal distribution and possible odorants contributing to swampy/septic odor, including dimethyl disulfide (DMDS), dimethyl trisulfide (DMTS), diisopropyl sulfide (DIPS), dipropyl sulfide (DPS), dibutyl sulfide (DBS), 2-methylisoborneol (2-MIB) and geosmin (GSM), was performed in source and finished water of 56 drinking water treatment plants (DWTPs) in 31 cities across China. While the musty/earthy and swampy/septic odors were dominant odor descriptors, the river source water exhibited a higher proportion of swampy/septic odor (38.5%) compared to much higher detection rate of musty/earthy odor (50.0%) in the lake/reservoir source water. The occurrence of swampy/septic odor, which was much easier to remove by conventional drinking water treatment processes compared to musty/earthy odors, was decreased by 62.9% and 46.3% in river and lake/reservoir source water respectively. Statistical analysis showed that thioethers might be responsible for the swampy/septic odor in source water (R2 = 0.75, p < 0.05). Specifically, two thioethers, DMDS and DMTS were detected, and other thioethers were not found in all water samples. DMDS was predominant with a maximum odor activity value (OAV) of 2.0 in source water and 1.3 in finished water. The distribution of the thioethers exhibited a marked regional characteristics with higher concentrations being detected in the east and south parts of China. The high concentrations of thioethers in lake/reservoir source water samples could be partly interpreted as the bloom of the cyanobacteria. This study provides basic information for swampy/septic odor occurrence in drinking water and will be helpful for further water quality management in water industry in China.

The Tibet Plateau, the so-called Third Pole of the world, is home to the headstreams of many great rivers. The levels of microplastic pollution in those rivers, however, are unknown. In this study, surface water and sediment samples were collected from six sampling sites along five different rivers. The surface water and sediment samples were collected with a large flow sampler and a stainless steel shovel, respectively. The abundance of microplastics ranged from 483 to 967 items/m3 in the surface water and from 50 to 195 items/kg in the sediment. A large amount of small, fibrous, transparent microplastics were found in this study. Five types of microplastics with different chemical compositions were identified using micro-Raman spectroscopy: polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polystyrene (PS), and polyamide (PA). These results demonstrate that rivers in the Tibet Plateau have been contaminated by microplastics, not only in developed areas with intense human activity but also in remote areas, where microplastic pollution requires further attention.

Estrogenic endocrine disrupting chemicals (EDCs) are natural hormones, synthetic compounds or industrial chemicals that mimic estrogens due to their structural similarity with estrogen's functional moieties. They typically enter aquatic environments through wastewater treatment plant effluents or runoff from intensive livestock operations. Globally, most natural and synthetic estrogens in receiving aquatic environments are in the low ng/L range, while industrial chemicals (such as bisphenol A, nonylphenol and octylphenol) are present in the μg to low mg/L range. These environmental concentrations often exceed laboratory-based predicted no effect concentrations (PNECs) and have been evidenced to cause negative reproductive impacts on resident aquatic biota. In vertebrates, such as fish, a well-established indicator of estrogen-mediated endocrine disruption is overexpression of the egg yolk protein precursor vitellogenin (Vtg) in males. Although the vertebrate Vtg has high sensitivity and specificity to estrogens, and the molecular basis of its estrogen inducibility has been well studied, there is growing ethical concern over the use of vertebrate animals for contaminant monitoring. The potential utility of the invertebrate Vtg as a biomonitor for environmental estrogens has therefore gained increasing attention. Here we review evidence providing support that the molluscan Vtg holds promise as an invertebrate biomarker for exposure to estrogens. Unlike vertebrates, estrogen signalling in invertebrates remains largely unclarified and the classical genomic pathway only partially explains estrogen-mediated activation of Vtg. In light of this, in the latter part of this review, we summarise recent progress towards understanding the molecular mechanisms underlying the activation of the molluscan Vtg gene by estrogens and present a hypothetical model of the interplay between genomic and non-genomic pathways in the transcriptional regulation of the gene.

Hydroxymethylfurfural (HMF) is a plant-based chemical building block that could potentially substitute petroleum-based equivalents, yet ecotoxicological data of this compound is currently limited. In this study, the effects of HMF on the reproduction and survival of Daphnia magna were assessed through validated ecotoxicological tests. The mechanism of toxicity was determined by analysis of transcriptomic responses induced by exposure to different concentrations of HMF using RNA sequencing. HMF exerted toxicity to D. magna with an EC₅₀ for effects on reproduction of 17.2 mg/l. HMF exposure affected molecular pathways including sugar and polysaccharide metabolism, lipid metabolism, general stress metabolism and red blood cell metabolism, although most molecular pathways affected by HMF exposure were dose specific. Hemoglobin genes, however, responded in a sensitive and dose-related manner. No induction of genes involved in the xenobiotic metabolism or oxidative stress metabolism pathway could be observed, which contrasted earlier observations on transcriptional responses of the terrestrial model Folsomia candida exposed to the same compound in a similar dose. We found 4189 orthologue genes between D. magna and F. candida, yet only twenty-one genes of those orthologues were co-regulated in both species. The contrasting transcriptional responses to the same compound exposed at a similar dose between D. magna and F. candida indicates limited overlap in stress responses among soil and aquatic invertebrates. The dose-related expression of hemoglobin provides further support for using hemoglobin expression as a biomarker for general stress responses in daphnids.

The objective of this study was to evaluate the potential of three C4 perennial grasses (Miscanthus x giganteus, Panicum virgatum and Spartina pectinata) for biomass production on arable land unsuitable for food crop cultivation due to Pb, Cd and Zn contamination. We assessed soil properties, biomass yield, metal concentrations, and the photosynthetic performance of each species. Physico-chemical and elemental analyses were performed on soil samples before plantation establishment (2014) and after three years of cultivation (2016), when leaf area index, plant height, yield and heavy metal content of biomass were also determined. Physiological measurements (gas exchange, pigment content, chlorophyll a fluorescence) were recorded monthly between June and September on mature plants in 2016. Cultivation of investigated plants resulted in increased pH, nitrogen, and organic matter (OM) content in soil, although OM increase (13%) was significant only for S. pectinata plots. During the most productive months, maximal quantum yield values of primary photochemistry (Fv/Fm) and gas exchange parameter values reflected literature data of those plants grown on uncontaminated sites. Biomass yields of M. x giganteus (15.0 ± 0.4 t d.m. ha−1) and S. pectinata (12.6 ± 1.2 t d.m. ha−1) were also equivalent to data published from uncontaminated land. P. virgatum performed poorly (4.1 ± 0.4 t d.m. ha−1), probably due to unfavourable climatic conditions, although metal uptake in this species was the highest (3.6 times that of M. x giganteus for Pb). Yield and physiological measurements indicated that M. x giganteus and S. pectinata were unaffected by the levels of contamination and therefore offer alternatives for areas where food production is prohibited. The broad cultivatable latitudinal range of these species suggests these results are widely relevant for development of the bioeconomy. We recommend multi-location trials under diverse contaminant and environmental regimes to determine the full potential of these species.

An anaerobic incubation was launched with varying nitrate (1, 5, 10 and 20 mM exogenous NaNO₃) and molybdate (20 mM Na₂MoO₄, a sulfate-reducing inhibitor) additions to investigate the characteristics of PCP dechlorination, as well as the reduction of natural co-occurring electron acceptors, including NO₃⁻, Fe(III) and SO₄²⁻, and the responses of microbial community structures under a unique reductive mangrove soil. Regardless of exogenous addition, nitrate was rapidly eliminated in the first 12 days. The reduction process of Fe(III) was inhibited, while that of SO₄²⁻ reduction depended on addition concentration as compared to the control. PCP was mainly degraded from orth-position, forming the only intermediate 2,3,4,5-TeCP by anaerobic microbes, with the highest PCP removal rate of average 21.9% achieved in 1 and 5 mM NaNO₃ as well as 20 mM Na₂MoO₄ treatments and the lowest of 7.5% in 20 mM NaNO₃ treatment. The effects of nitrate on PCP dechlorination depended on addition concentration, while molybdate promoted PCP attenuation significantly. Analyses of the Illumina sequencing data and the relative abundance of dominant microorganisms indicated that the core functional groups regulated PCP removal at genera level likely included Bacillus, Pesudomonas, Dethiobacter, Desulfoporosinus and Desulfovbrio in the nitrate treatments; while that was likely Sedimentibacter and Geosporobacter_Thermotalea in the molybdate treatment. Nitrate supplement but not over supplement, or addition of molybdate are suggested as alternative strategies for better remediation in the nitrate-deficient and sulfur-accumulated soil ecosystem contaminated by PCP, through regulating the growth of core functional groups and thereby coordinating the interaction between dechlorination and its coupled soil redox processes due to shifts of more available electrons to dechlorination. Our results broadened the knowledge regarding microbial PCP degradation and their interactions with natural soil redox processes under anaerobic soil ecosystems.

This study investigates the dynamics of glyphosate and AMPA in the soil surface layer of two fields growing glyphosate-resistant crops in the loess Pampas of Córdoba Province, Argentina. Glyphosate decay and AMPA formation/decay were studied after a single application, using decay kinetic models. Furthermore, glyphosate and AMPA concentrations were investigated in runoff to evaluate their off-site risk. During a 2.5-month study, cultivations of glyphosate-resistant soybean and maize received an application of 1.0 and 0.81 kg a.e. ha⁻¹, respectively, of Roundup UltraMax©. Topsoil samples (0–1, 1–2 cm) were collected weekly (including before application) and analysed for glyphosate, AMPA and soil moisture (SM) contents. Runoff was collected from runoff plots (3 m²) and weirs after 2 erosive rainfall events, and analysed for glyphosate and AMPA contents (water, eroded-sediment). Under both cultivations, background residues in soil before application were 0.27–0.42 mg kg⁻¹ for glyphosate and 1.3–1.7 mg kg⁻¹ for AMPA. In the soybean area, the single-first-order (SFO) model performed best for glyphosate decay. In the maize area, the bi-phasic Hockey-Stick (HS) model performed best for glyphosate decay, due to an abrupt change in SM regimes after high rainfall. Glyphosate half-life and DT₉₀ were 6.0 and 19.8 days, respectively, in the soybean area, and 11.1 and 15.4 days, respectively, in the maize area. In the soybean area, 24% of the glyphosate was degraded to AMPA. In the maize area, it was only 5%. AMPA half-life and DT₉₀ were 54.7 and 182 days, respectively, in the soybean area, and 71.0 and 236 days, respectively, in the maize area. Glyphosate and AMPA contents were 1.1–17.5 times higher in water-eroded sediment than in soil. We conclude that AMPA persists and may accumulate in soil, whereas both glyphosate and AMPA are prone to off-site transport with water erosion, representing a contamination risk for surface waters and adjacent fields.

Volatile organic compounds (VOCs) are an important factor affecting ambient air quality, and furniture production is one of the important sources of VOC pollution. High VOC concentrations have adverse effects on the environment and worker welfare in furniture factories. In order to control VOC emissions in a furniture workshop, the VOC species and concentration distributions were examined. Qualitative analysis of VOC species was carried out by headspace gas chromatography/mass spectrometry. The results showed that VOCs from a furniture workshop were mainly 12 substances including acetate, toluene, and xylene compounds. The heights and representative positions of VOCs released during the coating process were determined, and the results showed that VOC concentrations depended on environmental and height factors. The concentration of VOCs decreased with increasing altitude and reached a maximum concentration at 0.4 m above the ground. Because the concentration of VOCs varied with temperature, humidity, air pressure, and amount of spray paint, this paper established functional relationships between VOC concentrations and temperature, humidity, air pressure, and amount of spray paint. These results provide a theoretical basis for furniture workshops to automatically monitor and control VOCs.VOCs from the furniture workshop were mainly composed of 10 substances including acetate, toluene, and xylene compounds.

A limited number of studies have addressed environmental inequality, using various study designs and methodologies and often reaching contradictory results. Following a standardized multi-city data collection process within the European project EURO-HEALTHY, we conducted an ecological study to investigate the spatial association between nitrogen dioxide (NO2), as a surrogate for traffic related air pollution, and ten socioeconomic indicators at local administrative unit level in nine European Metropolitan Areas. We applied mixed models for the associations under investigation with random intercepts per Metropolitan Area, also accounting for the spatial correlation. The stronger associations were observed between NO2 levels and population density, population born outside the European Union (EU28), total crimes per 100,000 inhabitants and unemployment rate that displayed a highly statistically significant trend of increasing concentrations with increasing levels of the indicators. Specifically, the highest vs the lowest quartile of each indicator above was associated with 48.7% (95% confidence interval (CI): 42.9%, 54.8%), 30.9% (95%CI: 22.1%, 40.2%), 19.8% (95%CI: 13.4%, 26.6%) and 15.8% (95%CI: 9.9%, 22.1%) increase in NO2 respectively.The association with population density most probably reflects the higher volume in vehicular traffic, which is the main source of NO2 in urban areas. Higher pollution levels in areas with higher percentages of people born outside EU28, crime or unemployment rates indicate that worse air quality is typically encountered in deprived European urban areas. Policy makers should consider spatial environmental inequalities to better inform actions aiming to lower urban air pollution levels that will subsequently lead to improved quality of life, public health and health equity across the population.