Tricresyl phosphates (TCPs), as representative aromatic organophosphate flame retardants (OPFRs), have received much attention due to their potential neurotoxicity and endocrine-disrupting effects. However, the role of estrogen receptor α (ERα) and G protein-coupled estrogen receptor (GPER) in their estrogen disrupting effects remains poorly understood. Therefore, in this study, three TCP isomers, tri-o-cresyl phosphate (ToCP), tri-m-cresyl phosphate (TmCP) and tri-p-cresyl phosphate (TpCP), were examined for their activities on ERα by using two-hybrid yeast assay, and action on GPER by using Boyden chamber assay, cAMP production assay, calcium mobilization assay and molecular docking analysis. The results showed that three TCP isomers were found to act as ERα antagonists. Conversely, they had agonistic activity on GPER to promote GPER-mediated cell migration of MCF7 cells and SKBR3 cells. Both ToCP and TpCP activated GPER-mediated cAMP production and calcium mobilization, whereas TmCP had different mode of action, it only triggered GPER-mediated calcium mobilization, as evidenced by using the specific GPER inhibitor (G15) and GPER overexpressing experiments. Molecular docking further revealed that the way of interaction of TmCP and TpCP with GPER was different from that of ToCP with GPER, and higher activity of ToCP in activating GPER-mediated pathways might be associated with the alkyl substitution at the ortho position of the aromatic ring. Our results, for the first time, found a new target, GPER, for TCPs exerting their estrogen-disrupting effects, and demonstrated complex estrogen-disrupting effects of three TCP isomers involved their opposite activities toward ERα and GPER.

We investigated isoprene (ISO) emission and gas exchange in leaves from different positions along the vertical canopy profile of poplar saplings (Populus euramericana cv. ‘74/76’). For a growing season, plants were subjected to four N treatments, control (NC, no N addition), low N (LN, 50 kg N ha⁻¹year⁻¹), middle N (MN, 100 kg N ha⁻¹year⁻¹), high N (HN, 200 kg N ha⁻¹year⁻¹) and three O₃ treatments (CF, charcoal-filtered ambient air; NF, non-filtered ambient air; NF + O₃, NF + 40 ppb O₃). Our results showed the effects of O₃ and/or N on standardized ISO rate (ISOᵣₐₜₑ) and photosynthetic parameters differed along with the leaf position, with larger negative effects of O₃ and positive effects of N on ISOᵣₐₜₑ and photosynthetic parameters in the older leaves. Expanded young leaves were insensitive to both treatments even at very high O₃ concentration (67 ppb as 10-h average) and HN treatment. Significant O₃ × N interactions were only found in middle and lower leaves, where ISOᵣₐₜₑ declined by O₃ just when N was limited (NC and LN). With increasing light-saturated photosynthesis and chlorophyll content, ISOᵣₐₜₑ was reduced in the upper leaves but on the contrary increased in middle and lower leaves. The responses of ISOᵣₐₜₑ to AOT40 (accumulated exposure to hourly O₃ concentrations > 40 ppb) and PODY (accumulative stomatal uptake of O₃ > Y nmol O₃ m⁻² PLA s⁻¹) were not significant in upper leaves, but ISOᵣₐₜₑ significantly decreased with increasing AOT40 or PODY under limited N supply in middle leaves but at all N levels in lower leaves. Overall, ISOᵣₐₜₑ changed along the vertical canopy profile in response to combined O₃ and N exposure, a behavior that should be incorporated into multi-layer canopy models. Our results are relevant for modelling regional isoprene emissions under current and future O₃ pollution and N deposition scenarios.

The use of some systemic insecticides has been banned in Europe because they are toxic to beneficial insects when these feed on nectar. A recent study shows that systemic insecticides can also kill beneficial insects when they feed on honeydew. Honeydew is the sugar-rich excretion of hemipterans and is the most abundant carbohydrate source for beneficial insects such as pollinators and biological control agents in agroecosystems. Here, we investigated whether the toxicity of contaminated honeydew depends on i) the hemipteran species that excretes the honeydew; ii) the active ingredient, and iii) the beneficial insect that feeds on it. HPLC-MS/MS analyses demonstrated that the systemic insecticides pymetrozine and flonicamid, which are commonly used in Integrated Pest Management programs, were present in honeydew excreted by the mealybug Planococcus citri. However, only pymetrozine was detected in honeydew excreted by the whitefly Aleurothixus floccosus. Toxicological studies demonstrated that honeydew excreted by mealybugs feeding on trees treated either with flonicamid or pymetrozine increased the mortality of the hoverfly Sphaerophoria rueppellii, but did not affect the parasitic wasp Anagyrus vladimiri. Honeydew contaminated with flonicamid was more toxic for the hoverfly than that contaminated with pymetrozine. Collectively, our data demonstrate that systemic insecticides commonly used in IPM programs can contaminate honeydew and kill beneficial insects that feed on it, with their toxicity being dependent on the active ingredient and hemipteran species that excretes the honeydew. Insecticides recommended in Integrated Pest Management programs reach honeydew and kill beneficial insects that feed on it.

The plastic mulch films used in agriculture are considered to be a major source of the plastic residues found in soil. Mulching with low-density polyethylene (LDPE) is widely practiced and the resulting macro- and microscopic plastic residues in agricultural soil have aroused concerns for years. Over the past decades, a variety of biodegradable (Bio) plastics have been developed in the hope of reducing plastic contamination of the terrestrial ecosystem. However, the impact of these Bio plastics in agroecosystems have not been sufficiently studied. Therefore, we investigated the impact of macro (around 5 mm) and micro (<1 mm) sized plastic debris from LDPE and one type of starch-based Bio mulch film on soil physicochemical and hydrological properties. We used environmentally relevant concentrations of plastics, ranging from 0 to 2% (w/w), identified by field studies and literature review. We studied the effects of the plastic residue on a sandy soil for one month in a laboratory experiment. The bulk density, porosity, saturated hydraulic conductivity, field capacity and soil water repellency were altered significantly in the presence of the four kinds of plastic debris, while pH, electrical conductivity and aggregate stability were not substantially affected. Overall, our research provides clear experimental evidence that microplastics affect soil properties. The type, size and content of plastic debris as well as the interactions between these three factors played complex roles in the variations of the measured soil parameters. Living in a plastic era, it is crucial to conduct further interdisciplinary studies in order to have a comprehensive understanding of plastic debris in soil and agroecosystems.

International audience | The performance of 14 large pilot-scale horizontal flow wetlands (similar to 60 m(2)each) designed to treat polluted river water was tested in a 3-year study at the Chenshan Botanical Garden in Shanghai, China. Five local species,Arundo donax,Cyperus alternifolius,Phragmites australis,Thalia dealbataandTypha orientalis, were planted in monocultures and in a polyculture ofPhragmites,ThaliaandTypha.Total nitrogen (TN) removal was compared among species and to an unplanted bed.Each bed was replicated once, and the parallel setup received a TN inflow concentration of 16 mg L(-1)on average over each summer season, a level twice as high as for the beds receiving unspiked inflow. During the first 2 years of operation, the only significant differences in pollutant removal were between planted and unplanted systems. In the third year, significant differences appeared among planted beds in the high nutrient systems, withPhragmitesbeing the most efficient species in TN removal andArundothe least, suggesting that greater inflow and more maturity may be needed before differences can be detected. The polyculture was never significantly more efficient than the other planted systems. However, it ranked among the best systems in 2018. Yet, while a greater removal of the polyculture over the average TN removal of all monocultures taken together may develop over time, we found no evidence that the polyculture may get more efficient than the best monoculture. Observation over all phases of plant establishment made it possible to draw conclusions for future design and operation.

Plastic debris provides a stable substrate and novel ecological niche for microorganisms in the aquatic environment, which was referred to as “Plastisphere”. Little is known about distribution patterns and responses of ecological function and structure of microbial communities in the plastisphere along rivers which usually have antibiotics pollution gradient. In this study, the differences in the community structure between the plastisphere and the planktonic bacteria, and their spatial variation of the community structure and function along a river with increased antibiotics pollution gradient was investigated at the watershed scale. The diversity of bacteria colonized on most plastic debris was higher than in surrounding water. Plastic debris could accumulate a higher abundance of some potential pathogens than surrounding water even at high antibiotics concentrations. The source tracking results showed that downstream plastisphere inherited much higher proportions of bacterial taxa from upstream than planktonic bacteria. About 92.3–99.7% of bacteria communities in downstream water were not from upstream but from the input of downstream human activities. On the contrary, high proportions of bacterial taxa in downstream plastisphere were closely connected to upstream. The plastisphere possesses higher ecological functional diversity than the planktonic bacteria. Seventy nine functional groups across plastisphere were predicted using functional annotation of prokaryotic taxa and only 65 functional groups were found in the planktonic bacteria. Plastisphere also acts as hotspot for biogeochemical cycling of nutrients such as N and S. Intensive human activities of urban and downstream agriculture and aquaculture had great effects on microbial community structure and functional groups of the Urumqi River. Pastisphere communities are much more resistant to human disturbance than planktonic bacteria. Compared to surrounding water, plastisphere increased inheritance from upstream microbial structure and function and also increased survival and propagation of pathogens in the downstream water with high concentrations of antibiotics.

In recent years, implementation of aggressive and strict clean air policies has resulted in significant decline in observed PM₂.₅ concentration in the Beijing–Tianjin–Hebei (BTH) region and its surrounding areas (i.e., the “2 + 26” region). To eliminate the effects of interannual and seasonal meteorological variation, and to evaluate the effectiveness of emission abatement policies, we applied a boosted regression tree model to remove confounding meteorological factors. Results showed that the annual average PM2.5 concentration normalized by meteorology for the “2 + 26” region declined by 38% during 2014–2019 (i.e., from 96 to 60 μg/m³); however, the BTH region exhibited the most remarkable decrease in PM₂.₅ concentration (i.e., a 60% reduction). Certain seasonal trend in normalized PM₂.₅ level remained for four target subregions owing to the effects of anthropogenic emissions in autumn and winter. Although strong interannual variations of meteorological conditions were unfavorable for pollutant dispersion during the heating seasons of 2016–2018, the aggressive abatement policies were estimated to have contributed to reductions in normalized PM₂.₅ concentration of 19%, 10%, 19%, and 17% in the BTH, Henan, Shandong, and Shanxi subregions, respectively. Our study eliminated the meteorological contribution to concentration variation and confirmed the effectiveness of the implemented clean air policies.