Air quality in the State of Sao Paulo was evaluated during the first general State plan of mobility restrictions due to the COVID-19 pandemic (24th March to May 31, 2020). Nitrogen dioxide (NO₂), ozone (O₃), particulate matter PM₁₀ and PM₂.₅ and sulphur dioxide (SO₂) concentrations were assessed in cities of the Sao Paulo State with a monitoring station and compared to historical data. Linear regression models were built to investigate the relationship between the isolation of the population – determined using mobile phone monitoring data - and the concentration of each pollutant during the studied period. Although the reduction of pollutants such as NO₂, SO₂ and PM₂.₅ is very clear, the economic and climatic characteristics of each region were decisive in the general behaviour of O₃ and PM₁₀. It was not possible to establish a correlation between the pollutants and the isolation index, partly due to the lack of data, partly due to the compliance of the population to those measurements, which was variable over time. Another important limitation factor was the absence of data related to the pollutants of interest in many of the stations. However, the isolation measures carried out in the State opened the opportunity to individually assess the air quality measurements in each of the stations, enabling an understanding that will allow in the future the design of air quality policies together with local sanitary policies.

With the phase-out of legacy halogenated flame retardants (HFRs), such as decabromodiphenyl ether (BDE-209), emerging ones, such as decabromodiphenyl ethane (DBDPE), are being widely produced. We conducted field campaigns to assess the trophic transfer of legacy and emerging HFRs in estuarine and coastal food webs of Laizhou Bay, which are located near the largest HFR manufacturing base in China. Seawater, sediment, plankton, invertebrates, and fish were collected from both sites. BDE-209 was the predominant compound in the estuary, whereas DBDPE was the main contributor to HFRs in the bay, followed by BDE-209. Invertebrates, especially bivalves and sea cucumbers, showed higher levels of BDE-209 and DBDPE than fish. The HFR levels in the organisms of the two coastal zones were comparable to each other, although their concentrations in the estuarine water were one order of magnitude higher than those in the bay. The HFR profiles in benthic organisms were similar to those in the sediments, indicating that the bioaccumulation of HFRs in coastal food webs depended on the habitat. The ΣHFR concentrations followed the order filter-feeding > carnivorous for invertebrates, and demersal non-migratory fish showed higher HFR levels than oceanodromous fish. The trophic magnification factors estimated for BDE-209, dechlorane plus, and DBDPE were lower than 1, suggesting biodilution potential in both food webs, whereas several PBDE congeners exhibited biomagnification capacity. Feeding habits, habitats, hydrophobicity, bioavailability, and metabolism may be the main factors impacting the bioaccumulation of HFRs in organisms in estuarine–coastal ecosystems of northern China.

Sulfonated and hydroxy-sulfonated PCBs were recently discovered by our group as new PCB soil contaminants, constituting about 1% of their parent compounds in soil. Here we investigate for the first time the bioaccumulation of these metabolites as well as hydroxy-PCBs and native PCBs in earthworms. A sequence of three experiments, at increasing complexity and ecological realism, were performed with four different earthworm species (Eisenia foetida Savigny, Lumbricus terrestris L, Allolobophora chlorotica Savigny and Aporrectodea caliginosa Savigny) exposed to contaminated soils. The first experiment confirmed that when exposing earthworms to soil contaminated with a single hexa-chlorinated congener (PCB 155), no formation of polar metabolites in earthworms could be detected. This allowed to plan the following two experiments, using a soil from a PCB contaminated site and rich in relatively high levels (10–130 μg kg⁻¹) of hydroxy-, sulfonated-, and hydroxy-sulfonated-PCBs. Bioaccumulation factors (BAFs) and bioconcentration factors (BCFs) were then obtained in the second and third experiments, to compare the accumulation behavior of these chemicals in laboratory and natural conditions. Regressions between BAF/BCF and Log Kow/Log D, produced a variety of results, being generally significant between BCF and PCBs and not significant in the other cases. In general, the metabolites accumulated in earthworms with detectable concentrations in their tissues (8–115 μg kg⁻¹), although sulfonated and hydroxy-sulfonated PCBs showed BAF and BCF values lower (up to two orders of magnitude) than those calculated for the parent PCBs, given their lower lipophilicity.

In the past several decades, a variety of efforts have been made in the United States to improve air quality, and ambient particulate matter (PM) concentrations have been used as a metric to evaluate the efficacy of environmental policies. However, ambient PM concentrations result from a combination of source emission rates and meteorological conditions, which also change over time. Dispersion normalization was recently developed to reduce the influence of atmospheric dispersion and proved an effective approach that enhanced diel/seasonal patterns and thus provides improved source apportionment results for speciated PM mass and particle number concentration (PNC) measurements. In this work, dispersion normalization was incorporated in long-term trend analysis of 11–500 nm PNCs derived from particle number size distributions (PNSDs) measured in Rochester, NY from 2005 to 2019. Before dispersion normalization, a consistent reduction was observed across the measured size range during 2005–2012, while after 2012, the decreasing trends slowed down for accumulation mode PNCs (100–500 nm) and reversed for ultrafine particles (UFPs, 11–100 nm). Through dispersion normalization, we showed that these changes were driven by both emission rates and dispersion. Thus, it is important for future studies to assess the effects of the changing meteorological conditions when evaluating policy effectiveness on controlling PM concentrations. Before and after dispersion normalization, an evident increase in nucleation mode particles was observed during 2015–2019. This increase was possibly enabled by a cleaner atmosphere and will pose new challenges for future source apportionment and accountability studies.

The low value of nitrogen use efficiency (NUE) (around 30%) of crop production in China highlights the necessity to adopt reasonable N managements in national scale. After the implementation of ‘National Soil Testing and Formulated Fertilization’ program in 2005, many field experiments have reported an increase of NUE for crop productions in China. This has prompted discussion regarding the extent to which NUE in crop production has been improved. Here, we analyzed the temporal and spatial changes in NUE (crop N uptake/total N input) and cumulative synthetic and non-synthetic N fertilizer recovery efficiency of crop production in China during 1980–2014, and evaluated the relationship between NUE and economic growth (purchasing power parity, PPP) at national and provincial scale. The results showed that the overall NUE of crop production in China clearly increased from 35 to 42% during 2003–2014, and an increase in NUE was further evidenced by increases in cumulative recovery efficiency of both synthetic and non-synthetic N fertilizer. The relationship between NUE and PPP can be described by an environmental Kuznets curve at the national scale, with NUE first decreasing then increasing with PPP. However, this relationship exhibited large spatial variation: 1) In economically developed (e.g., Guangdong and Zhejiang) and undeveloped provinces (e.g., Yunnan and Guizhou), NUE generally decreased and then remained at low levels (20–35%) as PPP increased. 2) In major agricultural provinces with high (e.g., Shandong and Jiangsu) or intermediate levels (e.g., Hunan and Hebei) of economic development, a pronounced increasing trend in NUE with PPP was observed. These results highlight the necessity of developing region-oriented N management strategies to further increase the NUE of crop production in China, particularly in the economically developed and undeveloped provinces.

Chlorpyrifos (CPF), as an organophosphate insecticide extensively used in the modern agricultural system, has been gradually banned in many countries due to its reported health risks to organisms, including humans. This study used simulated paddy field experiments and carbon-14 tracing to explore the possibility of reducing environmental risks of chlorpyrifos application through appropriate agronomic practice. Results showed ¹⁴C-CPF concentration in rice plants planted in the red soil (RS) was significantly higher than that in black soil (BS) and fluvo-aquic soil (FS). The application of biochar and chicken manure in RS reduced ¹⁴C-CPF accumulation in rice plants, and the content of ¹⁴C-CPF in rice grains decreased by 25% and 50%, respectively. Adding biochar to all three soils reduced the migration of ¹⁴C-CPF, especially in FS with the highest risk of ¹⁴C-CPF migration. The addition of chicken manure in FS reduced the migration of ¹⁴C-CPF and the total residual amount of ¹⁴C-CPF in the soil. In addition, chicken manure treatment increased the formation of ¹⁴C-bound residues (BRs) in soils and changed the distribution ¹⁴C-BRs in humus. The results indicated that the degree of environmental risks associated with the CPF application varies with soil types and could be reduced by introducing suitable exogenous organic matter into different soils, which is of great significance for guiding the scientific application of chlorpyrifos in agronomic practices.

Neonicotinoids are among the chemicals most widely used against insects considered agricultural pests, although they may also affect nontarget species, as has been reported for social bees. Social wasps are recognized as efficient predators of larvae of other insects, including pest species, so they may have contact with insecticides, at least indirectly. However, to date, there have been no studies investigating the consequences for social wasps of the use of neonicotinoids. Therefore, the aim of this study was to obtain the topical and oral acute lethal mean doses of the neonicotinoid thiamethoxam, as well as to evaluate the effects of sublethal contamination, for the social wasp Polybia paulista. Foraging wasps were exposed orally and topically, with monitoring of their mortality after 24 and 48 h, in order to calculate the LD₅₀ values. Other wasps were then exposed with sublethal doses, in order to evaluate the effects of contamination on their mobility. The results indicated that P. paulista workers are as sensitive to thiamethoxam contamination as several nontarget species studied previously. Exposure to a sublethal dose (LD₁₀) negatively affected their mobility. It could be concluded that social wasp colonies may be as much affected by exposure to neonicotinoids as social bees. Further toxicological studies should be conducted, evaluating other parameters and different species, in order to understand the extent of the problems faced by these insects due to the use of neonicotinoids.

It is of great significance to explore the remediation pattern in actual heavy metal (HM) contaminated sites. The field trial was carried out to research the remediation effect of biochar near a lead-zinc smelter in Feng County, China, under the rotation condition of different crops. This kind of cultivation mode is very representative in northern of China. And the pattern of production and restoration is suitable for scarce land resources and large food demand in China. The changes of soil physiochemical properties with the biochar addition, crop growth and the accumulated HMs by crops were focused on. The results showed the biochar application was excellent in improving soil nutrient elements and crop growth. The contents of TK were more obvious than those of TN and TP, with an increase of 2.6%–28.2% compared with the controls (without the addition of biochar). The yield of first season crops, i.e., soybean and corn, increased by 30%–42% and 34%–61%, respectively, and the second season crops, i.e., rape and wheat, with the increment of 25%–41% and 9%–29%, respectively. The availability forms of Cd and Pb decreased by 1.07–10.0% and 2.92–8.35%, respectively. While the improvement on the status of the HMs accumulated by crops was disappointing. The contents of HMs accumulated by crops increased to varying degrees (e.g., Pb and Zn in root, Cu and Pb in grain, and Cd in stems and leaves). Moreover, the concentrations of HMs in seeds of crops were higher than the limited levels given by the Chinese directive. Considering the results of the study and food safety, it is suggested to change the nature of the land around the smelter into woodland or construction land to prohibit the cultivation of food crops in this area.

2,4,6-trinitrotoluene (TNT) is a highly toxic explosive that contaminates soil and water and may interfere with the degradation of co-occurring compounds, such as hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). We proposed that TNT may influence RDX-degrading bacteria via either general toxicity or a specific effect on the |RDX degradation mechanisms. Thus, we examined the impact of TNT on RDX degradation by Rhodococcus strains YH1, T7, and YY1, which were isolated from an explosives-polluted environment. Although partly degraded, TNT did not support the growth of any of the strains when used as either sole carbon or sole nitrogen sources, or as carbon and nitrogen sources. The incubation of a mixture of TNT (25 mg/l) and RDX (20 mg/l) completely inhibited RDX degradation. The effect of TNT on the cytochrome P450, catalyzing RDX degradation, was tested in a resting cell experiment, proving that TNT inhibits XplA protein activity. A dose-response experiment showed that the IC50/trans values for YH1, T7, and YY1 were 7.272, 5.098, and 9.140 (mg/l of TNT), respectively, illustrating variable sensitivity to TNT among the strains. The expression of xplA was also strongly suppressed by TNT. Cells that were pre-grown with RDX (allowing xplA expression) and incubated with ammonium chloride, glucose, and TNT, completely transformed into their amino dinitrotoluene isomers and formed azoxy toluene isomers. The presence of oxygen-insensitive nitroreductase that enable reduction of the nitro group in the presence of O2 in the genomes of these strains suggests that they are responsible for TNT transformation in the cultures. The experimental results concluded that TNT has an adverse effect on RDX degradation by the examined strains. It inhibits RDX degradation due to the direct impact on cytochrome P450, xplA, or its expression. The tested strains can transform TNT independently of RDX. Thus, degradation of both compounds is possible if TNT concentrations are below their IC50 values.

The adsorption of hydrophobic organic compounds (HOCs) by microplastics (MPs) has attracted great attention in recent years. However, the ultimate environmental fate of the HOCs sorbed on MPs (HOCs-MPs) is poorly understood. In this work, we investigated the potential influence of the biotransformation process on the environmental fate of phenanthrene (PHE, a model HOC) sorbed on MPs (PHE-MPs) under the existence of humic acid (HA, the main ingredient of dissolved organic matter (DOM)) in the aquatic environment. The results indicated that the adsorption behavior of PHE on MPs decreased its bioavailability and thus inhibited its biotransformation efficiency. However, HA significantly promoted the biodegradation rate and percentage of PHE-MPs. This was probably because HA improved the desorption of PHE from MPs, which promoted the acquisition of PHE by bacteria from the aqueous phase. Further, HA dramatically increased the bacterial community diversity and richness and altered the community composition. The richness of some PHE-degrading bacteria, such as Methylobacillus and Sphingomonas, significantly increased, which may also be an important factor for promoting PHE biodegradation. Molecular ecological network analysis implied that HA enhanced the modularity and complexity of bacterial interaction networks, which was beneficial to maintaining the functional stability of the consortium QY1. Besides, HA decreased the cytotoxicity of functional microbes induced by HOCs-MPs. This work broadens our knowledge of the environmental fate of HOCs-MPs and interactions of MPs, HOCs, DOMs and functional microbial consortiums in aqueous environments.