Forest understory plant communities in the eastern United States are often diverse and are potentially sensitive to changes in climate and atmospheric inputs of nitrogen caused by air pollution. In recent years, empirical and processed-based mathematical models have been developed to investigate such changes in plant communities. In the study reported here, a robust set of understory vegetation response functions (expressed as version 2 of the Probability of Occurrence of Plant Species model for the United States [US-PROPS v2]) was developed based on observations of forest understory and grassland plant species presence/absence and associated abiotic characteristics derived from spatial datasets. Improvements to the US-PROPS model, relative to version 1, were mostly focused on inclusion of additional input data, development of custom species-level input datasets, and implementation of methods to address uncertainty. We investigated the application of US-PROPS v2 to evaluate the potential impacts of atmospheric nitrogen (N) and sulfur (S) deposition, and climate change on forest ecosystems at three forested sites located in New Hampshire, Virginia, and Tennessee in the eastern United States. Species-level N and S critical loads (CLs) were determined under ambient deposition at all three modeled sites. The lowest species-level CLs of N deposition at each site were between 2 and 11 kg N/ha/yr. Similarly, the lowest CLs of S deposition, based on the predicted soil pH response, were less than 2 kg S/ha/yr among the three sites. Critical load exceedance was found at all three model sites. The New Hampshire site included the largest percentage of species in exceedance. Simulated warming air temperature typically resulted in lower maximum occurrence probability, which contributed to lower CLs of N and S deposition. The US-PROPS v2 model, together with the PROPS-CLF model to derive CL functions, can be used to develop site-specific CLs for understory plants within broad regions of the United States. This study demonstrates that species-level CLs of N and S deposition are spatially variable according to the climate, light availability, and soil characteristics at a given location. Although the species niche models generally performed well in predicting occurrence probability, there remains uncertainty with respect to the accuracy of reported CLs. As such, the specific CLs reported here should be considered as preliminary estimates.

The biological effects of nanoplastics are a growing concern. However, most studies have focused on exposure to high concentrations or short-term exposure. The potential effects of exposure to low environmental nanoplastic concentrations over the long-term and across multiple generations remain unclear. In the present study, Daphnia pulex was exposed over three 21-day generations to a typical environmental nanoplastic concentration (1 μg/L) and the effects were investigated at physiological (growth and reproduction), gene transcription and enzyme activity levels. Chronic exposure did not affect the survival or body length of D. pulex, whereas the growth rate and reproduction were influenced in the F2 generation. Molecular responses indicated that environmental nanoplastic concentrations can modulate the response of antioxidant defenses, vitellogenin synthesis, development, and energy production in the F0-F1 generations, and prolongation resulted in inhibitory effects on antioxidant responses in F2 individuals. Some recovery was observed in the recovery group, but reproduction and stress defenses were significantly induced. Taken together, these results suggest that D. pulex recovery from chronic exposure to nanoplastic may take several generations, and that nanoplastics have potent long-term toxic effects on D. pulex. The findings highlight the importance of multigenerational and chronic biological evaluations to assess risks of emerging pollution.

Due to high global demand, large amounts of abbattoir waste are generated from pork production. Mismanagement of abattoir waste on agricultural lands can result in soil and water contamination with pathogens and contaminants like metals and nutrients. Therefore, possible effects on soil organisms prior to application should be evaluated. Thus, the aim of this study was to determine the effects of fresh pig abattoir waste (PAWf) and waste after stabilization processes on E. andrei through tests of avoidance behavior, acute toxicity and chronic toxicity. In order to do this, the waste was evaluated fresh (i.e., non-treated), and after aerated composting (PAWa), natural composting (PAWn) and vermicomposting (PAWv). In addition, we used a natural soil with no history of agricultural use as control soil. The evaluation was based on avoidance behavior, mortality, initial and final earthworm weight, and reproduction, in addition to a set of enzyme assays formed by acetylcholinesterase, lipid peroxidation, catalase and glutathione S-transferase measured over time. The ecotoxicological results showed that PAWf and PAWa increased AChE activity at different experimental periods, while PAWn decreased activity at 14 days compared to the control. PAWf and PAWa increased TBARS levels at 7 and 14 days, respectively. CAT activity decreased at 3, 7 and 14 days in PAWv, while GST activity increased at 3 days in PAWa and at 3 and 14 days in PAWf compared to the control. In the acute toxicity test, PAWa and PAWn had a toxic effect on E. andrei, resulting in 100% mortality at 14 days of exposure. Based on our findings, pig abattoir waste should undergo vermicomposting prior to agricultural application to soils.

Mosses are frequently used to monitor atmospheric metal contamination but few studies on metal adsorption under controlled conditions are available. Here, the accumulation of the heavy metals copper and zinc was studied in the acrocarp moss Atrichum undulatum. An in vitro culture of A. undulatum was established and the same line, size and equally old remets were exposed to six different treatments representing various metal exposure times and washing scenarios as rain simulation. The metal treatments were done in copper and zinc salts (Cu-acetate, CuSO4, ZnSO4 and ZnCl2, respectively). Energy-Dispersive X-ray microanalysis (EDX) was employed to detect bound heavy metals on the moss plantlets. Element distribution in stems and leaves was measured separately. The aqueous solution of metal salts facilitated an adsorption of both elements in the moss tissue as compared to solid medium. Furthermore, A. undulatum can tolerate pollution of zinc and copper in a distinctive extent; our data point towards a higher zinc tolerance whereas copper is rather harmful. However, semi-quantitatively, less zinc was detected within the moss tissue compared to copper. Interestingly, a strong positive correlation between the accumulation of copper/zinc and iron, and a strong negative correlation between copper/zinc and magnesium, respectively, was documented.

Marine and freshwater plastic pollution is a challenging issue receiving large amounts of research and media attention. Yet, few studies have documented the impact of microplastic ingestion to aquatic organisms. In the Pacific Northwest, Chinook salmon are a culturally and commercially significant fish species. The presence of marine and freshwater microplastic pollution is well documented in Chinook salmon habitat, yet no research has investigated the impacts to salmon from microplastic ingestion. The majority of the marine microplastics found in the Salish Sea are microfibers, synthetic extruded polymers that come from commonly worn clothing. To understand the potential impacts of microfiber ingestion to fish, we ran a feeding experiment with juvenile Chinook salmon to determine if ingested fibers are retained or digestion rates altered over a 10 day digestion period. The experiment was completed in two trials, each consisted of 20 control and 20 treatment fish. Treatment fish were each fed an amended ration of 12 food pellets spiked with 20 polyester microfibers and control fish were fed the same ration without added microfibers. Fish were sampled at day 0, 3, 5, 7, and 10 to assess if fibers were retained in their gastrointestinal tract and to determine the rate of digestion. Fibers for the experiment came from washing a red polyester fleece jacket in a microfiber retention bag. Fibers had a mean length of 4.98 mm. Results showed fish were able to clear up to 94% of fed fibers over 10 days. Differences in mean gastrointestinal mass were not statistically significant at any sampled time between treatment and controls, suggesting that the ingestion of microfibers did not alter digestion rates. Further work is needed to understand if repeated exposures, expected in the environment, alter digestion or food assimilation for growth.

Airborne particulate matter (PM) contains numerous hazardous polycyclic aromatic hydrocarbons (PAHs) as well as their functionalized congeners. However, the lack of useful methods to identify the sources of PM has hindered the development of researches in atmospheric and public health fields. This report proposes a new method for estimating the source contribution of combustion-derived particulate (Pc) by using 1-nitropyrene (1-NP) and pyrene (Pyr) as markers. This is premised on the fact that the formation of nitrogen oxides in the flame gas and the subsequent nitration of PAHs are functions of combustion temperature and therefore the concentration ratios of NPAHs to PAHs are highly temperature dependent. This method divides combustion sources into two groups - high and low temperatures - which here are respectively represented by automobile engine and coal combustion in urban areas. Formulae are derived for combustion-derived particulate (Pc), whose fraction in the total particulate is y (0 < y < 1), and particulates from combustion sources with high temperatures (Pₕ), whose fraction in Pc is x (0 < x < 1), and low temperatures (Pₗ), whose fraction is (1 －x). When concentrations of 1-NP and Pyr in Pₕ and Pₗ are known, values x and y can be calculated from the formulae by determining atmospheric 1-NP and Pyr concentrations at monitoring sites. Then atmospheric concentrations of Pc, Pₕ and Pₗ can be calculated. The proposed method has been applied for total suspended particulate matter (TSP) samples collected in Kanazawa and Kitakyushu (Japan) and Beijing (China) having different types of atmospheric pollution to clarify the change of contributions of automobiles and coal combustion.

In this study, the light absorption properties of fine organic aerosols from the burning emissions of four biomass materials were examined using UV-spectrophotometry and Aethalometer-measurements, respectively. For wood chips and palm trees, the burning experiments were carried out with different combustion temperatures (200, 250, and 300 οC) in an adjustable, electrically heated combustor. The light absorptions of water and methanol extracts of aerosols, and smoke particles showed strong spectral dependence on the burning emissions of all biomass materials. However, the burning aerosols of wood chips showed stronger absorption than those of the other biomass burning (BB) emissions. For the burning aerosols of wood chips and palm trees, organic carbon/elemental carbon (OC/EC) decreased as the combustion temperature increased from 200 to 300 °C. Absorption Ångström exponent (AAE) values tended to decrease when combustion temperature increased for smoke aerosols and methanol extracts in smoke samples. The mass absorption efficiency at 365 nm (MAE₃₆₅, m² g⁻¹∙C⁻¹) of water- and methanol-extractable OC fractions was highest in wood chip burning smoke samples. MAE₃₆₅ values of methanol extracts for rice straw, pine needles, wood chips, and palm trees burning emission samples were 1.35, 0.92, 2.36–3.37, and 0.86–1.42, respectively. For wood chip and palm tree burning emissions, AAE₃₂₀–₄₃₀ₙₘ values of methanol extracts were strongly correlated with OC/EC (i.e., combustion temperature) with slopes of 0.11 (p < 0.001) and 0.02 (p < 0.001), and R² values of 0.87 and 0.74, respectively. Moreover, a linear regression between MAE₃₆₅ of methanol extractable OC and OC/EC showed slopes of −0.05 (p < 0.001) and −0.004 (p < 0.001) and R² of 0.72 and 0.74, respectively. The results of this study clearly demonstrate that burning condition and biomass type influence the light absorption properties of organic aerosols from BB emissions.

Previous epidemiological studies have indicated that prenatal exposure to individual metals affect fetal growth. However, the ordinary linear regression has not enough power to assess the mixture effect of multiple metals and cannot capture the possible differences in associations of metal exposures by subgroups of infant birth weight distribution. To investigate the associations of prenatal exposure to metal mixtures with birth weight, and further to assess whether the sensibilities to metal toxicity are dissimilar among infants with poor and normal fetal growth. A total of 16 metals were analyzed in 736 cord samples from a Chinese birth cohort study. Weighted quantile sum regression (WQSR) found the estimate of the metal mixtures was negatively related to birthweight z-score overall [β (95% CI): −0.31 (−0.42, −0.20)], and the major contributors to the mixture index were Cu (39.7%), Ni (18.3%), Mn (14.0%), and Cd (13.1%). Quantile regression showed stronger relations in the tails of birthweight z-score distribution [e.g. the associations of Cu at specific birth weight z-score quantiles were: 10th percentile −0.70 (95% CI: −1.06, −0.35), the 90th percentile −0.35 (95% CI: −0.63, −0.06)]. Our study found that prenatal exposure to Cu, Mn, Ni, and Cd were negatively linked with birthweight z-score. The associations observed were stronger in the tails of birth weight z-score distribution.

Currently, wastewater treatment plant (WWTP) upgrades have been implemented in various countries to improve the water quality of the receiving ecosystems and protect aquatic species from potential deleterious effects. The impact of WWTP upgrades on biological communities and functions in receiving waters is a fundamental issue that remains largely unaddressed, especially for microbial communities. Here, we selected two wastewater-dominant rivers in Beijing (China) as study sites, i.e., one river receiving water from an upgraded WWTP to explore the impacts of upgrade on aquatic ecosystems and another river receiving water from a previously upgraded WWTP as a reference. After a five-year investigation, we found that WWTP upgrade significantly decreased total organic nitrogen (N) in the receiving river. As a biological response, N-metabolism-related bacterioplankton are accordingly altered in composition and tend to intensively interact according to the network analysis. Metagenomic analysis based on the N-cycling genes and metagenomic-assembled genomes revealed that WWTP upgrade decreased the abundance of nitrifying bacteria but increased that of denitrifying and dissimilatory nitrate reduction to ammonium (DNRA) bacteria in the receiving river, according to their marker gene abundances. After calculation of the ratios between DNRA and denitrifying bacteria and quantification of genes/bacteria related to ammonium cycling, we deduced the changes in N-metabolism-related bacteria are likely an attempt to provide enough bioavailable N for plankton growth as conservation of ammonium was enhanced in receiving river after WWTP upgrade.

Problems with PM₂.₅ pollution in the Pearl River Delta (PRD) have been significantly reduced since the Chinese government released a series of emission control policies including the strengthened controls in the 13ᵗʰ Five-Year Plan. This study assessed the efficacy of emission control measures using the Community Multiscale Air Quality (CMAQ) model to provide data-driven support to government decision making, which is becoming increasingly important. This study aimed to quantitatively evaluate the integrated results of proposed policies for controlling PM₂.₅ concentrations. Accordingly, the regional 2015 emission inventory was modified with recently released government data for the PRD, and scenarios for four dynamical emission-reduction policies (S1–S4) were explored. The results show that all four proposed control measures can help to reduce PM₂.₅ concentrations throughout Hong Kong (HK), Macao, and the PRD economic zone (PRD EZ) by 2020. In all cases, reductions in PM₂.₅ concentrations were larger over PRD EZ than over HK. For HK, the predicted annual concentrations of PM₂.₅ were less than 20 μg/m³ for S1–S3 and less than 15 μg/m³ for S4. For Macao, the predicted annual concentrations of PM₂.₅ were less than 25 μg/m³ for S1 and less than 15 μg/m³ up to S3. Regionally, HK had the lowest PM₂.₅ levels, and the area around Foshan had the highest. Controlling the sources of air pollution (i.e., industry, transport, power production, and other sources) within PRD can get most of the PRD EZ region to below 35 μg/m³. Similar national air quality management efforts could reduce PM₂.₅ levels to less than 25 μg/m³ in the PRD EZ and less than 15 μg/m³ in HK. Control measures in S1 led to significant improvement in Shenzhen and HK, but the S3 option brought the greatest improvement for PRD EZ and Macao. The S4 policy option led to substantial reductions, particularly for HK.