The removal of particulate matter (PM) is an important issue in public health and the global atmospheric environment. Various PM removal methods have been suggested to effectively remove PM particles. However, the effects of various factors on PM deposition are not completely clear. We quantitatively investigated the effects of flow and humidity difference in a closed chamber on PM deposition. To elucidate the parameters affecting the deposition of PM particles, PM removal efficiency and deposition constant were examined at different flow rates, flow directions, and relative humidity (RH) inside the closed system. The highest PM deposition rate was achieved under humid condition with the upward direction flow at a fan speed of RPM = 150. Mean velocity fields inside the test chamber were obtained by a particle image velocimetry (PIV) technique to quantitatively examine the effect of flow conditions on the PM deposition. The flow structure and RH inside the closed chamber have significant influence on PM deposition.

Microplastics are an emerging pollutant of high concern, with their prevalence in the environment linked to adverse impacts on aquatic organisms. However, our knowledge of these impacts on freshwater species is rudimentary, and there is almost no research directly testing how these effects can change under ongoing and future climate warming. Given the potential for multiple stressors to interact in nature, research on the combined impacts of microplastics and environmental temperature requires urgent attention. Thus, we experimentally manipulated environmentally realistic concentrations of microplastics and temperature to partition their independent and combined impacts on metabolic and feeding rates of a model freshwater detritivore. There was a significant increase in metabolic and feeding rates with increasing body mass and temperature, in line with metabolic and foraging theory. Experimental warming altered the effect of microplastics on metabolic rate, which increased with microplastic concentration at the lowest temperature, but decreased at the higher temperatures. The microplastics had no effect on the amount of litter consumed by the detritivores, therefore, did not result in altered feeding rates. These results show that the metabolism of important freshwater detritivores could be altered by short-term exposure to microplastics, with greater inhibition of metabolic rates at higher temperatures. The consequences of these metabolic changes may take longer to manifest than the duration of our experiments, requiring further investigation. Our results suggest little short-term impact of microplastics on litter breakdown by gammarid amphipods and highlight the importance of environmental context for a better understanding of microplastic pollution in freshwater ecosystems.

In this study, we present the development of a mobile system to measure real-world total respiratory tract deposition of inhaled ambient black carbon (BC). Such information can be used to supplement the existing knowledge on air pollution-related health effects, especially in the regions where the use of standard methods and intricate instrumentation is limited. The study is divided in two parts. Firstly, we present the design of portable system and methodology to evaluate the exhaled air BC content. We demonstrate that under real-world conditions, the proposed system exhibit negligible particle losses, and can additionally be used to determine the minute ventilation. Secondly, exemplary experimental data from the system is presented. A feasibility study was conducted in the city of La Paz, Bolivia. In a pilot experiment, we found that the cumulative total respiratory tract deposition dose over 1-h commuting trip would result in approximately 2.6 μg of BC. This is up to 5 times lower than the values obtained from conjectural approach (e.g. using physical parameters from previously reported worksheets). Measured total respiratory tract deposited BC fraction varied from 39% to 48% during walking and commuting inside a micro-bus, respectively.To the best of our knowledge, no studies focusing on experimental determination of real-world deposition dose of BC have been performed in developing regions. This can be especially important because the BC mass concentration is significant and determines a large fraction of particle mass concentration. In this work, we propose a potential method, recommendations, as well as the limitations in establishing an easy and relatively cheap way to estimate the respiratory tract deposition of BC.

Groundwater in the Chalk aquifer is an important water resource whose quality has degraded due to fertilizer and pesticide use. Atrazine, classified as a priority substance, has been one of the most applied pesticides and also one of the most frequently detected pesticides in groundwater. The present study investigated the transfer and degradation of atrazine in the unsaturated zone of the Chalk aquifer in Northern France. The study was conducted in an underground quarry (Saint-Martin-le-Noeud), which provides a direct access to the water table and intercepts the unsaturated zone at different depths. The lake and the ceiling percolation of 16 sites throughout the quarry were followed. For 16 sites, the percolating flow rate and lake level were measured and the lake water was sampled for nitrate, atrazine and deethylatrazine (DEA, main degradation product of atrazine) analysis over 2.5 years. High spatial variations in hydrodynamics (percolating flow rate and lake level) and in lake water quality (atrazine between 55±11 and 202±40 ng L−1 and DEA between 269±53 and 1727±345 ng L−1) indicate that the properties of the unsaturated zone influence the transfer and the degradation of atrazine. A counterclockwise hysteresis characterizes the relationship between the lake level and atrazine concentration. Temporal variation shows that the atrazine is transferred through the matrix and fractures with a delay caused by the sorption process that differs in atrazine and DEA. The layer of clay-with-flints is shown to favor the degradation of atrazine near the surface. Preferential pathways may be created below clay-with-flints, through which the transfer of atrazine is quicker.

The Environmental Quality Standards (EQS) directive was an important improvement of long-term water quality monitoring at the European level, leading to the use of sediments and biota as relevant matrices for assessing priority substances under the European Water Framework directive. Currently, commonly accepted sediment EQS for Hg are missing in Europe. In this study we present a new, tiered approach to deriving sediment quality standards for Hg: the derivation of Predicted No-Effect Concentration (PNEC) from data in the literature, followed by adjusting values at regional scale, using ecological field data (macroinvertebrate community assessment) and field sediment ecotoxicity bioassays. The limited set of effect data available for Hg spiked-sediment ecotoxicity tests has resulted in unreliable PNEC values for sediment quality assessment. Field reference sites (n = 40) where the macroinvertebrate community status was assessed as High or Good were used to define the ecological background and threshold levels in sediments in northern Spain. Sediment QS developed in other areas were not suitable for specific basins in our study area, since they were within the range of our Hg background levels. Temporary sediment Quality Standards (QS) for Hg were developed for the Nalón River basin (where several mining districts occur), using field effect-based approaches such as sediment ecotoxicity data from Tubifex tubifex chronic bioassays and ecological assessment of macroinvertebrate communities. A proposal for Hg quality assessment in freshwater sediments of northern Spain is made based on ecologically relevant QS values, providing benchmark values for No-Effect and Effect Hg sediment concentrations.

Conjunctivitis has hazardous effects on patients’ quality of life through influencing school performance, work productivity, and daily activities such as driving. However, limited evidence is available on the contributory role of air pollution on conjunctivitis, particularly in China.We obtained data of 81,351 conjunctivitis outpatients from the largest comprehensive hospitals of four cities, China, between Jan 1, 2013 and Dec 31, 2014. Data on air pollutants, including particulate matter ≤2.5 μm in diameter (PM₂.₅), particulate matter ≤10 μm in diameter (PM₁₀), nitrogen dioxide (NO₂), ozone (O₃) and sulphur dioxide (SO₂) were collected from China National Environmental Monitoring Centre. Conjunctivitis outpatient visits were linked with air pollution concentrations by the visiting dates. A time-stratified case-crossover design with conditional logistic regression model was used to examine the effect of short-term exposure to air pollution on conjunctivitis outpatient visits.We found that the associations between air pollutants (per 10 μg/m³ increase) and hospital outpatient visits for asthma were [odds ratios (ORs) and 95% confidence intervals]: 1.004(1.002–1.007) for PM₂.₅, 1.004 (1.002–1.005) for PM₁₀, 1.012(1.005–1.020) for NO₂, 1.006 (1.001–1.011) for SO₂, and 1.007 (1.003–1.010) for O₃, respectively at lag0 day. Outpatients aged 35–64 years showed significant associations with exposure to PM₂.₅ (1.005, 1.001–1.010), PM₁₀ (1.005, 1.002–1.008), NO₂ (1.014, 1.003–1.026), and O₃ (1.005, 1.000–1.011), while those aged 15–34 years showed significant associations with exposure to O₃ (1.010, 1.004–1.017).Short-term exposure to air pollution has impacts on outpatient visits for conjunctivitis in China. This study suggests that improving air quality could protect eye health.

Lead (Pb) contaminated soil is of particular concern for infants and children due to their susceptibility to exposure, fast metabolic rates and rapidly developing neuronal systems. Determining the bioaccessibility of Pb in soils is critical in human health risk assessments, which can vary due to different soil properties and sources of Pb contamination. In this study, the potential relationships between soil properties and Pb bioaccessibility from various Pb sources including Pb contamination from mining (specifically, Broken Hill), three shooting ranges, a smelter and two industry sites (pottery and battery), were investigated using the Relative Bioavailability Leaching Procedure (RBALP). We found the following: (1) CEC, TOC, sand and silt content, and total Pb were significantly different (p < 0.05) between the two particle size fractions of < 2 mm and < 250 μm; (2) EC, CEC and total Pb were significantly correlated to Pb bioaccessibility (p < 0.05); and (3) soil analyses based on source of Pb demonstrated a strongly significant relationship between Pb bioaccessibility and soil properties (CEC, EC, clay content and total Pb) for mining soils from Broken Hill (r² = 0.86, p < 0.05, n = 18). These results demonstrated the influences of Pb contamination sources, soil properties and particle size fractions on Pb bioaccessibility as well as the prediction of Pb bioaccessibility using soil properties. The findings documented here will help in developing a predictive tool for human health risk assessment and the remediation of Pb contaminated soils.

Red mud, which is from the aluminum industry, is a potentially under-utilized resource. Technological processes for using low-cost red mud as an alternative precursor for detoxifying metal pollutants urgently need to be developed. In this study, we systematically investigated the feasibility of using red mud to detoxify metal-containing wastes (e.g., fly ash) via the formation of preferable crystalline phases. To understand the mechanism of metal detoxification by red mud, CuO, NiO, and ZnO were blended with red mud at different weight ratios and the mixtures were then subjected to ceramic-sintering. After sintering, the X-ray diffraction results revealed that all of the metals (i.e., Cu, Ni, and Zn) were able to be crystallographically incorporated into spinel lattices. Sintering the red mud at 1100 °C for 3 h effectively converted the metals into spinels. The mixing weight ratios strongly affected the efficiency of the metal incorporation. The red mud was able to incorporate 15 wt% of metal oxides. The incorporation mechanisms mainly occurred between the metal oxide(s) and hematite. Modified TCLP tests were conducted to further evaluate the metal stabilization performance of the red mud, which demonstrated the leachabilities of ZnO and the sintered red mud + ZnO product. The concentration of leached metal was substantially reduced after the incorporation process, thus demonstrating that red mud can be successfully used to detoxify metals. The results of this study reveal that waste red mud can be feasibly reused as a promising waste-to-resource strategy for stabilizing heavy metal wastes.

The pollution of antibiotics and antibiotic resistance genes (ARGs) has been highlighted on a global scale because of their serious threats to the environment and human health. Typical urban water in cities with high population density are ideal mediums for the acquisition and spread of antibiotics and ARGs. The pollution level of a broad range of antibiotics and ARGs in hospital wastewater, groundwater and the Wenyu River, and their fates through three sewage treatment plants (STPs) were investigated in this study. The concentrations of the 11 detected antibiotics ranged from not detected (ND)-16800 ng L⁻¹ in diverse water samples from Beijing, and fluoroquinolones were detected at the highest concentration, especially in the hospital samples. The maximum concentrations of antibiotics in STPs and hospital were 1–3 orders of magnitude higher than those in the surface water from Wenyu River and groundwater. Good removal efficiencies by treatment processes were observed for tetracyclines and quinolones, and low removal efficiencies were observed for sulfonamides and macrolides. These results also revealed that the sulfonamide resistance genes (sul1, sul2) and macrolide resistance genes (ermB) were detected at the highest relative abundances (7.11 × 10⁻²-1.18 × 10⁻¹) in the water bodies of Beijing. It was worth noting that sul1 abundance was the highest in groundwater samples. The relative abundance of most ARGs in STPs exhibited a declining trend in the order of influent > secondary effluents > effluent. However, the relative abundance of sul 1, sul 2 and tetC in the effluent was higher than those in the influent. The incomplete removal of antibiotics and ARGs in STPs poses a serious threat to the receiving rivers, and affects ecosystem security. Overall, our findings provide favorable support for a further investigation of the spread and risk of antibiotics and ARGs from diverse sources (e.g., STPs and hospitals) to the aquatic environment.

Evaluating the fate and transport of nanoparticles (NPs) in the subsurface environment is critical for predicting the potential risks to both of the human health and environmental safety. It is believed that numerous environmental factors conspire to control the transport dynamics of nanoparticles, yet the effects of organic phosphates on nanoparticles transport remain largely unknown. In this work, we quantified the transport process of TiO2 nanoparticle (nTiO2) and their retention patterns in water-saturated sand columns under various myo-inositol hexakisphosphate (IHP) or phosphate (Pi) concentrations (0–180 μM P), ferrihydrite coating fractions (λ, 0–30%), ionic strengths (1–50 mM KCl), and pH values (4–8). The transport of nTiO2 was enhanced at increased P concentration due to the enhanced colloidal stability. As compared with Pi at the equivalent P level, IHP showed stronger effect on the electrokinetic properties of nTiO2 particles due to its relatively more negative charge and higher adsorption affinity, thereby facilitating the nTiO2 transport (and thus reduced retention) in porous media. At the IHP concentration of 5 μM, the retention of nTiO2 increased with increasing λ and ionic strength, while decreased with pH. In addition, the retention profiles of nTiO2 showed a typical hyperexponential pattern for most scenarios mainly due to the unfavorable attachment, and can be well described by a hybrid mathematical model that coupled convection dispersion equations with a two-site kinetic model and DLVO theory. These quantitative estimations revealed the importance of IHP on affecting the transport of nTiO2 typically in phosphorus-enriched environments. It provides new insights into advanced understanding of the co-transport of nanoparticles and phosphorus in natural systems, essential for both nanoparticle exposure and water eutrophication.