Soot nanoparticles (SNPs) produced from incomplete combustion have strong impacts on aquatic environments as they eventually reach surface water, where their environmental fate and transport are largely controlled by aggregation. This study investigated the aggregation kinetics of SNPs in the presence of macromolecules including fulvic acid (FA), humic acid (HA), alginate polysaccharide, and bovine serum albumin (BSA, protein) under various environmentally relevant solution conditions. Our results showed that increasing salt concentrations induced SNP aggregation by suppressing electrostatic repulsion and that CaCl2 exhibited stronger effect than NaCl in charge neutralization, which is in agreement with the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. The aggregation rates of SNPs were variously reduced by macromolecules, and such stabilization effect was the greatest by BSA, followed by HA, alginate, and FA. Steric repulsion resulting from macromolecules adsorbed on SNP surfaces was mainly responsible for enhancing SNP stability. Such steric repulsion appeared to be affected by macromolecular structure, as BSA having a more compact globular structure on SNP surfaces imparted long-range steric repulsive forces and retarded the SNP aggregation rate by 10–100 times. In addition, alginate was shown to enhance SNP aggregation by ∼10 times at high CaCl2 concentrations due to alginate gel formation via calcium bridging. The results may bear strong significance for the fate and transport of SNPs in both natural and controlled environmental systems.

Alternative transportation fuels (ATFs) can reduce air pollution. However, the influence of conventional fuels—diesel and gasoline, and particularly ATFs on photochemical air pollution is not well-characterized, limiting assessments of ATFs and air quality. This is mainly due to frequent use of lumped chemical mechanisms by related atmospheric modeling. Here we hypothesized that applying a chemical mechanism that is specifically developed according to both emission fractions and photochemical ozone creation potential of volatile organic compounds (VOCs) is key to gaining reliable insights into the impact of transportation fuels on photochemistry. We used a heterogeneous chemical mechanism with 927 reactions and relatively detailed emission inventories to specifically meet the requirements for reliable simulation of the effect of exhaust emissions from vehicles fueled by selected model fuels—diesel, gasoline, and mixtures of 15% gasoline with 85% ethanol (E85) or 85% methanol (M85)—on photochemistry. These dispersion-box model simulations revealed a strong influence of atmospheric background balance between VOCs and nitrogen oxides (NOX = [NO] + [NO2]) on the impact of exhaust emissions on photochemistry, with higher tendency toward ozone (O3) formation or destruction for more VOC-limited or NOX-limited conditions, respectively. Accordingly, higher [NOX]/[VOC] exhaust emission, such as from diesel and M85, resulted in lower O3, not only locally but also downwind of the emission. This offers a new perspective and measure for transportation fuel assessment. Rapid conversion of O3 to hydroxyl and hydroperoxyl radicals downwind of the exhaust emission indicates the importance of simulating the impact of road transportation on photochemistry at high spatial and temporal resolution. Peroxyacetyl nitrate formation was more sensitive to VOC emission under VOC-limited conditions than to NOX emission under NOX-limited conditions. Secondary formaldehyde dominated over primary emitted formaldehyde several minutes after emission. These findings should be verified using a 3D modeling study under varying meteorological conditions.

In order to exhaustively investigate the physical and chemical mechanisms of heavy metal immobilization in sludge incineration residue (SIR)-based magnesium potassium phosphate cement (MKPC), this work investigated the influence of Pb²⁺ and Zn²⁺ on the compressive strength and microstructure of SIR-based MKPC, and the efficiency of Pb and Zn immobilization. Taking the difference of Ksp (solubility product) of different heavy metal compounds as the entry point, the physical and chemical mechanisms of Pb and Zn immobilization, and the competitive mechanism between coexisting ions, were comprehensively analyzed. It was discovered that Pb²⁺ is in the form Pb₃(PO₄)₂, and Zn²⁺ is immobilized in the form Zn₂(OH)PO₄ [Zn₃(PO₄)₂ is preferentially formed, when the pH > 7, Zn₃(PO₄)₂ is converted to Zn₂(OH)PO₄]. The low solubility of heavy metal phosphates is the main reason that Pb²⁺ and Zn²⁺ are well immobilized. The preferential formation of Pb₃(PO₄)₂ (Kₛₚ = 8 × 10⁻⁴³) and Zn₃(PO₄)₂ (Kₛₚ = 9.0 × 10⁻³³) reduced the amount of MgKPO₄·6H₂O (Kₛₚ = 2.4 × 10⁻¹¹), resulting in a decrease in compressive strength. Besides, coexisting Pb²⁺ and Zn²⁺ has a competitive effect: Pb²⁺ will weaken the immobilization efficiency of Zn²⁺. The new exploration of these mechanisms provide a theoretical basis for rationally adjusting the Magnesia/Phosphate ratio to enhance the compressive strength and improve the efficiency of heavy metals immobilization.

The consumption of tonnes of anti-tubercular and other anti-microbial compounds for the control of the tuberculosis epidemic and other opportunistic diseases associated with human immunodeficiency virus presents tuberculosis-endemic countries such as South Africa, with a problem regarding the occurrence and fate of these compounds in the aquatic environment. The majority of these compounds are not readily degradable and could persist in the aquatic environment with potential detrimental effect on the aquatic microbiota ecosystem, development and dissemination of anti-microbial resistance as well as chronic toxicity in humans due to long-term exposure. This review summarises and discusses the occurrence, fate and potential adverse effects of the commonly administered anti-tubercular compounds in the aquatic environment in tuberculosis-endemic countries and South Africa in particular. It further attempts to identify information gaps in the literature regarding anti-tubercular compounds in the environment that needs further investigation so that their risk can be comprehensively assessed and impact mitigated.

With the increased numbers of nuclear power plants constructed along the east coast of China, it is important to know radioactive sources and transport pathways between land and sea, in order to better understand the impact of these nuclear facilities to the marine environment. Two sediment cores collected from the East China Sea dated to 1959–2010 were analyzed for long-lived radioactive 129I and stable 127I. It was observed that 129I levels (129I/127I ratio of (15.0–75.0) × 10−12) were significantly increased compared to the pre-nuclear value (129I/127I = 1.5 × 10−12). Some 129I peaks were observed in layers of 1959, 1966, 1971 and 1976 (1977), corresponding to the atmospheric nuclear weapon tests at Pacific Proving Grounds and Lop Nor. The high values of 129I after the late 1970s are attributed to the releases from the European reprocessing plants. In addition to ocean current transport, the atmospheric dispersion through the interaction of the Westerlies with East Asia monsoon is the important pathway of large-scale transport of pollutants from high latitude West Europe to middle latitude East Asia. Riverine input is the main transport pathway of radioactive pollutants released from Lop Nor to the East China Sea through the atmospheric dispersion, deposition and runoff processes.

Lead (Pb) both in paints and children's Polyvinyl chloride (PVC) toys is a major public health concern which has attracted attention of the international community. Concentrations of Pb both in lead-based paints and children's PVC toys have been assessed through various studies across the globe. Therefore, the purpose of this article was to summarize the results reported in these studies and provide some comprehension on their implications to human health for law enforcement as well as for awareness raising to the general public. Highlights on identified gaps have been provided to pave ways for further research interventions in order to establish comprehensive information on the subject.Regardless of regulatory limits on the content of lead, both in paints and children's PVC toys existing in different countries in the world, some of the reviewed articles have revealed significant levels of lead in these two items far above the permissible limits.High lead levels in paints have been recorded in China (116,200 ppm), Cameroon (500,000 ppm), South Africa (189,000 ppm), Tanzania (120,862.1 ppm), Uganda (150,000 ppm), Thailand (505,716 ppm) and Brazil (170,258.4 ppm) just to mention a few.Lead poisoning cases in children have been reported in several countries including France, Morocco, South Africa and United States. Countries where high levels of lead in children's PVC toys have been recounted include; China (860,000 ppm), South Africa (145,000 ppm), United States (22,550 ppm), Thailand (4,486.11 ppm), Palestine (6,036 ppm) and India (2,104 ppm).Awareness raising among parents is vital to impart them with knowledge on the matter so that they can take strenuous measures to protect their children from lead poisoning emanating from playing with toys and paint dust. Law enforcement on phasing out lead-based paints and control of lead content in children's PVC toys worldwide is also highly recommended.

Arsenic (As) in rice grains is a serious food safety concern. Some coexisting engineered nanoparticles (ENPs) were shown to alter the accumulation and speciation of As in rice grains. However, investigation on the effects of copper oxide nanoparticles (CuO NPs), a popular ingredient in pesticides, on the uptake and accumulation of As is rare. We explored the potentially different impact of CuO NPs and corresponding Cu(II) ions on the accumulation of two As species in rice seedlings in a hydroponic system. Rice seedlings were treated with a combinations of 1 mg/L of arsenite (As(III)) or arsenate (As(V)) and 100 mg/L of CuO NPs or Cu(II) for 6 days. Both forms of Cu significantly reduced the accumulation of total As in rice tissues, with Cu(II) exhibiting significantly greater effect than CuO NPs. As speciation in rice roots was markedly affected by both forms of Cu, and the impacts were Cu-form dependent. For example, the co-existence of As(V) with CuO NPs led to a 45% decrease of As(V) in rice roots, while the co-existence of As(V) with Cu(II) caused a 47% increase in As(V) in rice roots. As speciation in rice shoots was less affected by co-present Cu than in rice roots. Co-occurring As(III) or As(V) lowered Cu concentration in rice roots by 40% and 50% in treatments with CuO NPs, but did not affect Cu content in rice roots co-exposed to Cu(II). The study confirmed the reciprocal effect of co-occurring CuO NPs or Cu(II) and As in rice paddies and highlighted the unique “nano-effect” of CuO NPs. The results alsos showed that the initial oxidation state of As plays an important role in the interactions between As and Cu. The results shed light on the current debate on the safe applications of nano-enabled agrichemicals vs. conventional metal salts in agriculture.

Bisphenol A (BPA) is an endocrine disruptor whose ubiquitous presence in the environment has been related with impairment of male reproduction. BPA can cause both transcriptomic and epigenetic changes during spermatogenesis. To evaluate the potential effects of male exposure to BPA, adult zebrafish males were exposed during spermatogenesis to doses of 100 and 2000 μg/L, which were reported in contaminated water bodies and higher than those allowed for human consumption. Fertilization capacity and survival at hatching were analysed after mating with untreated females. Spermatogenic progress was analysed through a morphometrical study of testes and apoptosis was evaluated by TUNEL assay. Testicular gene expression was evaluated by RT-qPCR and epigenetics by using ELISA and immunocytochemistry. In vitro studies were performed to investigate the role of Gper. Chromatin fragmentation and the presence of transcripts were also evaluated in ejaculated sperm. Results on testes from males treated with the highest dose showed a significant decrease in spermatocytes, an increase in apoptosis, a downregulation of ccnb1 and sycp3, all of which point to an alteration of spermatogenesis and to meiotic arrest and an upregulation of gper1 and esrrga receptors. Additionally, BPA at 2000 μg/L caused missregulation of epigenetic remodelling enzymes transcripts in testes and promoted DNA hypermethylation and H3K27me3 demethylation. BPA also triggered an increase in histone acetyltransferase activity, which led to hyperacetylation of histones (H3K9ac, H3K14ac, H4K12ac). In vitro reversion of histone acetylation changes using a specific GPER antagonist, G-36, suggested this receptor as mediator of histone hyperacetylation. Males treated with the lower dose only showed an increase in some histone acetylation marks (H3K14ac, H4K12ac) but their progeny displayed very limited survival at hatching, revealing the deleterious effects of unbalanced paternal epigenetic information. Furthermore, the highest dose of BPA led to chromatin fragmentation, promoting direct reproductive effects, which are incompatible with embryo development.

This study examined the spatial and temporal variations of severe particulate pollution days (SPPDs) in China by using observed PM₂.₅ concentrations during April 2013 to February 2018 from the Ministry of Environmental Protection of China. SPPDs were defined as those with observed daily mean PM₂.₅ concentrations larger than 150 μg m⁻³. Observations showed that northern China had the highest number of SPPDs during the studied period. Since 2015, the number of SPPDs in northwestern China is comparable to or even higher than that observed in Beijing-Tianjin-Hebei (BTH). The highest numbers of SPPDs observed within BTH and the Yangtze River Delta (YRD) were 122 (33), 95 (17), 57 (15), 78 (18), and 31 (25) days in 2013, 2014, 2015, 2016, and 2017, respectively, indicating a general decreasing trend as a result of emission reduction measures. SPPDs occurred mainly from November to February in BTH and in December and January in the YRD. The major circulation patterns associated with large-scale SPPDs were analyzed by using principal component analysis. Five typical synoptic weather patterns were identified for BTH. The most dominant weather type (a cold high centered over the Xinjiang and Mongolian regions) for BTH was also responsible for most of the SPPDs in the YRD. These results have important implications for emission control strategies during SPPDs. Emission control measures can be applied once the dominant circulation patterns have been predicted.

Thirteen secondary organic aerosol (SOA) tracers of isoprene, monoterpenes and sesquiterpenes were measured for PM₂.₅ aerosols collected at the summit of Mt. Wuyi (1139 m, a.s.l.), to investigate their seasonality and formation mechanism. Concentrations of the isoprene and monoterpene SOA tracers were much higher in summer than those in other seasons. In contrast, β-caryophyllinic acid was found to be the lowest in summer. Concentrations of those BSOA tracers showed a positive correlation with temperature (R² = 0.52–0.70), and a negative correlation with relative humidity (R² = 0.43–0.78). Moreover, thermodynamic model (i.e., ISORROPIA-II) calculation results showed that acidity conditions are favorable for BSOA formation. Robust linear correlations between the BSOA tracers and anthropogenic pollutants such as SO₂ (R² = 0.53–0.7) and NO₂ (R² = 0.37–0.54) were observed for all the samples, suggesting that SO₂ and NOx can enhance BSOA production in the remote mountain area of southeast China, which is related to an acid-catalyzed heterogeneous chemistry. Moreover, we also found a significant correlation between the concentrations of the BSOA tracers and levoglucosan especially for β-caryophyllinic acid, indicating that biomass burning plumes from the distant lowland regions could influence the production of BSOA in the mountain free troposphere. Our results clearly demonstrated that anthropogenic emissions in China could enhance BSOA formation in the distant mountain regions.