Black carbon (BC) exerts profound impacts on air quality and climate because of its high-absorption cross section over a broad band of solar spectrum. Non-BC materials coated on BC could alter the mixing state of BC particles and can considerably enhance its mass absorption coefficient. Quantification of this absorption enhancement remains a challenge due to incomplete understanding of the complex physical and chemical properties related to mixing states. In this paper, we summarize the recent progress in measurement and modeling studies on the BC mixing state and their effects on optical properties. Laboratory and field-based observations have shown that the transformation of a mixing state from a highly fractal nature to a more compact shape exhibits a decrease in electric mobility diameter but an increase in fractal dimension and effective density. Meanwhile, the transition behavior is also obviously influenced by emission source which can determine the components of BC mixtures. Based on the empirically determined parameters, accurate numerical modeling shows great capability on calculating BC optical properties. However, considering the significant uncertainties related to BC microphysical properties, proper parameterization considering realistic BC aggregates and coating fraction can help to understand the progress from an externally to internally mixed state.

PURPOSE OF REVIEW: The purpose of this review is to summarize the current understandings of atmospheric VOC characteristics in China and put forward the methodological drawbacks of the VOC measurement that need to be resolved and the research gaps that need to be filled. RECENT FINDINGS: Whereas in recent investigations in the North China Plain (NCP) a reduction (20–66%) in total VOC concentration is noticed compared with the ones published before 2015, an increase (13–127%) is observed for the Yangtze River Delta (YRD) region. Aromatics and oxygenated VOCs are frequently appearing as the most abundant VOC group in recent investigations. Industry-related VOC sources are more dominant in the YRD regions while vehicle-related sources are more influential in the NCP, Central China, and Pearl River Delta regions. Benzene, 1,3,5-trimethylbenzene, ethylbenzene, naphthalene, dichloromethane, 1,2-dichloroethane, 1,2-dichloropropane, chloroform, carbon tetrachloride, and 1,2-dibromoethane pose carcinogenic risk to exposed population in China and the most risk-prone areas are affected by the petrochemical industry, biomass burning, waste management, and vehicle emissions. Formaldehyde and toluene have relatively high concentrations among the different indoor VOCs observed and their concentrations noticed to be exceeded the national air quality standard. More investigations have to be performed on rarely studied health risk assessment of VOCs and characterization of indoor VOCs. BVOC studies are rarely conducted in China, which has to be performed on common plant species, different forest, and agricultural crops. VOC characterization in forest fire smokes and more process-specific emission characteristics in common industries need to be conducted.

In 2014–2019, a total of 31 blubber samples were collected from spotted seals (Phoca largha) in the western Sea of Japan. The samples were analyzed by gas chromatography to determine level of organochlorine pesticides (OCPs). The concentration of hexachlorocyclohexane and its isomers (∑HCH) ranged from 389 to 50,070 ng/g lipid weght; the concentration of dichlorodiphenyltrichloroethane and its metabolites (∑DDT), ranged from 62,720 to 1,110,930 ng/g lipid wt. Transfer of HCH and DDT from mother to pup during pregnancy and lactation was documented. The OCP concentration in blubber of spotted seals from the western Sea of Japan is one to two orders of magnitude higher than in spotted seals inhabiting waters off the Japan coast. Organochlorines detected in the western Sea of Japan likely come from some countries of Southeast Asia still using OCPs in the agriculture sector.

The Southern Corniche of Jeddah (SCJ) is located on the centre of the eastern Red Sea coast, Saudi Arabia and is increasingly affected by many anthropogenic activities, making it vulnerable to pollution. Sixty-three sediments and water samples were examined in regard to environmental parameters (temperature, salinity, dissolved oxygen (DO) and pH), grain size, organic matter (OM) and carbonate content and metals concentrations (Fe, Mn, Cu, Pb, Cr, Zn, Ni, and Co) in order to assess the level of contamination in SCJ's bottom sediment. The results showed that the highest concentrations of heavy metals in the shoreline and Lagoon areas are mainly due to the influx of domestic and industrial wastewater into the area where they were correlated with mud, OM, salinity and pH. The contamination factor (CF) for Fe and Co in the bottom sediments exhibited higher values than the threshold 3 value, particularly in the Lagoon and Al-Budhai area. The pollution load index (PLI) values of sediment samples could be classified as contaminated samples, especially in the nearshore samples indicating an increase of metals accumulation with decreasing distance from the source area. PCA has shown that Fe and Mn are positively correlated with all heavy metals, probably due to their high adsorption capacity in the presence of DO. The metals were Normalized with Fe, it was found that the bottom sediments of the SCJ could be reported as metal contaminated and mainly affected by natural and human sources.

Microplastics (MPs) in the surface water of the Qiantang River and its tributaries were investigated in this study, to evaluate the contribution of riverine discharge on emerging pollution load in the Hangzhou Bay. The abundance of MPs (mean 1183 ± 269 particles/m³) showed spatially and temporally heterogeneous in the surface water. Polyamide, polyester, and polyethylene teraphalate were the major components, accounting for 77.4% of all polymer types. Fiber was the most common shape, indicating the potential anthropogenic sources of MPs. The MPs flux from the Qiantang River to the Hangzhou Bay was estimated to be 2831 tons/year, implying the importance of riverine discharge in an estuarine bay. The inputs from the complicated tributaries system led to a 20-fold increase of MPs flux, and would significantly improve their budget of downstream and estuary, so we suggested the control and management on plastic pollution should be strengthened in all aspects.

The anthropogenic impact in the Wouri Estuary Mangrove located in the rapidly developing urban area of Douala, Cameroon, Africa, was studied. A set of 45 Persistent Organic Pollutant were analysed in surficial mangrove sediments at 21 stations. Chlorinated Pesticides (CLPs), Polychlorinated Biphenyls (PCBs) and Polycyclic Aromatic Hydrocarbons (PAHs) have concentrations ranging from 2.2 – 27.4, and 83 – 544 ng/g, respectively. The most abundant CLPs were endosulfan, alachlor, heptachlor, lindane (γ-HCH) and DDT, which metabolites pattern revealed recent use. Selected PAHs diagnostic ratios show pyrolytic input predominantly. The sum of 7 carcinogenic PAHs (ΣC-PAHs) represented 30 to 50% of Total PAHs (TPAHs). According to effect-based sediment quality guidelines, the studied POPs levels imply low to moderate predictive biological toxicity. This study contributes to depict how far water resources are shifting within what is now termed the Anthropocene due to increasing local pressures in developing countries or African countries.

This paper aimed at evaluating the total mercury content in five common fish species from the western European Atlantic coastal waters, and the associated risk of consumption. Mercury concentrations in muscle of Atlantic mackerel (Scomber scombrus), Atlantic chub mackerel (Scomber colias), European anchovy (Engraulis encrasicolus), Atlantic horse mackerel (Trachurus trachurus) and European pilchard (Sardina pilchardus) ranged from 0.003 to 0.20 mg kg⁻¹ wet weight, and no significant differences were observed between the average concentration in each species. A significant increasing trend in mercury content with fish size was observed for all species (except for European anchovy), suggesting mercury bioaccumulation throughout their life cycle. Still, the mercury content was far below the European Food Safety Authority and World Health Organization food safety thresholds in all species, highlighting the low risk to human health due to the ingestion of these species and the importance of consumer options for risk reduction.

The seabed off North West Europe contains much unexploded ordnance (UXO), posing a hazard to offshore developments such as windfarms. The typical removal method is through high-order detonation of a donor charge placed adjacent to the UXO. This method poses a risk of injury or death to marine mammals and other fauna from the high sound levels produced. This paper describes a controlled field experiment to compare the sound produced by high-order detonations with a low-order disposal method called deflagration, which uses a shaped charge of modest size, is less energetic, and offers reduced environmental impact from lower acoustic output. The results demonstrate a substantial reduction over high order detonation, with the peak sound pressure level and sound exposure level being more than 20 dB lower for the deflagration, and with the acoustic output depending only on the size of the shaped charge (rather than the size of the UXO).

A total of 23 sediment samples are collected from Ross Sea and Drake Passage to investigate the distribution characteristics of polychlorinated biphenyls (PCBs) in the Antarctic marine sediments. Over 51 kinds of PCBs are detected through exhaustive searches using multiple reaction monitoring system. The results show that the concentration of individual PCB congener and total PCBs vary greatly among sampling sites, ranging from not detected to 49.75 ng g⁻¹ and 3.77 to 246.86 ng g⁻¹, respectively. The average PCBs level in Ross Sea is ten times higher than that in Drake Passage. Two different homologues, hexa- and tetra-CBs, give high contributions to ∑PCBs level in most samples from Ross Sea and Drake Passage, respectively. Our results support that the marine sediments might be an important sink for PCBs. Besides, the biological pump and the primary productivity might be responsible for the distribution differences of PCBs between Ross Sea and Drake Passage.

We sought to determine mercury (Hg) and other trace metal concentrations in Adélie (Pygoscelis adeliae) and emperor penguin (Aptenodytes forsteri) breast feathers from the Ross Sea, Antarctica, and relate those concentrations to the trophic position and the habitats in which each of these species forage. Adélie penguin feathers from the southern Ross Sea colonies were higher in Hg than those sampled further north in the Ross Sea, potentially due to greater exposure to local sources, such as volcanism. Female Adélie penguins had lower feather total Hg concentrations than males. This may reflect female penguin's capacity to eliminate Hg through the egg development and laying process, or the larger and/or older prey items that male birds can consume, reflected by their higher trophic position. Emperor penguins have higher Hg concentrations than Adélie penguins which is also partially explained by Adélie penguins feeding at lower trophic levels than emperor penguins.