Polyhalogenated carbazoles (PHCZs) have attracted mounting environmental concerns since they were recently discovered in sediments and soil. Current knowledge on their occurrence, environmental behavior and fate remains very limited in general. In the present study, 11 PHCZ congeners were screened in surface sediments of Lake Tai, an important freshwater system located in the Yangtze River Delta, China. Total concentrations of PHCZs (∑PHCZs) ranged up to 15.8 ng/g dry weight (median: 1.54 ng/g dw), rivaling those of polybrominated diphenyl ethers (∑PBDEs, 0.07–15.9 ng/g dw) in the same sediments. The PHCZ congener composition profiles revealed a dominance of 3,6-dichlorocarbazole and 3,6-dibromocarbazole with comparable concentrations. These two dominant congeners differed in spatial distribution patterns in Lake Tai, indicating different sources or origins. Potential toxic effects associated with the levels of PHCZs in the sediments were evaluated via the toxic equivalent (TEQ) approach. The TEQs of PHCZs in Lake Tai sediments ranged up to 1.36 pg TEQ/g dw. As the first report on the occurrence of PHCZs in an Asian waterbody, our findings suggest that PHCZs should be given more attention during environmental monitoring and risk assessments of hazardous chemicals, as they may represent another group of persistent organic pollutants with dioxin-like effects and wide distributions.

To constrain sources of anthropogenic nitrogen (N) deposition is critical for effective reduction of reactive N emissions and better evaluation of N deposition effects. This study measured δ¹⁵N signatures of nitrate (NO3⁻), ammonium (NH4⁺) and total dissolved N (TDN) in precipitation at Guiyang, southwestern China and estimated contributions of dominant N sources using a Bayesian isotope mixing model. For NO3⁻, the contribution of non-fossil N oxides (NOx, mainly from biomass burning (24 ± 12%) and microbial N cycle (26 ± 5%)) equals that of fossil NOx, to which vehicle exhausts (31 ± 19%) contributed more than coal combustion (19 ± 9%). For NH4⁺, ammonia (NH3) from volatilization sources (mainly animal wastes (22 ± 12%) and fertilizers (22 ± 10%)) contributed less than NH3 from combustion sources (mainly biomass burning (17 ± 8%), vehicle exhausts (19 ± 11%) and coal combustions (19 ± 12%)). Dissolved organic N (DON) accounted for 41% in precipitation TDN deposition during the study period. Precipitation DON had higher δ¹⁵N values in cooler months (13.1‰) than in warmer months (−7.0‰), indicating the dominance of primary and secondary ON sources, respectively. These results newly underscored the importance of non-fossil NOx, fossil NH3 and organic N in precipitation N inputs of urban environments.

The aim of the present study was to determine the effect of activated carbon (AC) or biochars on the bioaccessibility (Cbioacc) of polycyclic aromatic hydrocarbons (PAHs) in soils vegetated with willow (Salix viminalis). The study determined the effect of willow on the Cbioacc PAHs and the effect of the investigated amendments on changes in dissolved organic carbon (DOC), crop yield and the content of PAHs in plants. PAH-contaminated soil was amended with 2.5 wt% AC or biochar. Samples from individual plots with and without plants were collected at the beginning of the experiment and after 3, 6, 12 and 18 months. The Cbioacc PAHs were determined using sorptive bioaccessibility extraction (SBE) (silicon rods and hydroxypropyl-β-cyclodextrin). Both AC and biochar caused a decrease in the Cbioacc PAHs. Immediately after adding AC, straw-derived biochar or willow-derived biochar to the soil, the reduction in the sum of 16 (Σ16) Cbioacc PAHs was 70.3, 38.0, and 29.3%, respectively. The highest reduction of Cbioacc was observed for 5- and 6-ring PAHs (from 54.4 to 100%), whereas 2-ring PAHs were reduced only 8.0–25.4%. The reduction of Cbioacc PAHs increased over time. Plants reduced Cbioacc in all soils although effects varied by soil treatment and PAH. Willow grown in AC- and biochar-amended soil accumulated less phenanthrene than in the control soil. The presence of AC in the soil also affected willow yield and shoot length and DOC was reduced from 53.5 to 66.9% relative to unamended soils. In the biochars-amended soil, no changes in soil DOC content were noted nor effects on willow shoot length.

The role of marine plastic debris and microplastics as a carrier of hazardous chemicals in the marine environment is an emerging issue. This study investigated expanded polystyrene (EPS, commonly known as styrofoam) debris, which is a common marine debris item worldwide, and its additive chemical, hexabromocyclododecane (HBCD). To obtain a better understanding of chemical dispersion via EPS pollution in the marine environment, intensive monitoring of HBCD levels in EPS debris and microplastics was conducted in South Korea, where EPS is the predominant marine debris originate mainly from fishing and aquaculture buoys. At the same time, EPS debris were collected from 12 other countries in the Asia-Pacific region, and HBCD concentrations were measured. HBCD was detected extensively in EPS buoy debris and EPS microplastics stranded along the Korean coasts, which might be related to the detection of a quantity of HBCD in non-flame-retardant EPS bead (raw material). The wide detection of the flame retardant in sea-floating buoys, and the recycling of high-HBCD-containing EPS waste inside large buoys highlight the need for proper guidelines for the production and use of EPS raw materials, and the recycling of EPS waste. HBCD was also abundantly detected in EPS debris collected from the Asia-Pacific coastal region, indicating that HBCD contamination via EPS debris is a common environmental issue worldwide. Suspected tsunami debris from Alaskan beaches indicated that EPS debris has the potential for long-range transport in the ocean, accompanying the movement of hazardous chemicals. The results of this study indicate that EPS debris can be a source of HBCD in marine environments and marine food web.

In recent years, behavior-related endpoints have been proposed as rapid and reliable ecotoxicological tools for risk assessment. In particular, the use of detritivores to test the toxicity of pollutants through feeding is currently becoming a well-known method. Experiments combining feeding with other behavioral endpoints can provide relevant information about direct and indirect toxicological effects of chemicals. We carried out a feeding experiment with the shredder Gammarus pulex in order to detect indirect (through leaf conditioning) and direct effects (through water exposure) of two pollutants at environmentally relevant concentrations: the fungicide prochloraz (6 μg/L) and the antidepressant fluoxetine (100 ng/L). Prochloraz inhibited fungal growth on leaves, but it did not affect either the microbial breakdown rates or the C:N ratio of the leaves. Individuals of G. pulex that were fed with treated leaves presented lower consumption rates, not only those fed with prochloraz-treated leaves, but also those fed with fluoxetine-treated leaves, and those fed with the mixture-treated leaves. Mixed-effects models revealed that the swimming velocity of the amphipods after the experiment was modulated by the exposure to fluoxetine, and also by the exposure to prochloraz. We demonstrate that both the antidepressant and the fungicide may cause significant sublethal effects at low concentrations. The combination of behavioral endpoints together with the application of mixed models provided a useful tool for early detection of the effects of toxicity mixtures in freshwater ecosystems.

Mining activities have contaminated many riverine floodplains with arsenic (As). When floodplain soils become anoxic under water-saturated conditions, As can be released from the solid phase. Several microbially-driven As solubilization processes and numerous influential factors were recognized in the past. However, the interplay and relative importance of soil properties and the influence of environmental factors such as temperature remain poorly understood, especially considering the (co)variation of soil properties in a floodplain. We conducted anoxic microcosm experiments at 10, 17.5, and 25 °C using 65 representative soils from the mining-impacted Ogosta River floodplain in Bulgaria. To investigate the processes of As solubilization and its quantitative variation we followed the As and Fe redox dynamics in the solid and the dissolved phase and monitored a range of other solution parameters including pH, Eh, dissolved organic C, and dissolved Mn. We related soil properties to dissolved As observed after 20 days of microcosm incubation to identify key soil properties for As solubilization. Our results evidenced reductive dissolution of As-bearing Fe(III)-oxyhydroxides as the main cause for high solubilization. The availability of nutrients, most likely organic C as the source of energy for microorganisms, was found to limit this process. Following the vertical nutrient gradient common in vegetated soil, we observed several hundred μM dissolved As after 1–2 weeks for some topsoils (0–20 cm), while for subsoils (20–40 cm) with comparable total As levels only minor solubilization was observed. While high Mn contents were found to inhibit As solubilization, the opposite applied for higher temperature (Q10 2.3–6.1 for range 10–25 °C). Our results suggest that flooding of nutrient-rich surface layers might be more problematic than water-saturation of nutrient-poor subsoil layers, especially in summer floodings when soil temperature is higher than in winter or spring.

Methane (CH4) and ammonia (NH3) directly and indirectly affect the atmospheric radiative balance with the latter leading to aerosol generation. Both have important spectral features in the Thermal InfraRed (TIR) that can be studied by remote sensing, with NH3 allowing discrimination of husbandry from other CH4 sources. Airborne hyperspectral imagery was collected for the Chino Dairy Complex in the Los Angeles Basin as well as in situ CH4, carbon dioxide (CO2) and NH3 data. TIR data showed good spatial agreement with in situ measurements and showed significant emissions heterogeneity between dairies. Airborne remote sensing mapped plume transport for ∼20 km downwind, documenting topographic effects on plume advection. Repeated multiple gas in situ measurements showed that emissions were persistent on half-year timescales. Inversion of one dairy plume found annual emissions of 4.1 × 10⁵ kg CH4, 2.2 × 10⁵ kg NH3, and 2.3 × 10⁷ kg CO2, suggesting 2300, 4000, and 2100 head of cattle, respectively, and Chino Dairy Complex emissions of 42 Gg CH4 and 8.4 Gg NH3 implying ∼200k cows, ∼30% more than Peischl et al. (2013) estimated for June 2010. Far-field data showed chemical conversion and/or deposition of Chino NH3 occurs within the confines of the Los Angeles Basin on a four to six h timescale, faster than most published rates, and likely from higher Los Angeles oxidant loads. Satellite observations from 2011 to 2014 confirmed that observed in situ transport patterns were representative and suggests much of the Chino Dairy Complex emissions are driven towards eastern Orange County, with a lesser amount transported to Palm Springs, CA. Given interest in mitigating husbandry health impacts from air pollution emissions, this study highlights how satellite observations can be leveraged to understand exposure and how multiple gas in situ emissions studies can inform on best practices given that emissions reduction of one gas could increase those of others.

Bisphenol A (BPA), a suspected endocrine disruptor, can modify normal plant growth and development. Photosynthesis provides material and energy for the growth and development of plants, in which chlorophyll (Chl) plays a significant role. Many studies have shown that the growth and metabolism of plants vary at different growth stages. Thus the sensitivity of plant's responses to environmental pollution is correspondingly different. We studied the effects of BPA on the Chl contents of soybean (Glycine Max L.) at different growth stages (seedling, flowering and podding, seed-filling and maturation) by measuring the contents of essential intermediates (5-aminolevulinic acid, porphobilinogen, protoporphyrin IX, magnesium protoporphyrin and protochlorophyll) and the activities of key enzymes (5-aminolaevulinic acid dehydratase, porphobilinogen deaminase, uroporphyrinogen III synthase, magnesium chelatase) in chlorophyll synthesis. Low-dose (1.5 mg/L) BPA exposure increased the activities of key enzymes in addition to the contents of intermediates in Chl synthesis at different growth stages, resulting in increases in Chl contents and net photosynthetic rate. In contrast, medium and high-dose (17.2, 50.0 mg/L) BPA exposure produced inhibitory effects on the indices. Following the withdrawal of BPA exposure, the indices recovered to a degree that was related to the plant growth stage. The effect level (high to low) of BPA on these indices at different growth stages was: seedling stage > maturation stage > flowering and podding stage > seed-filling stage. The reverse effect was observed following the withdrawal of BPA exposure. The responses of key enzymes in plant Chl synthesis to BPA illustrate how BPA affects Chl contents. The effects of BPA show clear differences at different plant growth stages.

Biological degradation is the main process for oil degradation in a subsurface oil plume. There is, however, little information on the biodegradation potential of Arctic, marine subsurface environments. We therefore investigated oil biodegradation in microcosms at 2 °C containing Arctic subsurface seawater from the Disko Bay (Greenland) and crude oil at three concentrations of 2.5–10 mg/L. Within 71 days, the total petroleum hydrocarbon concentration decreased only by 18 ± 18% for an initial concentration of 5 mg/L. The saturated alkanes nC13-nC30 and the isoprenoids iC18-iC21 were biodegraded at all concentrations indicating a substantial potential for biodegradation of these compound classes. Polycyclic aromatic compounds (PACs) disappeared from the oil phase, but dissolution was the main process of removal. Analysis of diagnostic ratios indicated almost no PAC biodegradation except for the C1-naphthalenes. To conclude, the marine subsurface microorganisms from the Disko Bay had the potential for biodegradation of n-alkanes and isoprenoids while the metabolically complex and toxic PACs and their alkylated homologs remained almost unchanged.

Baltic amber, adored for its beauty already in Homer's Odyssey (ca. 800 B.C.E), has its material density close to that of wide-spread plastics like polyamide, polystyrene, or acrylic. Migrations of amber stones in the sea and their massive washing ashore have been monitored by Baltic citizens for ages. Based on the collected information, we present the hypothesis on the behaviour of microplastic particles in sea coastal zone. Fresh-to-strong winds generate surface waves, currents and roll-structures, whose joint effect washes ashore from the underwater slope both amber stones and plastics – and carries them back to the sea in a few days. Analysis of underlying hydrophysical processes suggests that sea coastal zone under stormy winds plays a role of a mill for plastics, and negatively buoyant pieces seem to repeatedly migrate between beaches and underwater slopes until they are broken into small enough fragments that can be transported by currents to deeper areas and deposited out of reach of stormy waves. Direct observations on microplastics migrations are urged to prove the hypothesis.