The spatial distributions, possible sources of C₉–C₁₇ chlorinated paraffins (CPs), and the ecological risks posed in mangrove sediment in Dongzhai Harbor (Hainan Island, China) were investigated. Comprehensive two-dimensional gas chromatography combined with electron capture negative ionization mass spectrometry was used to determine 50 C₉–C₁₇ CP congener groups. The concentrations of C₉-CPs, short-chain CPs (SCCPs), and medium-chain CPs (MCCPs) in the mangrove sediment samples were 8.28–79.7, 89.2–931, and 58.8–834 ng g⁻¹ dry weight, respectively. The CPs concentrations in the mangrove sediment samples were moderate compared with those found in other regions worldwide. The spatial distributions and congener patterns of the CPs indicated that the CP concentrations were mainly controlled by local emissions and that wastewater discharged from livestock and shrimp breeding facilities and domestic sewage were the main sources of CPs in mangrove sediment in Dongzhai Harbor. C₁₀Cl₆–₇ and C₁₄Cl₇–₈ were the dominant SCCP and MCCP congener groups, respectively. The MCCP concentrations and total organic carbon contents significantly correlated (R² = 0.607, P < 0.05). Hierarchical cluster analysis and principal component analysis indicated that the SCCP and MCCP congeners were from different commercial CP formulations and sources. Risk assessments suggested that SCCPs and MCCPs in mangrove sediment in Dongzhai Harbor do not currently pose marked risks to sediment-dwelling organisms.

Trace chemicals are common in marine and freshwater ecosystems globally. It is recognized that in the environment, individual chemicals are rarely found in isolation. Insufficient work has examined which chemicals co-occur and which methods best identify these mixtures. Using an existing data set, we found evidence that simple correlation analysis is better at identifying mixtures of commonly co-occurring trace chemicals than more commonly used PCA methods. Moreover, simple correlation analysis, unlike PCA, can be used in cases with unbalanced designs and with data points below reportable limits. Application of this approach allowed identification of 10 groups of chemicals commonly found together in freshwaters of the continental US, representing common “chemical syndromes.” Better identification of co-occurring chemical combinations could aid in our understanding of biological and ecological effects of aquatic contaminants. This research provides evidence of correlation analyses as a more effective method for identifying commonly co-occurring aquatic contaminants. We also examined the patterns of these mixtures with a dataset consisting of concentrations of 406 trace chemicals from 38 sample locations across the continental US.

Routine waterway dredging activities generate huge volumes of dredged sediment. The remediation of dredged contaminated sediment is a worldwide challenge. Novel and sustainable ex-situ remediation technologies for contaminated sediment have been developed and adopted in recent years. In this review paper, the state-of-art ex-situ treatment technologies and resource utilisation methods for contaminated sediment were critically reviewed. By applying different techniques, sediment could been successfully transformed into sustainable construction materials, such as ceramsite, supplementary cementitious materials, fill materials, paving blocks, partition blocks, ready-mixed concrete, and foamed concrete. We highlighted that proper remediation technologies should be cleverly selected and designed according to the physical and chemical characteristics of sediment, without neglecting important aspects, such as cost, safety, environmental impacts, readiness level of the technology and social acceptability. The combination of different assessment methods (e.g., environmental impact assessment, cost-benefit analysis, multi-criteria decision analysis and life cycle assessment) should be employed to comprehensively evaluate the feasibility of different sustainable remediation technologies. We call on the scientific community in a multidisciplinary fashion to evaluate the sustainability of various remediation technologies for contaminated sediment.

Restoring woody vegetation to riparian zones helps to protect waterways from excessive sediment and nutrient inputs. However, the associated leaf litter can be a major source of dissolved organic matter (DOM) leached into surface waters. DOM can lead to the formation of disinfection by-products (DBPs) during drinking water treatment. This study investigated the DBPs formed during chlorination of DOM leached from leaf litter and assessed the potential toxicity of DBPs generated. We compared the leachate of two native Australian riparian trees, Casuarina cunninghamiana and Eucalyptus tereticornis, and a reservoir water source from a catchment dominated by Eucalyptus species. Leachates were diluted to dissolved organic carbon concentrations equivalent to the reservoir (~9 mg L⁻¹). E. tereticornis leachates produced more trihalomethanes (THMs), haloacetic acids (HAAs), and haloketones after chlorination, while C. cunninghamiana produced more chloral hydrate and haloacetonitriles. Leachate from both species produced less THMs and more HAAs per mole of carbon than reservoir water. This may be because reservoir water had more aromatic, humic characteristics while leaf leachates had relatively more protein-like components. Using in vitro bioassays to test the mixture effects of all chemicals, chlorinated E. tereticornis leachate induced oxidative stress in HepG2 liver cells and bacterial toxicity more frequently and at lower concentrations than C. cunninghamiana and reservoir water. Overall, this study has shown that the DOM leached from litter of these species has the potential to generate DBPs and each species has a unique DBP profile with differing bioassay responses. E. tereticornis may pose a relatively greater risk to drinking water than C. cunninghamiana as it showed greater toxicity in bioassays. This implies tree species should be considered when planning riparian zones to ensure the benefits of vegetation to waterways are not offset by unintended increased DBP production and associated toxicity following chlorination at downstream drinking water intakes.

East Asian oceans are possibly affected by a high nitrogen (N) burden because of the intense anthropogenic emissions in this region. Based on high-resolution regional chemical transport modeling with horizontal grid scales of 36 and 12 km, we investigated the N burden into East Asian oceans via atmospheric deposition in 2010. We found a high N burden of 2–9 kg N ha⁻¹ yr⁻¹ over the Yellow Sea, East China Sea (ECS), and Sea of Japan. Emissions over East Asia were dominated by ammonia (NH₃) over land and nitrogen oxides (NOₓ) over oceans, and N deposition was dominated by reduced N over most land and open ocean, whereas it was dominated by oxidized N over marginal seas and desert areas. The verified numerical modeling identified that the following processes were quantitatively important over East Asian oceans: the dry deposition of nitric acid (HNO₃), NH₃, and coarse-mode (aerodynamic diameter greater than 2.5 μm) NO₃⁻, and wet deposition of fine-mode (aerodynamic diameter less than 2.5 μm) NO₃⁻ and NH₄⁺. The relative importance of the dry deposition of coarse-mode NO₃⁻ was higher over open ocean. The estimated N deposition to the whole ECS was 390 Gg N yr⁻¹; this is comparable to the discharge from the Yangtze River to the ECS, indicating the significant contribution of atmospheric deposition. Based on the high-resolution modeling over the ECS, a tendency of high deposition in the western ECS and low deposition in the eastern ECS was found, and a variety of deposition processes were estimated. The dry deposition of coarse-mode NO₃⁻ and wet deposition of fine-mode NH₄⁺ were the main factors, and the wet deposition of fine-mode NO₃⁻ over the northeastern ECS and wet deposition of coarse-mode NO₃⁻ over the southeastern ECS were also found to be significant processes determining N deposition over the ECS.

Anaerobic digestion is an attractive waste treatment technology, achieving both pollution control and energy recovery. Though the inhibition of polystyrene nanoplastics in anaerobic granular sludge is well studied, no direct evidence has been found on the interaction of methanogens and nanoplastics. In this study, to characterize the location of nanoplastics, Pd-doped polystyrene nanoplastics (Pd-PS) were used to explore the inhibition mechanism of anaerobic sludge through short-term exposure to Methanosarcina acetivorans C2A. The results showed that Pd-PS inhibited the methanogenesis of the anaerobic sludge, and the methane production decreased as the Pd-PS increased, with a 14.29% reduction at the Pd-PS concentration of 2.36 × 10¹⁰ particles/mL. Also, Pd-PS interacted with the protein in the extracellular polymeric substances (EPS). Furthermore, Pd-PS inhibited the methanogenesis of M. acetivorans C2A without exhibiting an evident reduction in the growth. The inhibition of Pd-PS on methane was due to the inhibition of methane production related genes, MtaA and mcrA. These results provide potential explication for the inhibition of nanoplastics on the methanogens, which will fulfill the knowledge on the stability of methanogens under the short-term exposure of nanoplastics.

Halogenated flame retardants (HFRs) market is continuously evolving and have moved from the extensive use of polybrominated diphenyl ether (PBDE) to more recent introduced mixtures such as Firemaster 550, Firemaster 680, DP-25, DP-35, and DP-515. These substitutes are mainly composed of non-PBDEs HFRs such as 2-ethyl-hexyl tetrabromobenzoate (TBB), bis(2-ethylhexyl) tetrabromophthalate (TBPH), 1,2-bis-(2,4,6-tribromophenoxy) ethane (BTBPE) and decabromodiphenyl ethane (DBDPE). Other HFRs commonly being monitored include Dechlorane Plus (DP), Dechlorane 602 (Dec602), Dechlorane 603 (Dec603), Dechlorane 604 (Dec604), 5,6-dibromo-1,10, 11, 12,13,13-hexachloro- 11-tricyclo[8.2.1.02,9]tridecane (HCDBCO) and 4,5,6,7-tetrabromo-1,1,3-trimethyl-3-(2,3,4,5-tetrabromophenyl)-2,3-dihydro-1H-indene (OBTMPI). This review aims at highlighting the advances in the past decade (2010–2020) on both the analytical procedures of HFRs in human bio-specimens using gas chromatography coupled with single quadrupole mass spectrometry and synthesizing the information on the levels of these HFRs in human samples. Human specimen included in this review are blood, milk, stool/meconium, hair and nail. The review summarizes the analytical methods, including extraction and clean-up techniques, used for measuring HFRs in biological samples, which are largely adopted from those for analysing PBDEs. In addition, new challenges in the analysis to include both PBDEs and a wide range of other HFRs are also discussed in this review. Review of the levels of HFRs in human samples shows that PBDEs are still the most predominant HFRs in many cases, followed by DP. However, emerging HFRs are also being detected in human despite of the fact that both their detection frequencies and levels are lower than PBDEs and DP. It is clearly demonstrated in this review that people working in the industry or living close to the industrial areas have higher HFR levels in their bodies.

Cadmium (Cd) and lead (Pb) are toxic heavy metals that impact human health and biodiversity. Removal of Cd/Pb from contaminated soils is a means for maintaining environmental sustainability and biodiversity. In this study, we applied a newly modified material fly ash (NA), zeolite (ZE), and fly ash (FA) to the paddy soils and evaluated the effects of Cd/Pb accumulation in rice via a one-year field experiment. The results showed that the application of NA and ZE enhanced the soil pH and nutrients to a large extent and reduced the availability of Cd/Pb in soil. The Cd and Pb concentrations in rice grains decreased by 32.8% and 62.9%, respectively, with the NA treatments. Similarly, the application of ZE reduced the Cd and Pb concentrations in rice grains by a factor of 27.9% and 63.5%, respectively, which indicates that the amendments can promote the transfer of Cd and Pb from acid-exchangeable fraction to oxidizable and residual fractions. The Cd/Pb showed a significant positive correlation to other metal ions and a negative correlation to the nutrients. Generally, the application of NA and ZE was effective in reducing Cd/Pb accumulation and improving rice yield. Moreover, the NA was more cost-effective than ZE. Hence, this study proves that NA may be a better amendment for remediation of Cd/Pb contaminated soils.

The hydrothermal preparation of o-dianisidine and triazine interlinked porous organic polymer and its successive derivatisation via metal infusion (Ni, Cu) under hydrothermal and calcination conditions (700 °C) to yield pristine (ANIPOP-700) and Ni/Cu decorated porous carbon are described here (Ni-ANIPOP-700 and Cu-ANIPOP-700). To confirm their chemical and morphological properties, the as-prepared materials were methodically analyzed using solid state ¹³C and ¹⁵N NMR, X-ray diffraction, Raman spectroscopy, field emission scanning and high resolution transmission electron microscopic techniques, and x-ray photoelectron spectroscopy. Furthermore, the electrocatalytic activities of these electrocatalysts were thoroughly investigated under standard oxygen evolution (OER) and hydrogen evolution reaction (HER) conditions. The results show that all of the materials demonstrated significant activity in water splitting as well as displayed excellent stability (22 h) in both acidic (HER) and basic conditions (OER). Among the electrocatalysts reported in this study, Ni-ANIPOP-700 exhibited a lower overpotential η₁₀ of 300 mV in basic medium (OER) and 150 mV in acidic medium (HER), as well as a lower Tafel slope of 69 mV/dec (OER) and 181 mV/dec (HER), indicating 30% lower energy requirement for overall water splitting. Gas chromatography was used to examine the electrolyzed products.

Air pollution represents one of the major concerns worldwide, fueled by the increasing urbanization and related PM production worsening air quality in open air as well as in confined environments. In the present work, exposure to atmospheric metal pollution was investigated in 20 paired indoor (I)-outdoor (O) sites located in two urban areas of Italy and Belgium, by chemical (ICP-MS) and magnetic (saturation isothermal remanent magnetization, SIRM) analyses of Hypnum cupressiforme moss exposed in bags. After 12 weeks, the elemental profiles of the moss material exposed in the two countries largely overlapped, except for some elements which specifically accumulated in Belgium (Ag, As, Cd, Mo, Pb and Sb) and in Italy (Ca, Mg, Co, Cr, Sr, Ti and U). Element concentrations were higher in moss exposed outdoors, with the Italian sites mostly showing a terrigenous footprint, and the Belgian sites mostly affected by elements of environmental concern (e.g., As, Pb, Sb). The Indoor/Outdoor ratios (mostly lower than 0.75) indicated indoor pollution as strongly affected by outdoor pollution, although specific elements could be of indoor origin or magnified in indoor environments (e.g., Al, Ag, Cd and Co). In line with the chemical analysis, the SIRM signal was significantly higher in outdoor than indoor moss material. A positive, significant correlation was observed between SIRM and several accumulated elements indicating SIRM analysis as a powerful tool to predict the level of metal pollution. Moss bags were confirmed as a useful and versatile tool to highlight metal contamination even in confined environments, an essential prerogative in the perspective of the evaluation of the total exposure risk for humans to these pollutants.