The aim of this work was to develop a new modified graphite felt (GF) as carbonaceous cathode for electro-Fenton (EF) application loaded with nitrogen-doped porous carbon (NPC) carbonized by zeolitic imidazolate framework-8 (ZIF-8) nanocrystals as carbon precursor. At initial pH 7, the highest generation rate of H₂O₂ was 0.74 mg h⁻¹ cm⁻² by applying 12.5 mA cm⁻² by modified cathode, but in the same condition, the GF only had 0.067 mg h⁻¹ cm⁻². The production efficiency increased 10 times. Additionally, phenol (50 mg L⁻¹) could be largely removed by NPC modified cathode, the mineralization ratio and TOC reached 100% and 82.61% at 120 min of optimization condition, respectively. The NPC cathode kept its stability after 5 cycles. The materials were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and linear sweep voltammetry (LSV). The results demonstrated that a homogenous NPC covered the carbon-based material GF. The existing graphitic-N and sp² carbon of NPC promoted the electron transfer between carbon surface and oxygen molecules, as well as accelerated the oxygen reduction reaction (ORR) and the modified graphite felt had much higher electrocatalytic activity. In this work, several manufacturing parameters like the current, pH and load of NPC were optimized. The optimized design could improve the efficiency of new cathode with in situ electro-chemical production of H₂O₂ and significantly offer a potential material for degradation of organic pollutants.

The aim of the present study was to optimize the protocol for sampling marine macroalgae to be used to biomonitor heavy metal contamination in marine ecosystems. For this purpose, we collected 50 subsamples of the brown seaweed Fucus vesiculosus at random in each of three sampling sites (SS) and determined the concentrations of Al, As, Cd, Co, Cr, Cu, Fe, Hg, N, Ni, Pb, Zn and δ15N. We used semivariograms to explore the possible existence of spatial structure in the concentrations of the elements. Spatial structure was observed in 88% of the semivariograms studied, with element concentrations varying longitudinally and transversally along the SS. Using randomization techniques, we estimated that in each SS, a minimum of 30 evenly distributed subsamples should be collected within three bands parallel to the coastline (and also at different heights on the rocks if necessary), and analyzed in a single composite sample representative of the intra-SS variability.

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.

Hexabromocyclododecane (HBCD) and tetrabromobisphenol A (TBBPA) are legacy brominated flame retardants which are still produced and used in China. In this study, 187 surface soils from the Pearl River Delta (PRD) urban conurbation in China were collected, and the effects of urban conurbation development on the concentrations, distributions and human exposure risk of HBCDs and TBBPA were investigated. The concentration ranges of Σ3HBCD (sum of α-, β-, and γ-HBCD) and TBBPA in soil were below the limit of quantification (<LOQ) to 300 ng g−1 dry weight (dw) and < LOQ to 53.1 ng g−1 dw, respectively. Concentration levels of HBCDs and TBBPA in the PRD were affected both by distributions of land-use type and by the location of the city. Soils from residential areas contained the highest concentrations of Σ3HBCD (median: 1.75 ng g−1 dw) and TBBPA (1.92 ng g−1 dw) among all land-use types. In addition, soils from the central PRD had higher Σ3HBCD and TBBPA levels (0.46 and 0.90 ng g−1 dw) than those from the surrounding areas (0.17 and 0.07 ng g−1 dw). The concentrations of Σ3HBCD and TBBPA were highly correlated with urbanization level, population density, regional GDP and per capita income in all cities studied (p < 0.01), which indicates that the prosperity of the urban conurbation may play an important role in soil contamination of HBCDs and TBBPA in the PRD. Children living in residential areas had the highest estimated daily intakes of Σ3HBCD (7.09 pg kg−1 d−1) and TBBPA (7.76 pg kg−1 d−1), suggesting that people living in residential areas have a relatively higher exposure risk of HBCDs and TBBPA. This is a comprehensive study to report the effects of prosperity indices and land use indicators of an urban conurbation on the occurrence of HBCDs and TBBPA in soil in China.

Microplastic pollution in the environment has received growing attention worldwide. A major impediment for accurate measurements of microplastics in environmental matrixes is to extract the particles. The most commonly-used method for separation from soil or sediment is flotation in dense liquid based on the relatively low density of plastic particles. This study provides an improved and optimized process for extraction of microplastic particles by modifying the floatation technique and floatation solution. Microplastics in soils and sediments are extracted by adding 200 g dry soil or sediment sample to 1.3 L mix of the saturated NaCl and NaI solutions in a volume ratio of 1:1 and aerating for 40 s then filtering the supernatant. The accuracy and precision of the new approach is validated by recovery experiments using soil and sediment samples spiked with six common microplastic compounds: polyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS) and expanded polystyrene (EPS), and comparison with the previous method. The optimized approach is further compared with the previous approach using the real soil and sediment samples.

This study critically evaluated the native pygmy mussel (Xenostrobus securis) as a biomonitor of the key metal contaminants in the highly urbanised Sydney Estuary, south-eastern Australia. Five metals (Cd, Cr, Cu, Pb and Zn) were identified as key contaminants, based on their enrichment factors (EFs) in the whole soft tissue of X. securis at 24 sampling sites, relative to baseline values from near-pristine reference sites in the adjacent Hawkesbury Estuary. Inverse relationships established between mussel size (dry tissue weight) and tissue concentrations of each metal were used to reduce variance (by 4-fold) among individuals; gender and reproductive status had no significant (p > 0.05) effect on tissue metal concentrations in X. securis. Metal concentrations in three environmental matrices – filtered (<0.2 μm) surface water (operationally defined as the dissolved/colloidal phase), suspended particulate matter (SPM; >0.2 μm) and surface sediment (<2 mm particle size), which are most relevant to a suspension-feeding estuarine bivalve, were also determined at each sampling site. For each of the five metals, highly significant (p < 0.01) positive linear regressions were established between metal EFs for mussel tissue and each environmental matrix. Metals in surface sediment and SPM explained 80–91% and 81–90%, respectively, of the variability in metal concentrations in mussel tissue, with filtered surface water explaining 74–86%. Cumulative mussel tissue EFs of all five metals, when regressed against each environmental matrix, showed that surface sediment concentrations explained 93% of their variability between sites, SPM 94% and filtered surface water 87–90%. Hence, X. securis very closely reflects the metal concentrations in its aquatic environment. The study provides a quality-assured benchmark of key metal contamination in the Sydney Estuary, and an appropriate methodology that may be used to discern any changes in metal contaminant status using X. securis.

This study assesses for the first time the ingestion of microplastics by giant clams and evaluates their importance as a sink for this pollutant. A total of 24 individuals of two size classes were collected from the Red Sea and then exposed for 12 days to 4 concentrations of polyethylene microbeads ranging from 53 to 500 μm. Experiments revealed that clams actively take up microplastic from the water column and the average of beads retained inside the animal was ∼7.55 ± 1.89 beads individual −1 day −1 (5.76 ± 1.16 MPs/g dw). However, the digestive tract itself cannot be considered the only sink of microbeads in Tridacnids. Indeed, shells play a key role as well. The abundance of microplastic adhering to the shells, which was estimated directly, was positively correlated to the concentration of beads found in the surrounding seawater. Therefore, clams’ shells contribute to the removal of 66.03 ± 2.50% of the microplastic present in the water column. Furthermore, stress responses to the exposure to polyethylene were investigated. Gross Primary Production:Respiration (GPP:R) ratio decreased throughout of the experiment, but no significant difference was found between treatments and controls.

The potential impacts of mining activities on tropical coastal ecosystems are poorly understood. In particular, limited information is available on the effects of metals on scleractinian corals which are foundation species that form vital structural habitats supporting other biota. This study investigated the effects of dissolved nickel and copper on the coral Acropora muricata and its associated microbiota. Corals collected from the Great Barrier Reef were exposed to dissolved nickel (45, 90, 470, 900 and 9050 μg Ni/L) or copper (4, 11, 32 and 65 μg Cu/L) in flow through chambers at the National Sea Simulator, Townsville, Qld, Australia. After a 96-h exposure DNA metabarcoding (16S rDNA and 18S rDNA) was undertaken on all samples to detect changes in the structure of the coral microbiome. The controls remained healthy throughout the study period. After 36 h, bleaching was only observed in corals exposed to 32 and 65 μg Cu/L and very high nickel concentrations (9050 μg Ni/L). At 96 h, significant discolouration of corals was only observed in 470 and 900 μg Ni/L treatments, the highest concentrations tested. While high concentrations of nickel caused bleaching, no changes in the composition of their microbiome communities were observed. In contrast, exposure to copper not only resulted in bleaching, but altered the composition of both the eukaryote and bacterial communities of the coral's microbiomes. Our findings showed that these effects were only evident at relatively high concentrations of nickel and copper, reflecting concentrations observed only in extremely polluted environments. Elevated metal concentrations have the capacity to alter the microbiomes which are inherently linked to coral health.

An accurate estimation of PM2.5 (fine particulate matters with diameters ≤ 2.5 μm) concentration is critical for health risk assessment and generating air pollution control strategies. In this study, a hybrid remote sensing and machine learning approach, named RSRF model is proposed to estimate daily ground-level PM2.5 concentrations, which integrates Random Forest (RF), one of machine learning (ML) models, and aerosol optical depth (AOD), one of remote sensing (RS) products. The proposed RSRF model provides an opportunity for an adequate characterization of real-time spatiotemporal PM2.5 distributions at uninhabited places and complex surfaces. It also offers advantages in handling complicated non-linear relationships among a large number of meteorological, environmental and air pollutant factors, as well as ever-increasing environmental data sets. The applicability of the proposed RSRF model is tested in the Beijing-Tianjin-Hebei region (BTH region) during 2015–2017. Deep Blue (DB) AOD from Aqua-retrieved Collection 6.1 (C_61) aerosol products of Moderate Resolution Imaging Spectroradiometer (MODIS) is validated with Aerosol Robotic Network. The validation results indicate C_61 DB AOD has a high correlation with ground based AOD in the BTH region. The proposed RSRF model performed well in characterizing spatiotemporal variations of annual and seasonal PM2.5 concentrations. It not only is useful to quantify the relationships between PM2.5 and relevant factors such as DB AOD, meteorological and air pollutant variables, but also can provide decision support for air pollution control at a regional environment during haze periods.

Pharmaceuticals and analogs of bisphenol A (BPA) are increasingly threatening environmental pollutants. In this study, mixtures of selected pharmaceuticals (diclofenac sodium salt, chloramphenicol, oxytetracycline hydrochloride, fluoxetine hydrochloride, estrone, ketoprofen, progesterone, gemfibrozil and androstenedione) were prepared with BPA and its two analogs (namely, bisphenols F and S) at such ratios to reflect environmentally detectable levels. Then, the mixture solutions were studied with a XenoScreen YES/YAS assay to determine the variations in the initial hormonal response of each pharmaceutical compound due to the presence of a bisphenol analog. The results obtained were modeled with the concentration addition (CA) and independent action (IA) approaches, the trueness of which was studied with model deviation ratios (MDR). The estrogenic agonistic activity of the drugs studied was most strongly affected by the presence of BPA in solution (twenty-one cases of synergy observed for CA models versus twelve cases of antagonism in the case of IA predictions). BPS shows a strong agonistic estrogenic impact on most of the drugs studied at medium and high concentration levels; androgenic agonistic activity was also impaired with elevated concentrations of BPS. Increasing the concentration of BPF in a reaction mixture also increased the number of YES + synergism incidences (for CA modeling). Estrone, progesterone and androstenedione were mostly affected by the highest BPF concentrations studied in the case of androgenic agonistic research performed.