The derivation of sediment quality guideline values (SQGVs) presents significant challenges. Arguably the most important challenge is to conduct toxicity tests using contaminated sediments with physico-chemistry that represents real-world scenarios. We used a novel metal spiking method for an experiment that ultimately aims to derive a uranium SQGV. Two pilot studies were conducted to inform the final spiking design, i.e. percolating a uranyl sulfate solution through natural wetland sediments. An initial pilot study that used extended mixing equilibration phases produced hardened sediments not representative of natural sediments. A subsequent percolation method produced sediment with similar texture to natural sediment and was used as the method for spiking the sediments. The range of total recoverable uranium (TR-U) concentrations achieved was 8–3200 mg/kg. This reflected the concentrations found in natural wetlands and water management ponds found on a uranium mine site and was above natural levels. Dilute-acid extractable uranium (AE-U) concentrations were >80% of total concentrations, indicating that much of the uranium in the spiked sediment was labile and potentially bioavailable. The portion of TR-U extractable as AE-U was similar at the start and end of the 4.5-month field-deployment. Porewater uranium (PW–U) analyses indicated that partition coefficients (Kd) were 2000–20,000 L/kg, and PW-U was greater in post- than pre-field-deployed samples when TR-U was ≤1500 mg/kg, indicating the binding became weaker during the field-deployment period. At higher spiked-U concentrations, the PW-U was lower post-field-deployment. Comparing the physico-chemical data of the spiked sediments with environmental monitoring data from sediments in the vicinity of a uranium mining operation indicated that they were representative of sediments contaminated by mining and that the U-spiked sediments had a clear U concentration gradient. This confirmed the suitability of the spiking procedure for preparing sediments that were suitable for deriving a SQGV for uranium.

The long-term groundwater contamination risks posed by steroidal estrogens (SEs) in animal-manured agricultural soils are closely associated with the soil organic matter (SOM) content and composition. In this study, the bioavailability of estrone (E1) and 17β-estradiol (17β-E2) under different sorption mechanism in humic acids (HA1 and HA2) and humin (HM) extracted with sequential alkaline-extraction technique (SAET) were examined. These SOMs extracted by SAET showed various properties and sorption characteristics for SEs. The alkyl carbon and condensed SOM increased during SAET, but aromatic carbon decreased and the same trend for polarity. Quick sorption was the major SEs sorption mechanism on HA1 and HA2, which contributed more than 69%; whilst slow sorption rate was about 50% in soil and HM. The logKₒc values were proportional to the TOC of SOM according to Freundlich fitting, and the sorption capacity of sorbent for E1 and 17β-E2 was related to the logKₒw values, indicating that the main mechanism controlling the SEs sorption was hydrophobic interaction. The larger micropore volume of HM and soil was more conducive to the micropore filling of SEs. Meanwhile, the specific sorption of SEs on condensed domain of SOM was the main reason for the strong desorption hysteresis and slow sorption in HM and soil. The SEs degradation rate was positively correlated with the contribution rate of quick adsorption and negatively correlated with the contribution rate of slow adsorption, indicating that the bioavailability of SEs sorbed by hydrophobic interaction was higher than that of micropore filling or specific sorption, which was also the reason for the low bioavailability of SEs in HM and soil. This work confirms the regulation of on-site SOM compositions and their properties on SEs sorption and bioavailability. Characterization of these details is crucial for the improved prediction of long-term risks to groundwater.

Microplastics (<5 mm) are emerging pollutants in oceans worldwide. As such small particles are easily ingested, microplastics are found in numerous pelagic and benthic organisms. However, information on microplastics in rocky intertidal organisms and habitats is relatively scant. Therefore, we examined snails and water samples from wave-sheltered and wave-exposed rocky intertidal habitats in Helgoland (North Sea), Cap Ferrat and Giglio (Mediterranean) and Madeira (Atlantic Ocean) in 2019–2020 for microplastics. Furthermore, we examined snails from the same habitats in Helgoland, Cap Ferrat and Giglio in 2007–2009. In total, we performed 362 individual micro-Fourier-transform infrared spectroscopy (μFTIR) measurements on the snails and water samples. While the snails contained 50 microplastics (composed of nine polymer types), the water samples contained 24 microplastics (comprising six polymer types). Microplastic load and polymer type composition in the snails were rather similar across locations, wave exposure and years. Also, microplastic load and polymer composition in the water samples were similar across locations and wave exposure. Moreover, snail and water microplastic loads were significantly correlated which indicates that snails are useful bioindicators for microplastic loads in rocky intertidal habitats. Interestingly, the majority of the microplastics consisted of paint chips that likely derived from ships. Overall, our study provides the first comprehensive microplastic record in rocky intertidal organisms across locations, wave exposure and years that can serve as a baseline to examine historic and future microplastic dynamics in rocky intertidal systems.

Bauxite residue, an industrial alkaline solid waste, has a low organic carbon content which hinders plant growth. Dissolved organic matter (DOM) drives many biogeochemical processes including carbon storage and soil formation in soils. Input of exogenous organic materials may provide organic carbon and accelerate soil formation processes in bauxite residue. However, the potential effects of ameliorants on the quantity and quality of DOM in bauxite residue are still poorly understood. Here, the integration of ultraviolet–visible (UV–Vis) spectra, fluorescence spectra, and parallel factor (PARAFAC) analysis were used to investigate the vertical characteristics of DOM in bauxite residue treated by PV (the combined addition of 2% phosphogypsum and 4% vermicompost, w/w) and BS (6% w/w including 4% bagasse and 2% bran) with 2-year column experiments. The content of DOM in untreated residues ranged from 0.064 to 0.096 g/kg, whilst higher contents of DOM were observed in PV (0.13 g/kg) and BS (0.26 g/kg) treatment. Meanwhile, with the increase of residue depth, the aromaticity and hydrophobic components of DOM in residue decreased, which indicated that the degree of humification of the treated residues in the upper layer was higher than that in the lower layer. Compared with BR, BS and PV treatment accumulated the related content of fulvic acid-like substance from 36.14% to 71.33% and 74.86%, respectively. The incorporation of vermicompost and biosolids increased the content of humic-like substances, whilst decreasing the content of protein-like substances in the surface layer, which may be due to the enrichment of the microbial community. During soil formation processes, the application of organic amendments reduced both salinity and alkalinity, enhanced microbial community diversity, and changed the quantity and quality of DOM in bauxite residue. These findings improve our understanding of the dynamics of DOM and response of DOM to soil formation processes in bauxite residue.

Riverine carbon (C) composition and export are closely related to changes in the coastal environment and climate. Excessive C inputs from rivers to seas and their subsequent decomposition could result in harmful algal blooms and ecosystem degradation in the coastal sea. In this study, we explored the C transportation and composition in the 24 major rivers of the Bohai Sea (BS) Rim based on the investigation of dissolved organic carbon (DOC), carbon stable isotopes (δ¹³CDOC) and chromophoric dissolved organic matter (CDOM). The results showed that the riverine DOC concentrations were high (10.6 ± 6.04 mg/L) in the BS Rim compared with the DOC levels in the main rivers in Eastern China (4.98 ± 2.45 mg/L). The δ¹³CDOC ranged from −28.29‰ to −25.32‰ in the rivers of the BS Rim, suggesting that the DOC mainly originated from riverine plankton, soil organic matter mainly induced by C3 plants, and sewage. The excitation-emission matrix fluorescence spectroscopy of the CDOM indicated that a soluble, microbial by product-like material accounted for the largest proportion (approximately 40%) of CDOM in these rivers and that CDOM mainly originated from autochthonous riverine sources with high protein-like components. The rivers in the BS Rim transported approximately 0.55 Tg C of DOC to the BS each year, with more than 70% of reactive C based on the CDOM composition. The DOC yields in terms of unit drainage area transported from the small rivers to the BS were higher compared to those of the larger rivers in the world, which indicated that the small rivers in the Bohai Rim could be an important source of the C in the BS. This study would enrich our understanding of environmental evolution in coastal areas with numerous small rivers.

The aim of this study was to evaluate the effects of Pb exposure on full-scale IQ score in pediatric subjects. Following PRISMA guidelines, the data from January 2010 to April 2020 were systematically searched and collected on electronic databases (PubMed, Scopus, and Embase). The eligibility criteria included cross-sectional, cohort, and case-control studies that were published in English, from 2010 to 2020, that analyzed the blood Pb levels of pediatric subjects (0–19 years) and possible changes in the full-scale IQ score. In this study, 2174 scientific papers were collected from three electronic databases. From those, 726 were duplicates and 1421 were excluded because they did not meet the eligibility criteria, resulting in a total of 27 papers, from which, seven were used to perform the meta-analysis. The 27 scientific papers systematically selected for this study were separated by the country where the study was realized in developed and underdeveloped/developing countries. In the underdeveloped/developing countries the blood Pb levels are higher and showed a greater variation (1.30–11.66 μgPb/dL of blood) than in countries with higher development index (0.57–4.80 μgPb/dL of blood). The full-scale IQ score are inversely proportional to the blood Pb values, and it is possible to see that in the underdeveloped/developing countries the full-scale IQ score showed lower values and greater variation (59.2–111) compared to the individuals from developed countries (91.9–114.5). In conclusion, it was observed that blood Pb levels alter the full-scale IQ score. Thus, policies for the prevention of environmental contamination and the reduction of Pb exposure must be taken, mainly, in underdeveloped/developing countries.

Marine sediments act as a sink for various heavy metals, which may have profound impact on sedimentary microbiota. However, our knowledge about the collaborative response of bacterial community to chronic heavy metal contamination remains little. In this study, concentrations of seven heavy metals (As, Cd, Cr, Cu, Hg, Pb, and Zn) in sediments collected from the East China Sea were analyzed and Illumina Miseq 16 S rRNA sequencing was applied to characterize the structure of bacterial community. Microbiota inhabiting sediments in the East China Sea polluted with heavy metals showed different community composition from relatively pristine sites. The response of bacterial community to heavy metal stress was further interrogated with weighted correlation network analysis (WGCNA). WGCNA revealed ten bacterial modules exhibiting distinct co-occurrence patterns and among them, five modules were related to heavy metal pollution. Three of them were positively correlated with an increase in at least one heavy metal concentration, hubs (more influential bacterial taxa) of which were previously reported to be involved in the geochemical cycling of heavy metals or possess tolerance to heavy metals, while another two modules showed opposite patterns. Our research suggested that ecological functional transition might have occurred in East China Sea sediments by shifts of community composition with sensitive modules majorly involved in the meaningful global biogeochemical cycling of carbon, sulfur, and nitrogen replaced by more tolerant groups of bacteria due to long-term exposure to low-concentration heavy metals. Hubs may serve as indicators of perturbations of benthic bacterial community caused by heavy metal pollution and support monitoring remediation of polluted sites in marine environments.

This study assessed the human health risk of exposure to legacy PAHs in the Nwaenebo River sediments that received effluents for over two decades from the Nigeria National Petroleum Corporation (NNPC) petroleum product Depot in Emene, Enugu, Nigeria. The study went further to estimate economic costs of the sediment PAHs pollution based on the human health risk of exposure. The human health risks were determined by estimating carcinogenic and mutagenic risks via Benzo[a]pyrene total potential equivalent (BaP TPE) and mutagenic equivalent quotient (MEQ). The economic costs of the sediment pollution comprised costs due to mortality and those due to morbidity and were estimated using the value of statistical lives (VSLs) and cost of illness (CoI), respectively. The study, with an appropriate selection of sampling points established that the NNPC petroleum Depot was responsible for the Nwaenebo River sediment PAHs pollution with ƩPAHs concentration 14.3–163 mg/kg. The carcinogenic and mutagenic risks varied from 1.3*10^-5 to 4.7*10^-5 and 1.4*10^-5 to 6.0*10^-5 respectively. Based on risk threshold of 10^-6, these risks were high. The long term economic costs of pollution of the sediments by the PAHs were estimated at 60.5 million USD and 0.46 million USD for mortality and morbidity costs, respectively.

Current mitigation strategies to offset marine plastic pollution, a global concern, typically rely on preventing floating debris from reaching coastal ecosystems. Specifically, clean-up technologies are designed to collect plastics by removing debris from the aquatic environment such as rivers and estuaries. However, to date, there is little published data on their potential impact on riverine and estuarine organisms and ecosystems. Multiple parameters might play a role in the chances of biota and organic debris being unintentionally caught within a mechanical clean-up system, but their exact contribution to a potential impact is unknown. Here, we identified four clusters of parameters that can potentially determine the bycatch: (i) the environmental conditions in which the clean-up system is deployed, (ii) the traits of the biota the system interacts with, (iii) the traits of plastic items present in the system, and, (iv) the design and operation of the clean-up mechanism itself. To efficiently quantify and assess the influence of each of the clusters on bycatch, we suggest the use of transparent and objective tools. In particular, we discuss the use of Bayesian Belief Networks (BBNs) as a promising probabilistic modelling method for an evidence-based trade-off between removal efficiency and bycatch. We argue that BBN probabilistic models are a valuable tool to assist stakeholders, prior to the deployment of any clean-up technology, in selecting the best-suited mechanism to collect floating plastic debris while managing potential adverse effects on the ecosystem.

Electric and magnetic fields characterized by high efficiency, low consumption and environment-friendly performance have recently generated interest as a possible measure to enhance the performance of the biological treatment process used to remove refractory organics. Few studies have been carried out to-date regarding the simultaneous application of electric and magnetic fields on biofilm process to degrade diclofenac. In this study, 3DEM-BAF was designed to evaluate the electrio-magnetic superposition effect on diclofenac removal performance, kinetics, community structure and synergistic mechanism. The results show that 3DEM-BAF could significantly increase the average removal rate of diclofenac by 65.30 %, 57.46 %, 9.48 % as compared with that of BAF, 3DM-BAF, 3DE-BAF, respectively. The diclofenac degradation kinetic constants and dehydrogenase activity of 3DEM-BAF were almost 6.72 and 2.53 times higher than those of BAF. Microorganisms of 3DEM-BAF in the Methylophilus and Methyloversatilis genera were distinctively enriched, which was attributed to the screening function of electric field and propagation effect of magnetic field. Moreover, three processes were found to contribute to diclofenac degradation, namely electro-magnetic-adsorption, electro-chemical oxidation and electro-magnetic-biodegradation. Thus, the simultaneous application of electric and magnetic fields on biofilm process was demonstrated to be a promising technique as well as a viable alternative in diclofenac degradation enhancement.