Seas worldwide are threatened by an emerging source of pollution as millions of tons of warfare materials were dumped after the World Wars. As their metal shells are progressively corroding, energetic compounds (EC) leak out and distribute in the marine environment. EC are taken up by aquatic organisms and pose a threat to both the marine ecosphere and the human seafood consumer because of their toxicity and potential carcinogenicity. Here, sediment samples and fish from different locations in the German North Sea of Lower Saxony were examined to determine whether EC transfer to fish living close to munition dumping areas. EC were found in sediments with a maximum concentration of 1.5 ng/kg. All analyzed fish muscle tissues/fillets and bile samples were positive for EC detection. In bile, the max. EC concentrations ranged between 0.25 and 1.25 ng/mL. Interestingly, while detected TNT metabolites in the muscle tissues were in concentrations of max. 1 ng/g (dry weight), TNT itself was found in concentrations of up to 4 ng/g (dry weight). As we found considerable higher amounts of non-metabolized TNT in the fish muscle, rather than TNT metabolites, we conclude an additional absorption route of EC into fish other than per diet. This is the first study to detect EC in the edible parts of fish caught randomly in the North Sea.

Thirteen elements including Al, Ag, As, Co, Cu, Cd, Cr, Fe, Mn, Ni, Se, Zn, and Pb were measured in 107 surface grab sediment samples and 175 segments of eight cores from Lakes Superior, Michigan, and Huron, using inductively coupled plasma mass spectrometry (ICP-MS). Concentrations in Ponar grabs vary considerably among metals and among locations, ranging from the highest median for Fe in Lake Superior (42,000 mg/kg) to the lowest median for Ag in the main Lake Huron (0.05 mg/kg). The inventory at coring sites ranged from 7 × 106 mg/m2 of Fe to 3 mg/m2 of Ag. The background concentrations were estimated from deeper core segments, and enrichment factors (EFs) were calculated with Fe or Al as the reference element. The results show that Al, Fe, Co, Cr, and Mn did not enrich, Ag, Cu, and Ni were present higher than expected from natural sources alone, while Pb, Cd, Se, Zn, and As have been enriched at most sites after European settlement in the region. EFs of most metals are higher for Lake Michigan than the other lakes. However, EF comparison among sampling sites revealed intrinsic problems of this approach for the assessment of human interference. Preliminary risk assessment, conducted by calculating risk quotients, revealed environmental risks of some metals in each lake; however, the results should be interpreted with caution because the approach used is considered to be conservative.

Metal contamination is a crucial environmental issue because of its persistence and toxicity, which can have deleterious effects on aquatic ecosystems. Coastal sediments serve as reservoirs for metals. Aquaculture is an important human activity in coastal areas; however, the actual status of metal distribution in these areas has not been well characterized. We investigated the distribution and geochemical speciation of metals in the sediments of the Japanese aquaculture areas of Shidugawa and Furue Bays. Total metals were generally in the order Zn > Cu > Ni > Cd > Pb and occurred at high levels at the sites in the inner parts and near the fish cages in the sampling areas. Pearson\'s correlations and principal component analysis results suggested that the metals in these aquaculture areas might originate from several sources, such as fish feces, fish feeds, corrosion of antifouling material residues, and local anthropogenic activities, including fertilizers and manures. Furthermore, metals were mainly in silts and fine sediments, associated with residual speciation, followed by organic fractions, oxides, and high fractions of exchangeable Cd. These results provide important insights into the accumulation of metals in sediments for better managing marine aquaculture in Japan.

This study delves into the unexplored distribution and accumulation of chlorinated paraffins (CPs), pervasive industrial contaminants used as flame retardants and plasticizers, within the hadal trenches, some of Earth\'s most isolated marine ecosystems. Analysis of sediments from the Mussau (MS) and Mariana trench (MT) reveals notably high total CP concentrations (∑SCCPs + ∑MCCPs) of 10,963 and 14,554 ng g-1 dw, respectively, surpassing those in a reference site in the western Pacific abyssal plain (8533 ng g-1 dw). In contrast, the New Britain Trench (NBT) exhibits the lowest concentrations (2213-5880 ng g-1 dw), where CP distribution correlates with clay content, δ13C and δ15N values, but little with total organic carbon and depth. Additionally, amphipods from these trenches display varying CP levels, with MS amphipods reaching concerning concentrations (8681-16,138 ng g-1 lw), while amphipods in the MT-1 site show the lowest (4414-5010 ng g-1 lw). These bioaccumulation trends appear to be primarily influenced by feeding behaviors (δ13C) and trophic levels (δ15N). Utilizing biota-sediment accumulation factor values and principal component analysis, we discern that CPs in sediment may come from surface-derived particulate organic matters, while those in amphipods may come from the above carrion. Our findings elucidate the profound impacts of the emerging pollutants on the Earth\'s least explored marine ecosystems.

The role of sediment oxygen demand (SOD) in causing dissolved oxygen (DO) depletion is widely acknowledged, with previous studies mainly focusing on chemical and biological SOD separately. However, the relationship between the putative functions of sediment microbes and SOD, and their impact on DO depletion in overlying water, remains unclear. In this study, DO depletion was observed in the downstream of the Gan River during the summer. Sediments were sampled from three downstream sites (YZ, Down1, and Down2) and one upstream site (CK) as a control. Aquatic physicochemical parameters and SOD levels were measured, and microbial functions were inferred from taxonomic genes through analyses of the 16S rRNA gene. The results showed that DO depletion sites exhibited a higher SOD rate compared to CK. The microbial community structure was influenced by the spatial variation of Proteobacteria, Chloroflexi, and Bacteroidota, with total organic carbon (TOC) content acting as a significant environmental driver. A negative correlation was observed between microbial diversity and DO concentration (p < 0.05). Aerobic microbes were more abundant in DO depletion sites, particularly Proteobacteria. Microbes involved in various biogeochemical cycles, such as carbon (methane oxidation, methanotrophs, and methylotrophs), nitrogen (nitrification and denitrification), sulfur (sulfide and sulfur compound oxidation), and manganese cycles (manganese oxidation), exhibited higher abundance in DO depletion sites, except for the iron cycle (iron oxidation). These processes were negatively correlated with DO concentration and positively with SOD (p < 0.05). Overall, the results highlight that aerobic bacteria\'s metabolic processes consume oxygen, increasing the SOD rate and contributing to DO depletion in the overlying water. Additionally, the study underscores the importance of targeting the removal of in situ microbial molecular mechanisms associated with toxic H2S and CH4 to support reoxygenation efforts in rehabilitating DO depletion sites in the Gan River, aiding in identifying factors controlling DO consumption and offering practical value for the river\'s restoration and management.

Denitrification, anammox, and DNRA are three important nitrogen (N) reduction pathways in estuarine sediments. Although salinity is an important variables controlling microbial growth and activities, knowledge about the effects of changing salinity on those three processes in estuarine and coastal wetland sediments are not well understood. Herein, we performed a 60-d microcosms experiment with different salinities (0, 5, 15, 25 and 35 ‰) to explore the vital role of salinity in controlling N-loss and N retention in estuarine wetland sediments. The results showed that sediment organic matter, sulfide, and nitrate (NO3-) were profoundly decreased with increasing salinity, while sediment ammonium (NH4+) and ferrous (Fe2+) varied in reverse patterns. Meanwhile, N-loss and N retention rates and associated gene abundances were differentially inhibited with increasing salinity, while the contributions of denitrification, anammox, and DNRA to total nitrate reduction were apparently unaffected. Moreover, denitrification rate was the most sensitive to salinity, and then followed by DNRA, while anammox was the weakest among these three processes. In other words, anammox bacteria showed a wide range of salinity tolerance, while both denitrification and DNRA reflected a relatively limited dynamic range of it. Our findings could provide insights into temporal interactive effects of salinity on sediment physico-chemical properties, N reduction rates and associated gene abundances. Our findings can improve understanding of the effects of saltwater incursion on the N fate and N balance in estuarine and coastal sediments.

A quick, easy, cheap, effective, rugged, and safe method was developed for the multi-residue analysis of pesticides and antibiotics in aquaculture sediment using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The developed method is based on ultrasonic extraction with acetonitrile and phosphate buffer, salting with sodium chloride, and cleaning with dispersive solid-phase extraction adsorbent using primary secondary amine, C18, and graphitized carbon black, followed by HPLC-MS/MS detection. We optimized different extraction methods and the ratio of the cleanup adsorbents to achieve good recoveries at three spiking levels that ranged from 60.4% to 114% with a relative standard deviation below 15% (n = 6). For all analytes, except for flufenoxuron, the limits of quantification were between 1 and 5 µg/kg (dry weight). The validated method was successfully applied to real samples collected from 20 aquacultural ponds, confirming the feasibility of the proposed method. The concentrations of the target analytes in the sediments (dry weight) were in the ranges of 2.2-35.0 µg/kg for sulfonamides, 0-409.1 µg/kg for quinolones, 0-6.56 µg/kg for macrolides, and 0-4.9 µg/kg for pesticides. Moreover, the co-occurrence of pesticides and antibiotics may potentially pose a high risk to sediment-dwelling organisms in nine out of the 20 investigated locations.

Organic matter (OM) accumulation in lake sediments has doubled owing to human activities over the past 100 years, which has negatively affected the restoration of submerged vegetation and ecological security. Changes in the pollution structure of sediments caused by plant recovery and rhizosphere chemical processes under different sediment OM levels are the theoretical basis for the rational application of plant rehabilitation technology in lake management. This study explored how Vallisneria natans mediates changes in sediment N and P through rhizospheric metabolites and microbial community and function under low (4.94 %) and high (17.35 %) sediment OM levels. V. natans promoted the accumulation of NH4-N in the high-OM sediment and the transformation of Fe/Al-P to CaP in the low-OM sediment. By analyzing 63 rhizospheric metabolites and the sediment microbial metagenome, the metabolites lactic acid and 3-hydroxybutyric acid and the genus Anammoximicrobium were found to mediate NH4-N accumulation in the high-OM sediment. Additionally, 3-hydroxy-decanoic acid, adipic acid, and the genus Bdellovibrionaceae mediated the transformation of Fe/Al-P to CaP in the low-OM sediment. The growth of V. natans enriched the abundance of functional genes mediating each step from nitrate to ammonia and the genes encoding urease in the high-OM sediment, and it up-regulated three genes related to microbial phosphorus uptake in the low-OM sediment. This study revealed the necessity of controlling endogenous pollution by recovering submerged macrophytes under high- and low-OM conditions from the perspective of the transformation of inorganic nitrogen and phosphorus.

In this study, a straightforward and quick analytical technique based on the self-weighted alternating trilinear decomposition (SWATLD) algorithm in conjunction with excitation-emission matrix (EEM) fluorescence for the simultaneous determination of the antibiotics levofloxacin (LVFX) and ciprofloxacin (CIP) in environmental waters and sediments was developed. This approach completely utilizes the \"second-order advantage\" and inherits the great sensitivity of classic fluorescence. It replaces or improves the conventional \"physical/chemical separation\" with \"mathematical separation\", enabling direct and quick quantification of the target analytes even in the presence of unknown interferences, greatly streamlining sample preparation procedures, consuming less solvent, and speeding up analysis time, and allows successful and environmentally friendly solution of overlapping fluorescence spectra of multiple components in complicated environmental matrices without cumbersome pretreatment steps and complex and expensive instrumentation. The limits of detection varied between 0.34 and 0.67 ng mL- 1, and the average spiking recoveries of LVFX and CIP in water and sediment ranged from 97.6 to 107.7% with relative standard deviations lower than 6.6%. The developed method shows the reliability of the technology and the ability to quickly detect trace antibiotics in lake water even in the presence of unidentified interferents.

Microplastic (MP) pollution in global marine environments has been extensively reported and attracted significant concerns, but MP distribution in mudflat has rarely been studied. In this paper, the abundance, features and ecological risk of MP in South Yellow Sea Mudflat were investigated comprehensively. MP were both detected in waters (5.4 ± 0.38-11.3 ± 0.78 items/L) and sediments (5.1 ± 0.36-10.1 ± 0.69 items/g) from South Yellow Sea Mudflat. There existed different MP abundance tendencies from sampling Group I (coastal estuary or port) and II (purely coastal mudflat), while MP abundance in water from Group II was lower than that from Group I generally, but MP abundance in sediment from Group I was lower than that from Group II generally. This suggested that MP abundance in mudflat water could be associated with frequent human activities significantly, and disturbance might not be beneficial to MP accumulation in sediments. Fragments, transparent, polyethylene (PE), polypropylene (PP) and polystyrene (PS) were major MP features in mudflat water and sediment, and maximum proportion of size of MP was 0.001-0.25 mm in both water and sediment. Furthermore, the primary risk assessment indicated that MP pollution load for mudflat was low level. However, potential MP ecological risk for mudflat could reach dangerous level to very dangerous level by calculating and evaluating polymer risk index (PRI) and potential ecological risk index (PERI), which could be caused by high proportions of polyvinyl chloride (PVC) and polyacrylonitrile (PAN) with high hazard score. For the first time, reference data about MP pollution from South Yellow Sea Mudflat were supplied in this paper, which would be helpful for management and control of MP in mudflat.