Marine Surface Sediments Research Articles

Influence of Organo‐Mineral Associations on Terrestrial Particulate Organic Matter Dispersal in the Northern Gulf of Mexico

AbstractWe investigate the influence of organo‐mineral associations on the dispersal of terrestrial organic matter (TerrOM) along a land‐sea transect offshore the Atchafalaya river in the northern Gulf of Mexico (GoM). We analyzed bulk sediment properties, mineral surface area, and clay composition and used lipid biomarkers to distinguish plant‐derived (long‐chain n‐alkanes and n‐alcohols) freshwater aquatic (C32 1,15‐diols) and soil‐microbial (branched glycerol dialkyl glycerol tetraethers (brGDGTs)) OM‐pools in different grain size fractions (≥250, 250–125, 125–63, 63–30, 30–10 and <10 μm) of marine surface sediments. Concentrations and mineral loadings of the targeted biomarkers were highest in the <30 μm fractions, suggesting an affinity with clay minerals. Spatially, concentrations of higher plant‐derived n‐alkanes remained relatively constant along the transect, whereas those of the other OM‐pools rapidly decreased further offshore. This suggests that the association of plant‐derived OM with mineral surfaces is better maintained than that of freshwater and soil‐microbial OM. In addition, similar distributions among grain size fractions at each site for the C32 1,15‐diols and brGDGTs suggest that these compounds are likely not associated with mineral surfaces in the marine realm. Furthermore, as TerrOM might be stripped from mineral surfaces upon discharge in the marine realm, the dispersal of TerrOM‐pools could also represent a degradation signal, as n‐alkanes are more resistant than long‐chain diols and brGDGTs. Together, our results indicate that the stability of organo‐mineral associations in the marine realm differs per TerrOM‐pool and can lead to a differential dispersal of these pools, and thus OM sequestration patterns in the northern GoM.

Brevibacterium litoralis sp. nov., a cellulose-degrading strain isolated from marine surface sediment.

A Gram stain-positive, non-spore-forming, non-motile, short-rod actinomyces strain GXQ1321T was isolated from maritime surface sediments in Beihai (21° 41' 21.65″ N, 109° 05' 76.56″ E), Guangxi Zhuang Autonomous Region, and a number of categorization studies were performed. Following a period of 72h of incubation at a temperature of 30°C within a modified actinomycete culture medium, the colony was light-yellow, circular, smooth, central bulge, convex, opaque, with a 1.2-2.3mm diameter. Strain GXQ1321T had the ability to degrade cellulose. Chemotaxonomic studies revealed that the major methylnaphthoquinones in strain GXQ1321T was MK-8(H2). The most prevalent cellular fatty acids were anteiso-C19:0, anteiso-C15:0, anteiso-C17:0, and iso-C16:0. The whole-cell sugars of the strain GXQ1321T were identified rhamnose, xylose and glucose. Meso-diaminopimelic acid was found in the peptidoglycan hydrolysate, and the polar lipids were identified as diphosphatidylglycerol, three phosphoglycolipid, phosphatidylglycerol and two unknown glycolipid. This strain had 69.6% DNA G+C content. Strain GXQ1321T is classified as Brevibacterium based on its 16S rRNA gene sequence. It is closely related to Brevibacterium samyangense SST-8T (96.8%) and Brevibacterium rongguiense 5221T (96.3%). The average nucleotide identity (ANI) values of GXQ1321T and the above two type strains were 73.9-77.1%, and the digital DNA-DNA hybridisation (dDDH) values were 15.3-21.1%. Based on the phylogenetic, chemotaxonomic and physiological data, strain GXQ1321T was considered to be a novel species of the genus Brevibacterium, named Brevibacterium litoralis sp. nov, with the type strain GXQ1321T (= MCCC 1K08964T = KCTC 59167T).

Cycling and persistence of iron-bound organic carbon in subseafloor sediments

Reactive iron (FeR) serves as an important sink of organic carbon (OC) in marine surface sediments, which preserves approximately 20% of total OC (TOC) as reactive iron-bound OC (FeR-OC). However, the fate of FeR-OC in subseafloor sediments and its availability to microorganisms, remain undetermined. Here, we reconstructed continuous FeR-OC records in two sediment cores of the northern South China Sea encompassing the suboxic to methanic biogeochemical zones and reaching a maximum age of ~100 kyr. The downcore FeR-OC contributes a relatively stable proportion of 13.3 ± 3.2% to TOC. However, distinctly lower values of less than 5% of TOC, accompanied by notable 13C depletion of FeR-OC, are observed in the sulfate-methane transition zone (SMTZ). FeR-OC is suggested to be remobilized by microbially mediated reductive dissolution of FeR and subsequently remineralized, the flux of which is 18–30% of the methane consumption in the SMTZ. The global reservoir of FeR-OC in microbially active Quaternary marine sediments could be 19-46 times the size of the atmospheric carbon pool. Thus, the FeR-OC pool may support subseafloor microorganisms and contribute to regulating Earth’s carbon cycle.

Multiresidue determination and predicted risk assessment of emerging contaminants in sediments from Kongsfjorden, Svalbard

The present work provides the first data on the occurrence of different classes of pharmaceuticals and personal care products (PPCPs) in surface marine sediments from an Arctic fjord (Kongsfjorden, Svalbard Islands, Norway). The target compounds included: ciprofloxacin; enrofloxacin; amoxicillin; erythromycin; sulfamethoxazole; carbamazepine; diclofenac; ibuprofen; acetylsalicylic acid; paracetamol; caffeine; triclosan; N,N-diethyl-meta-toluamide; 17β-estradiol; 17α-ethinyl estradiol and estrone. Sampling was performed in the late summer, when high sedimentation rates occur, and over 5 years (2018–2022). Based on the environmental concentrations (MECs) found of emerging contaminants and the relative predicted no-effect concentrations (PNECs), an environmental risk assessment (ERA) for sediments was performed, including the estimation of the Risk Quotients (RQs) of selection and propagation of antimicrobial resistance (AMR) in this Arctic marine ecosystem. Sediments were extracted by Pressurized Liquid Extraction (PLE) and the extracts were purified by Solid Phase Extraction (SPE). Analytical determination was conducted with liquid chromatography-high-resolution mass spectrometry (HPLC-HRMS). PPCPs were detected in the sediments along the fjord in all the years investigated, with overall concentrations similar in most cases to those reported in urbanized areas of the planet and ranging from a minimum of 6.85 ng/g for triclosan to a maximum of 684.5 ng/g for ciprofloxacin. This latter was the only antibiotic detected but was the most abundant compound (32 %) followed by antipyretics (16 %), hormones (14 %), anti-inflammatories (13 %), insect repellents (11 %), stimulants (9 %), and disinfectants (5 %). Highest concentrations of all PPCPs detected were found close to the Ny-Ålesund research village, where human activities and the lack of appropriate wastewater treatment technologies were recognized as primary causes of local contamination. Finally, due to the presence in the sediments of the PPCPs investigated, the ERA highlights a medium (0.1 < RQ < 1) to high risk (RQ > 1) for organisms living in this Arctic marine ecosystem, including high risk of the spread of AMR.

Radioactivity of Surface Marine Sediments of Chaun Bay: Analysis of Natural and Anthropogenic Factors

Radioactivity of Surface Marine Sediments of Chaun Bay: Analysis of Natural and Anthropogenic Factors

Radiolarian assemblages related to the ocean–ice interaction around the East Antarctic coast

Abstract. The Southern Ocean plays a central role in Earth's climate, ecology, and biogeochemical cycles. Therefore, understanding long-term changes in Southern Ocean water masses in the geologic past is essential for assessing the role of the Southern Ocean in the climate system. Radiolarian fossils are a useful tool to reconstruct the water masses of the Southern Ocean. However, the radiolarian assemblages in the high latitudes of the Southern Ocean (south of the polar front (PF)) are still poorly understood. In this paper, we report the radiolarian assemblages in surface marine sediment and plankton tow samples collected from the high latitudes south of the PF. In the surface sediments, four factors (named F1–F4) of the radiolarian assemblages were identified using Q-mode factor analysis, which are related to different water masses and hydrological conditions. F1 is related to the surface waters south of the southern boundary (SB) of the Antarctic Circumpolar Current (ACC), which are cooled by melting sea ice and ice sheets. F2 is associated with water masses north of the SB. A comparison with the vertical distribution of the radiolarian assemblages in plankton tow samples indicates that characteristic species are associated with the Circumpolar Deep Water (CDW) and surface waters north of the SB. F3 is associated with modified Circumpolar Deep Water (mCDW). The radiolarian assemblage of F4 does not seem specifically related to any of the water mass here analyzed. However, the species in this assemblage are typically dwells within ice shelf and/or sea ice edge environments. Radiolarian assemblages here identified and associated with water masses, and ice edge environments are useful to reconstruct the environment south of the PF in the geologic past.

Mercury distribution in the coastal zone of Central Chile, Southeast Pacific: A comprehensive assessment of seawater, sediment, and biota

This study examines the mercury content in the marine matrices water column, surface sediment and benthic invertebrates of Coronel and Coliumo bays, central Chile, under winter and summer conditions. Coronel Bay has been subject to intense industrialization in the last three decades, while Coliumo Bay remains as a fisherman's cove and a popular summer tourism destination. Our results reveal significantly higher mercury concentrations in the three environmental matrices analyzed for Coronel Bay, while Coliumo Bay exhibits levels within the range considered natural. Moreover, the mercury levels in Coronel Bay exceed the optimal criteria for aquatic life, indicating a deterioration in environmental quality of this locality. Industrial development is identified as main factor explaining the differences observed between these two coastal water bodies. This study presents the most updated record of mercury levels in the Southeast Pacific and represents the first comprehensive evaluation of marine environmental matrices in two bays with divergent activities.

Millennial-scale variations in Arctic sea ice are recorded in sedimentary ancient DNA of the microalga Polarella glacialis

Sea ice is a critical component of the Earth’s Climate System and a unique habitat. Sea-ice changes prior to the satellite era are poorly documented, and proxy methods are needed to constrain its past variability. Here, we demonstrate the potential of sedimentary DNA from Polarella glacialis, a sea-ice microalga, for tracing past sea-ice conditions. We quantified P. glacialis DNA (targeting the nuclear ribosomal ITS1 region) in Arctic marine and fjord surface sediments and a sediment core from northern Baffin Bay spanning 12,000 years. Sea ice and sediment trap samples confirmed that cysts of P. glacialis are common in first-year sea ice and sinking particulate matter following sea-ice melt. Its detection is more efficient with our molecular approach than standard micropaleontological methods. Given that the species inhabits coastal and marine environments in the Arctic and Antarctic, P. glacialis DNA has the potential to become a useful tool for circum-polar sea-ice reconstructions.

Paleoproductivity drivers in the Banggai Waters, Sulawesi, Indonesia: Insights from elemental analysis of marine surface sediment

Marine productivity, a pivotal factor in marine ecosystems and global carbon cycling, is influenced by various factors including upwelling and terrigenous nutrient influx. We investigated past marine productivity in Banggai Waters, Indonesia, using sediment samples (BUDEE22-29BC and BUDEE22-57BC) and Micro X-Ray Fluorescence (micro-XRF) analyses. Geochemical proxies (K/Ti, Ba/Al, and Zr/Al) help to assess terrigenous influx, upwelling events, and paleoproductivity. Our methodology categorizes productivity into upwelling-driven (UPW), terrigenous influx-driven (TER), and TUP (combined). The incorporation of geochemical proxy data has enabled a comprehensive understanding of historical marine productivity patterns. In BUDEE22-29BC, the K/Ti ratio initially rises and then falls below its threshold, whereas Ba/Al shows spikes and declines before rising again. Zr/Al ratios vary across depths, indicating different paleoproductivity drivers such as terrigenous influence and upwelling. BUDEE22-57BC displayed similar trends in K/Ti, Ba/Al, and Zr/Al ratios, with fluctuations indicating changes in paleoproductivity drivers, including mixing and upwelling effects. The unique positioning of Banggai Waters allows interactions between upwelling, terrigenous influx, and productivity. This study lays the groundwork for further research on past productivity changes and their drivers, thereby enhancing our understanding of marine dynamics.

Chemical composition of marine surface sediments around Tokara Islands (GB21-2 and 21-3 Cruise), Japan

Chemical composition of marine surface sediments around Tokara Islands (GB21-2 and 21-3 Cruise), Japan

Degradation and accumulation of organic matter in euxinic surface sediments

The impact of oxygen on the preservation of organic matter in marine surface sediments is still controversial. We revisited this long-standing debate by determining the burial efficiency of sedimentary organic matter in the Black Sea, the largest anoxic and euxinic basin in the modern ocean. Surface sediments were sampled in the Danube paleodelta on the northwestern margin of the Black Sea at 420–1550 m water depth. Steady-state modeling of solid species (particulate organic carbon and nitrogen) and solutes (ammonium, sulfate, and total alkalinity) in sediments was performed to quantify rates of mass accumulation, particulate organic matter (POM) degradation, and POM burial. We develop a novel analytical model to quantify these rates applying an inverse modelling approach to down core data accounting for molecular diffusion, sediment burial and compaction. Our model results indicate that 56.7 ± 6.6 % of the particulate organic matter deposited in the study area is not degraded in surface sediments but accumulates below 10 cm sediment depth. This burial efficiency is substantially higher than those previously derived for seafloor areas underlying oxygenated bottom waters. Hence, our study confirms previous studies showing that euxinic bottom water conditions promote the preservation of particulate organic matter in marine sediments.

Dinoflagellate cyst and pollen assemblages as tracers for marine productivity and river input in the northern Gulf of Mexico

Abstract. Both marine dinoflagellate cysts and terrestrially derived pollen and spores are abundant in coastal sediments close to river mouths, making sediment records from such settings ideal to simultaneously study land–ocean climate interactions, marine productivity patterns and freshwater input over time. However, few studies consider the combined calibration of these palynological proxies in modern coastal sediments offshore from rivers, which is needed to strengthen the interpretation of paleoreconstructions. Here, we analyze the palynological content of marine surface sediments along land–sea transects off the Mississippi and Atchafalaya river mouths in the northern Gulf of Mexico (GoM) and test three palynological indices which are often employed in the paleo-domain: (i) the abundance of cysts of heterotrophic and autotrophic dinoflagellates (dinocysts) as a tracer for primary productivity (H/A ratio) and (ii) the ratio between non-bisaccate pollen and bisaccates (P/B) as well as (iii) the ratio between pollen (excluding bisaccates) and dinocysts (P/D), which are both tracers for river input and distance to the coast. Our results show that dinoflagellate cysts are most abundant on the shelf, where heterotrophic dinocyst species dominate coastal assemblages in reach of the river plume, while autotrophic taxa are more present in the oligotrophic open ocean. This is clearly reflected in decreasing H/A values further offshore. Individual dinocyst taxa also seem to inhabit specific niches along an onshore–offshore transect, linked to nutrient availability and proximity to the turbid river plume. The highest pollen concentrations are found close to the Mississippi river mouth and mostly represent a mixture of local coastal and upstream vegetation, whereas bisaccate pollen was most abundant further offshore of the Mississippi river. Multivariate redundancy analysis (RDA) performed on both pollen and dinocyst assemblages, a set of environmental parameters, and the three palynological ratios showed that net primary productivity was the most important variable influencing the dinocyst assemblages, likely as the result of nutrient input. Additionally, the RDA confirmed that the H/A ratio indeed seems to track primary productivity, while the P/B ratio results in a robust indicator for distance to the coast, and the P/D ratio better reflects river input. Together, our data confirm and further specify the suitability of these three palynological ratios in river-dominated coastal margins as proxies for (past) marine productivity and distance to the coast and river.

Biogeographic patterns of micro-eukaryotic generalists and specialists and their effects on regional α-diversity at inter-oceanic scale

Inter-oceanic scale studies allow us to understand the global spread of micro-organisms in marine ecosystems. In this study, micro-eukaryotic communities in marine surface sediment were collected from tropical to Arctic sites. We found that micro-eukaryotic generalists had much higher intraspecific variation than specialists which allow them to distribute more widely through higher spatiotemporal asynchrony and complementary niche preferences among conspecific taxa. Moreover, comparing to the host-associated protozoa and small metazoa, the algae and free-living protozoa with higher intraspecific variation allow them to have wider distribution ranges. Species abundance also played an important role in driving the distribution ranges of generalists and specialists. The generalists had important effects on regional α-diversity even at an inter-oceanic scale which led to the micro-eukaryotic species richness in polar sites to be mainly influenced by the regional generalists but not the local specialists. In particular, more than 97% of algal species in polar sites were shared with the tropical and subtropical sites (including toxic dinoflagellate). Overall, our study suggests that the effects of global change and human activities on the vulnerable high latitude habitats may lead to biotic homogenization for the whole microbial community (not only the dispersal of some harmful algae) through the potential long-distance spread of generalists.

Climatic controls on leaf wax hydrogen isotope ratios in terrestrial and marine sediments along a hyperarid-to-humid gradient

Abstract. The hydrogen isotope composition of leaf wax biomarkers (δ2Hwax) is a valuable tool for reconstructing continental paleohydrology, since it serves as a proxy for the hydrogen isotope composition of precipitation (δ2Hpre). To yield robust palaeohydrological reconstructions using δ2Hwax in marine archives, it is necessary to examine the impacts of regional climate on δ2Hwax and assess the similarity between marine sedimentary δ2Hwax and the source of continental δ2Hwax. Here, we examined an aridity gradient from hyperarid to humid along the Chilean coast. We sampled sediments at the outlets of rivers draining into the Pacific as well as soils within catchments and marine surface sediments adjacent to the outlets of the studied rivers and analyzed the relationship between climatic variables and δ2Hwax values. We found that apparent fractionation between leaf waxes and source water is relatively constant in humid and semiarid regions (average: −121 ‰). However, it becomes less negative in hyperarid regions (average: −86 ‰) as a result of evapotranspirative processes affecting soil and leaf water 2H enrichment. We also observed that along strong aridity gradients, the 2H enrichment of δ2Hwax follows a non-linear relationship with water content and water flux variables, driven by strong soil evaporation and plant transpiration. Furthermore, our results indicate that δ2Hwax values in marine surface sediments largely reflect δ2Hwax values from the continent, confirming the robustness of marine δ2Hwax records for paleohydrological reconstructions along the Chilean margin. These findings also highlight the importance of considering the effects of hyperaridity in the interpretation of δ2Hwax values and pave the way for more quantitative paleohydrological reconstructions using δ2Hwax.

The Impact of Changes in Sea Level and East Asian Monsoon on Sediment Transport on the Sunda Shelf Since the Last Deglaciation

AbstractThe Sunda Shelf plays a key role in the sedimentation of the southern South China Sea (SCS). However, the impact of past climate changes on sediment transfer to the Sunda Shelf and the southern SCS is still unresolved. Here, we present new data on grain size, clay mineralogy, and Sr‐Nd isotopes of three marine cores, river sediments, and surface sediments of the Sunda Shelf. The results indicate that clay fractions of the central Sunda Shelf and the Gulf of Thailand derived mainly from the Mekong River and the rivers of northern Thailand since the last deglaciation. Significant changes in sediment sources are observed at 7.5 cal ka BP. From 13.3 to 7.5 cal ka BP, sediments in the Gulf of Thailand mainly originated from the rivers of northern Thailand, with contributions from the Mekong River increasing after 7.5 cal ka BP. An opposite shift is observed in the central Sunda Shelf. Such variations in the spatial distribution result from a combination of sea level and East Asian monsoon effects. After 7.5 cal ka BP, less Mekong River sediments were transported southeastwards into the southern SCS, and more sediments were gradually trapped within the delta and transported in a southwesterly direction into the Gulf of Thailand due to intense East Asian winter monsoon, which forced a strong southwestward coastal current. Our results demonstrate the important impact of East Asian winter monsoon strengthening and sea level rise in the mid‐Holocene, which can change sediment sources and transport processes on the Sunda Shelf.

Impact of submarine karst sulfur springs on benthic foraminiferal assemblage in sediment of northern Adriatic Sea

PurposeThis work highlights the sedimentary characteristics and the role of submarine sulfur-rich karstic springs in the distribution of benthic foraminifera in the northern part of the Adriatic Sea (Bay of Koper). Little is known about how local conditions such as temperature and sulfur bursts may influence sediment properties, benthic habitat variability, and composition of foraminiferal assemblages. Here we compare the distribution of total and living benthic assemblages in surface sediment samples collected from a funnel-shaped depression created by submarine sulfur springs.Materials and methodsSampling was performed at water depths between 24.6 and 32.2 m in fine-grained sandy silt to silty sand (partially washed). Sedimentological, mineralogical, and geochemical analyses of the sediment were carried out and the distribution of benthic foraminifera living around the springs was studied.Results and discussionIn general, sediment characteristics (i.e., mineralogical, geochemical, and organic content) around the sulfur springs do not show prominent deviations from the marine surface sediment of the area; however, some differences exist among depressions of different depths. Deeper depressions in the lower parts probably extend to older continental sediments of Late Pleistocene age with alluvial features, while shallower depressions were formed entirely in Holocene marine sediments typical of a wider area. Only one of the five samples (M05) contained living foraminifera in sufficient abundance for biocenosis research. The benthic foraminiferal assemblages of moderate diversity are composed of opportunistic species. Elphidium translucens, Ammonia ex gr. tepida, Haynesina depressula, and Porosononion granosum dominate, while A. neobeccarii, Reussella spinulosa, and Textularia bocki are subordinate.ConclusionsThe distribution and diversity of foraminifera in the sediment near sulfur springs can be explained by several factors and their interactions. The intensity of the spring discharge affects the mixing/oxygenation of the sediment, the shape of spring depressions, and the granulometry of the coarser sediment around the springs. Sediment characteristics indicate different types of sediment origin. This is related to and can be explained by the depth of spring depressions.

Identification of the sediment-water interface during field full-flow penetration tests

The undrained shear strength of marine surface sediments is critically important for both the development of marine resources and environmental protection. In situ full-flow penetration tests offer significant advantages for evaluating these surface sediments, particularly those with low strength. Accurately analyzing the strength of surface sediments during in situ full-flow penetration tests relies on correctly identifying the sediment-water interface, also known as the mudline. Unfortunately, there is currently no established method for solving this problem. This study utilizes computational fluid dynamics to conduct a numerical analysis of full-flow penetrometer probes (specifically of ball and T-bar probes) as they penetrate marine surface sediments of varying strengths and densities from different heights. By examining the variation in the dimensionless drag force coefficient of the probes in relation to the dimensionless penetration depth, the impact of the mudline on the drag force trend is systematically analyzed. Additionally, a methodology for determining the mudline location using a mudline distinguishing factor is proposed. This mudline distinguishing factor was tested during a field trial of the in situ ball full-flow penetration device in the Philippine Sea, The proposed methodology for identifying the mudline and analyzing the strength of marine surface sediments has significant value for the field.

Quantification of carbon cycling within the aerobic zone in surface sediments of the Bohai Sea, China

Evaluating the carbon cycling driven by aerobic oxidation of methane (AeOM) in surface marine sediments and calculating the CH4 flux to the seawater is critical for assessing the risk of greenhouse gas emission, as well as exploring for gas field. This study provides quantitative results of carbon cycling in the aerobic zone of the Bohai Sea, China, and the function of AeOM for CH4 interception via numerical simulations constrained by laboratory experiments. TOUGH + HR, an integrated simulation package, was used to numerically characterize the microbial AeOM, which couples water/gas transport and biogeochemistry. Based on the laboratory experiments and measured data in the Bohai Sea, a one-dimensional column conceptual model was constructed and solved by TOUGH + HR. The results show that when the upward CH4 flux into the aerobic zone is between 4.5 × 10−9 and 4.8 × 10−9 kg/s/m2, the simulated dissolved methane matched the measured data well. Under this condition, most of the CH4 source flux (18.63 mmol·carbon/m2/day) was oxidized to dissolved inorganic carbon (DIC), which finally discharged into the seawater with the flux of 18.44 mmol·carbon/m2/day, while only a tiny part of CH4 leaked into the seawater with the flux of 0.0003 mmol·carbon/m2/day. Therefore, it can be concluded that the aerobic zone in the sediments intercepts the majority of CH4, which mitigates the greenhouse gas emission from marine sediments. At the same time, the sensitivity analyses in this study indicate that carbon cycling is affected by methane flux and temperature, which influences the proportion of carbon sources and sinks. The results have important guidance for gas exploration and carbon cycling when the AeOM in the aerobic zone is considered.

Short- and Medium-Chain Chlorinated Paraffins in the Sediment of the East China Sea and Yellow Sea: Distribution, Composition, and Ecological Risks.

Chlorinated paraffins (CPs), a class of complex mixtures synthesized from polychlorinated n-alkanes, are widely used as flame retardants, plasticizers, lubricant additives, coolants, metalworking cutting fluids, and sealants. This study investigated the spatial distribution, the potential pollution sources, and ecological risk of 24 short-chain CPs (SCCPs) and 24 medium-chain CPs (MCCPs) from 29 surface marine sediment samples from the East China Sea and Yellow Sea in September 2019. All of the 48 CPs were detected. The concentrations of SCCPs and MCCPs ranged from 0.703 to 13.4 ng/g dw and 0.0936 to 4.19 ng/g dw, respectively. C10 congeners showed the highest abundancy. The median concentrations of the SCCPs and MCCPs declined gradually with carbon atoms and chlorine atoms, except for Cl5 congeners. Spatial variations showed that all CP congeners in the East China Sea were larger than in the Yellow Sea and displayed a point-source-type distribution, which is consistent with the industrial park distribution. Although the potential ecological risk was at a relatively low level, bioaccumulation and trophic magnification could amplify the risk to marine organisms. Our results provide data support and theoretical assistance for SCCP and MCCP pollution control and sewage outlets in the East China Sea and Yellow Sea.

A meta-analysis of the occurrence of alkylphenols and alkylphenol ethoxylates in surface waters and sediments in the United States between 2010 and 2020

Nonylphenol (NP), Octylphenol (OP), and their ethoxylates (NPEO and OPEO) have been the subject of considerable scientific and regulatory attention, primarily due to concerns about their aquatic toxicity and endocrine activity. Environmental monitoring has been conducted and reported for these substances in the United States (U.S.) for several decades. This paper develops an updated statistically based meta-analysis of the occurrence and ecological relevance of these substances in fresh and marine surface waters and sediments in the U.S. between 2010 and 2020. The overall objectives of this study were: (1) to evaluate the impact of analytical detection limits (DLs) and treatment of censored or non-detected (ND) samples on reported results, (2) to summarize and evaluate recent (2010–2020) occurrence and concentrations of these substances in surface waters and sediments, (3) to conduct an ecological screening assessment of the potential risks of these substances to aquatic organisms in surface waters and sediments for this same period, and (4) to examine temporal trends of these substances in surface waters and sediments relative to previous investigations. Given that a large proportion of all NP, NPEO, OP and OPEO samples in recent (2010–2019) U.S. monitoring studies were below their respective method Limit of Detection/Limit of Quantification (LOD/LOQ) detection frequency ranging from 0 to 24%), proxy values were imputed using robust regression of order statistics (ROS). Nationally, NP and OP concentrations in fresh surface waters and sediments have decreased from 2010 to 2019. In contrast, changes in NP and OP concentrations in marine waters and sediments were more variable with some increases noted. A screening environmental risk assessment indicated that less than 1% of all samples exceeded U.S. or Canadian environmental quality guidelines. No exceedances were noted after 2016 which indicates a low potential for risk to aquatic organisms.