A baseline survey of sediment contamination was undertaken at 14 locations around the coastline of Bahrain in May 2017, followed by a focused survey of 20 sites, in November 2019. Samples were assessed for industrial pollutants, including metals, PAHs and a suite of organohalogen compounds. The data generated indicated that levels of chemical contaminants were generally low and did not pose a toxicological risk when assessed against commonly applied sediment quality guidelines (SQG). The highest concentrations of PAHs and PCBs were identified in samples collected at coastal sites adjacent to a refinery area known to contain a diverse mix of industry. Tubli Bay, a heavily stressed small bay receiving high loads of sewage effluent, was also identified as an area warranting further investigation with elevated concentrations of BDE209, PFOS and metal contamination. Such data provides a useful baseline assessment of sediment contamination, against which management control measures can be assessed.

A simplified particle-tracking model with an idealised coastline was used to investigate how the interaction between variable winds and water level (VaWWL) operates spatially along a coast. The model included a constant along-coast current, horizontal diffusion, onshore/offshore wind drift, beach/cliff combinations and point/distributed litter sources. The default model reproduced basic properties of observed beach litter loadings (zero net accumulation, negatively skewed loading distributions) and the observed spatial pattern along the Scottish east coast, with average loadings increasing in the coastal current direction. The VaWWL effect moved the along-coast flux of floating litter offshore as debeaching events occur during offshore winds. Varying diffusion, coastal current speed, windage, beach/cliff combinations and different foreshore boundary conditions were investigated. Reconciling model predictions with previous estimates of plastic inflow suggested sinking rates of up to 90% soon after first entry into the sea. The VaWWL effect offers a realistic boundary condition for particle-tracking models.

The pollution of continental shelf sea sediments has always been an important issue for scientists because it can directly affect marine life and marine ecology. Thus, we carried out detailed studies of environmental magnetism and heavy metals in 145 surface sediment samples from the area southeast of the Zhoushan Islands in the East China Sea. The magnetic minerals in the sediments are mainly magnetite with a small amount of goethite and hematite. The magnetic mineral particles are mainly pseudosingle domain and contain a certain amount of superparamagnetic particles. The distribution of the magnetic mineral content shows a gradual decreasing trend from land to sea, which is closely related to the sediment transport pattern. The anhysteretic remanent magnetization (χARM) and χARM ratio to magnetic susceptibilities (χARM/χ) were more sensitive than other indexes to sediment pollution and could be used as indicators for environmental pollution in the nearshore area. Additionally, a correlation analysis with the major elements showed that the χARM ratio to saturation isothermal remanence (χARM/SIRM) can well explain the sources of terrigenous sediment. Therefore, the environmental magnetic parameters in the continental shelf area can be used as a precursor for geochemical research and provide data support for further research.

In this study, we investigated the historical variation, source identification, and distribution of heavy metal pollution in sediments of the Pearl River Estuary (PRE) using ²¹⁰Pb dating. Our results suggest that the heavy metal concentrations were higher in the western part of the estuary. For all heavy metals, Cd was significantly enriched in the sediments. The Pearl River Delta (PRD) has experienced rapid economic development in the past 40 years, a decreasing trend in heavy metal fluxes after 2004 was identified, which suggests a reduction in heavy metal concentrations due to the removal of heavy polluting industries and the effective control of sewage discharge. A binary mixing model reveals that the contributions of anthropogenic Pb ranged from 45.4 to 64%. Based on lead isotopic ratios (²⁰⁶/²⁰⁷Pb and ²⁰⁸/²⁰⁶Pb), it was found that geologic materials and industrial pollution were the main sources of heavy metals in the PRE sediments.

A simple, sensitive and effective method was developed and validated for selective adsorption and quantitation of norfloxacin (NFX) from marine sediments and seawater samples using the novel molecularly imprinted silica polymers as sorbents followed by high-performance liquid chromatographic analysis with diode array detection (HPLC-DAD). The imprinted particles were characterized by different techniques and the molecular recognition for NFX was also investigated. Several parameters affecting the extraction efficiency of molecularly imprinted solid-phase extraction (MISPE) process were optimized. Three sediment and seawater samples from Weihai bay in China were analyzed and the results show that satisfactory recoveries (77.2–98.7%) were achieved in seawater samples with low relative standard deviation (RSD) values less than 6.89% (n = 3), and the recoveries in sediments were in the range of 75.5–91.7%. The limits of detection are respectivley 2 μg L⁻¹ in seawater samples and 5 μg kg⁻¹ in sediments.

Prior studies indicated salt marsh periwinkles (Littoraria irrorata) were strongly impacted in heavily oiled marshes for at least 5 years following the Deepwater Horizon oil spill. Here, we detail longer-term effects and recovery over nine years. Our analysis found that neither density nor population size structure recovered at heavily oiled sites where snails were smaller and variability in size structure and density was increased. Total aboveground live plant biomass and stem density remained lower over time in heavily oiled marshes, and we speculate that the resulting more open canopy stimulated benthic microalgal production contributing to high spring periwinkle densities or that the lower stem density reduced the ability of subadults and small adults to escape predation. Our data indicate that periwinkle population recovery may take one to two decades after the oil spill at moderately oiled and heavily oiled sites, respectively.

Bioaccumulation of organochlorine pesticides (OCPs) in red, green, and brown seaweeds from the Gulf of Mannar was investigated using gas chromatography–mass spectrometry (GC–MS). The concentration of OCPs in all the seaweeds was in the order of endosulfan > endrin > HCH > DDT > aldrin > heptachlor > methoxychlor. The concentrations of HCH, endrin, endosulfan, and DDT in Sargassum wightii and Gelidiella acerosa, and HCH and endosulfan in Gracilaria verrucosa were above the limits prescribed by the European Commission. However, in Ulva lactuca, except for endosulfan, all other OCPs were below the permissible level. The bioaccumulation of OCPs in seaweeds was in the order of S. wightii > G. acerosa > Gracilaria verrucosa > U. lactuca. The results of comparative analysis of the levels of the investigated pesticides against the standard human health risk assessment revealed that pesticide exposure from seaweeds is hazardous to human health and the marine environment of the Gulf of Mannar.

Chemical-surveys of sediments are source of information about historical-pollution in aquatic-ecosystems, because ecological/human-health risks may arise from polycyclic-aromatic-hydrocarbons (PAHs) and nitrogen-PAHs presence in aquatic-environments, particularly sediments, where they partition. Despite this, sediment-PAHs/N-PAHs have not been reported in the Niger Delta. This study investigated vertical-profiles of PAHs/N-PAHs in 2 cm-intervals-segments from Bonny Estuary, Niger Delta. Analysis showed that ƩPAHs/ƩN-PAHs in segments ranged from 8699 to 22,528 μg/kg and 503 to 2020 μg/kg, respectively. Abundant-PAH/N-PAH are 2,6-dimethyl-naphthalene and benzo[a]acridine. PAHs/N-PAHs in the samples appeared to be from petrogenic and pyrogenic-sources. Petrogenic-PAHs/N-PAHs were predominated by 2-, 3-rings, alkylated-substituents, while, pyrogenic-PAHs/N-PAHs were dominated by 4-, 5-, 6-rings. Surface-sediments were dominated by petrogenic-PAHs/N-PAHs while, deeper-cores were heavily-contaminated with pyrogenic-PAHs/N-PAHs. ƩPAHs exceeded the ISQGs and PELs of CSQGs. Ʃ-quinoline/Ʃ-acridine exceeded the guidelines for protection of aquatic-life. Furthermore, there are concerns over toxic-ratios >70% in the estuary. Such surveys may be helpful in future sediment-management-decisions for contaminated-systems and long-term-monitoring of sediments to assess remediation/recovery.Distinct sources of PAHs and N-PAHs exist in the Niger Delta ecosystem and, there are concerns over toxic ratios >70% in the oil rich region and the potential for adverse biological effects.

The objective of the present study was to conduct an ecological and health risk assessment of heavy metals in the seawater of the southeast coast of India. The distribution profile of heavy metals in the surface seawater was Fe (79.60 ± 21.57 μg/L) > Zn (9.31 ± 1.33 μg/L) > Cu (5.19 ± 2.00 μg/L) > Ni (2.45 ± 0.76 μg/L) > Mn (1.20 ± 1.00 μg/L) > U (0.44 ± 0.23 μg/L) > Pb (0.36 ± 0.06 μg/L) > Cr (0.31 ± 0.57 μg/L) > Cd (0.11 ± 0.05 μg/L) > Co (0.07 ± 0.20 μg/L). Cu level for most of the samples exceeded the USEPA criteria for acute CMC (criterion maximum concentration) and chronic CCC (criterion continuous concentration). Other studied metals, Cd, Cr, Pb, and Ni, remained below the acute CMC and chronic CCC guidelines. The seawater pollution index (Iwₚ) of Cr, Ni, Zn, Cd, and Pb complied with the category–I seawater (<1, unpolluted). The ERI values (0.46–3.99) of the seawater of the studied coast mostly fell under the ecologically low risk category with respect to heavy metals. Dermal Hazard index values were orders of magnitude lower than one, indicating no potential health concern due to dermal exposure.