Twenty-five surface sediments and one sediment core sample were collected from the study area. Grain size, major elements, and heavy metals were determined. The content of fine-grained sediments (silt and clay), as well as the concentrations of major elements and heavy metals, showed seaward decreasing trends, with high content in the coastal areas of the East China Sea (ECS) and south west of Jeju Island. Low enrichment factor (EF) and geoaccumulation index (Igeo) values were found, indicating that the ecological risk of heavy metals was low. The EF values obtained from the high-resolution sedimentary records of heavy metals in the Yangtze River Estuary could be divided into Stage 1 (1950s to the late 1970s) and Stage 2 (late 1970s to the current sampling day), which coincided with economic development of the Yangtze River Basin, implementation of environmental protection, and impoundment of the Three Gorges Dam.

Metal concentrations in sediments were investigated in the Gulf of Tunis, Tunisia, in relation to anthropic activities along the Mejerda River and Ghar El Melh Lagoon, with effluents discharged into the gulf. Distribution of grain size showed that the silty fraction is dominant with 53%, while sand and clay averages are 34 and 12% respectively. Zn concentration increased in the vicinity of the Mejerda River while Pb was at its highest levels at the outlet of Ghar El Mehl Lagoon. Sediment elutriate toxicity, as measured by oyster embryo bioassays, ranged from 10 to 45% abnormalities after 24h, but no relation was found between metal concentration and sediment toxicity. The AVS fraction that represents monosulfide concentrations in the sediment was higher in the central part of the gulf than in the coastal zone. The results reveal the influence of AVS, TOC and grain size on metal speciation and sediment toxicity.

The ability to calculate the oil droplet size distribution (DSD) and its dynamic behavior in the water column is important in oil spill modeling. Breaking waves disperse oil from a surface slick into the water column as droplets of varying sizes. Oil droplets undergo further breakup and coalescence in the water column due to the turbulence. Available models simulate oil DSD based on empirical/equilibrium equations. However, the oil DSD evolution due to subsequent droplet breakup and coalescence in the water column can be best represented by a dynamic population model. This paper develops a phenomenological model to calculate the oil DSD in wave breaking conditions and ocean turbulence and is based on droplet breakup and coalescence. Its results are compared with data from laboratory experiments that include different oil types, different weathering times, and different breaking wave heights. The model comparisons showed a good agreement with experimental data.

It is well established that anthropogenic nutrient inputs harm estuarine seagrasses, but the influence of nutrients in rocky intertidal ecosystems is less clear. In this study, we investigated the effect of anthropogenic nutrient loading on Phyllospadix spp., a rocky intertidal seagrass, at local and regional scales. At sites along California, Washington, and Oregon, we demonstrated a significant, negative correlation of urban development and Phyllospadix bed thickness. These results were echoed locally along an urban gradient on the central California coast, where Phyllospadix shoot δ15N was negatively associated with Phyllospadix bed thickness, and experimentally, where nutrient additions in mesocosms reduced Phyllospadix shoot formation and increased epiphytic cover on Phyllospadix shoots. These findings provide evidence that coastal development can threaten rocky intertidal seagrasses through increased epiphytism. Considering that seagrasses provide vital ecosystem services, mitigating eutrophication and other factors associated with development in the rocky intertidal coastal zone should be a management priority.

In this study, sea urchin Paracentrotus lividus were sampled seasonally at three stations during 2012 in the coastal areas of the Gulf of Annaba (southeast Mediterranean). For all sea urchins, the gonad index was calculated to determine sea urchin reproductive status. Moreover, a set of biochemical parameters, including biomarkers and oxidative stress parameters, was measured in gonads. The pesticides and physiochemical parameters were measured and dosed in sea water.The results obtained highlighted that the levels of pesticide were generally low and below those commonly applied by environmental quality standards (EQS), indicating that no alarm state is currently present in the Gulf of Annaba. In addition to pollution, seasonal change is an important factor influencing biomarker activity, and the significant increases in biomarker levels in spring are a major observed trend. This activity may also be related to reproductive status. Seasonal variability was confirmed by the significant results of the Kruskal-Wallis test and by the high degree of divergence between seasons in PCA, with a total of 83.83% of variance explained.These results indicate that environmental factors that vary seasonally may affect the antioxidant status of the sea urchin Paracentrotus lividus.

A field survey to collect microplastics with sizes <5mm was conducted in the Southern Ocean in 2016. We performed five net-tows and collected 44 pieces of plastic. Total particle counts of the entire water column, which is free of vertical mixing, were computed using the surface concentration (particle count per unit seawater volume) of microplastics, wind speed, and significant wave height during the observation period. Total particle counts at two stations near Antarctica were estimated to be in the order of 100,000pieceskm−2.

The present investigation aimed to study the effect of monsoonal and anthropogenic influences on the water quality parameters of Puducherry coastal waters. Surface water sampling was performed at three fixed stations in four distinct seasons during 2011. Physical water quality parameters such as salinity and TSM showed strong seasonal and spatial variability. Evaporation and monsoonal runoff seem to be the major controlling forces for these parameters in the coastal waters. Seasonal distribution of the parameters showed a random pattern for nitrate and a well-defined pattern for silicate. Chl-a was minimum during monsoon when high TSM was encountered in the system. Moreover, factors that regulated the phytoplankton biomass varied with seasons. Moreover, TSM was strongly correlated with silicate. The relationship between Chl-a and nutrients were more consistent throughout the year, and much weaker correlations were noticed between Chl-a and TSM. Cluster analysis depicted the existence of a marked seasonal heterogeneity.

Sediments were grouped in three zones of the bay: two in the northern basin with higher metal contamination; and another in the southern basin, where lithogenic metals were predominant. Sediment pollution classification made using Index of geoaccumulation and Enrichment factor was consistent, indicating higher accumulation of Cd and Pb in the northern basin. The negative influence of activities linked to petrol was predicted by V/Ni and V/(Ni+V) ratios. Cd and Pb did not represent a potential risk; while Cu and Ni could be risky for biota in most sediment, according to Screening Quick Reference Tables (SQuiRTs). Comparison of bioavailable fraction of metals with references in SQuiRTs corroborated the low potential damage on the biota due to As, Cd, Pb, Cr, Zn; and a higher potential damage due to Cu; while an attenuation of the risk due to Ni predicted by SQuiRTs could be expected.

This study assessed the impact of derelict fishing gear (DFG) on navigation. The Republic of Korea's navy (ROKN) recorded every case of approximately 170 naval ships associated with propeller entanglement by DFG from January 2010 to December 2015. The frequency of cases was 2.3 per ship and 397.7 (±37.5) per year. The amount of DFG disentangled was 0.025tons per ship and 10.0 (±1.7) tons per year. The frequency temporally decreased whereas the amount increased over these six years. To disentangle propellers, 3.1 divers were needed on average per case. Propeller entanglement occurred in all local seas and some of these areas showed increases over time. Our study highlights that the impact of DFG on navigational threats has been persistent and ubiquitous and can potentially be reduced by preventing DFG in fishing areas, with a focus on improved management by fishermen and government and with more efficient retrieval of DFG.