Forty-three surface sediment samples and one gravity core obtained from the offshore area of the Changjiang River were analyzed for selected heavy metals (Cu, Pb, Zn, Cd, As, Hg) to evaluate the spatial distribution and potential ecological risk during the last century. The results indicated that the sediments are composed of silty sand, sandy silt and silt and were deposited in a relatively stable environment over the last century. The studied marine sediments are fine and easily adsorb heavy metals from aquatic systems. The heavy metal concentrations were found to be enriched in the sediments and were generally closely related to anthropogenic activities. However, the data analysis demonstrated that the levels of heavy metal contamination were below background values during the last century, indicating low ecological risk. Spatially, a higher concentration was found at the entrance to the Changjiang River, while it decreased to the northeast. The vertical distribution of contamination levels and ecological risk can be divided into four periods based on the downcore variation in heavy metals: pre-1940s, 1940s–1970s, 1970s–1990s and the late 1990s to the present. These conclusions form the basis for implementing appropriate policies to protect marine sediment quality.

Benthic indices are commonly used tools for assessing the environmental quality, because they represent a simple source of scientific information. However, their performance could vary depending on the application area and perturbation types, thus they should be tested before used in other remote geographic regions. This study aims to test the use of some of the most widely common benthic biotic indices for assessing the environmental quality of Montevideo’s coastal zone at a seasonal scale against many physicochemical variables. From all the evaluated indices, AMBI appears to be the most suitable one to assess the environmental quality. The study also allowed us to infer the most relevant physicochemical variables: protein, lipid and heavy metal sediment concentration. Additionally, site-specific threshold effect levels for heavy metals and biopolymers were established, which appear to be useful to determine tolerable levels of such stressors in future assessments or monitoring programs for the study area.

The Tupinambás Ecological Station (TES) is a Marine Protected Area consisting of two sectors: the Archipelago of Alcatrazes and the Cabras and Palmas islets. This investigation aimed to provide a first diagnosis of the concentrations of metals (Al,Cr,Cu,Fe,Hg,Ni,Pb,Zn), As and P in sediments from the TES. 24 sediment samples were collected in both sectors using a Van Veen grab sampler. Sediment textures and levels of Organic Matter (OM) and CaCO3 were determined, as well as the concentrations of the above-mentioned elements after partial acid digestion. Sediments were predominantly sandy. Higher levels of CaCO3 occurred in the Alcatrazes sector, whereas the OM contents were higher in the islets sector. Metals concentrations were low and associated with fines, while P and As presented a different behavior. The observed concentrations to all studies elements in sediments from the TES were considered as background values.

Rhamnolipid biosurfactant-producing bacteria, Bacillus Lz-2, was isolated from oil polluted water collected from Dongying Shengli oilfield, China. The factors that influence PAH solubilization such as biosurfactant concentration, pH, ionic strength and temperature were discussed. The results showed that the solubilities of naphthalene, phenanthrene and pyrene increased linearly with the rise of rhamnolipid biosurfactant dose above the biosurfactant critical micelle concentration (CMC). Furthermore, the molar solubilization ratio (MSR) values decreased in the following order: naphthalene>phenanthrene>pyrene. However, the solubility percentage increased and followed the opposite order: pyrene>phenanthrene>naphthalene. The solubilities of PAHs in rhamnolipid biosurfactant solution increased with the rise of pH and ionic strength, and reached the maximum values under the conditions of pH11 and NaCl concentration 8g·L−1. The solubility of phenanthrene and pyrene increased with the rise of temperature.

The Alang–Sosiya shipbreaking yard (ASSBY) is considered the largest of its kind in the world, and a major source of anthropogenic pollutants. The aim of this study was to investigate the impact of shipbreaking activities on the bacterial community structure with a combination of culture-dependent and culture-independent approaches. In the culture-dependent approach, 200 bacterial cultures were isolated and analyzed by molecular fingerprinting and 16S ribosomal RNA (r-RNA) gene sequencing, as well as being studied for degradation of polycyclic aromatic hydrocarbons (PAHs). In the culture-independent approach, operational taxonomic units (OTUs) were related to eight major phyla, of which Betaproteobacteria (especially Acidovorax) was predominantly found in the polluted sediments of ASSBY and Gammaproteobacteria in the pristine sediment sample. The statistical approaches showed a significant difference in the bacterial community structure between the pristine and polluted sediments. To the best of our knowledge, this is the first study investigating the effect of shipbreaking activity on the bacterial community structure of the coastal sediment at ASSBY.

In order to determine the source of organic matter and the fingerprint of the oil components, 50 samples collected from the near-surface sediments of the oil spill area in Bohai Sea, China, were analyzed for grain size, total organic carbon, aliphatic hydrocarbons (AHs), and polycyclic aromatic hydrocarbons (PAHs). The concentrations of C15–35 n-alkanes and 16 United States Environmental Protection Agency (US EPA) priority pollutant PAHs were found in the ranges of 0.88–3.48μg g−1 and 9.97–490.13ng/g, respectively. The terrestrial organic matters characterized by C27–C35 n-alkanes and PAHs, resulting from the combustion of higher plants, are dominantly contributed from the transportation of these plants by rivers. Marine organic matters produced from plankton and aquatic plants were represented by C17–C26 n-alkanes in AHs. Crude oil, characterized by C17–C21 n-alkanes, unresolved complex mixture (UCM) with a mean response factor of C19 n-alkanes, low levels of perylene, and a high InP/(InP+BghiP) ratio, seeped into the oceans from deep hydrocarbon reservoirs, as a result of geological faults.

This study investigated the levels, sources and potential risks of 17 polycyclic aromatic hydrocarbons in surface sediment samples collected along the Mithi River of Mumbai. The concentration level of ΣPAHs found in the present study was in the range of 1206–4735ng/gdw. The composition patterns of PAHs by ring size in sediment were surveyed which indicate the dominance of four rings followed by five and three ring PAHs. In the study it was observed that the high molecular weight PAHs (HMW PAHs) made greater contributions of 90.83% as compared to that of low molecular PAHs (LMW PAHs) contributing to 9.17% to the total PAH concentrations. Toxicity and biological risk were assessed using toxic equivalent quantity and sediment quality guideline quotient. It is feared that the pollution level of PAHs in the sediments might increase in coming times resulting in an unconspicuous risks for the environment and humans through food chains.

In Mar del Plata (Argentine, SW Atlantic), a large seaside resort, the sewage discharges impact the littoral ecosystem. The invader polychaete Boccardia proboscidea has developed reefs since spring of 2008. The effect of this species on the richness, diversity and structure of epilithic intertidal community was assessed through an MBACI design in both sewage-impacted and reference sites, and Before/After the invasion. The presence of reefs of B. proboscidea since spring 2008 has caused a significant reduction of total individuals, total taxa and diversity in sewage-impacted sites regarding the reference ones. The species analyzed showed a high variable response because patterns were dominated by small-scale variability. Occasional peaks in abundance were observed on a single sampling site and time and a large variation among replicates. The associated fauna, formerly rich and diverse in impacted sites, shows a tendency to disappear as the ecosystem engineer Brachidontes rodriguezii is replaced by monocultures of B. proboscidea.

The whole-sediment Toxicity Identification Evaluation (TIE) approach is a useful technique that allows for the identification of the contaminants responsible for the toxicity of complex sediment samples. This study aimed to compare the effectiveness of this technique in identifying the causes of toxicity when the test organism used in the toxicity test is capable of ingesting sediment particles. Two forms of exposure were compared: whole-sediment (WS), which integrates dermic and dietary exposures; and sediment–water interface (SWI), which involves dermic exposure only. The combined analysis of the TIE experiments revealed that metals, ammonia and, at one station, organic compounds, were responsible for sediment toxicity. The integrated use of WS and SWI TIE manipulations provided a more complete overview of the causes of toxicity, and thus enabled a better comprehension of complex contamination situations and, consequently, a better ecological assessment.

Concentration of toxic cyanobacteria blooms on the downwind shore of high recreational amenity water bodies with largely increases the risk of exposure to cyanotoxins. In this study analysis of phytoplankton structure, cyanotoxin composition and concentration was performed on cyanobacteria scum material, high- and low-density bloom samples in the Curonian Lagoon. We found that the concentration of cyanotoxins in the scum material increased from ∼30 to ∼300-fold compared to bloom samples. In Microcystis aeruginosa dominated samples microcystin-LR was present at the highest concentration, while the dominance of Planktothrix agardhii was associated with the occurrence of dmMC-RR as the major microcystin variant. The toxicological potential of cyanobacterial scums in the Curonian Lagoon is emphasized, and management by removal of these scums is proposed.