In this study, 76 μm polyoxymethylene (POM) strips were evaluated as a passive air sampler (PAS) for monitoring the volatile emissions from dredged material placed in confined disposal facilities (CDF). Laboratory evaluations were used to assess the uptake kinetics, average equilibrium time, and estimate the POM-air partition coefficients (KPOM₋A) of 16 PCB congeners. The uptake kinetics defined the effective averaging time for air sampling and ranged from about a week for dichlorobiphenyls to 2 weeks or more for tetra- and pentachlorobiphenyls at ∼20 °C under internal mass transfer resistance control which was applicable for Log KPOM₋A < 8. The measured Log KPOM₋A for PCBs ranged from 5.65 to 9.34 and exhibited an average deviation of 0.19 log unit from the theoretical value of KPOM₋W/KAW. The PAS approach was then tested with a preliminary field application (n = 17) at a CDF allowing equilibration over 42 days. The field application focused on lower congener PCBs as a result of the estimated increase in KPOM₋A and longer uptake times expected at the low ambient temperatures during the field study (average of 3.5 °C). Total PCB air concentrations around the CDF averaged 0.32 ng/m³ and varied according to proximity to placement of the dredged materials and predominant wind directions. Average PAS concentration of low congener number PCBs (15, 18, 20/28, 31) were compared to available high volume air sampler (HVAS) measurements. The PAS concentrations were within 20% of HVAS in the dominant north and south directions and showed similar trends as east and west HVAS samplers although PAS concentrations were as much as an order of magnitude below the west HVAS.

The objective of this study was to characterize and understand the water quality of Boston’s Muddy River prior to restoration, to help guide those activities and evaluate their success. We use a combination of monitoring, data analysis and mathematical modeling. The seasonal pattern of temperature, pollutant signatures (identified using a principal component analysis), correlations with precipitation and spatial patterns all point to a significant wastewater input at one of the outfalls and suggest significant receiving water impact. However, a quantitative analysis using a mathematical model (QUAL2K) suggests this source is not significant. Rather, internal loading from algae, sediment bed and waterfowl dominate the spatial pattern of water quality. These results suggest significant improvement can be expected from planned sediment dredging. The paper provides a case study of water quality assessment in the context of urban river restoration, and it illustrates the utility of combining monitoring and data analysis with modeling.

The problem of effective assessment of risk posed by complex mixtures of toxic chemicals in the environment is a major challenge for government regulators and industry. The biological effect of the individual contaminants, where these are known, can be measured; but the problem lies in relating toxicity to the multiple constituents of contaminant cocktails. The objective of this study was to test the hypothesis that diverse contaminant mixtures may cause a greater toxicity than the sum of their individual parts, due to synergistic interactions between contaminants with different intracellular targets. Lysosomal membrane stability in hemocytes from marine mussels was used for in vitro toxicity tests; and was coupled with analysis using the isobole method and a linear additive statistical model. The findings from both methods have shown significant emergent synergistic interactions between environmentally relevant chemicals (i.e., polycyclic aromatic hydrocarbons, pesticides, biocides and a surfactant) when exposed to isolated hemocytes as a mixture of 3 & 7 constituents. The results support the complexity-based hypothesis that emergent toxicity occurs with increasing contaminant diversity, and raises questions about the validity of estimating toxicity of contaminant mixtures based on the additive toxicity of single components. Further experimentation is required to investigate the potential for interactive effects in mixtures with more constituents (e.g., 50–100) at more environmentally realistic concentrations in order to test other regions of the model, namely, very low concentrations and high diversity. Estimated toxicant diversity coupled with tests for lysosomal damage may provide a potential tool for determining the toxicity of estuarine sediments, dredge spoil or contaminated soil.

Portmán Bay is a heavily contaminated area resulting from decades of metal mine tailings disposal, and is considered a suitable shallow-water analogue to investigate the potential ecotoxicological impact of deep-sea mining. Resuspension plumes were artificially created by removing the top layer of the mine tailings deposit by bottom trawling. Mussels were deployed at three sites: i) off the mine tailings deposit area; ii) on the mine tailings deposit beyond the influence from the resuspension plumes; iii) under the influence of the artificially generated resuspension plumes. Surface sediment samples were collected at the same sites for metal analysis and ecotoxicity assessment. Metal concentrations and a battery of biomarkers (oxidative stress, metal exposure, biotransformation and oxidative damage) were measured in different mussel tissues. The environmental hazard posed by the resuspension plumes was investigated by a quantitative weight of evidence (WOE) model that integrated all the data. The resuspension of sediments loaded with metal mine tails demonstrated that chemical contaminants were released by trawling subsequently inducing ecotoxicological impact in mussels’ health. Considering as sediment quality guidelines (SQGs) those indicated in Spanish action level B for the disposal of dredged material at sea, the WOE model indicates that the hazard is slight off the mine tailings deposit, moderate on the mine tailings deposit without the influence from the resuspension plumes, and major under the influence of the resuspension plumes. Portmán Bay mine tailings deposit is a by-product of sulphide mining, and despite differences in environmental setting, it can reflect the potential ecotoxic effects to marine fauna from the impact of resuspension of plumes created by deep-sea mining of polymetallic sulphides. A similar approach as in this study could be applied in other areas affected by sediment resuspension and for testing future deep-sea mining sites in order to assess the associated environmental hazards.

It has been shown that the current approach to the assessment of contamination in the sediments obtained during the dredging works in the Baltic countries indicates the presence of "non-contaminated" dredged material. The concentration limits of heavy metals, Polycyclic Aromatic Hydrocarbons (PAHs), Polychlorinated Biphenyls (PCBs) have been exceeded only in 1% of the samples obtained during the dredging works (2005–2015) within the Polish coastal zone. After 2008, no contaminated sediments have been found. Also, in the remaining Baltic countries, sediments are very rarely contaminated. As a result of this assessment, the sediments can be stored in the sea or have a practical application. However, it has been questioned whether the large cost of determining the numerous chemical parameters is justified. It has been proposed to carry out simple screening tests. Following the preliminary screening, the decision on more detailed (and expensive) chemical tests of individual pollutants would be made.

Dredged sediments have different physical and chemical characteristics compared with the sediments in place, which generates multiple effects on the environment.In this study, we show that the sampling strategy used to monitor the effects of dredge spoil deposition on the surrounding environment can lead to different interpretations. It appears that sediment sample replicates may or may not be necessary, depending on the studied area, the prevailing environmental forcings before sediment sampling and the combination of these two factors. The proposed modus operandi allows us to optimize both the confidence on the obtained results and the cost of the sediment studies (sampling and laboratory analyses). The results are based on the sediment fine fraction, which is considered as a key environmental component due, for example, to its strong association with the structure of benthic faunal communities as well as its role in the build-up of pollutants.

In 2014, the concentrations of 13 heavy metals in surface sediments from 14 sampling stations were analyzed and compared to samples from previous years to evaluate the remediation effectiveness of the “rest-year” (RY) system and capping with dredged material at the Yellow Sea-Byung dumping site offshore Korea. Since the 2006 introduction of the RY system, annual variations in metal concentrations at stations within the RY zone have gradually decreased over time. Heavy metal concentrations at most stations were lower than sediment quality guidelines, indicating the success of the RY system. Additionally, the effects of capping the contaminated sediment with dredged materials were investigated. The results indicate that dredged materials successfully capped the contaminated sediment within the dredged material dumping area, as the concentrations of Cr and total organic carbon were significantly reduced. We conclude that dredged materials may be used as capping materials for the remediation of contaminated sediments.

The influence of the sediment’s physico–chemical properties and black carbon content, on the distribution of polycyclic aromatic hydrocarbons and polychlorinated biphenyls in benthic sediments of the Gulf of Gdansk (Baltic Sea) was determined. Sediments from port, marine dump site of dredged spoils, the Vistula river mouth, Gdansk Deep were selected. The concentrations of ∑PAHs (fluoranthene, pyrene, benzo(a)anthracene, benzo(k)fluoranthene, benzo(a)pyrene, dibenzo(ah)anthracene, benzo(ghi)perylene) were 294–2200ng/g d.w. and for ∑PCBs (28, 52, 101, 118, 138, 153, 180) were 2.4–11.3ng/g d.w. The sediments content of loss on ignition was 1.13–16.15%, total organic carbon was 0.89–7.15%, black carbon was 0.20–1.15%. The highest correlation coefficient values (r=0.76–0.92, p<0.05) for a relationship between the concentrations of organic pollutants, and organic matter, organic and black carbon contents were obtained in harbor sediments with low content of organic matter (<5%) and high share of black carbon in total carbon (up to 40%).

An investigation into the abundance and distribution of meso- and microplastics within the Port of Durban was conducted using a static immersible water pump and particle filtration system to collect meso- and microplastics from the water column, microplastics from sediment samples and corresponding CTD. Microplastics were detected in all samples under investigation. Results suggest that sewage overflow, stormwater drains, port operations, followed by rivers are input areas for mitigation to focus on. Identifying meso- and microplastics inputs, baselines and distribution allow for long term monitoring and management in a harbour environment. This can potentially contribute to the control and regulation of small plastics particles in harbours, and the subsequent transport of these pollutants via dredged material into other ecosystems.

Currently, our understanding of the mechanisms for, and potential functional implications of, changes in seabed assemblages resulting from dredged material disposal is relatively unknown. Based on empirical data from 17 disposal sites, we address this by quantifying the nature and magnitude of shifts in the relative composition of response and effects traits within disposal site assemblages relative to their reference assemblages.Differing shifts in both response and effects traits were observed across sites, regardless of the trait composition of the reference assemblages. Notable differences in the magnitude of traits changes were also observed for both trait types. Traits shifts are difficult to predict as they appear to reflect both environmental conditions and disposal regime. Temporal data revealed that some sites display relatively consistent responses while others presented large inter-annual variability. These findings are discussed in relation to dredged material monitoring and with respect to conservation objectives of marine protected areas.