China is the world's largest mariculture producer. However, there is limited detailed information on organic matter distribution generated by mariculture in China. This study assessed the total organic carbon (TOC), total nitrogen (TN), and isotopic composition (δ13C and δ15N) in surface sediments from Zhelin Bay in South China. TOC, TN, δ13C and δ15N ranged from 0.46–1.23%, 0.08–0.20%, −22.07 to −21.13‰ and 5.28–7.14‰, respectively, and followed similar spatial patterns. The C/N ratio coupled with isotopic composition (δ13C and δ15N), indicates that the TOC originated from both terrestrial and marine sources. In general, surface sediments of Zhelin Bay were dominated by marine derived organic carbon; this form of carbon was separately calculated based on δ13C-based two end-member mixing and C/N ratio models.

The Ecological Status of subtidal benthic communities within a commercial kelp farm on the southwest coast of Ireland was not impacted by macroalgal cultivation. Additionally, there was no effect on the biomass of Zostera marina, a key habitat under the EU Habitats Directive and OSPAR Commission. However, sediment grain size and total organic matter (TOM) were influenced by abiotic and biotic aspects of the farm. A temporal effect on univariate and multivariate species data, Infaunal Quality Index (IQI) and Z. marina biomass was observed. This effect was likely a community response to high storm disturbance in winter 2013/14.The use of IQI to assess the impact of macroalgal cultivation on benthic communities is a novel approach. This study supports a view that environmental impacts of macroalgal cultivation are relatively benign compared to other forms of aquaculture. Further research must be conducted to understand all interactions between aquaculture activities and the environment.

The Weihai coast is a representative zone with fifty-year history of mariculture in China. Algae and shellfish are the main cultured species, other species including fish and sea cucumber are also cultivated. In this study, heavy metals in surface sediments, sampled along the Weihai coast during May yearly between 2009 and 2013 were investigated in terms of their contents and spatiotemporal variation. The contents of Zn, Cr, Cu, Cd, Pb and As showed different spatiotemporal variations and ranged between 11.6 and 115.9, 4.15–51.3, 5.2–21.9, 0.02–0.33, 6.0–54.2, and 2.9–18.7μgg−1, respectively. Among them, Zn, Cu and As declined during the five years. Ecological risk assessment revealed that Cd posed a moderate risk, as compared to other five elements, which were relatively low risks in surface sediments. Source analysis revealed that Zn, Cr and Cd were mainly from lithogenic contribution, while As was likely from anthropogenic discharges.

Butter clams, blue mussels, and Nuttall's cockle are important traditional food of the Gitga'at First Nation in Canada. Samples were collected and analyzed for polycyclic aromatic hydrocarbon (PAH) from the Gitga'at harvest sites from 2006 to 2015 to: 1) establish baseline conditions; 2) determine the likely source; 3) understand species specific response to spills; and 4) evaluate health risk associated with consumption. Baseline lipid normalized-total PAH in mussels was 2.36 (±2.86, 95%CI) μg/g in mussels, 3.26(±4.14) μg/g in clams and 3.98 (±4.98) μg/g in cockles. PAHs varied according to proximity to point sources and became less petrogenic through time. Concentrations of PAHs were elevated in all three species following diesel spills but returned to baseline levels within 5months. However, Gitga'at harvesters avoided bivalves from spill-affected habitats for several years because of their detection of reduced quality and palatability, highlighting the importance of incorporating local knowledge into future monitoring programs.

Natural and anthropogenic activities along the coastal region of densely populated Kerala may introduce hazardous components into the coastal environment. The present study aimed to investigate the sources and impacts of hazardous components in beach sediments by environmental magnetism methods as additional tools. Magnetic parameters (such as mass-specific magnetic susceptibility χ=−1.2–154.4×10−8m3kg−1) and ratios that describe the magnetic properties of minerals such as Fe-oxides, indicate variable concentration of mixtures of magnetite and hematite (magnetite/hematite). The direct significant relationships between the variables indicate that higher concentration magnetic parameters are associated with higher radionuclides and metal contents. Magnetic properties and multivariate statistical analyses evidence the presence of contrasting groups defined only using a reduced number of magnetic variables. One of these groups, the central area of the Kerala coastline, showed the highest magnetic concentrations of mixtures of magnetite/hematite and higher values (up to 6.7) of pollution load index because of extensive anthropogenic activities.

Marine debris such as plastic fragments and fishing gears are accumulating in the ocean at alarming rates. This study assesses the incidence of debris in the gastrointestinal tracts of seabirds feeding at different depths and found stranded along the Brazilian coast in the period 2010–2013. More than half (55%) of the species analysed, corresponding to 16% of the total number of individuals, presented plastic particles in their gastrointestinal tracts. The incidence of debris was higher in birds feeding predominantly at intermediate (3–6m) and deep (20–100m) waters than those feeding at surface (<2m). These results suggest that studying the presence of debris in organisms mainly feeding at the ocean surface provides a limited view about the risks that this form of pollution has on marine life and highlight the ubiquitous and three-dimensional distribution of plastic in the oceans.

Since 1925, dilution analysis has been used to minimize pathogenic impacts to bivalve molluscan shellfish growing areas from treated wastewater effluent in the National Shellfish Sanitation Program (NSSP). For over twenty five years, the U.S. Food and Drug Administration (FDA) has recommended a minimum of 1000:1 dilution of effluent within prohibited closure zones established around wastewater treatment plant (WWTP) discharges. During May 2010, using recent technologies, a hydrographic dye study was conducted in conjunction with a pathogen bioaccumulation study in shellfish adjacent to a WWTP discharge in Yarmouth, ME. For the first time an improved method of the super-position principle was used to determine the buildup of dye tagged sewage effluent and steady state dilution in tidal waters. Results of the improved method of dilution analysis illustrate an economical, reliable and more accurate and manageable approach for estimating the buildup and steady state pollutant conditions in coastal and estuarine waters.

The evolution of the impacts of anthropogenic activities in Todos os Santos Bay was evaluated by profiles of trace metals and Pb isotopes determined in sediment cores. Fluxes of metals increased up to 12, 4 and 2 times for Cu, Pb, and Zn, respectively, compared to those recorded in the beginning of the 20th century. Stable Pb isotopes identified a decommissioned lead smelter and burning of fossil fuels as the main sources of Pb. Most metals showed minor to moderate enrichment factors (EF<4), but Cu and Pb were highly enriched (EF=28 and 6, respectively) at the Aratu harbor. Temporal changes in sediments were associated to different activities, namely Pb smelting, burning of fossil fuels, maritime traffic, petroleum related activities, inputs of domestic effluents, and changes in land uses. The effects of the implementation of environmental policies to improve the waters of the bay could not be identified in the evaluated cores.

Aerobic respiration and nitrification are important processes for dissolved inorganic nitrogen (DIN) composition change and CO2 production in human-perturbed coastal waters. On-site incubations and field investigations were conducted in the eastern Jiaozhou Bay, a high-urbanization region, from May to August 2014. Results show that aerobic respiration rates reached 15.58μmolO2L−1d−1, and NH4+ and NO2− oxidation rates were 0.53 and 0.13μmolNL−1d−1, respectively, in the human-perturbed northeastern area. The intense aerobic respiration there contributed to high-concentration NH4+, and meanwhile caused a pH decrease of 0.042units and a pCO2 increase of 166μatm per day. Moreover, the linear relationship between excess CO2 and apparent oxygen utilization suggested that the excess CO2 in the entire eastern Jiaozhou Bay was mainly from the aerobic respiration. This study may help us better understand the role of aerobic respiration in DIN composition and CO2 sink/source pattern in coastal waters.

New particle formation (NPF) has been expected to be less favored in the polluted atmosphere than in the clean atmosphere. However, highly polluted regions in developing countries like China and India are becoming hot spots of NPF. Understanding nucleation and growth mechanisms of aerosol particles in polluted environments have important implications in their global climate impact and health effect. This paper reviewed recent publications from atmospheric field and laboratory measurements under conditions relevant to the polluted atmosphere. NPF probability in polluted environments was discussed by exploring the uncertainties in coagulation sink and growth rate estimations. Future directions and challenges in understanding NPF in highly polluted environments are presented.