This study determined the effect of monsoonal changes on the composition of atmospheric surfactants in coastal areas. The composition of anions (SO42−, NO3−, Cl−, F−) and the major elements (Ca, K, Mg, Na) in aerosols were used to determine the possible sources of surfactants. Surfactant compositions were determined using a colorimetric method as methylene blue active substances (MBAS) and disulphine blue active substances (DBAS). The anion and major element compositions of the aerosol samples were determined by ion chromatography (IC) and inductively coupled plasma mass spectrometry (ICP-MS), respectively. The results indicated that the concentrations of surfactant in aerosols were dominated by MBAS (34–326pmolm−3). Monsoonal changes were found to significantly affect the concentration of surfactants. Using principal component analysis-multiple linear regressions (PCA-MLR), major possible sources for surfactants in the aerosols were motor vehicle emissions, secondary aerosol and the combustion of biomass along with marine aerosol.

The release of phosphorus (P) from benthic sediments can affect the P content, nutrient status and quality of overlying waters in coastal ecosystem. This study was carried out to investigate the influence of oxidation-reduction potential (ORP) and sulfide on P release from sediments in the coastal estuary of the Yuniao River, China. The results showed that ferric iron-bound P was the main P burial phase in the sediments. The P concentration in overlying water increased with ORP decrease and sulfide increase, displaying a significant linear correlation with the ORP and sulfide concentration. The results indicate that decreased ORP may elevate the zero equilibrium phosphorus concentration, enhancing the capability of P release. And increased sulfide may react or capture reactive iron in sediments, reducing the P adsorption capacity and accelerating P release. Therefore, the control of ORP and sulfide production is important in the sink/source conversion of P in coastal sediments.

The performances of aluminum chloride modified clay (AC-MC), aluminum sulfate modified clay (AS-MC) and polyaluminum chloride modified clay (PAC-MC) in the removal of Aureococcus anophagefferens were compared, and the potential mechanisms were analyzed according to the dispersion medium, suspension pH and clay surface charges. The results showed that AC-MC and AS-MC had better efficiencies in removing A.anophagefferens than PAC-MC. The removal mechanisms of the three modified clays varied. At optimal coagulation conditions, the hydrolysates of AC and AS were mainly monomers, and they transformed into Al(OH)3(am) upon their addition to algae culture, with the primary mechanism being sweep flocculation. The PAC mainly hydrolyzed to the polyaluminum compounds, which remained stable when added to the algae culture, and the flocculation mainly occurred through polyaluminum compounds. The suspension pH significantly influenced the aluminum hydrolysate and affected the flocculation between the modified clay and algae cells.

Atmospheric deposition from non-ferrous mining and smelting is one of the dominant sources of heavy metal pollution in soil. Jiyuan City in Henan Province, China produces about 900 000 tonnes of lead annually. Heavy metal soil contamination and elevated blood lead levels (BLLs) of local children in Jiyuan have been reported. This work investigated As, Cd and Pb deposition fluxes over 17 consecutive months at collection sites about 1000 m from a major lead smelter in Jiyuan. Mean As, Cd and Pb deposition fluxes were 17.2, 3.45 and 88.8 mg/m2/(30 d), respectively, lower values occurred from July to September during the traditional rainy season. Decreasing deposition fluxes of Cd and Pb were observed during the 17 month period, while As increased in the same period. Deposition fluxes of As, Cd and Pb of the sites near the smelter were 22.6, 29.2 and 29.4 times of those of a clean background site (0.762, 0.118 and 3.03 mg/m2/(30 d), respectively) far away from the smelter. Annually, the deposition enriches agricultural soil (0–20 cm plow zone) at the sampling sites with 0.805, 0.161 and 4.16 mg/kg As, Cd and Pb, respectively.

Mangroves are critically threatened by human activities, despite the important ecosystem functions and services they provide. Mangroves in Cameroon represent no exception to the worldwide trend of mangrove destruction, especially around Douala, on the Wouri river estuary. In two sites around Douala, we assessed the presence of sterols, PAHs, PCBs, DEHP, DDT and its metabolite p,p'-DDE and potentially toxic metals in sediment samples. As a proxy of ecological quality, we measured the diversity and abundance of macrobenthos assemblages. We detected p,p'-DDE contamination, with concentrations higher than 3μgkg−1 in 16 out of 26 samples which were attributed to recent widespread use of DDT. The detection of sterols revealed faecal contamination. Significant sensitivity of the macrobenthos to contaminants was revealed, with possible implications on the overall mangrove vulnerability to climate change and on the provision of ecosystem services to local populations.

The contents of Cu, Pb, Zn, Cd, Cr, Hg and As in the surface sediments of over 668 sites were monitored in a comprehensive program for assessing the degree of heavy-metal pollution and adverse biological effects of the offshore sediments in China. The contamination factor and geoaccumulation index indicated that As and Pb might be two of the most influential pollution loading in these metals. Cluster analysis separated 19 areas in China's near seas into 7 groups with different pollution characteristic, where the sediments along Zhejiang coast were the most highly-contaminated. Based on biological adverse effects index and sediment quality guideline for As, nearly half of sites in China's near seas induced slight adverse biological effects. With correlation analysis, self-organizing map and factor analysis, different sources as well as various adsorption mechanisms/anthropogenic factors were suggested to be important roles in altering the concentration of heavy metals in the sediments.

Excess nutrients are potential factors that drive phase shifts from seagrasses to macroalgae. We carried out a manipulative field experiment to study the effects of macroalgae Ulva pertusa loading and nutrient addition to the water column on the nitrogen (N) and carbon (C) contents (i.e., fast indicators) as well as on the morphology and structure (i.e., slow indicators) of Zostera marina. Our results showed rapid impact of increased macroalgae and nutrient load on Z. marina C/N ratios. Also, macroalgae addition resulted in a trend of decreasing belowground biomass of seagrasses, and nutrient load significantly decreased above to belowground biomass ratio. Although some morphological/structural variables showed relatively fast responses, the effects of short-term disturbance by macroalgae and nutrients were less often significant than on physiological variables. Monitoring of seagrass physiological indicators may allow for early detection of eutrophication, which may initiate timely management interventions to avert seagrass loss.

Microplastic pollution (particles <5mm) is a widespread marine threat and a trigger for biological effects, especially if ingested. The mussel Perna perna, an important food resource, was used as bioindicator to investigate the presence of microplastic pollution on Santos estuary, the most urbanized area of the coast of São Paulo State, Brazil. A simple and rapid assessment showed that 75% of sampled mussels had ingested microplastics, an issue of human and environmental concern. All sampling points had contaminated mussels and this contamination had no clear pattern of distribution along the estuary. This was the first time that microplastic bioavailability was assessed in nature for the southern hemisphere and that wild P. perna was found contaminated with this pollutant. This is an important issue that should be better assessed due to an increase in seafood consumption and culture in Brazil and worldwide.

We propose a belt transect setting strategy for mark-recapture experiments (MREs) to evaluate the time-independent 1D diffusion coefficient (〈Dp0〉) of marine litter in the cross-shore direction that determines the backwashing flux of the litter, based on two-year MREs for plastic floats (PFs) on Wadahama Beach, Nii-jima Island, Japan. When the alongshore width of the belt transect (Lt) was of the order of, or longer than, the length scale of wave-induced nearshore current circulation (Lc), the PFs were rarely transported alongshore across the selected transects prior to being backwashed offshore. Thus, the transect residence time became longer and showed a much weaker dependence on the transect position, in contrast to when Lt was even shorter than Lc. We therefore obtained the diffusion coefficients close to the value of (〈Dp0〉) when we set Lt to the order of, or longer than, Lc.