Temporal evolution, source apportionment and transport pathways of particulate matter (PM2.5 and PM10) are analysed over Guwahati, located in the Brahmaputra River Valley (BRV), as a function of meteorological dynamics. During the study period (July 2013–June 2014), the mean PM2.5 and PM10 mass concentrations were found to be 52 ± 37 and 91 ± 60 μg m−3, respectively, both exhibiting higher concentrations during December–March and very low during summer. The annual mean ratio of PM2.5/PM10 was 0.57 ± 0.11, varying from 0.24 to 0.86, suggesting dominance of anthropogenic vs natural emissions during winter and spring, respectively. Diurnal variation reveals higher PM concentrations during morning (∼9:00 local time (LT)) and evening (∼23:00 LT) and lowest around ∼14:00 to 17:00 LT due to influence of dilution processes and higher mixing-layer height over the region. Bivariate plots and Conditional Bivariate Probability Function (CBPF) analysis showed that the highest PM2.5 and PM10 concentrations are mostly associated with weak northwestern winds (<1.5 ms−1) in all seasons except spring, when the highest PM10 are for southwestern winds above 4–6 ms−1, indicating dust transport from SW Asia. Analysis reveals that the local emissions, transported aerosols, along with seasonally-changed air masses, meteorology and boundary-layer dynamics control the concentrations, evolution and fractions of PM over BRV. The turbid air masses transported over Guwahati mostly from western and southwestern directions contribute to higher PM concentrations, either carrying anthropogenic pollution from Indo-Gangetic Plains or locally and LRT dust from BRV and western India, respectively.

The study characterized the enrichment, ecological risk and possible source of heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb and Zn) in sediments from a typical mariculture bay. The concentrations of the metals were analyzed in sediments collected from Zhelin bay. The distribution variation was examined during the past decade, which had an increase tendency till 2011. The enrichment factor and geoaccumulation indices suggested Pb, As, Cu and Zn were minor enrichment and unpolluted to moderately polluted, and Ni at cage mariculture area was moderately-severe enrichment and strongly polluted. This area had medium to high ecological risk, especially at the northwest coastal area of semi-closed bay, with high-medium to high ecological risk. Correlation and principal component analyses indicated that most of heavy metals, especially for As, Pb and Ni, primarily resulted from the combustion of gasoline and diesel fuel and the ship protective layer.

Green tides have occurred in Qingdao coast in China for seven consecutive years from 2007 to 2013. To provide information on the genetic structure of these blooms, 210 free-floating green algae samples isolated from the green tide in Qingdao coast on June 19, 2013 were identified based on the ITS, rbcL and 5S sequence, and genetic diversity was investigated by microsatellite markers. According to ITS, rbcL and 5S sequence, all the 210 samples belonged to Ulva prolifera. Nei's genetic diversity and Shannon index estimated using eight microsatellite markers indicated that the genetic diversity of U. prolifera population within Qingdao's green bloom in 2013 was low. Taking into account previous reports about life history and physiology of U. prolifera, we proposed that the limited origin area of the free-floating biomass and asexual reproduction of U. prolifera might be responsible for the lower diversity of free floating U. prolifera.

Sediment characteristics and benthic communities on a finer sampling scale in four contrasting environments in subtropical Hong Kong were analyzed in summer and winter 2012. In two harbour habitats which suffered from historic sewage pollution or hypoxic events, organic carbon, nutrient and trace metal content in the sediment were significantly higher than that in an offshore area and a marine reserve. The relatively low organic and nutrient content in the offshore habitat could be resulted from enhanced resuspension of such materials from the seabed owing to intense water mixing and disturbance caused by bottom trawling. The biotic indices AMBI and M-AMBI were shown to be useful in assessing the benthic ecological status of these habitats. Such indices can also be more sensitive than sediment physico-chemical parameters in differentiating the response of macrofauna to seasonal changes in the benthic environment.

The need to detect and monitor introduced marine species has increased with the increasing number of marine invasions. To complement standard detection and monitoring techniques, new approaches using environmental DNA (eDNA) have recently been developed. However, most of the eDNA work has focused on vertebrate species in spatially limited freshwater habitats while benthic invertebrates in coastal environments have received much less attention. Here, we evaluated the suitability of the eDNA approach for detecting benthic, hard-shelled, crustacean mud crab species in a brackish water environment. We demonstrated for the first time that eDNA from an introduced mud crab Rhithropanopeus harrisii can be successfully amplified in aquarium water samples and detected in the brackish water environment. However, the detection rate was rather low. This suggests that in contrast to freshwater vertebrates, it may be more challenging to develop a highly sensitive eDNA method for detecting crustacean species in a marine environment.

This paper aims to identify the concentrations of PAHs in the sediments of four coastal zones in Lebanon and determine their possible sources and effects. For each region (Tripoli, Jounieh, Dora, and Tyre), sampling, lyophilization, Soxhlet extraction, rotary evaporation, and gas chromatography were performed on 11, 10, 7, and 11 samples, respectively. The total PAHs concentrations ranged from 1.22 to 731.93μg/kg dry weight. The lowest concentrations were found in Tyre and the highest in Dora and Jounieh. The level of PAHs was classified as low to moderate and their source was mainly pyrogenic.

The deterioration of dissolved oxygen conditions in the Pearl River Estuary (PRE) in summer has recently attracted considerable-scientific and political-attention. This paper documents the development, calibration, and verification of a coupled three-dimensional hydrodynamic and water quality model for the PRE. A comparison of the model's performance against field observations indicated that the model is capable of reproducing key hydrodynamic and water quality characteristics of the estuary within an acceptable range of accuracy. Furthermore, a scenario analysis showed that the extent of the hypoxic zone responds differently to changes in the river discharge at different inlets. Moreover, the hypoxic zone also changes in response to variations in the southwest wind in summer; specifically, a larger hypoxic zone develops as southwest winds blow in a more southward direction. However, the hypoxic conditions are much more sensitive to changes in the wind speed than changes in the wind direction.

As land–ocean interaction zones, mangrove systems receive substantial polycyclic aromatic hydrocarbons (PAHs) from sewage and combustion of fossil fuel. In this study, we investigated the relationship between dissolved inorganic nitrogen (DIN) availability and degradation rate of phenanthrene, a typical PAH compound, in mangrove plant-sediment systems, using Avicennia marina as a model plant. After 50day incubation, phenanthrene removal ratios in sediments ranged from 53.8% to 97.2%. In non-rhizosphere sediment, increasing DIN accessibility increased microbial biomass and total microbial activity, while enhancements in population size of phenanthrene degradation bacteria (PDB) and phenanthrene degradation rates were insignificant. In contrast, the presence of excessive DIN in rhizosphere sediment resulted in a significantly large number of PDB, leading to a rapid dissipation rate of phenanthrene. The differences in degradation rates and abundances of degrader in sediment may be explained by the enhanced root activity due to the elevation in DIN accessibility.

In this study, macrobenthic diversity data were collected from intertidal habitats of island wetlands in Yangtze Estuary before and after reclamation. Three survey regions based on habitat features were investigated: protected region, normal region, and self-restored region. The pattern of diversity variation showed a sharp decrease in reclamation sites and an obvious increase in vegetated sites of the self-restored region before and after reclamation. A declining trend in habitat health was observed in reclamation sites, but the degree of perturbation was relatively weaker in protected region than in normal region. The vegetated site showed a better self-restoration of biodiversity than the bald site. These results suggest that reclamation may have a negative influence on biodiversity and habitat health status in the intertidal wetland. Also, there is a possibility of self-restoration in tidal flats disturbed by reclamation and the resistance effect in nature reserve may reduce the disturbances resulting from reclamation.

In order to characterize the state of oil spill research and describe how the field has changed since its inception in the 1960s and since the Deepwater Horizon spill in 2010, we examined approximately 10% of oil spill literature (1255 of over 11,000 publications) published from 1968 to 2015. We find that, despite its episodic nature, oil spill research is a rapidly expanding field with a growth rate faster than that of science as a whole. There is a massive post-Deepwater Horizon shift of research attention to the Gulf of Mexico, from 2% of studies in 2004–2008 to 61% in 2014–2015, thus ranking Deepwater Horizon as the most studied oil spill. There is, however, a longstanding gap in research in that only 1% of studies deal with the effects of oil spills on human health. These results provide a better understanding of the current trends and gaps within the field.