Estuaries in the tropical Gulf of Carpentaria (GOC) in Australia are under increasing pressure from catchment water development, potentially affecting productivity. We examined the potential effect of changes in freshwater inputs on the primary productivity of three estuaries (Flinders, Gilbert and Mitchell Rivers). The addition of nutrients stimulated mudflat primary production in all estuaries at multiple sampling times, suggesting chronic nutrient limitation. All three estuaries were productive with the Flinders estuary being the most productive of the three estuaries, compared to the Gilbert and Mitchell estuaries. This is despite the fact that the Flinders estuary has the shortest period of freshwater flow and more variable flows from year-to-year compared with the other estuaries. This makes the Flinders highly vulnerable to excessive water development. This study suggests that water extraction which significantly reduces freshwater inputs and associated nutrients has the potential to impact on productivity within these estuaries.

Trace element pollution in the marine system is a global concern as the exposure of marine organisms to this pollution results in bioaccumulation and further transfer of the trace elements to humans through food chain. In the present study, the distribution of trace elements, namely chromium, cobalt, nickel, iron, copper, zinc, arsenic, cadmium, mercury, and lead, in gills, bone, liver, and muscle of eight commercially important fish collected along the southeast coast of India was analyzed using an inductively coupled plasma mass spectrometer. The liver was the main organ of accumulation for copper, zinc, arsenic, cadmium, and mercury; bone for chromium, cobalt, and lead; gills for copper; and muscle for arsenic and mercury. The concentration of toxic trace elements such as arsenic, cadmium, mercury, and lead in the edible portion of fish was lower than the recommended International Legislation limits, indicating that the fish of this region are safe for consumption.

The concentrations of four trace metals (Cd, Cu, Pb, and Zn) were investigated for the first time in phytoplankton, zooplankton, and the seawater samples collected from the coast of Gabès, Tunisia, Mediterranean Sea. For over 40 years, this coast has witnessed significant anthropogenic impacts form fertilizer processing. Results obtained for Cd, Cu, Pb, and Zn in seawater far exceed the concentration reported for other Mediterranean coastal waters, highlighting the Gulf of Gabès as a pollution hotspot. The average metals concentration was in the order Zn > Pb > Cu > Cd in water, and phytoplankton, whereas Pb > Zn > Cu > Cd in zooplankton. The biomagnification in phytoplankton and zooplankton for Zn, Pb, Cu, and Cd was 116, 56, 38, 31, and 127, 157, 30 and 27. The biomagnification of Zn and Pb was higher in zooplankton than phytoplankton, while Cu and Cd were higher in phytoplankton.

PURPOSE OF REVIEW: Sediment contamination by heavy metals has been known as one of the most serious environmental challenges due to the abundance, persistence, toxicity, and subsequent bioaccumulation of heavy metals. Microbial activities play a significant role in the fate and transport and mobility of heavy metals in the interface of sediment-water, which affect the distribution of heavy metals along the food chain. However, a comprehensive review elucidating the roles and mechanisms of microbial-driven remediation of heavy metals in sediments is not available. RECENT FINDINGS: This review discusses various microbial processes affecting the transformation and speciation of heavy metals in sediments. It also emphasizes the importance of modern biotechnologies and approaches in improving the ability of microbial activities to effectively transform heavy metals at a faster rate and highlights recent advances in microorganism-mediated remediation of heavy metals in sediments as well as future prospects and limitations. The current bioremediation practice using diverse microbial processes is promising for sustainable removal of heavy metals from sediments. However, additional research applying advanced biotechnology such as omics-based molecular tools and nanotechnology would further enhance the potential of microbes to remediate heavy metal–contaminated sediments.

PURPOSE OF REVIEW: Many of the highly populated and industrialized countries are paying more attention to green fuels. The conventional methods for biodiesel purification processes result in a large quantity of polluted water, leading to serious environmental concerns. To overcome the challenges in the existing process, addressing the membrane technology is a viable solution to direct further research toward sustainable membrane-based green production. RECENT FINDINGS: The developing membrane technology is an alternative method for eliminating wastewater during biodiesel production from conventional processes. This paper provides a comprehensive review of recent development applications of the catalytic membrane and membrane materials for high-quality biodiesel production. Both polymeric and ceramic membranes result in optimum performance of more than 90% effective conversion and purification. The catalytic membrane reactor integrates chemical reaction and product separation concurrently in a single device system to produce high-quality biodiesel. Glycerol purification of 99% was achieved in the potential membrane distillation process. This review critically summarizes biodiesel production and purification using membrane techniques and membrane reactors. Membrane material and separation efficiency were discussed in a short view. Besides, the significance of catalytic membrane reactor is outlined. Glycerol separation and purification by removal of water and other residual impurities were potentially achieved using membrane technology. Apart from applications of the membrane, the novel attempt of a combined description of influencing factors and limitations of the membrane during biodiesel production was revealed. Therefore, membrane applications in high-grade biodiesel and value-added byproduct production are the predominant green technological approach for next-generation biofuels.

In order to evaluate the long-term pollution level(s) of Monastir Bay (Tunisian-Mediterranean coastal area), four sediment cores were collected from the meeting points between the main local streams and the marine environment and investigated. Macroscopic observations and granulometric and chemical compositions showed that this Bay received heterogeneous materials. The distribution of 15 total PAH (priority pollutants) concentrations in different levels of core sediments ranged from 222 to 2992 μg kg⁻¹. Thus, the Bay had been polluted for a long time, and sediments and pollutants had varied anthropogenic sources. After that, local hydrodynamism controlled their distributions. Molecular-weight Polycyclic Aromatic Hydrocarbons (PAHs) and calculated LMW/HMW ratios showed that pollutants were principally a mixture of pyrolytic and petrogenic sources. One part of these pollutants had local origins, and the most important amounts were of distant origins. Monastir Bay was considered a moderate to highly polluted area, and sediments had an ecosystem risk.

Seabird eggs are considered a favourable matrix for monitoring marine pollutants and are widely used as higher trophic level indicators. Concentrations of Polycyclic aromatic hydrocarbons (Σ15PAH) were determined in the eggs of four piscivorous seabirds in Ireland from multiple colonies for the first time, Common Guillemot Uria aalge, Northern Gannet Morus bassanus, Common Tern Sterna hirundo and Arctic Tern S. paradisaea. PAH concentrations were generally lower than levels detected in eggs from other seabird studies and considerably lower than concentrations associated with no adverse effect in the eggs of domestic avian species. This study indicates potential site and species differences in PAH concentrations. Baseline data of PAHs in a range of seabird species from this study may provide an important reference point should a major pollution event occur in European waters, such as an oil spill.

Spatiotemporal distribution and ecological risk of the polyethylene terephthalate (PET) plastic polymer and plasticizer di-(2-ethylhexyl) phthalate (DEHP) were investigated using both surface and core sediments in Jiaozhou Bay, China. The concentrations of PET and DEHP ranged 210.6–1929.7 μg/kg and 0–591.2 μg/kg, respectively. The depth profiles of PET and DEHP in the sediment cores indicated that PET and DEHP pollution increased since the 1970s, which is in accord with the regional PET and DEHP consumption history. The levels of PET in Jiaozhou Bay was found to represent low ecological risk based on the assessment models for Potential Ecological Risk factor and Potential Ecological Risk. The amounts of DEHP also posed a low risk to the aquatic organisms in the sediment phase as indicated by the Risk Quotient method.