Detection of enteroviruses near deep marine sewage outfalls

At the present time there are approximately 160 million gallons per day of municipal sewage being discharged into the waters off the southeastern coast of Florida. Present in these sewage effluents are human pathogenic viruses whose fate in marine waters is not completely understood. Virus surveillance in waters receiving domestic wastewater discharge has concentrated on estuarine areas where water quality and depth are significantly different from the deep marine outfalls. Using the membrane filter adsorption technique, viruses were detected in the vicinity of deep marine outfalls discharging both raw and chlorinated, secondarily treated sewage.     

Contribution to the study of phosphate ion desorption during the dilution of urban sewage outfalls in the marine environment

The study of continental effluents discharged into the marine environment has enabled us to show that phosphate ion concentration does not follow the linear law of dilution exhibited by a true solution. We were able to show that the dilution of sewage in seawater allows the particles and colloids to desorb phosphate ions, thus increasing the amount of already dissolved inorganic phosphate.     

Environmental response to sewage treatment strategies: Hong Kong's experience in long term water quality monitoring

In many coastal cities around the world, marine outfalls are used for disposal of partially treated wastewater effluent. The combined use of land-based treatment and marine discharge can be a cost-effective and environmentally acceptable sewage strategy. Before 2001, screened sewage was discharged into Victoria Harbour through many small outfalls. After 2001, the Hong Kong Harbour Area Treatment Scheme (HATS) was implemented to improve the water quality in Victoria Harbour and surrounding waters. Stage I of HATS involved the construction of a 24 km long deep tunnel sewerage system to collect sewage from the densely populated urban areas of Hong Kong to a centralized sewage treatment plant at Stonecutters Island. A sewage flow of 1.4 million m³ d⁻¹ receives Chemically Enhanced Primary Treatment (CEPT) followed by discharge via a 1.2 km long outfall 2 km west of the harbor. The ecosystem recovery in Victoria Harbour and the environmental response to sewage abatement after the implementation of HATS was studied using a 21-year data set from long term monthly water quality monitoring. Overall, the pollution control scheme has achieved the intended objectives. The sewage abatement has resulted in improved water quality in terms of a significant reduction in nutrients and an increase in bottom DO levels. Furthermore, due to the efficient tidal mixing and flushing, the impact of the HATS discharge on water quality in the vicinity of the outfall location is relatively limited. However, Chl a concentrations have not been reduced in Victoria Harbour where algal growth is limited by hydrodynamic mixing and water clarity rather than nutrient concentrations. Phosphorus removal in the summer is suggested to reduce the risk of algal blooms in the more weakly-flushed and stratified southern waters, while nutrient removal is less important in other seasons due to the pronounced role played by hydrodynamic mixing. The need for disinfection of the effluent to reduce bacterial (E. coli) concentrations to acceptable levels is also confirmed and has recently been implemented.     

Reducing sewage pollution in the Antarctic marine environment using a sewage treatment plant

Despite Antarctica being the largest pristine wilderness on Earth, many coastal Antarctic research stations release untreated sewage waste into the marine environment, which may have negative effects on local wildlife. In February 2003 a sewage treatment plant was installed at Rothera Research Station (Adelaide Island, Antarctic Peninsula). After one year of operation the sewage treatment plant had dramatically reduced the microbiological pollution in the near-shore marine environment around the outfall and seawater quality conformed to European Union Bathing Water Standards.     

Monitoring of toxic substances in the Hong Kong marine environment

A long-term programme for monitoring toxic substances in the marine environment was established in Hong Kong in 2004, focusing on chemicals of potential ecological and health concern. The programme ran on 3-year cycles, with the first two years monitoring marine water, sediment, biota, and the third year monitoring pollution sources. Twenty-four priority chemicals were measured, including dioxins/furans, dioxin-like PCBs, total PCBs, PAHs, DDTs, HCHs, TBTs, phenol, nonylphenol (NP), NP ethoxylates, PBDEs and metals. Results from the first three years of monitoring indicate that toxic substances in the Hong Kong marine environment were within the range reported for the coastal waters in China and other regions, but generally lower than in the Pearl River Estuary. The levels met the standards for protecting aquatic life and human consumption. Sewage effluent, stormwater and river water were possible sources of phenolic compounds; whereas air deposition or regional pollution, rather than local discharges, may contribute to the dioxins/furans, PAHs and PCBs found in the marine environment.     

Monitoring of toxic substances in the Hong Kong marine environment

A long-term programme for monitoring toxic substances in the marine environment was established in Hong Kong in 2004, focusing on chemicals of potential ecological and health concern. The programme ran on 3-year cycles, with the first two years monitoring marine water, sediment, biota, and the third year monitoring pollution sources. Twenty-four priority chemicals were measured, including dioxins/furans, dioxin-like PCBs, total PCBs, PAHs, DDTs, HCHs, TBTs, phenol, nonylphenol (NP), NP ethoxylates, PBDEs and metals. Results from the first three years of monitoring indicate that toxic substances in the Hong Kong marine environment were within the range reported for the coastal waters in China and other regions, but generally lower than in the Pearl River Estuary. The levels met the standards for protecting aquatic life and human consumption. Sewage effluent, stormwater and river water were possible sources of phenolic compounds; whereas air deposition or regional pollution, rather than local discharges, may contribute to the dioxins/furans, PAHs and PCBs found in the marine environment.     

Some effects of sewage discharge upon phytoplankton in Hong Kong

The coastal waters of Hong Kong constitute a transition from estuarine conditions in the west to more oceanic conditions in the east, with a major discharge of untreated sewage located at the mid-point. Chlorophyll a was determined and net phytoplankton was sampled at 45 stations throughout this transition. Over a period of 20 months, chlorophyll a values rarely exceeded 2 μg l.^?1 in unpolluted coastal waters. Estuarine waters generally contained 2–6 μg l.^?1 and, in waters influenced by sewage discharge, values sometimes exceeded 20 μg l.^?1. There was no evidence of a reduction in taxonomic diversity in polluted areas except in summer, when the net phytoplankton was dominated by Chaetoceros spp. In the autumn and early winter, Skeletonema costatum was abundant in the central polluted areas.     

Predicting effects of toxic chemicals in the marine environment

Ecological risks are typically characterized in risk assessment procedures by considering the ratio between exposure concentrations and critical effect concentrations. In OECD countries, critical effect concentrations are typically derived from laboratory-based ecotoxicity tests using well-defined protocols on a limited number of species. More and more countries in the tropics are adopting this approach in environmental assessment, protection, and management. In this article we consider a number of issues associated with such an approach, and in particular potential problems with extrapolating effects on individuals observed in laboratory-based ecotoxicological investigations to effects on ecosystems. It is hoped that by making explicit some of the assumptions made in the potential limitations of these tests, we can better target our limited resources to protect valuable and vulnerable systems.     

Spatial distribution of heavy metals in Hong Kong's marine sediments and their human impacts: a GIS-based chemometric approach

A geographic information system (GIS)-based chemometric approach was applied to investigate the spatial distribution patterns of heavy metals in marine sediments and to identify spatial human impacts on global and local scales. Twelve metals (Zn, V, Ni, Mn, Pb, Cu, Cd, Ba, Hg, Fe, Cr and Al) were surveyed twice annually at 59 sites in Hong Kong from 1998 to 2004. Cluster analysis classified the entire coastal area into three areas on a global scale, representing different pollution levels. Backward discriminant analysis, with 84.5% correct assignments, identified Zn, Pb, Cu, Cd, V, and Fe as significant variables affecting spatial variation on a local scale. Enrichment factors indicated that Cu, Cr, and Zn were derived from human impacts while Al, Ba, Mn, V and Fe originated from rock weathering. Principal component analysis further subdivided human impacts and their affected areas in each area, explaining 87%, 84% and 87% of the total variances, respectively. The primary anthropogenic sources in the three areas were (i) anti-fouling paint and domestic sewage; (ii) surface runoff, wastewater, vehicle emissions and marine transportation; and (iii) ship repainting, dental clinics, electronic/chemical industries and leaded fuel, respectively. Moreover, GIS-based spatial analysis facilitated chemometric methods.     

Sewage and the community—One view of Sydney's deepwater outfalls, the environmental monitoring programme and the future of sewage disposal

Sydney's sewage disposal problems have been the catalyst for wider questioning by the community about the management of the water cycle in the Sydney Basin. Public concern over the deepwater ocean outfalls generated an involvement in the Environmental Monitoring Programme (EMP) which provided a number of insights into the marine environment offshore Sydney, interactions between agencies and the role of public interest groups. The EMP has not provided sufficient information to make decisions about the value of higher levels of treatment. However, public interest in these outfalls is being subsumed by demands for the greater recycling of water and mechanisms for reducing water use.     

Biological effects in the management of chemicals in the marine environment

Coastal ecosystems are impacted by many stressors, of which chemicals are possibly not the most important. Chemicals differ from most other stressors such as eutrophication and hypersedimentation in the time scale-effects from the latter act on the scale of weeks or months, whereas effects from chemicals may take years to manifest themselves in population or community changes. There are four different approaches available to manage chemicals in marine ecosystems: target contaminant levels, target individual effects, target community impacts (biodiversity) and, finally, target processes. These four differ in the analytical methods available and the analyst's ability to separate effects from chemicals from other environmental factors and natural variation. There is furthermore, a need to develop a framework to integrate biological effects methods with risk assessment methodology. Such integration will improve the basis for risk-based assessment of chemicals. A problematic issue relevant to all aspects of environmental management are the interactions between chemicals, and between chemicals and eutrophication or sedimentation. There is a clear need for more knowledge about such interactions.     

Research needed to determine chronic effects of oil on the marine environment

The participants in a workshop considering research needed to determine chronic effects of oil on the marine environment agree that much more research is needed and that high priorities, both in time and money, should be given to an ecosystem approach involving multidisciplinary studies. Initially, careful selection of study sites should be made by a marine scientist task force. A combination of laboratory, field, and experimental ecosystem observations is essential. Biological, chemical, physical, and geological oceanographers must work together to collect, catalogue, and analyse samples and interpret results.     

Methyltins in the marine environment

Methyltins were occasionally observed in some natural waters. The nature of a marine sediment determines its organotin burdens. Mono- and dimethyltin compounds were found in polluted marine sediments whereas non-polluted, oxiccoastal sediments contained primarily trimethyltin. The net methylation rate is evidently independent of the inorganic tin content of a sediment. Methyltin in fish is about 3–6% of the total tin content while limpets contain significant amounts of organotin compounds, ranging between 35 and 75% of the total tin. No trimethyltin was detected in green macro-algae and seawater, although limpets, fish and sediments have measurable levels.     

Microplastics in the marine environment

This review discusses the mechanisms of generation and potential impacts of microplastics in the ocean environment. Weathering degradation of plastics on the beaches results in their surface embrittlement and microcracking, yielding microparticles that are carried into water by wind or wave action. Unlike inorganic fines present in sea water, microplastics concentrate persistent organic pollutants (POPs) by partition. The relevant distribution coefficients for common POPs are several orders of magnitude in favour of the plastic medium. Consequently, the microparticles laden with high levels of POPs can be ingested by marine biota. Bioavailability and the efficiency of transfer of the ingested POPs across trophic levels are not known and the potential damage posed by these to the marine ecosystem has yet to be quantified and modelled. Given the increasing levels of plastic pollution of the oceans it is important to better understand the impact of microplastics in the ocean food web.     

Biological effects of gold mine tailings on the intertidal marine environment in Nova Scotia,Canada

From 1861 to the 1940s, gold was produced from 64 mining districts in Nova Scotia, where mercury amalgamation was the dominant method for the extraction of gold from ore until the 1880s. As a result, wastes (tailings) from the milling process were contaminated by mercury and were high in naturally occurring arsenic. In 2004 and 2005, sediments, water and mollusc tissues were collected from 29 sampling stations at nine former gold mining areas along the Atlantic coastline and were analysed for arsenic and mercury. The resulting data were compared with environmental quality guidelines. Samples indicated high potential risk of adverse effects in the intertidal environments of Seal Harbour, Wine Harbour and Harrigan Cove. Arsenic in Seal Harbour was bioavailable, resulting in high concentrations of arsenic in soft-shell clam tissues. Mercury concentrations in tissues were below guidelines. This paper presents results of the sampling programs and implications of these findings.     

The usefulness of transplantation studies in monitoring of metals in the marine environment: South African experience

Due to their close proximity to the point sources of pollution, estuaries and harbours are exposed to metals. Mussels are used worldwide to monitor marine pollution due to their ability to take up contaminants and the ease of transplantation. Mussels were collected from two reference sites and transplanted in Richards Bay Harbour (2006 and 2010) and in three harbours. Transplanted and resident mussels were removed after 6 weeks exposure and metal concentrations were analysed using ICP-MS techniques. Transplanted mussels had higher metal concentrations than the resident mussels. This was attributed to regulation of metals by the resident mussels. Metal regulation was greater in mussels that are continuously submerged as opposed to those that undergo tidal influences. For monitoring it is essential that the reference population for transplantation is considered carefully as upwelling events in the pristine reference location results in significant increases in metal bioaccumulation.