This research aims to identify and map any contamination of mercury, total petroleum hydrocarbons and pollutants known as persistent organic pollutants (POPs) within sediment in Barnegat Bay–Little Egg Harbor estuary and associated tidal creek and salt marshes.
This work also aims to pinpoint sources of pollution and to compare the contaminant concentrations against published soil guide line values to evaluate any possible impact upon ecological habitat.
The results form a baseline survey to record the levels of contaminants which could then be used for comparison should there be any future contamination of the area.
The Barnegat Bay–Little Egg Harbor estuary, in the SE New Jersey, is characterised by organogenic (high preservation of organic material) salt marshes and tidal creek system. The shallow (1–7 metres), narrow (4.5–14 km) bay is separated from the Atlantic Ocean by a back barrier island complex (Long Beach Island) which is heavily developed and a major area of tourism.
The salt marshes are protected and managed as part of the Edwin B. Forsythe National Wildlife Refuge. This comprises 186 km2 of wetlands and 145 km2 of salt marshes and has a mixed pattern of watershed land use such as forestry (45.9%), wetlands (25.2%), urban/residential (19.5%) and agricultural (6.6%).
Fifteen surface sediments (0–10 cm) were collected from the banks of tidal creeks within Edwin B. Forsythe National Wildlife Refuge in June 2007 using a stainless steel trowel. Sediments were sealed in polyethylene plastic bags and transported in a cool box at ~4°C then immediately frozen. In the laboratory an aliquot of each (~500 g) sediment was freeze-dried, sieved through a mesh aperture of 2 mm and the <2 mm fractions ground to a fine powder using a Retsch PM400 ball mill.
Mercury (Hg) concentrations ranged from <0.02 to 2.61 mg/kg, the mean of the study area was 0.31 mg/kg. The Hg concentrations confirmed a low Hg content indicative of natural background for 14 of the 15 sites. The highest concentration of Hg (2.61mg/kg) was situated in the upper non-tidal reaches of Cedar Run.
Total hydrocarbon concentrations for surface sediments of Barnegat Bay–Little Egg Harbor estuary ranged from 47 mg/kg at Turtle Cove (site 3), to 1003 mg/kg at Parker Run. Overall, the range of hydrocarbon concentrations encountered in the Little Egg Harbor estuary, are consistent with biologically derived hydrocarbon source augmented by low levels of anthropogenic (man-made) hydrocarbon contamination.
Total PAH concentrations ranged from 37 µg/kg at Mill Creek to 1696 µg/kg at Tuckerton Creek with a mean for the study area of 671 µg/kg. The sources of PAH are not of petroleum origin and are likely to be a combination of localised source from human activity and from that which is transported around the world by wind.
All sites showed some degree of PCB contamination, the highest concentrations were along Parker Run (50 µg/kg) and the lowest at Turtle Cove (4 µg/kg). Comparison with published marine sediment quality criteria showed that 13 of the 15 sites are below those judged to be harmful to sensitive biota and the concentrations at Parker Run are unlikely to have an adverse effect on biota living in the surface sediments. No clear spatial trend in PCB values were observed from the coast to the upper reaches of the creeks suggesting diffuse and atmospheric pollution as compared to single point sources.
Mercury (Hg) is one of the most important heavy metals in estuarine and coastal sediments. This is due to its toxic effect on marine invertebrates and tendency for the methyl-Hg to bio-accumulate up trophic levels, where it can enter humans via the ingestion of fish and shellfish.
This is a term used to describe chemical compounds which come from crude oil that can pollute the environment.
Persistent organic pollutants are a suite of organic compounds which do not degrade. They can remain in the environment (e.g. the Barnegat Bay–Little Egg Harbor) and can be transported long distances. They can be present in human and animal tissue and are thought to have impacts on human health.
PAHs can come from biological, geological or combustion sources such as wood, coal or oil burning. They are also found in traffic fumes and a high density of riverside industries, e.g. chemical works, power stations, sewage works, docks, boat dismantlers, oil refineries, paper works etc.
PCBs are man-made compounds, which were widely used as plasticisers and heat-transfer fluids in the manufacturer of such products as transformers. Their use is now banned in the USA due to their high toxicity if released into the environment, but residues persist and significant amounts continue to enter estuaries, such as the Barnegat Bay–Little Egg Harbor, through rivers, ocean currents and the atmosphere.
Contact Dr Christopher Vane for more information.