Fishery Enhancement Reef Building Exercise

The constructive use of coal-fired power station waste products for building artificial reefs is being explored for the first time in the U.K. at present, the practice of sea dumping of raw pulverised fuel ash (PFA) from coal combustion is under review and the use of consolidated PFA blocks offers a possible alternative. the planned fitting of flue gas desulphurisation (FGD) plant in the U.K. will additionally produce large quantities of gypsum. to test the environmental compatability of such materials in marine structures, an experimental reef has been constructed off the central south coast of the U.K. Fifty tonnes of blocks made from different combinations of PFA, gypsum, FGD waste water sludge, cement and gravel using standard concrete as the control material, were deployed. the site selected is remote from prominent sea bed features in an area of flat sand with limited species variety.The preliminary studies leading to the licensing of this project included bioassay experiments with diatom cultures, field trials with test tiles and trace metal bioaccumulation studies the stages of consultation and licensing of the project are outlined.

Colonisation of the reef has been rapid, initially by shoaling fish, particularly by bib (Trisopterus luscus) then, within the first month, by representatives of the commercial crab and lobster species typical of the local natural rocky coast. After three months the epifauna and flora were well established. at this stage some 80 species of flora and fauna have been identified in association with the reef with no differentiation in colonisation apparent between the PFA/gypsum mixtures and the concrete control. the number of species far exceeds that of PFA powder dumping grounds. Analyses for heavy metal ions in the reef blocks after 2 months immersion have not shown any significant difference from the original composition.     

Stability of a Coal Waste Artificial Reef

The feasibility of using U.K. coal-fired power station waste materials for artificial reef production is being examined. in June, 1989, an experimental artificial reef was constructed in Poole Bay, off the central south coast of the U.K., using three different mixtures of pulverised fuel ash (PFA), flue gas desulphurisation (FGD) gypsum and slurry, stabilized with cement and formed into blocks. Fifty tonnes of 40 × 20 × 20 cm blocks were formed into eight conical reef units replicating three different PFA/gypsum mixtures and one concrete control. the reef structure is 10m below chart datum on a flat sandy sea-bed.

Combustion of coal concentrates the heavy metal content in the resultant ash. the purpose of stabilization of the ash as blocks is twofold: to immobilize heavy metals (or other components) and to provide hard substratum for the attachment of organisms. to examine the effectiveness of this stabilization and hence the environmental compatibility of the block materials, heavy metal (Cd, Cr, Cu, Pb, Mn, Ni, Zn) content of the blocks has been monitored routinely over two years, to determine leaching rates. Sectional profiles indicate partial replacement of calcium content by magnesium. Associated with this there has also been some redistribution of heavy metals. Only in the case of cadmium has there been a detectable loss from the surface of blocks. Chromium and manganese concentrations appear to have increased. the metal content of the reef epibiota (including ascidians, Ascidia mentula; hydroids, Halecium spp.; bryozoans, Bugula spp. and red algae) growing on the ash blocks has been compared to that of epibiota attached to the concrete controls and surrounding sea-bed. to date no evidence of excess bioaccumulation of metals has been detected.

The physical integrity of the ash reef blocks has been maintained. There is evidence that the blocks are increasing in compressive strength.

An indication of the fishery enhancement potential of the experimental structure is given by the presence of eight commercially fished species (crustaceans and molluscs) including lobsters (Homarus gammarus).     

Stability of a Coal Waste Artificial Reef

The feasibility of using U.K. coal-fired power station waste materials for artificial reef production is being examined. in June, 1989, an experimental artificial reef was constructed in Poole Bay, off the central south coast of the U.K., using three different mixtures of pulverised fuel ash (PFA), flue gas desulphurisation (FGD) gypsum and slurry, stabilized with cement and formed into blocks. Fifty tonnes of 40 × 20 × 20 cm blocks were formed into eight conical reef units replicating three different PFA/gypsum mixtures and one concrete control. the reef structure is 10m below chart datum on a flat sandy sea-bed.

Combustion of coal concentrates the heavy metal content in the resultant ash. the purpose of stabilization of the ash as blocks is twofold: to immobilize heavy metals (or other components) and to provide hard substratum for the attachment of organisms. to examine the effectiveness of this stabilization and hence the environmental compatibility of the block materials, heavy metal (Cd, Cr, Cu, Pb, Mn, Ni, Zn) content of the blocks has been monitored routinely over two years, to determine leaching rates. Sectional profiles indicate partial replacement of calcium content by magnesium. Associated with this there has also been some redistribution of heavy metals. Only in the case of cadmium has there been a detectable loss from the surface of blocks. Chromium and manganese concentrations appear to have increased. the metal content of the reef epibiota (including ascidians, Ascidia mentula; hydroids, Halecium spp.; bryozoans, Bugula spp. and red algae) growing on the ash blocks has been compared to that of epibiota attached to the concrete controls and surrounding sea-bed. to date no evidence of excess bioaccumulation of metals has been detected.

The physical integrity of the ash reef blocks has been maintained. There is evidence that the blocks are increasing in compressive strength.

An indication of the fishery enhancement potential of the experimental structure is given by the presence of eight commercially fished species (crustaceans and molluscs) including lobsters (Homarus gammarus).     

Stabilized Coal Ash Artificial Reef Studies

In 1989, an experimental stabilized coal ash reef was deployed in Poole Bay off the southern coast of the UK. Three different mixtures of pulverised fuel ash, gypsum, flue gas desulphurisation sludge and cement were used along with concrete controls. the aim was to study the environmental compatibility of the reef materials through heavy metal analyses of the blocks to determine if any leaching or changes were occurring. at the same time, reef encrusting and associated biota have been analyzed together with material from concrete control and natural reefs to determine if there was any evidence for excess bioaccumulation.

This paper presents the results from studies of sectioned reef blocks immersed for 3 and 4 years. No significant change in levels of heavy metals (Cd, Cr, Cu, Mn, Ni, Pb, Zn) has been detected. Surface loss of calcium, presumably associated with the gypsum component, is confirmed with evidence of replacement by magnesium. Trends in data suggest initial surface changes which slow with time.

Epibiota have been analyzed for heavy metal content. the variety of reef-associated organisms has been extended to include mobile, resident species which are higher in the food chain: molluscs, crustaceans and territorial fish. No consistent evidence of bioaccumulation of a range of heavy metals (above those levels found in organisms associated with control reefs) has been detected. Monitoring of the encrusting species range and densities shows little difference between colonisation of the concrete and ash mixture blocks.     

Experiences of Coal Ash Artificial Reefs in Taiwan

A feasibility study for using fly-ash from Taiwan coal-fired power stations for artificial reef production was started in 1983. Various mixtures of fly ash stabilized with lime, cement, or industrial wastes and formed into blocks were tested in the laboratory. the results showed that the development of compressive strength of those blocks immersed in the sea water was much better than those exposed in the air. Heavy metal (Cd, Cr, Cu, Ni, Pb, Zn) content of the blocks has been monitored routinely to determine the leaching rates. the result indicates that solidification of fly-ash could indeed immobilize heavy metals better than the original fly ash. From March 1984 to February 1987, 3,682 coal ash stabilized blocks with total weight of 300 tons were designed, fabricated and installed at both Hsin-ta, south western coast, and Kuei-hou, northern coast of Taiwan, for field trials. After four years' underwater observations on 100 cubic blocks at Wan-Li, northern Taiwan, it was shown that the physical integrity of the ash reef blocks had been maintained. the compressive strength and durability was better than the concrete artificial reefs nearby. the ash reefs could also attract fishes and the colonization by benthic organisms was similar to that on concrete reefs. Eighty-eight species of fishes were observed, of which 27 were commercially important, comprising more than 80% of the total biomass. These results demonstrate a potential use for stabilized coal ash as artificial reefs to replace traditionally used concrete reefs to protect and enhance the coastal fishery resources in Taiwan in the future.     

Behaviour of Dioxins, Furans and Metals Associated with Stabilized Msw Combustor Ash in Sea Water

This report presents the results of a research programme designed to examine the engineering and environmental acceptability of stabilizing municipal solid waste (MSW) combustor ash for artificial reef construction. Municipal solid waste combustor ash was combined with Portland cement to form solid blocks using conventional construction block making technology. the resultant stabilized combustor ash (SCA) blocks were used to construct an artificial habitat in Conscience Bay, Long Island Sound, New York and compared to identical concrete blocks, fabricated using natural aggregates. Over a 4.5 year period divers periodically returned to the site to monitor the interaction of SCA blocks with the marine environment and compare the performance of these blocks with the concrete control blocks. Results show that the SCA blocks retain their strength after prolonged sea water exposure. Contaminants of environmental concern, including metals, dioxins and furans, were retained within the cementitious matrix of the SCA blocks after prolonged sea water submersion. in addition, organisms growing on the surfaces of the SCA blocks did not accumulate contaminants from the blocks.     

Behaviour of Dioxins,Furans and Metals Associated with Stabilized Msw Combustor Ash in Sea Water

This report presents the results of a research programme designed to examine the engineering and environmental acceptability of stabilizing municipal solid waste (MSW) combustor ash for artificial reef construction. Municipal solid waste combustor ash was combined with Portland cement to form solid blocks using conventional construction block making technology. the resultant stabilized combustor ash (SCA) blocks were used to construct an artificial habitat in Conscience Bay, Long Island Sound, New York and compared to identical concrete blocks, fabricated using natural aggregates. Over a 4.5 year period divers periodically returned to the site to monitor the interaction of SCA blocks with the marine environment and compare the performance of these blocks with the concrete control blocks. Results show that the SCA blocks retain their strength after prolonged sea water exposure. Contaminants of environmental concern, including metals, dioxins and furans, were retained within the cementitious matrix of the SCA blocks after prolonged sea water submersion. in addition, organisms growing on the surfaces of the SCA blocks did not accumulate contaminants from the blocks.     

Gypsum Waste Disposal: Land vs Sea or Recycling

The disposal of waste gypsum wallboard at landfill sites in British Columbia (B.C.), Canada, resulted in the generation of hydrogen sulphide gas and toxic leachates. Although some remedial measures were taken to reduce or eliminate problems resulting from past dumping practices, many landfill operators refused to accept new waste for fear of litigation over the pollution of nearby streams and rivers. with the availability of legitimate disposal sites greatly reduced, a serious waste management problem arose. the two most promising options for reducing the accumulating waste appeared to be recycling and ocean disposal.

Agricultural use of the waste for soil conditioning would account for only a small portion of the waste generated annually. Manufacturing plants were reluctant to accept waste gypsum with a high paper fibre content for fear it would lower the quality of the new wallboard product or interfere with the existing equipment and processes in the plants. the technology for economically removing and separating the paper from the used or substandard wallboard had yet to be developed.

The environmental implications of disposal at sea were assessed by a government advisory committee under the provisions of the Canadian Environmental Protection Act. Although results of a test dump in internal waters of B.C. were positive, the committee felt that valuable amenities of nearshore waters would only be assured by restricting dumping to a remote offshore location. an acceptable disposal method with minimal impact on the marine environment was eventually found with appropriate pretreatment of the waste and the use of remotely controlled bottom dump scows. Recent progress in the processing of waste wallboard to make it acceptable to the manufacturing industry should significantly reduce if not eliminate the need to dispose of gypsum wallboard wastes at sea.     

The disposal of flue gas desulphurisation waste: sulphur gas emissions and their control

Flue gas desulphurisation (FGD) equipment to be fitted to UK coal-fired power stations will produce more than 0.8 Mtonnes of calcium sulphate, as gypsum. Most gypsum should be of commercial quality, but any low grade material disposed as waste has the potential to generate a range of sulphur gases, including H₂S, COS, CS₂, DMS and DMDS. Literature data from the USA indicates that well-oxidised waste with a high proportion of calcium sulphate (the main UK product of FGD) has relatively low emissions of sulphur gases, which are comparable to background levels from inland soils. However, sulphur gas fluxes are greatly enhanced where reducing conditions become established within the waste, hence disposal strategies should be formulated to prevent the sub-surface consumption of oxygen.     

Stabilised Coal Ash Studies in Italy

The ENEL Ash Research Centre - (Brindisi, Italy) - has started a research programme on the use of coal ash derived from its thermoelectric power plants as a component of blocks for artificial habitats. After preliminary laboratory tests, systematic physical, chemical, and biological tests were carried out in an experimental installation constructed in the area of the Torrevaldaliga power plant (80 km NW of Rome).

Two reef models - each made by assembling pyramids of 225 20 × 20 × 20 cm blocks - were submerged in two tanks (10 × 2 × 1.5 m) with running sea water (water flow: 3-5 cm s-1). the ash blocks were composed of fly ash (52.1%), bottom ash (26.1%), hydrated lime (5.2%) and water 16.6%, while concrete blocks were made of pozzolanic cement, sand and gravel. After two years, ash based blocks showed no weathering, volume variation or swelling; marked compressive strength and sonic velocity increases have, on the contrary, been recorded. No significant leaching of chemical elements of environmental concern was found. the biotic settlement on the ash blocks proved greater in quantity and better in quality than that on the concrete blocks; on ash blocks 62 species were found, compared to 54 on concrete. Ash-based materials seem to be more suitable for the settlement of the macrobenthos.     

Overview of Radioactive Waste Disposal at Sea

For hundreds of years, the seas have been used as a place to dispose of wastes from human activities. Although no high level radioactive waste has been disposed of into the sea, variable amounts of packaged low level radioactive wastes have been dumped at 47 sites in the northern part of the Atlantic and Pacific Oceans. in 1946 the first sea dumping operation took place at a site in the North-East Pacific Ocean. the last dumping operation was in 1982, at a site off the European continental shelf in the Atlantic Ocean. Between these two dates, an estimated 46 PBq (1.24 MCi) of radioactive waste coming from research, medical, military and industrial activities have been disposed of at sea. the present trend, through the Convention for the Prevention of Marine Pollution by Dumping of Wastes and other Matter and other Regional Conventions, points towards the prohibition of the dumping of any radioactive waste into the marine environment.     

Overview of Radioactive Waste Disposal at Sea

For hundreds of years, the seas have been used as a place to dispose of wastes from human activities. Although no high level radioactive waste has been disposed of into the sea, variable amounts of packaged low level radioactive wastes have been dumped at 47 sites in the northern part of the Atlantic and Pacific Oceans. in 1946 the first sea dumping operation took place at a site in the North-East Pacific Ocean. the last dumping operation was in 1982, at a site off the European continental shelf in the Atlantic Ocean. Between these two dates, an estimated 46 PBq (1.24 MCi) of radioactive waste coming from research, medical, military and industrial activities have been disposed of at sea. the present trend, through the Convention for the Prevention of Marine Pollution by Dumping of Wastes and other Matter and other Regional Conventions, points towards the prohibition of the dumping of any radioactive waste into the marine environment.     

Littoral fauna of the Red Sea: the population of non-scleractinian anthozoans of shallow waters of the Red Sea (Eilat)

Approximately 22 species of sea anemones and 20 species of alcyonarians were found on the reef fringing the shallow water at Eilat (Gulf of Aqaba) and other localities along the Red Sea coast of the Sinai Peninsula. Investigations showed that these 2 groups of non-scleractinian coelenterates from (on different substrates) well identified colonies, part of them inhabiting sandy bottoms, other groups growing on the reef surface. Observations lead to the conclusion that several of the sea anemones and alcyonarians can act, under certain conditions, as factors limiting the development of hermatypic corals. In some areas, several species of the 2 groups of animals are found together with their symbiotic partners, such as fishes and crustaceans.This research has been sponsored partly by a grant from the Smithsonian Institution, No. SFC-7-0074 to L. B. Slobodkin (N. Y.) and L. Fishelson (T.-A.).     

Chemical Behaviour of Calcium in Stabilized Oil Ash Reef Blocks After Five Years in the Ocean

Abstract

Reef blocks made from stabilized oil ash were taken from the sea after five years in the ocean to examine the chemical behaviour of calcium. Experiments included (1) determination of the calcium leaching rate and a comparison with the rate for unexposed blocks to test the validity of a diffusion model for predicting long term (5 years) leaching rates, (2) determination of the effect of biological cover (shell) on the leaching rate, (3) determination of the leaching rate of the core of exposed reef blocks, (4) determination of the calcium content in ‘ring areas’ - regions of discoloration observed in sectioned exposed reef blocks, and (5) determination of the leachable fraction of the total calcium in exposed reef blocks. Results showed the presence of a pronounced calcium discontinuity zone located 3–7 cm from the outside surface of the reef blocks. Cumulated calcium release rates ranged from 2.81–3.14 μmol cm^?2 day^?1 for original unexposed reef blocks and the core of exposed (in the ocean for five years) blocks, respectively, to 0.47–0.50 μmol cm^?2 day^?1 for outside (facing sea water) surfaces of exposed reef blocks. Tank leaching studies also showed that the presence or absence of hard biological cover (shells) had little or no effect on the calcium release rate. the diffusion model normally used in modelling the chemical behaviour of calcium cannot be used to predict the long term (five years) leaching of calcium. the core of the exposed blocks released calcium at a rate similar to new, unexposed reef block material. Overall, it appears that the calcium discontinuity zone is probably responsible for restricting the release of calcium and hence the failure of the diffusion model.     

Chemical Behaviour of Calcium in Stabilized Oil Ash Reef Blocks After Five Years in the Ocean

Reef blocks made from stabilized oil ash were taken from the sea after five years in the ocean to examine the chemical behaviour of calcium. Experiments included (1) determination of the calcium leaching rate and a comparison with the rate for unexposed blocks to test the validity of a diffusion model for predicting long term (5 years) leaching rates, (2) determination of the effect of biological cover (shell) on the leaching rate, (3) determination of the leaching rate of the core of exposed reef blocks, (4) determination of the calcium content in 'ring areas' - regions of discoloration observed in sectioned exposed reef blocks, and (5) determination of the leachable fraction of the total calcium in exposed reef blocks. Results showed the presence of a pronounced calcium discontinuity zone located 3-7 cm from the outside surface of the reef blocks. Cumulated calcium release rates ranged from 2.81-3.14 μmol cm^-2 day^-1 for original unexposed reef blocks and the core of exposed (in the ocean for five years) blocks, respectively, to 0.47-0.50 μmol cm^-2 day^-1 for outside (facing sea water) surfaces of exposed reef blocks. Tank leaching studies also showed that the presence or absence of hard biological cover (shells) had little or no effect on the calcium release rate. the diffusion model normally used in modelling the chemical behaviour of calcium cannot be used to predict the long term (five years) leaching of calcium. the core of the exposed blocks released calcium at a rate similar to new, unexposed reef block material. Overall, it appears that the calcium discontinuity zone is probably responsible for restricting the release of calcium and hence the failure of the diffusion model.     

Heavy Metal Concentrations in Sea Urchin Tissues From Egypt, Ireland and United Kingdom

Sea urchins (Paracentrotus lividus) were collected from the Mediterranean coast off Alexandria, Egypt and the Atlantic coast of Ireland to the west of Galway. Samples of another urchin species, Psammechinus miliaris, were collected from the entrance to Southampton Water, U.K. Both the Alexandria coast and Southampton Water receive domestic and industrial waste water inputs whilst the western Irish coast is relatively unpolluted.

Sampled animals were dissected to separate coelomic fluids, Aristotle's lantern, gonads and tissue (digestive tract plus connective tissue). the concentrations of heavy metals (cadmium, copper, lead, nickel and zinc) in the different parts were measured using flame atomic absorption spectroscopy.

Many levels of heavy metals in the different parts were similar in specimens taken across the wide range of sites and the two species. A notable exception was the high level of copper (33 μg g^-1 dry wt.) and zinc 328 μg g^-1- dry wt.) in urchin tissue from Southampton Water.

The metal concentrations in the gonads of Paracentrotus lividus are of particular interest because of human consumption of this species. the highest levels of copper (3.3-5.2 g^-1- dry wt.) and zinc (74-181 μ g^-1- dry wt.) dry wt.) in gonads were found in the samples from Egypt. Data from this study are compared with other results reported from the Mediterranean.

A simple, short term, elevated water column copper uptake experiment was undertaken with Paracentrotus lividus which showed an increase in gonad concentrations of this element.     

Heavy Metal Concentrations in Sea Urchin Tissues From Egypt,Ireland and United Kingdom

Abstract

Sea urchins (Paracentrotus lividus) were collected from the Mediterranean coast off Alexandria, Egypt and the Atlantic coast of Ireland to the west of Galway. Samples of another urchin species, Psammechinus miliaris, were collected from the entrance to Southampton Water, U.K. Both the Alexandria coast and Southampton Water receive domestic and industrial waste water inputs whilst the western Irish coast is relatively unpolluted.

Sampled animals were dissected to separate coelomic fluids, Aristotle's lantern, gonads and tissue (digestive tract plus connective tissue). the concentrations of heavy metals (cadmium, copper, lead, nickel and zinc) in the different parts were measured using flame atomic absorption spectroscopy.

Many levels of heavy metals in the different parts were similar in specimens taken across the wide range of sites and the two species. A notable exception was the high level of copper (33 μg g^?1 dry wt.) and zinc 328 μg g^?1? dry wt.) in urchin tissue from Southampton Water.

The metal concentrations in the gonads of Paracentrotus lividus are of particular interest because of human consumption of this species. the highest levels of copper (3.3–5.2 g^?1? dry wt.) and zinc (74–181 μ g^?1? dry wt.) dry wt.) in gonads were found in the samples from Egypt. Data from this study are compared with other results reported from the Mediterranean.

A simple, short term, elevated water column copper uptake experiment was undertaken with Paracentrotus lividus which showed an increase in gonad concentrations of this element.     

Uptake of Cd, Cu, Ni and Zn by the Water Hyacinth, Eichhornia Crassipes (Mart.) Solms from Pulverised Fuel Ash (PFA) Leachates and Slurries

The main solid waste product from coal-fired power stations is pulverised fuel ash (PFA), which can be enriched in toxic elements. Disposal of PFA by dry (in landfills) or wet (by slurrying) disposal methods can release these elements into the environment. Thereafter, the contaminants can be taken up by biota such as Eichhornia crassipes, a common aquatic plant, which has the ability to accumulate elements from water. This study investigates the uptake of Cd, Cu, Ni and Zn by E. crassipes grown in leachates and slurries prepared from two different PFA samples. PFA samples were obtained from Indraprastha Power Station (IPP Stn.) in New Delhi, India and the Ratcliffe-on-Soar Power Station in the UK. E. crassipes grown in PFA leachates and slurries at 1:5 and 1:50 solid:liquid (PFA:deionised water) ratios show that the plant has a very high accumulation capacity for Cd, Cu, Ni and Zn from both leachates and slurries and the uptake of these metals is stronger in the roots than in the tops of the plant. Metal accumulation, as shown by the accumulation factor (AF) values, is higher from both leachates and slurries for plants grown in the 1:50 (PFA:DIW) ratios than in the 1:5 ratios, initial metal concentrations being higher in the 1:5 ratios than in the 1:50 ratios. Lower metal accumulation in the plants grown in slurries than in leachates is related to the high turbidity of growth medium in slurries resulting in ash particles adhering to the root surfaces thus reducing the surface area of metal absorption. Eichhornia plants are able to reduce the pH of all leachates, especially the highly alkaline Ratcliffe leachates to near neutral conditions. Accumulation of Cd and Zn by the plant is higher from the lower pH IPP leachates than the Ratcliffe leachates, indicating that these metals are more soluble and bioavailable in the acidic medium. However, accumulation of Cu and Ni is independent of the pH of the leachates, indicating that other factors, such as metal species, presence of complexing agents in the growth solutions, and effects of competing metal ions may be contributory factors towards the metal uptake and accumulation by the plant.     

Control Criteria and Activities in Dumping Management in Italy

In Italy, two different types of wastes can be dumped in the seas: industrial wastes and dredged material. There are no cases of sludges from urban treatment plants being discharged into the sea.

The sea dumping of harbour dredging sludges is a long standing practice, while the disposal of industrial wastes dates back to 1965.

Two specific laws regulate these two activities, although they do not establish quality standards for the receiving sea environment. Careful evaluation must be made, case by case, of possible effects of discharge with regard to physico-chemical characteristics of materials, to general oceanological characteristics of the dumpsite and to the uses to which such a dumpsite is designated.

The analysis of different cases of industrial waste dumping, carried out at the pre-operational level and during discharge, revealed some potential for negative long-term effects on the sea environment. This, as well as the increasing public sensitivity to environmental problems, led the management agencies in Italy to take several measures aimed to stop all forms of sea dumping of industrial wastes and to revise the general criteria in issuing permits for the discharge of dredged material.     

The Distribution and Impacts of Dioxins and Polychlorinated Biphenyls in the Taiwan Er-Jen River

The distribution and impacts of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/DFs) and polychlorinated biphenyls (PCBs) in the Taiwan Er-Jen River were investigated by monitoring fish distribution and measuring PCDD/DFs and PCBs levels in sediment and fish samples. Most of the fish collected are pollution-resistant species such as Oreochromis spp, Liza macrolepsis, Channa spp and Megalops cyprinoides. the most polluted river sections are in the upstream where large amount of waste effluents from households, livestock rearing and nearby dumping sites were discharged into the river, and the lower reaches of the river where metal recovery activities including open burning of waste electrical wire/scrap occurred. Sediment samples collected near the burning site show 2,3,7,8-TCDD toxicity equivalents (TEQ) ranging from 0.014 to 14.2 ng g^-1 by PCDD/DFs and from 0.015 to 1.03 ng g^-1 by coplanar PCBs (Co-PCBs). the fish samples show TEQ ranging from 0.029 to 0.615 ng g^-1 by PCDD/DFs and from 0.012 to 0.12 ng g^-1 by Co-PCBs. Possible PCDD/DFs sources are discharged PCBs, open burning of waste wire/scrap, and pentachlorophenol. the consumption of these fish will cause an average intake of 54 pg kg^-1 d^-1 TEQ. the prevention of direct discharge of livestock and the dumping of waste effuents into River Er-Jen as well as the control of metal recovery activities appears to be the first step toward the restoration of River Er-Jen.