Gary Denton | University of Guam (original) (raw)

Papers by Gary Denton

Environmental Science and Pollution Research, 2016

Your article is protected by copyright and all rights are held exclusively by Springer-Verlag Ber... more Your article is protected by copyright and all rights are held exclusively by Springer-Verlag Berlin Heidelberg. This e-offprint is for personal use only and shall not be selfarchived in electronic repositories. If you wish to self-archive your article, please use the accepted manuscript version for posting on your own website. You may further deposit the accepted manuscript version in any repository, provided it is only made publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be accompanied by the following text: "The final publication is available at link.springer.com".

Marine Pollution Bulletin, 2005

Journal of Toxicology and Environmental Health, Part A, 2011

This article may be used for research, teaching and private study purposes. Any substantial or sy... more This article may be used for research, teaching and private study purposes. Any substantial or systematic reproduction, redistribution , reselling , loan, sub-licensing, systematic supply or distribution in any form to anyone is expressly forbidden. The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The accuracy of any instructions, formulae and drug doses should be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims, proceedings, demand or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material.

Journal of Toxicology and Environmental Health, Part A, 2009

and-conditions-of-access.pdf This article may be used for research, teaching and private study pu... more and-conditions-of-access.pdf This article may be used for research, teaching and private study purposes. Any substantial or systematic reproduction, redistribution , reselling , loan or sub-licensing, systematic supply or distribution in any form to anyone is expressly forbidden. The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The accuracy of any instructions, formulae and drug doses should be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims, proceedings, demand or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material.

Journal of Environmental Sciences, 2009

This initial research examined the presence, distribution and bioavailability of Cu, Cr, Ni, Mn a... more This initial research examined the presence, distribution and bioavailability of Cu, Cr, Ni, Mn and Fe in a wetland area of southern Guam. The research sites are within an area covered with saporite, a soil type derived from volcanic deposits on the island. Leaf tissue of Pandanus tectorius was extracted and analysed to determine the bioaccumulation of the target metals. Metal accumulation at sites considered aerobic and anaerobic was investigated together with an attempt to correlate actual accumulation of the target metals in the plant tissue with a recognised bioavailability indicator, in this case, three step sequential extraction scheme. Manganese was found to be accumulated in relatively high concentrations and to a lesser extent Cu was also accumulated. Chromium, Ni and Fe however exhibited very low accumulation factors. Accumulation of Mn in particular was significantly affected by aerobic conditions whereas the converse effect was experienced by Cu. Significant correlation between various steps of a Sequential Extraction Scheme and actual accumulation was not achieved although the degree of aerobic conditions at each site and soil pH did affect concentrations of metals extracted by differing steps of SES. Results obtained suggest that further research in the area should be undertaken using different plant species and tissues.

Ground Water Monitoring & Remediation, 2010

Comparison of Background Values ..

Procedia Environmental Sciences, 2013

Marine Biology, 1981

... true for lead concentrations (Table 4). For cadmium, all first-order interaction combinations... more ... true for lead concentrations (Table 4). For cadmium, all first-order interaction combinations were significant (Table 3), and there was a significant second-order interaction between the effect of tissue, tempera-ture and salinity (A x B x C) for mercury and cadmium but not lead. ...

Environmental Pollution (1970), 1976

Mercenaria mercenaria fed Aroclor 1254 adsorbed onto the surface of alumina particles at 1.25 and... more Mercenaria mercenaria fed Aroclor 1254 adsorbed onto the surface of alumina particles at 1.25 and 12.5 parts/lO 9 seawater for 21 days showed a maximum concentration factor of !-8 x 103 with visceral mass: muscular foot residues of less than 5:1 in general. Only the muscular foot of clams on a high dosage showed a diminution in PCB content after six month~ in clean seawater. PCB levels in visceral mass: muscular foot:surface mud for clams in Southampton water are in the ratio of 2:1:2. Tissue samples contained relatively more lower chlorinated isomers compared with the A1254 standard whilst faeces and mud samples showed an increased proportion of higher chlorinated PCB isomers. Clams may, therefore, exert both a qualitative and a quantitative effect upon the distribution of PCB in the estuarine ecosystem.

Problem and Research Objectives Guam's only municipal solid waste disposal site is centrally loca... more Problem and Research Objectives Guam's only municipal solid waste disposal site is centrally located in the village of Ordot and has been in use for over fifty years. Lacking in the conventional technology built in to modern day sanitary landfills, the site is essentially an open dump covering ~20 acres of the upper Lonfit River valley. The dump was operated by the US Navy at the end of WWII and transferred to the Government of Guam shortly thereafter. Although slated for closure more than 20 years ago, it still receives around 200 tons of solid waste per day from the civilian community. Early records of the types of materials disposed of at the Ordot Dump are nonexistent but are suspected to include the same array of toxic chemicals found at other military dumpsites on island. Today, there is some control over the bulk disposal of industrial chemicals, waste oil, and metallic waste at Ordot Dump. However, household waste is rarely screened and is known to contain a variety of hazardous substances, both biological and chemical. Leachate streams occur in several places around the perimeter of the dump and course their way down gradient into the Lonfit River and out into Pago Bay. Their chemical composition is largely unknown and their impact on the local environment in terms of ecology, agriculture, and human health remains to be investigated.

Science of The Total Environment, 2007

A survey of the different forms of arsenic species: inorganic arsenic (As), As(III), As(V) and or... more A survey of the different forms of arsenic species: inorganic arsenic (As), As(III), As(V) and organic As(III) and (V) was carried out on spring waters located along Tumon Bay in Guam. The results show that total arsenic concentrations in the spring water samples ranged from <0.3-1.2 microg/L. Inorganic arsenate, As(V), appears to be the dominant species in the spring water samples tested. The concentrations are much lower than previously reported, probably due to a much more rigorous methodological approach and requires further investigations on the status of As contamination in groundwater on the island.

Marine Pollution Bulletin, 1981

... production of around 10 000 tons required to meet the demands of industry, agriculture and me... more ... production of around 10 000 tons required to meet the demands of industry, agriculture and medical science (Therkelsen, 1977). ... halibut Long-toothed flounder Drab jew fish Black-tipped sardine Yellow-banded grinner Hamilton's anchovy Sillago analis Golden-lined whiting ...

Marine Pollution Bulletin, 1986

... GRW DENTON and C. BURDONJONES Department of Marine Biology, School of Biological Sciences, Ja... more ... GRW DENTON and C. BURDONJONES Department of Marine Biology, School of Biological Sciences, James Cook University of North Queensland, Townsville, Qld. 4811, Australia. Zinc,copper, cadmium, nickel, lead and mercury con centrations were examined in 48 species ...

Marine Pollution Bulletin, 1986

ABSTRACT Various octocorallian and scleractinian corals from within the Great Barrier Reef Provin... more ABSTRACT Various octocorallian and scleractinian corals from within the Great Barrier Reef Province were analysed for zinc, copper, cadmium, nickel and lead by atomic absorption spectroscopy. Of the two coral groups, the octocorals accumulated significantly greater amounts of all detectable metals. The soft coral, Sarcophyton sp., revealed distinct inter-locational differences for zinc, copper and cadmium. The potential of this genus for monitoring trace metal pollution in tropical reef waters is briefly discussed.

Marine Pollution Bulletin, 1986

ABSTRACT Zinc. copper, cadmium, nickel, lead and mercury analyses were conducted on muscle and li... more ABSTRACT Zinc. copper, cadmium, nickel, lead and mercury analyses were conducted on muscle and liver samples from 50 species of fish from the Great Barrier Reef. In muscle tissue, zinc ranged from 4.3 to 41.8 μg g−1 dry weight with 76% between 10.0 and 20.0 μg g−1. Copper ranged from 0.47 to 2.4 μg g−1 with 70% between 0.50 and 1.0 μg g−1. Cadmium, nickel and lead were not detected. Mercury ranged from <0.002 to 1.9 μg g−1 wet weight of which 90% did not exceed 0.200 μg g−1. Zinc, copper, cadmium and mercury in liver samples were often greatly in excess of those present in respective muscle samples whilst nickel and lead were rarely detected. Only mercury in fish showed evidence of size and trophic level dependance. Levels of all metals in muscle tissue generally ranked among the lowest reported in the literature, and (with the exception of mercury in 5% of the total) were well below the Australian National Health and Medical Research Council's standards for human consumption.

Marine Pollution Bulletin, 2014

Environmental Science and Pollution Research, 2016

Your article is protected by copyright and all rights are held exclusively by Springer-Verlag Ber... more Your article is protected by copyright and all rights are held exclusively by Springer-Verlag Berlin Heidelberg. This e-offprint is for personal use only and shall not be selfarchived in electronic repositories. If you wish to self-archive your article, please use the accepted manuscript version for posting on your own website. You may further deposit the accepted manuscript version in any repository, provided it is only made publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be accompanied by the following text: "The final publication is available at link.springer.com".

Marine Pollution Bulletin, 2005

Journal of Toxicology and Environmental Health, Part A, 2011

This article may be used for research, teaching and private study purposes. Any substantial or sy... more This article may be used for research, teaching and private study purposes. Any substantial or systematic reproduction, redistribution , reselling , loan, sub-licensing, systematic supply or distribution in any form to anyone is expressly forbidden. The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The accuracy of any instructions, formulae and drug doses should be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims, proceedings, demand or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material.

Journal of Toxicology and Environmental Health, Part A, 2009

and-conditions-of-access.pdf This article may be used for research, teaching and private study pu... more and-conditions-of-access.pdf This article may be used for research, teaching and private study purposes. Any substantial or systematic reproduction, redistribution , reselling , loan or sub-licensing, systematic supply or distribution in any form to anyone is expressly forbidden. The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The accuracy of any instructions, formulae and drug doses should be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims, proceedings, demand or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material.

Journal of Environmental Sciences, 2009

This initial research examined the presence, distribution and bioavailability of Cu, Cr, Ni, Mn a... more This initial research examined the presence, distribution and bioavailability of Cu, Cr, Ni, Mn and Fe in a wetland area of southern Guam. The research sites are within an area covered with saporite, a soil type derived from volcanic deposits on the island. Leaf tissue of Pandanus tectorius was extracted and analysed to determine the bioaccumulation of the target metals. Metal accumulation at sites considered aerobic and anaerobic was investigated together with an attempt to correlate actual accumulation of the target metals in the plant tissue with a recognised bioavailability indicator, in this case, three step sequential extraction scheme. Manganese was found to be accumulated in relatively high concentrations and to a lesser extent Cu was also accumulated. Chromium, Ni and Fe however exhibited very low accumulation factors. Accumulation of Mn in particular was significantly affected by aerobic conditions whereas the converse effect was experienced by Cu. Significant correlation between various steps of a Sequential Extraction Scheme and actual accumulation was not achieved although the degree of aerobic conditions at each site and soil pH did affect concentrations of metals extracted by differing steps of SES. Results obtained suggest that further research in the area should be undertaken using different plant species and tissues.

Ground Water Monitoring & Remediation, 2010

Comparison of Background Values ..

Procedia Environmental Sciences, 2013

Marine Biology, 1981

... true for lead concentrations (Table 4). For cadmium, all first-order interaction combinations... more ... true for lead concentrations (Table 4). For cadmium, all first-order interaction combinations were significant (Table 3), and there was a significant second-order interaction between the effect of tissue, tempera-ture and salinity (A x B x C) for mercury and cadmium but not lead. ...

Environmental Pollution (1970), 1976

Mercenaria mercenaria fed Aroclor 1254 adsorbed onto the surface of alumina particles at 1.25 and... more Mercenaria mercenaria fed Aroclor 1254 adsorbed onto the surface of alumina particles at 1.25 and 12.5 parts/lO 9 seawater for 21 days showed a maximum concentration factor of !-8 x 103 with visceral mass: muscular foot residues of less than 5:1 in general. Only the muscular foot of clams on a high dosage showed a diminution in PCB content after six month~ in clean seawater. PCB levels in visceral mass: muscular foot:surface mud for clams in Southampton water are in the ratio of 2:1:2. Tissue samples contained relatively more lower chlorinated isomers compared with the A1254 standard whilst faeces and mud samples showed an increased proportion of higher chlorinated PCB isomers. Clams may, therefore, exert both a qualitative and a quantitative effect upon the distribution of PCB in the estuarine ecosystem.

Problem and Research Objectives Guam's only municipal solid waste disposal site is centrally loca... more Problem and Research Objectives Guam's only municipal solid waste disposal site is centrally located in the village of Ordot and has been in use for over fifty years. Lacking in the conventional technology built in to modern day sanitary landfills, the site is essentially an open dump covering ~20 acres of the upper Lonfit River valley. The dump was operated by the US Navy at the end of WWII and transferred to the Government of Guam shortly thereafter. Although slated for closure more than 20 years ago, it still receives around 200 tons of solid waste per day from the civilian community. Early records of the types of materials disposed of at the Ordot Dump are nonexistent but are suspected to include the same array of toxic chemicals found at other military dumpsites on island. Today, there is some control over the bulk disposal of industrial chemicals, waste oil, and metallic waste at Ordot Dump. However, household waste is rarely screened and is known to contain a variety of hazardous substances, both biological and chemical. Leachate streams occur in several places around the perimeter of the dump and course their way down gradient into the Lonfit River and out into Pago Bay. Their chemical composition is largely unknown and their impact on the local environment in terms of ecology, agriculture, and human health remains to be investigated.

Science of The Total Environment, 2007

A survey of the different forms of arsenic species: inorganic arsenic (As), As(III), As(V) and or... more A survey of the different forms of arsenic species: inorganic arsenic (As), As(III), As(V) and organic As(III) and (V) was carried out on spring waters located along Tumon Bay in Guam. The results show that total arsenic concentrations in the spring water samples ranged from <0.3-1.2 microg/L. Inorganic arsenate, As(V), appears to be the dominant species in the spring water samples tested. The concentrations are much lower than previously reported, probably due to a much more rigorous methodological approach and requires further investigations on the status of As contamination in groundwater on the island.

Marine Pollution Bulletin, 1981

... production of around 10 000 tons required to meet the demands of industry, agriculture and me... more ... production of around 10 000 tons required to meet the demands of industry, agriculture and medical science (Therkelsen, 1977). ... halibut Long-toothed flounder Drab jew fish Black-tipped sardine Yellow-banded grinner Hamilton's anchovy Sillago analis Golden-lined whiting ...

Marine Pollution Bulletin, 1986

... GRW DENTON and C. BURDONJONES Department of Marine Biology, School of Biological Sciences, Ja... more ... GRW DENTON and C. BURDONJONES Department of Marine Biology, School of Biological Sciences, James Cook University of North Queensland, Townsville, Qld. 4811, Australia. Zinc,copper, cadmium, nickel, lead and mercury con centrations were examined in 48 species ...

Marine Pollution Bulletin, 1986

ABSTRACT Various octocorallian and scleractinian corals from within the Great Barrier Reef Provin... more ABSTRACT Various octocorallian and scleractinian corals from within the Great Barrier Reef Province were analysed for zinc, copper, cadmium, nickel and lead by atomic absorption spectroscopy. Of the two coral groups, the octocorals accumulated significantly greater amounts of all detectable metals. The soft coral, Sarcophyton sp., revealed distinct inter-locational differences for zinc, copper and cadmium. The potential of this genus for monitoring trace metal pollution in tropical reef waters is briefly discussed.

Marine Pollution Bulletin, 1986

ABSTRACT Zinc. copper, cadmium, nickel, lead and mercury analyses were conducted on muscle and li... more ABSTRACT Zinc. copper, cadmium, nickel, lead and mercury analyses were conducted on muscle and liver samples from 50 species of fish from the Great Barrier Reef. In muscle tissue, zinc ranged from 4.3 to 41.8 μg g−1 dry weight with 76% between 10.0 and 20.0 μg g−1. Copper ranged from 0.47 to 2.4 μg g−1 with 70% between 0.50 and 1.0 μg g−1. Cadmium, nickel and lead were not detected. Mercury ranged from <0.002 to 1.9 μg g−1 wet weight of which 90% did not exceed 0.200 μg g−1. Zinc, copper, cadmium and mercury in liver samples were often greatly in excess of those present in respective muscle samples whilst nickel and lead were rarely detected. Only mercury in fish showed evidence of size and trophic level dependance. Levels of all metals in muscle tissue generally ranked among the lowest reported in the literature, and (with the exception of mercury in 5% of the total) were well below the Australian National Health and Medical Research Council's standards for human consumption.

Marine Pollution Bulletin, 2014