Geology topics

Mark J. Melancon

Publications and source records attributed to Mark J. Melancon.

6 recordsLinked to original sources

USGS2009

Bioindicators of contaminant exposure and effect in aquatic and terrestrial monitoring

Bioindicators of contaminant exposure presently used in environmental monitoring arc discussed. Some have been extensively field-validated and arc already in routine application. Included are (1) inhibition of brain or blood cholinesterase by anticholinesterase pesticides, (2) induction of hepatic microsomal cytochromes P450 by chemicals such as PAHs and PCBs, (3) reproductive problems such as terata and eggshell thinning, and (4) aberrations of hemoglobin synthesis, including the effects of lead and of certain chlorinated hydrocarbons. Many studies on DNA damage and of histopathological effects, particularly in the form of tumors, have already been completed. There are presently numerous other opportunities for field validation. Bile metabolites of contaminants in fish reveal exposure to contaminants that might otherwise be difficult to detect or quantify. Bile analysis is beginning to be extended to species other than fishes. Assessment of oxidative damage and immune competence appear to be valuable biomarkers. needing only additional field validation for wider use. The use of metallothioneins as biomarkers depends on the development of convenient, inexpensive methodology that provides information not available from measurements of metal ions. The use of stress proteins as biomarkers depends on development of convenient, inexpensive methodology and field validation. Gene arrays and proteomics hold promise as bioindicators for contaminant exposure or effect, particularly because of the large amount of data that could be generated, but they still need extensive development and testing.

Book chapter↗

USGS2009

Organochlorine and PBDE concentrations in relation to cytochrome P450 activity in livers of Forster’s Terns ( Sterna forsteri ) and Caspian Terns ( Hydroprogne caspia ), in San Francisco Bay, California

We measured halogenated organic contaminants (HOCs) [polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), and dichloro-diphenyl-trichloroethane (DDT)] and P450 [e.g., ethoxyresorufin- O -dealkylase (EROD)] stress in livers from Caspian tern ( Hydroprogne caspia ) adults and Forster’s tern ( Sterna forsteri ) adults and chicks in San Francisco Bay (SFB). Penta BDEs and tetra PBDEs composed 46–66% of ∑PBDE in terns. PCB homologues di, tri, penta, hexa, and hepta composed 93–95% of ∑PCBs and p ′ p -DDE composed 82–98% of all ∑DDTs. We found similar concentrations of ∑PBDEs [mean micrograms per gram wet weight (ww) ± standard error = 0.4 ± 0.1], ∑PCBs (5.9 ± 1.6), and ∑DDTs (0.6 ± 0.1) among species, sexes, and regions. However, concentrations were higher in Forster’s tern adults than chicks (∑PBDEs = 0.4 ± 0.1 and 0.1 ± 0.1; ∑PCBs = 7.08 ± 2.4 and 2.4 ± 1.4; ∑DDTs = 0.5 ± 0.1 and 0.1 ± 0.1; respectively), and there was a nonsignificant trend of elevated ∑PBDEs and ∑PCBs for adult Forster’s terns in the Central South Bay and Lower South Bay portions of SFB. Combined Forster’s tern and Caspian tern ∑DDTs bioaccumulated similarly to selenium, but not mercury, and there was a nonsignificant but positive trend for ∑PBDEs and ∑PCBs bioaccumulation with mercury. P450 protein activity was higher in adult Forster’s terns than Caspian terns, higher in Central South Bay than in Lower South Bay, and higher in adult Forster’s terns than in chicks.

California↗

USGS1998

Reproduction and environmental contamination in tree swallows nesting in the Fox River drainage and Green Bay, Wisconsin, USA

Concentration, accumulation, and effects of polychlorinated biphenyls (PCBs) o nreproduction in tree swallows ( Tachycineta bicolor ) were studied at four sites in the Fox River drainage and in Green Bay, Lake Michigan, Wisconsin, USA, in 1994 and 1995. Total PCBs in eggs and newly hatched young (mean = 3.01 μg/g wet weight, years and sites combined) and 12-d-old nestlings (mean = 2.34 μg/g wet weight) at two contaminated sites (Kidney Island and Arrowhead) were higher than concentrations at two reference sites (Lake Poygan and High Cliff State Park, years and sites combined, pippers mean = 0.26 μg/g, nestlings mean = 0.01 μg/g). Concentrations of 11 PCB congeners were also higher at contaminated compared to reference sites. Polychlorinated biphenyls (PCBs) accumulated in nestlings at a higher rate (1.34–6.69 μg/d) at contaminated sites compared to reference locations (0.06–0.42 μg/d). Dichlorodiphenyldichloroethylene (DDE) was the only other organochlorine found in all samples; concentrations for all samples averaged ≤0.20 μg/g wet weight. Total PCBs and p,p ′-DDE concentrations did not differ among clutches where all eggs hatched, some eggs hatched, and no eggs hatched.

Wisconsin↗

USGS1997

Cytochrome P450 and organochlorine contaminants in black-crowned night-herons from the Chesapeake Bay region, USA

Black-crowned night-heron ( Nycticorax nycticorax ) offspring were collected from a relatively uncontaminated coastal reference site (next to Chincoteague National Wildlife Refuge, VA, USA) and two sites in the Chesapeake Bay watershed (Baltimore Harbor, MD and Rock Creek Park, Washington, DC, USA). Hepatic microsomal activities of benzyloxyresorufin- O -dealkylase and ethoxyresorufin- O -dealkylase were significantly elevated (up to sixfold and ninefold induction, respectively) in pipping embryos from the Baltimore Harbor colony compared to the reference site, whereas values in embryos from the Rock Creek Park colony were intermediate. Concentrations of organochlorine pesticides and metabolites in pipping embryos from both sites in the Chesapeake watershed were greater than at the reference site but below the known threshold for reproductive impairment. However, concentrations of 10 arylhydrocarbon receptor-active polychlorinated biphenyl (PCB) congeners and estimated toxic equivalents were up to 37-fold greater in embryos collected from these two sites in the Chesapeake Bay region, with values for toxic congeners 77 and 126 exceeding those observed in pipping heron embryos from the Great Lakes. Monooxygenase activity of pipping embryos was associated with concentrations of several organochlorine pesticides, total PCBs, arylhydrocarbon receptor-active PCB congeners, and toxic equivalents ( r = 0.30–0.59), providing further evidence of the value of cytochrome P450 as a biomarker of organic contaminant exposure. Organochlorine contaminant levels were greater in 10-d-old nestlings from Baltimore Harbor than the reference site but had no apparent effect on monooxygenase activity or growth. These findings demonstrate induction of cytochrome P450 in pipping black-crowned night-heron embryos in the Chesapeake Bay region, probably by exposure to PCB congeners of local origin, and the accumulation of organochlorine pesticides and metabolites in nestling herons from Baltimore Harbor. Bio-monitoring with additional waterbird species (e.g., bald eagle, common tern, great blue heron) that appear to be more sensitive to PCBs than black-crowned night-herons is recommended to document health of waterbirds and remediation of the Chesapeake Bay.

Chesapeake Bay region↗

USGS1996

Cytochrome P450 and contaminant concentrations in nestling black-crowned night-herons and their interrelation with sibling embryos

Hepatic cytochrome P450-associated monooxygenase activities were measured in 11-d-old nestling black-crowned night-herons ( Nycticorax nycticorax ) collected from a reference site (next to Chincoteague National Wildlife Refuge, VA, USA) and three contaminated sites (Cat Island, Green Bay, WI, USA; Bair Island, San Francisco Bay, CA, USA; and West Marin Island, San Francisco Bay, CA, USA). Arylhydrocarbon hydroxylase and benzyloxyresorufin- O -dealkylase activities of nestlings from contaminated sites were only slightly elevated (less than threefold) compared with the reference site. Organochlorine pesticide and total polychlorinated biphenyl (PCB) concentrations in nestlings were greatest at contaminated sites, although much lower than found in concurrently collected eggs and pipping embryos. Pollutant concentrations of nestlings were rarely associated with monooxygenase activity. In contrast, concurrently collected pipping heron embryos (often siblings of the nestlings) exhibited pronounced monooxygenase induction (means at contaminated sites were elevated up to sevenfold and values of some embryos exceeded 25-fold induction). Furthermore, monooxygenase activity of pipping embryos was significantly correlated with total PCBs, arylhydrocarbon receptor-active PCB congeners, and toxic equivalents. The modest monooxygenase responses of heron nestlings suggest that this biomarker may have only limited value during this rapid-growth life stage.

California, Virginia, Wisconsin↗

USGS1995

Bioindicators used in aquatic and terrestrial monitoring

There are many different types of contaminants present in the environment ranging from synthetic chemicals, which would not be present in the environment without man's intervention, to trace metals that are required for life. Concerns range from possible harmful effects on flora and fauna to possible harm to humans consuming such organisms. The complete chemical analysis for all possible environmental contaminants in sediments, water, air, and every species and sample of interest would not only be excessively costly, but the facilities to handle do many samples do not exist. Such chemical analysis would only establish the presence of contaminants, without revealing how available or active they were within the organism. Bioindicators, sometimes called biomarkers , are responses in living organisms that may simply signify exposure to contaminants, may predict future harm, or may themselves be harmful effects. In this chapter, a bioindicator will be interpreted to mean the same as a biomarker (a biochemical, physiological, or morphological response), but not a population or ecosystem bioindicator such as a sentinel species, genetic variability, or species richness. thus, a bioindicator (biomarker) may be studied in a particular species to assess the status of that species, or in a sentinel species to assess habitat status. Individuals of the sentinel species might be those already residing at the site of interest or might be pristine organisms brought to the site and maintained in cages (fish) or released and recovered (birds).

Book chapter↗