東華大學圖書館 |

Language: English

Help

回圖書館首頁

手機版館藏查詢

Back

Switch To: Labeled | MARC Mode | ISBD

Modeling contaminant behavior in Lak...

Michigan Technological University., Civil & Environmental Engineering.

Linked to FindBook

Google Book

Amazon

博客來

Modeling contaminant behavior in Lake Superior: A comparison of PCBs, PBDEs, and mercury.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Modeling contaminant behavior in Lake Superior: A comparison of PCBs, PBDEs, and mercury./
Author:	Rowe, Mark D.
Description:	60 p.
Notes:	Adviser: Judith A. Perlinger.
Contained By:	Masters Abstracts International47-05.
Subject:	Atmospheric Sciences. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=1464086
ISBN:	9781109129700

Modeling contaminant behavior in Lake Superior: A comparison of PCBs, PBDEs, and mercury.
Rowe, Mark D.

Modeling contaminant behavior in Lake Superior: A comparison of PCBs, PBDEs, and mercury. - 60 p.

Adviser: Judith A. Perlinger.

Thesis (M.S.)--Michigan Technological University, 2009.

A mass-balance model for Lake Superior was applied to polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and mercury to determine the major routes of entry and the major mechanisms of loss from this ecosystem as well as the time reuired for each contaminant class to approach steady state. A two-box model (water column, surface sediments) incorporating seasonally adjusted environmental parameters was used. Both numerical (forward Euler) and analytical solutions were employed and compared. For validation, the model was compared with current and historical concentrations and fluxes in the lake and sediments. Results for PCBs were similar to prior work showing that air-water exchange is the most rapid input and loss process. The model indicates that mercury behaves similarly to a moderately-chlorinated PCB, with air-water exchange being a relatively rapid input and loss process. Modeled accumulation fluxes of PBDEs in sediments agreed with measured values reported in the literature. Wet deposition rates were about three times greater than dry particulate deposition rates for PBDEs. Gas deposition was an important process for tri- and tetra-BDEs (BDEs 28 and 47), but not for higher-brominated BDEs. Sediment burial was the dominant loss mechanism for most of the PBDE congeners while volatilization was still significant for tri- and tetra-BDEs. Because volatilization is a relatively rapid loss process for both mercury and the most abundant PCBs (tri- through penta-), the model predicts that similar times (from 2--10 yr) are required for the compounds to approach steady state in the lake. The model predicts that if inputs of Hg(II) to the lake decrease in the future then concentrations of mercury in the lake will decrease at a rate similar to the historica decline in PCB concentrations following the ban on production and most uses in the U.S. In contrast, PBDEs are likely to respond more slowly if atmospheric concentrations are reduced in the future because loss by volatilization is a much slower process for PBDEs, leading to lesser overall loss rates for PBDEs in comparison to PCBs and mercury. Uncertainties in the chemical degradation rates and partitioning constants of PBDEs are the largest source of uncertainty in the modeled times to steady-state for this class of chemicals. The modeled organic PBT loading rates are sensitive to uncertainties in scavenging efficiencies by rain and snow, dry deposition velocity, watershed runoff concentrations, and uncertainties in air-water exchange such as the effect of atmospheric stability.

ISBN: 9781109129700Subjects--Topical Terms:

1019179
Atmospheric Sciences.

Modeling contaminant behavior in Lake Superior: A comparison of PCBs, PBDEs, and mercury.
LDR:03619nmm 2200325 a 45 001 874436
005 20100824
008 100824s2009 ||||||||||||||||| ||eng d
020 $a 9781109129700
035 $a (UMI)AAI1464086
035 $a AAI1464086
040 $a UMI $c UMI
100 1 $a Rowe, Mark D. $3 1043712
245 1 0 $a Modeling contaminant behavior in Lake Superior: A comparison of PCBs, PBDEs, and mercury.
300 $a 60 p.
500 $a Adviser: Judith A. Perlinger.
500 $a Source: Masters Abstracts International, Volume: 47-05, page: 3016.
502 $a Thesis (M.S.)--Michigan Technological University, 2009.
520 $a A mass-balance model for Lake Superior was applied to polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and mercury to determine the major routes of entry and the major mechanisms of loss from this ecosystem as well as the time reuired for each contaminant class to approach steady state. A two-box model (water column, surface sediments) incorporating seasonally adjusted environmental parameters was used. Both numerical (forward Euler) and analytical solutions were employed and compared. For validation, the model was compared with current and historical concentrations and fluxes in the lake and sediments. Results for PCBs were similar to prior work showing that air-water exchange is the most rapid input and loss process. The model indicates that mercury behaves similarly to a moderately-chlorinated PCB, with air-water exchange being a relatively rapid input and loss process. Modeled accumulation fluxes of PBDEs in sediments agreed with measured values reported in the literature. Wet deposition rates were about three times greater than dry particulate deposition rates for PBDEs. Gas deposition was an important process for tri- and tetra-BDEs (BDEs 28 and 47), but not for higher-brominated BDEs. Sediment burial was the dominant loss mechanism for most of the PBDE congeners while volatilization was still significant for tri- and tetra-BDEs. Because volatilization is a relatively rapid loss process for both mercury and the most abundant PCBs (tri- through penta-), the model predicts that similar times (from 2--10 yr) are required for the compounds to approach steady state in the lake. The model predicts that if inputs of Hg(II) to the lake decrease in the future then concentrations of mercury in the lake will decrease at a rate similar to the historica decline in PCB concentrations following the ban on production and most uses in the U.S. In contrast, PBDEs are likely to respond more slowly if atmospheric concentrations are reduced in the future because loss by volatilization is a much slower process for PBDEs, leading to lesser overall loss rates for PBDEs in comparison to PCBs and mercury. Uncertainties in the chemical degradation rates and partitioning constants of PBDEs are the largest source of uncertainty in the modeled times to steady-state for this class of chemicals. The modeled organic PBT loading rates are sensitive to uncertainties in scavenging efficiencies by rain and snow, dry deposition velocity, watershed runoff concentrations, and uncertainties in air-water exchange such as the effect of atmospheric stability.
590 $a School code: 0129.
650 4 $a Atmospheric Sciences. $3 1019179
650 4 $a Biology, Limnology. $3 1018638
650 4 $a Engineering, Environmental. $3 783782
650 4 $a Environmental Sciences. $3 676987
690 $a 0725
690 $a 0768
690 $a 0775
690 $a 0793
710 2 $a Michigan Technological University. $b Civil & Environmental Engineering. $3 1043711
773 0 $t Masters Abstracts International $g 47-05.
790 $a 0129
790 1 0 $a Green, Sarah A. $e committee member
790 1 0 $a Perlinger, Judith A., $e advisor
790 1 0 $a Urban, Noel R. $e committee member
791 $a M.S.
792 $a 2009
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=1464086