Denitrification Along Pangborn Creek in the Abbotsford-Sumas Aquifer, Washington

Author

Leslie B. (Leslie Braverman) McKee, Western Washington University

Date Permissions Signed

5-12-2018

Date of Award

Summer 2004

Document Type

Masters Thesis

Degree Name

Master of Science (MS)

Department

Geology

First Advisor

Mitchell, Robert J. (Geologist)

Second Advisor

Babcock, R. Scott (Randall Scott)

Third Advisor

Matthews, Robin A., 1952-

Abstract

The Abbotsford-Sumas aquifer is a shallow, unconfined aquifer located in the agricultural regions of southwestern British Columbia and northwestern Washington and has a history of nitrate contamination. I monitored nitrate distributions in a study area bisected by a wide- scale peat deposit within a portion of the Whatcom County component of the aquifer to assess the current nitrate distribution, evaluate ground and surface water interactions in the peat, and determine the affect of peat on denitrification.

The water quality dataset and statistical analyses showed that nitrate contamination was heavily concentrated upgradient of the peatlands. In general, shallow wells (table) north of the peatlands had higher nitrate concentrations than deeper wells (>10 m below the median water table). Some upgradient wells showed low nitrate concentrations and data suggest they received denitrified ground water from unmapped peat deposits. Nitrogen isotope data (δ¹⁵N on nitrate) indicated that nitrate sources included manure and inorganic commercial fertilizers. The contamination south of the peatlands was significantly lower than the contamination to the north and the median nitrate levels within the peatlands were near the detection limit. Nitrogen gas measurements and a combination of nitrogen (δ¹⁵N on nitrate) and oxygen (δ¹⁸0 on water) isotopes confirmed that denitrification occurred in the peatlands and in much of the ground water south of the peatlands. In addition, the gas measurements suggested that iron, manganese, sulfate, and methane occurred throughout the peatlands and may have contributed to redox reductions.

The implication of these findings is that a natural means for nitrate reduction exists in this region. Hydrostratigraphic data suggest that peat deposits occur throughout Whatcom County at various unmapped depths. Identifying these peat deposits and quantifying the upgradient ground water nitrate contributions may help facilitate nutrient management in the region.

Type

Text

Keywords

Abbotsford-Sumas aquifer, Nitrate distributions, Nitrate contaminiation

DOI

https://doi.org/10.25710/tgsy-m938

Publisher

Western Washington University

OCLC Number

1050450215

Subject – LCSH

Water--Purification--Nitrogen removal--British Collumbia--Abbotsford Region; Water--Purification--Nitrogen removal--Washington (State)--Sumas Region; Groundwater--Purification--British Collumbia--Abbotsford Region; Groundwater--Purification--Washington (State)--Sumas Region; Water--British Collumbia--Abbotsford Region--Analysis; Water--Washington (State)--Sumas Region--Analysis; Groundwater----British Collumbia--Abbotsford Region--Analysis; Groundwater--Washington (State)--Sumas Region--Analysis

Geographic Coverage

Sumas Region (Wash.); Abbotsford Region (B.C.)

Format

application/pdf

Genre/Form

masters theses

Language

English

Rights

Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this thesis for commercial purposes, or for financial gain, shall not be allowed without the author's written permission.

Recommended Citation

McKee, Leslie B. (Leslie Braverman), "Denitrification Along Pangborn Creek in the Abbotsford-Sumas Aquifer, Washington" (2004). WWU Graduate School Collection. 760.
https://cedar.wwu.edu/wwuet/760