Groundwater contamination of the Abbotsford aquifer by 1,2-dichloropropane (1,2-DCP) was reported previously. The purpose of the present study is to quantify groundwater contamination by other chlorinated hydrocarbon compounds which are present in fumigant formulations containing 1,2-DCP. Widespread contamination of 1,2,2-trichloropropane (1,2,2-TCP) was measured consistent with a non-point source. 1,2,2-TCP concentration generally decreased with depth suggesting a surface source. Localized contamination by 1,2,3-trichloro-propane, 2,3-dichloropropene and 1,3-dichloropropane was detected. Detection of these compounds was associated with higher concentrations of 1,2-DCP suggesting contamination by these compounds may have been from the same fumigant sources. The lack of a decrease in the concentration of most of these compounds over time suggests that the measured contamination will persist for some time. The results highlight the potential for persistent trace impurities in chlorinated fumigant formulations to contaminate groundwater in vulnerable aquifers.
Forty piezometers at 13 sites in the Canadian portion of the Abbotsford aquifer were tested for 1,2-dichloropropane (1,2-DCP) and 1,3-dichloropropene (1,3-DCP) on an approximate monthly interval from July 1991 to June 1994. Detectable levels of 1,2-DCP were found in 32 of the 40 piezometers. Average 1,2-DCP concentrations within a piezometer ranged up to 2.23 µg/L and a maximum concentration of 7.07 µg/L was recorded in one piezometer. 1,3-DCP was detected for only a short period of time in one piezometer and at a maximum concentration of 0.23 µg/L. 1,2-DCP contamination in the aquifer is attributed to application of fumigants containing this compound as an active ingredient or as an impurity for the control of root nematodes in red raspberry crops. The nature of the contamination is consistent with a non-point source that is highly variable in space and time. Although soil fumigants containing 1,2-DCP as an active ingredient are no longer used in the Abbotsford area, fairly constant values of 1,2-DCP would indicate there is still a contaminant source providing input to the groundwater. 1,2-DCP has apparently accumulated on the soil sediments above the water table and is slowly being released to the groundwater. In the top 15 m of the saturated zone, concentrations generally decreased with depth below the water table to near nondetectable levels. Correlation between contaminant levels and rainfall or other environmental factors that might affect the distribution of 1,2-DCP could not be established. More detailed soil measurements and controlled laboratory experiments are needed to determine 1,2-DCP movement as well as rates of dissipation in the Abbotsford aquifer.
Groundwater samples were collected from 60 piezometers and 23 domestic wells from March 1991 to April 1992 as part of a study to quantify NO−3 and pesticide contamination of the Abbotsford Aquifer, located in the lower Fraser Valley, southwestern British Columbia, Canada. A new contaminant, 1,2,2‐trichloropropane (1,2,2‐TCP), was detected and confirmed in 296 of the 514 samples by purge and trap GC/MS, and its concentration was determined in 150 of the samples collected between January and April 1992. The contaminant was detected in 34 (57%) of the piezometers sampled, and 10 (44%) of the domestic wells sampled. Mean 1,2,2‐TCP concentration (±1 SD) was 0.12 ± 0.11 µg L−1 in 123 piezometer samples and 0.14 ± 0.09 µg L−1 in 27 domestic well samples. The highest 1,2,2‐TCP concentrations measured were 0.62 and 0.32 µg L−1 for piezometers and domestic wells, respectively. The probable nonpoint sources of the contaminant are the synthetic pesticides, Telone (mixture of 1,3‐dichloropropene and 1,2‐dichloropropane) and Telone II (1,3‐dichloropropene), used to control pathogenic nematodes in raspberry (Rubus idaeus L.) production. Analyses of Telone and Telone II confirmed the presence of 1,2,2‐TCP as impurities in both products. The study demonstrates that an impurity present in pesticide formulations in trace quantities, which is persistent in soil and water, has the potential to result in significant groundwater contamination under the appropriate soil and climatic conditions.
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