Contamination in Ontario farmstead domestic wells and its association with agriculture:

Abstract

Groundwater provides about 30% of water requirements in Ontario, but farm families depend almost entirely on private wells. Major potential contaminants on farms are nitrate (NO ), pathogenic micro-organisms, pesticides and petroleum derivatives. A survey of farm 3 drinking water wells was conducted throughout the Province of Ontario, Canada, in 1991 and 1992 and tested for these contaminants. Main objectives of the survey were to determine the quality and safety of drinking water for farm families, and determine the effect of agricultural management on groundwater quality at a provincial scale.Four farm wells were chosen in each township where >50% of the land area was used for agricultural production. Elsewhere one well per township was usually sampled. Within each township the types of farming activity and dominant soils were additional criteria for selection.The network comprised 1292 of the estimated 500,000 water-wells in Ontario, and the study conformed to a stratified random survey. A subset of 160 wells, chosen by farm type, soil, and the presence or absence of a fuel storage tank, was investigated for the presence of petroleum derivatives: benzene, toluene, ethyl benzene, and xylene.About 40% of farm wells tested contained one or more of the target contaminants above the maximum acceptable concentration; 34% of wells had more than the maximum acceptable number of coliform bacteria, 14% contained NO -N concentrations above 10 mg L limit and 3 -1 about 7% were contaminated with both bacteria and NO . Only six wells contained pesticide 3 residues above the interim maximum acceptable concentration (IMAC), but pesticides were detected in 7% of wells in winter and in 11% in summer. No wells contained detectable petroleum derivatives. These results for NO contamination were not significantly different from 3 3 those reported for a survey of Ontario wells for the period 1950-1954, but the frequency of contamination by Escherichia coli was greater in the present study.None of the point sources investigated contributed significantly to the NO contamination. The 3 percentage of wells contaminated by coliform bacteria decreased significantly with increasing separation of the well from the feedlot or exercise yard on livestock farms. A full statistical model including the type of well construction, depth, age and soil hydrologic group was developed to describe the frequency of NO contamination.3

Drinking Water Quality of a Rice Land in Turkey by Statistical and GIS Perspectives

“…As a result of the mentioned study, nitrate levels in 15.7% of investigated wells had exceeded the critical limit of 10 mg/L [30]. In another study that investigated nitrate in Ontario, Canada, 14% of farmstead domestic wells contained nitrate above the 10 mg/L limit [31]. In the present study, nitrate contents in 23% of investigated stations including Tevfikiye, Karaağaç, and İbriktepe, which have formed a separate cluster (C6) in Cluster Analysis (CA), and Esetçe stations were recorded as quite close to the EPA maximum contaminant level (MCL) of 10 mg/L (8.840 mg/L, 9.160 mg/L, 8.410 mg/L and 9.730 mg/L respectively), and also nitrate concentrations recorded in Pazardere station, which has formed a separate cluster (C3) in CA, has exceeded the MCL limit two times (19.3 …”

Antibiotic resistant bacteria in terrestrial and aquatic environments: A review

“…In Ontario, private wells where manure is commonly applied on farms are frequently contaminated with bacteria. Feces contaminated effluents from animal farms infiltrate wells [70]. In addition, waste from septic tanks and manure storage sites can seep or spill into surrounding watersheds and ground water sources [71].…”

Study of the Factors Influencing the Shallow Groundwater Quality in Two Settlements with Different Characteristics

“…The authors also showed that when the shallow groundwater leaves the agricultural areas, the nitrate concentration quickly decreases mainly due to denitrification. Goss et al (1998) studied the pollution of the shallow groundwater in some farms of Ontario, Canada. The authors also examined the factors influencing the degree of contamination and proved, based on the examinations of 1292 wells, that the degree of nitrate pollution principally depends on the depth of the shallow groundwater.…”