Microbial Groundwater Sampling Protocol for Fecal‐Rich Environments

Abstract

Inherently, confined animal farming operations (CAFOs) and other intense fecal-rich environments are potential sources of groundwater contamination by enteric pathogens. The ubiquity of microbial matter poses unique technical challenges in addition to economic constraints when sampling wells in such environments. In this paper, we evaluate a groundwater sampling protocol that relies on extended purging with a portable submersible stainless steel pump and Teflon® tubing as an alternative to equipment sterilization. The protocol allows for collecting a large number of samples quickly, relatively inexpensively, and under field conditions with limited access to capacity for sterilizing equipment. The protocol is tested on CAFO monitoring wells and considers three cross-contamination sources: equipment, wellbore, and ambient air. For the assessment, we use Enterococcus, a ubiquitous fecal indicator bacterium (FIB), in laboratory and field tests with spiked and blank samples, and in an extensive, multi-year field sampling campaign on 17 wells within 2 CAFOs. The assessment shows that extended purging can successfully control for equipment cross-contamination, but also controls for significant contamination of the well-head, within the well casing and within the immediate aquifer vicinity of the well-screen. Importantly, our tests further indicate that Enterococcus is frequently entrained in water samples when exposed to ambient air at a CAFO during sample collection. Wellbore and air contamination pose separate challenges in the design of groundwater monitoring strategies on CAFOs that are not addressed by equipment sterilization, but require adequate QA/QC procedures and can be addressed by the proposed sampling strategy.

Assessing biosynthetic potential of agricultural groundwater through metagenomic sequencing: A diverse anammox community dominates nitrate-rich groundwater

“…Each water sample was tested for the presence of USDA pathogenic bacteria by inoculating liquid enrichment media and plating on selective nutrient media [20–22]. The specific pathogens tested for were Salmonella , Enterococcus , Escherichia coli , and E .…”

“…Likewise Anaerorhabdus , Coprobacillus , Halochromatium , and Acholeplasma are abundant at >5% in LAG and ~1% in DOM. Airborne dust was ever-present while we sampled, and despite extensive containment efforts, some exposure of the apparatus to dust occurred [20]. However, the rest of the DOM metagenome is remarkably distinct from the other samples, suggesting that, with the exception of the known contaminants, it is still representative of the deep groundwater.…”

Does Pumping Volume Affect the Concentration of Micropollutants in Groundwater Samples?

“…Although Roudnew et al () suggested more stability of microbial parameters due to a constant recharge by a river, this can only partly be concluded from this study. Harter et al () suggested that field water quality parameters were sufficient indicators to screen wellbore and near‐well microbiological contamination. However, with microscopic analysis we found high numbers of biofilm particles (faintly stained fluffs with intensive bacterial colonization) present once the micropollutants and physicochemical parameters stabilized.…”

“…The current standard procedure for sampling groundwater is to pump the monitoring well for three to five well volumes (USEPA ; DVWK ; Nielsen and Nielsen ) or until various physicochemical parameters, such as pH, temperature, electrical conductivity (EC), and dissolved oxygen, ­stabilize (Robin and Gillham ; BMLFUW ). In several studies, field tests for obtaining representative groundwater samples were performed (Robin and Gillham ; Gibs and Imbrigiotta ; Barcelona et al ; Puls and Paul ; Novak and Watts ; Barcelona et al ; Kwon et al ; Kozuskanich et al ; Shani et al ; Harter et al ; Roudnew et al ). Most focused on standard chemical parameters or microbiological constituents.…”

Performance Evaluation of Metakaolin as Low Cost Adsorbent for Manganese Removal in Anoxic Groundwater

“…The utilization of purging duration on groundwater sample is totally depends on water quality characteristics. There are abundance of studies on groundwater quality to determine physical [17], [18], chemical [17]- [20] and microbial properties [18], [19], [21], [22]. One of the chemical properties that are substantial to determine the suitability for human consumption is heavy metals concentration.…”