Patricia A. Chambers

Development of Environmental Thresholds for Nitrogen and Phosphorus in Streams

Inputs of nutrients (P and N) to freshwaters can cause excessive aquatic plant growth, depletion of oxygen, and deleterious changes in diversity of aquatic fauna. As part of a National Agri-Environmental Standards Initiative, the Government of Canada committed to developing environmental thresholds for nutrients to protect ecological condition of agricultural streams. Analysis of data from >200 long-term monitoring stations across Canada and detailed ecological study at ~70 sites showed that agricultural land cover was associated with increased nutrient concentrations in streams and this, in turn, was associated with increased sestonic and benthic algal abundance, loss of sensitive benthic macroinvertebrate taxa, and an increase in benthic diatom taxa indicative of eutrophication. Chemical thresholds for N and P were defined by applying five approaches, employing either a predetermined percentile to a water chemistry data set or a relationship between water chemistry and land cover, to identify boundaries between minimally disturbed and impaired conditions. Comparison of these chemical thresholds with biological thresholds (derived from stressor-response relationships) produced an approach for rationalizing these two types of thresholds and deriving nutrient criteria. The resulting criteria were 0.01 to 0.03 mg L(-1) total P and 0.87-1.2 mg L(-1) total N for the Atlantic Maritime, 0.02 mg L(-1) total P and 0.21 mg L(-1) total N for the Montane Cordillera, ~0.03 mg L(-1) total P and ~1.1 mg L(-1) total N for the Mixedwood Plains, and ~0.10 mg L(-1) total P and 0.39-0.98 mg L(-1) total N for the interior prairies of Canada. Adoption of these criteria should result in greater likelihood of good ecological condition with respect to benthic algal abundance, diatom composition, and macroinvertebrate composition.

Inorganic nitrogen, sterols and bacterial source tracking as tools to characterize water quality and possible contamination sources in surface water

The effects of agricultural activities on stream water quality were assessed by nitrogen analysis, further investigated by gas chromatography mass spectrometry (GC-MS) sterol analysis (including chemometric analysis), and characterized by bacterial source tracking (BST). Surface water samples were collected from five sites, throughout the agriculturally-influenced Nathan Creek watershed, British Columbia, Canada and a nearby control site between October 2005 and March 2006. From a total of 48 samples, Canadian Water Quality Guidelines were exceeded nineteen times for nitrate (NO3-; guideline value: 2.94 mg/L N) and four times for un-ionized ammonia (NH3; guideline value 0.019 mg/L N). Gas chromatography mass spectrometry single ion monitoring (GC-MS SIM) analysis of 18 sterols showed that five fecal sterols (coprostanol, episoprostanol, cholesterol, cholestanol, desmosterol) were detected at all sites except the control site (where only cholesterol, cholestanol and desmosterol were detected). Three phytosterols (campesterol, stigmasterol and β-sitosterol) were also detected at all sites while the hormone estrone was present at one site on two occasions at concentrations of 0.01 and 0.04 μg/L. Chemometric analysis (principal component analysis and cluster analysis) grouped sites based on their similarities in sterol composition. Analysis of ten sterol ratios (seven for identifying human fecal contamination and four for differentiating sources of fecal contamination) showed multiple instances of human and animal contamination for every site but the control site. Application of a Bacteroides-BST method confirmed contamination from ruminant animals, pigs and dogs in varying combinations at all impact sites. Together, these results confirmed the impact of agricultural activities on the Nathan Creek watershed and support a need for better land management practices to protect water quality and aquatic life.

Sewage Treatment Plants Efficiencies in Removal of Sterols and Sterol Ratios as Indicators of Fecal Contamination Sources

This study assessed the efficiency of sewage treatment plants (STPs) in removing sterols based on chemical analyses of both influents and effluents. Samples from 3s and three tertiary plants were collected and analyzed by gas chromatography mass spectrometry for 23 individual sterols including mestranol, norethindrone, equol, estrone, equilin, norgestrel, 17α-ethinylestradiol, 17α-estradiol, 17β-estradiol, estriol, dihydrocholesterol (cholestanol), coprostanol, epicoprostanol, cholesterol, desmosterol, campesterol, stigmasterol, β-sitosterol, coprostanone, cholestanone, epicholestanol, stigmastanol, and 24-ethylcoprostanol. The percentage of sterols remaining in effluent samples (compared to influent samples) ranged from 0% to 80% and varied among sterol compounds and with STP location and treatment type. Differences in the efficiency of sterol removal for secondary and tertiary STPs were statistically significant. Although the concentration of sterol compounds differed between influents and effluents, sterol abundances remained the same. The most abundant sterol detected was cholesterol, followed by the fecal sterol coprostanol, and the plant sterols 24-ethylcoprostanol and β-sitosterol. For three STPs, the hormone estrone was detected in effluents at concentrations of 0.03–0.05xa0μgxa0L−1. Ten sterol ratios specific for human fecal contamination and eight sterol ratios for differentiating among multiple sources of fecal contamination were calculated and showed that 12 ratios for influent and nine ratios for effluent were successful for human fecal source tracking. Based on sterol ratio values in this study, new criteria for identification of human fecal contamination were suggested.

Development of environmental thresholds for streams in agricultural watersheds.

Global increases in consumption of chemical nutrients, application of pesticides, and water withdrawal to enhance agricultural yield have resulted in degraded water quality and reduced water availability. Efforts to safeguard or improve environmental conditions of agroecosystems have usually focused on managing on-farm activities to reduce materials loss and conserve habitat. Another management measure for improving environmental quality is adoption of environmental performance standards (also called outcome-based standards). This special collection of six papers presents the results of four years of research to devise scientifically credible approaches for setting environmental performance standards to protect water quantity and quality in Canadian agriculturally dominated watersheds. The research, conducted as part of Canadas National Agri-Environmental Standards Initiative, aimed to identify Ideal Performance Standards (the desired environmental state needed to maintain ecosystem health) and Achievable Performance Standards (the environmental conditions achievable using currently available and recommended best available processes and technologies). Overviews of the papers, gaps in knowledge, and future research directions are presented. As humans, livestock, and wildlife (both terrestrial and aquatic) experience greater pressures to share the same limited water resources, innovative research is needed that incorporates a landscape perspective, economics, farm practices, and ecology to advance the development and application of tools for protecting water resources in agricultural watersheds.

Determination of veterinary pharmaceuticals in poultry litter and soil by methanol extraction and liquid chromatography-tandem mass spectrometry

Pharmaceuticals are emerging contaminants with potential risks to the environment and human health. A liquid chromatography-tandem mass spectrometry (LC-MS-MS) method was developed for determination of the antimicrobials virginiamycin, monensin, salinomycin, narasin and nicarbazin in poultry litter and soil. This method involves methanol extraction and clean-up of extracts through glass microfibre filters, introduction of the extracts and separation of compounds on a Zorbax Eclipse XDB C8 column, and compound detection in a Quattro Micro Micromass spectrometer. For litter samples, Method Detection Limits ranged from 0.1–0.6 μg Kg− 1, while Limits of Quantitation (LOQs) were 2, 1, 0.4, 1 and 2 μg Kg− 1 for virginiamycin, monensin, salinomycin, narasin and nicarbazin, respectively. For soil samples calculated LOQs were 2, 3, 1, 1, and 1 μg Kg− 1 for virginiamycin, monensin, salinomycin, narasin and nicarbazin, respectively. Application of the LC-MS-MS method for detection of veterinary pharmaceuticals in litter collected from commercial poultry farms showed that compounds were present at concentrations ranging from 10–11,000 μg Kg− 1.

Eutrophication of agricultural streams: defining nutrient concentrations to protect ecological condition.

Inputs of nutrients (phosphorus, P, and nitrogen, N) to coastal and fresh waters can accelerate eutrophication, resulting in excessive aquatic plant growth, depletion of oxygen, and deleterious changes in abundance and diversity of organisms. Using long-term (approximately 1995-2005) monitoring data from agriculturally-dominated watersheds in southern Ontario and Quebec, Canada, we developed and tested several approaches for setting targets for N and P. Our research showed that it is possible to set scientifically-credible targets for total P and total N to protect ecological condition of streams in agricultural landscapes, and define achievable targets attainable following adoption of beneficial management practices.

Seasonal Variation in Nutrient Export Along Streams in the Northern Great Plains

Spatial and temporal trends in nutrient concentrations and loads were analyzed for three rivers in the Red River watershed, Manitoba, Canada to determine changes in nutrient export across hydrologic seasons and along river continua in the Great Plains. Annual patterns in all three rivers were strongly influenced by the snowmelt period: 25–89xa0% of the total annual river volume, 42–92xa0% of the total annual TP load, and 41–81xa0% of the total annual TN load were delivered during snowmelt. Concentrations of TP and TN varied among the hydrologic seasons (snowmelt, summer, fall, and winter), but showed more variability and larger values during winter and snowmelt, with peak values reaching 1.960xa0mg TP L−1 and 16.07xa0mg TN L−1. Although the flat topography and semi-arid climate of the Red River watershed results in hydrological disconnects along river continua, discharge and nutrient export increased along the three river gradients. In contrast, TP or TN concentrations showed no significant longitudinal change for the two agriculturally dominated watersheds yet increased along the forested stream. Our finding that TP and TN exports from northern Great Plains rivers are strongly influenced by seasonal hydrology, with snowmelt being a critical period for nutrient export has implications for design and implementation of appropriate management practices to minimize nutrient export to proximal and downstream aquatic ecosystems.

Quantifying seasonal variation in total phosphorus and nitrogen from prairie streams in the Red River Basin, Manitoba Canada

Abstract A three-year study (2010, 2013 and 2014) was conducted to identify temporal and spatial patterns in phosphorus (P) and nitrogen (N) concentrations and loads in 11 sub-watersheds of the Red River Valley, Manitoba, Canada in relation to human activity on the landscape. Discharge exhibited a strong seasonal pattern in all sub-watersheds with high discharge during snowmelt, generally lower discharge with rainfall-induced peaks during spring, summer and fall, and low or no discharge during winter. Consistent with the hydrologic pattern, nutrient concentrations were highest during snowmelt such that 62% of the annual TP load and 67% of the annual TN load were delivered during the 12–18xa0day snowmelt period. Partial least squares regression analysis indicated that land use activities such as fertilizer application, livestock density and sewage were critical factors influencing TP and TN concentrations. In contrast, physical aspects such as water temperature and discharge were the primary determinants of TP and TN loads. The finding that stream water nutrients concentrations are associated with human activity on the landscape whereas nutrient loads are largely influenced by hydrologic events suggests that different types of beneficial management practices are needed for protection of instream ecological processes negatively affected by high nutrient levels versus reduction of nutrient export to downstream receiving bodies such as Lake Winnipeg.

Application of nitrogen and phosphorus criteria for streams in agricultural landscapes

Efforts to control eutrophication of water resources in agriculturally dominated ecosystems have focused on managing on-farm activities to reduce nutrient loss; however, another management measure for improving water quality is adoption of environmental performance criteria (or outcome-based standards). Here, we review approaches for setting environmental quality criteria for nutrients, summarize approaches developed in Canada for setting ideal and achievable nutrient criteria for streams in agricultural watersheds, and consider how such criteria could be applied. As part of a National Agri-Environmental Standards Initiative, the Government of Canada committed to the development of non-regulatory environmental performance standards that establish total P (TP) and total N (TN) concentrations to protect ecological condition of agricultural streams. Application of four approaches for defining ideal standards using only chemistry data resulted in values for TP and TN spanning a relatively narrow range of concentrations within a given ecoregion. Cross-calibration of these chemically derived standards with information on biological condition resulted in recommendations for TP and TN that would likely protect aquatic life from adverse effects of eutrophication. Non-point source water quality modelling was then conducted in a specific watershed to estimate achievable standards, i.e. chemical conditions that could be attained using currently available and recommended management practices. Our research showed that, taken together, short-term achievable standards and ultimate ideal standards could be used to set policy targets that should, if realized, lower N and P concentrations in Canadian agricultural streams and improve biotic condition.

Development of reference conditions for suspended solids in streams

Our aim was to develop protective physical and biological thresholds that identify the upper limit of the least disturbed (reference) condition for total suspended solids (TSS). The study focuses on streams in agricultural regions across Canada from which we collected contemporary TSS and benthic invertebrate data, and compiled long-term TSS data sets. Reference conditions for TSS were analyzed by five approaches previously applied in Canada, Australia and New Zealand, and the USA. In addition, ecological reference conditions for TSS were developed using regression-tree analysis to determine change-points along TSS gradients for three invertebrate metrics (percentage Ephemeroptera-Plecoptera-Trichoptera, total richness, and modified family biotic index). Increased agricultural land-cover was linked to higher TSS in most agricultural regions which, in turn, was associated with degraded environmental conditions and a reduction in the relative abundance of pollution-intolerant taxa. The five physical approaches produced a narrow range of regional TSS reference condition values (2.7 to 6.2 mg L–1). Ecological reference conditions for TSS ranged from 3.5 to 11.1 mg L–1 across Canada. We conclude that long-term TSS databases may serve to generate interim sediment criteria because ecological reference conditions were similar to those calculated from physical data alone. These interim sediment criteria may be appropriate targets for use in evaluation of restoration programs designed to improve environmental quality of aquatic ecosystems (e.g., beneficial or best management practice applications).