Ali Madani

Integrated surface water quality assessment of a rural watershed in Nova Scotia, Canada

Integrated water quality assessments that pertain not only to crop production nsystems but also public health at the watershed level are growing in popularity. The Thomas nbrook is a small (760 ha) tributary of the Cornwallis river located in the Annapolis Valley of nNova Scotia, Canada. The Annapolis valley is the most intensively managed agroecosystem in nthe province, characterized by both agricultural and residential land uses. The objective of this research was to: (i) quantify concentration and loading levels of nutrients (nitrogen and nphosphorus) and total coliform bacteria in the surface waters and (ii) attempt to identify the nprimary sources of pollution within the Thomas brook. Five sampling stations were strategically nstationed in the watershed based on the different land uses within the watershed. Water quality nand stream flow were monitored at these monitoring stations during a three year period (May to nNovember from 2001 to 2003). Water quality indicators monitored included total phosphorus n(TP; 0.09 mg L-1), soluble reactive phosphorus (SRP; 0.09 mg L-1), nitrate-nitrogen (NO3 n--N; n2.28 mg L-1), ammonium-nitrogen (NH4+ -N; 0.24 mg L-1) and E. coli (403 cfu 100ml-1). nResults show that P concentrations were greatest in a section close to an adjacent dairy farm. nThe largest mass loadings of nitrogen to the stream were observed in the lower reaches of the nwatershed, which is surrounded by agricultural cropping systems. Whereas fecal coliform nloading along stream reaches were affected by both livestock operations and residential ndwellings. These findings support the suggestion that integrated water quality assessment is a nkey to develop management strategies that minimize health and environmental risks through the ncontamination of water.

Modeling the impacts of tillage practices on water table depth, drain outflow and nitrogen losses using DRAINMOD

Hydrology and nitrate loads of a field under two tillage practices were evaluated.Effects of tillage practices on flow and nitrate loss was assessed using DRAINMOD.During the study period, flow was significantly higher under NT than CT.Nitrate loss in tile flow was not significantly different during the study period.In future, both flow and nitrate are expected to increase significantly under NT. Water pollution by nitrate removed from agricultural systems through subsurface tile drains is a major environmental concern in Ontario. The control and reduction of the loading of chemicals to water bodies requires knowledge on the contribution of agricultural systems to water pollution under different cropping management practices. In this study, DRAINMOD model was implemented to predict the effects of conventional tillage (CT) and no tillage (NT) treatments on water table depth, tile effluent and NO3-N losses through subsurface drainage from a 14ha agricultural field at the Green Belt Farm of Agriculture and Agri-Food Canada in Ottawa, Ontario. During the study period, flow was significantly higher under NT than CT mainly during the snowmelt and spring periods. Total nitrate loss under NT was higher than CT but the difference was not significant during the 4years of study period. The climate change scenario of PRECIS was then applied to assess the effect of tillage practices under future climate change. In the future, the changes in climate will result in a significant increase in flow and nitrate under both NT and CT practices. It was also noted that, in future, NO3-N losses under no till treatment are expected to be significantly higher than those under conventional tillage practices in future.

Modeling the effects of controlled drainage at a watershed scale using SWATDRAIN

The recently developed SWATDRAIN model was employed to assess the impact of controlled drainage on the water table dynamics, subsurface drainage, and surface runoff in an agricultural watershed in Ontario, Canada. Controlled drainage was defined with a depth of 1.0xa0m to restrict flow at the drain outlet to maintain the water table at 0.5xa0m below the surface level during the winter (November–April) and at 0.6xa0m during the summer (June–August) months. The effects of the absence, or implementation, of drainage water management were predicted for the 3-year period of 1991–1993. Implementing controlled drainage resulted in a 16xa0% reduction in the mean annual drain flow, while increasing surface runoff by as much as 71xa0%. This indicates that overall watershed hydrology could be significantly impacted by the implementation of controlled drainage. This research demonstrates the SWATDRAIN model’s ability to predict the controlled drainage in small agricultural watersheds.

Environmental Impacts of Mink Manure and Poultry Litter Stockpiling on Air Quality and Water Quality

The environmental impact of three manure stockpiling systems - uncovered poultry litter, covered poultry litter and uncovered mink manure - on surface and subsurface water quality and air quality was evaluated during a 592 day in situ field storage experiment. Surface runoff and subsurface leachate was analyzed to determine TKN, NH3-N, NO3-N, and TP concentrations and mass loadings. Surface runoff was the main transportation mechanism of P loss from the stockpiles with the majority lost during the two fall seasons. N losses from the poultry litter stockpiles were greatest during the initial 250 days of storage with most of the N lost to subsurface leaching. In mink stockpiles, however, the majority of N was lost in surface runoff. E. coli counts in runoff and leachate samples were highest during the first several rainfall events, with low levels detectable after 200 days. Peak NH3, N2O and CH4 fluxes were observed during the initial stages of stockpiling with the majority of total emissions released during the first 17, 125 and 45 days, respectively.

Odour Emissions Following Application of Hog Slurry to Grassland

Nuisance odours emanating from livestock operations are a major concern to the non-farming public. Several field experiments were conducted to evaluate the effect of management strategies and meteorological conditions on odour emissions from hog slurry applied to grass. Management strategies included slurry application rate, soil water status, slurry dilution with water and rainfall simulation shortly after field application. It was found that doubling (120,000 L ha-1) the application rate had no impact on odour emissions. Tripling (180,000 L ha-1) the application rate, however, increased emissions, relative to a conventional (60,000 L ha-1) application rate. Applying slurry to soil that received rainfall prior to application increased emissions in one of the experiments, compared to soil that did not receive water. On average, diluting slurry with water decreased emissions by only 11%. Meanwhile, rainfall immediately after application increased odour emissions by 17%. Odour fluxes increased with higher windspeed, net radiation and evapotranspiration. Odour emissions can therefore, be reduced by following proper application rates, but most importantly, by applying slurry during calm, cool days. However, such stable weather conditions may increase odour persistence due to lack of vertical mixing, reduced transfer rates and slow drying of the slurry.

An Initial Assessment of a Wetland-Reservoir Drainage Water Treatment and Reuse System in Nova Scotia

Nutrient and pathogen export from agricultural drainage water is a major source of surface water quality degradation. Wetland-reservoir drainage water treatment and reuse systems have the potential to mitigate this pollution, as well as conserve water, improve crop yields, and increase bio-diversity. This study will assess the viability of this type of system in a colder climate. Specific objectives are to assess (i) system hydraulics and water balances; (ii) wetland treatment efficiencies; and (iii) reservoir water quality.

An Integrated Modeling Approach for Evaluation of On-Site Wastewater System Phosphorus Loading in Rural Nova Scotia Watersheds

Phosphorus (P) loading from poorly designed or hydraulically failed residential on-site wastewater treatment systems (OWS) into neighbouring surface water systems is typically an unquantified process in many rural and suburban watersheds. The transport of P from OWS to surface waters is typically related to the subsoil conditions surrounding the OWS disposal field (DF), which impact lateral movement of the wastewater plume and P sorption capacity, and the level of OWS management by the homeowner (Gold and Sims, 2000). In Nova Scotia (NS), Canada there is a wide abundance of low permeability soils, shallow bedrock and high water tables that can cause failure and improper functioning of OWS DFs (Havard et al., 2008). McCray et al. (2005) identified a need for quantitative approaches, such as watershed computer models, to assess OWS pollutant loads because of the increased importance of total maximum daily load (TMDL) planning and watershed management. Current updates to the Soil and Water Assessment Tool (SWAT) watershed scale model (version 2009) include algorithms for simulating OWS using a biozone based treatment process (Jeong et al., 2011). However, there are no specific algorithms within SWAT (version 2009) to simulate P transport via lateral subsurface flow to surface water systems, demonstrating a need for an integrated approach to simulate P fate and transport from OWS at the watershed scale.

Impact of Climate Change on Drainage Outflow and Water Quality in Eastern Canada

The potential effects of climate change on the drainage outflow and nitrogen pollution of a 4.2 ha tile-drained experimental field research facility located at St. Emmanuel, Quebec are predicted using the latest version of the DRAINMOD 6.0 model. Under the assumption of no change in land cover and land management, the model is applied in order to simulate annual, seasonal and monthly changes in flow and NO3-N loads under current and future climate conditions. The climate scenario under consideration in this study (1961 to 2100) is based on projections from the Canadian Regional Climate Model (CRCM). The simulation results from the CRCM model suggest an increase in temperature and precipitation in the region being studied. Those changes result in a considerable increase in simulated mean annual subsurface flow in the study area.

Growing Season Surface Water Loading of Fecal Bacteria within a Rural Watershed

Water quality within the Thomas Brook watershed, a 750 ha mixed land-use catchment located in the headwaters of the Cornwallis River drainage basin, was assessed using an integrated monitoring program. The research objective was to examine spatial and temporal characteristics of fecal bacteria loading from a watershed during the growing season. Fecal coliform, Escherichia coli, total suspended solids (TSS) concentrations and stream flow were monitored at five points in the watershed during a six growing season period (May to Oct, 2001-2006). A nested watershed monitoring approach was used to determine bacterial loading from distinct source types (residential vs. agricultural). Daily loading was further differentiated into stormflow and baseflow. Bacterial loading per hectare increased in each nested watershed moving downstream through the watershed and were highest in the three subcatchments dominated by agricultural activities. Upper watershed bacterial loading from an agricultural subcatchment (Annual Avg 8.92x1010 CFU/ha) was consistently higher than a residential subcatchment (Annual Avg 8.43x109 CFU/ha). Annual stormflow bacterial loads were higher than baseflow loads. The highest daily fecal bacteria load per annum ranged from 8.1 to 20.1% of the total annual growing season load and were all preceded by at least 38 mm of precipitation. Annual fecal bacteria loads were found to be greater during growing seasons with greater annual precipitation. A positive linear relationship was observed between E. coli and TSS loading during the 2005 and 2006 growing seasons when both parameters were monitored. The E. coli and TSS loading relationship was weakest during baseflow periods (R2=0.40), higher for stormflow periods (R2=0.50), and strongest (R2=0.60) when all flow conditions were included in the regression. Further year round watershed and intensive stormflow monitoring are required to expand the understanding of fecal bacteria loading in the Thomas Brook watershed.

A Simple, Cost Effective Technique for Collecting Subsurface Water Samples for Dissolved Nitrous Oxide Gas Analysis

It is often assumed that the nitrous oxide (N2O) produced from denitrification in soil systems is lost primarily as a gas from the soil surface. However, the degassing of N2O dissolved in soil solution from agricultural drainage water has been shown to be a significant loss pathway from agricultural systems. The quantification of this pathway of N2O loss is limited by available methodologies for measuring dissolved gases in drainage water samples. Here a simple method is presented as a means of sampling dissolved N2O found in agricultural drainage water. Tile water is collected in 1 L ISCO water sampling bottles, outfitted with modified 10 mL volumetric pipettes. To maintain the integrity of the sample, the potential for the sample to degas must be minimized. The pipettes allow this to be accomplished, as they significantly reduce the surface area of the water exposed to the atmosphere. The samples are collected using 20 gauge 30.5 cm penetration needles, drawing 5 mL of water from within the bulb of each of the pipettes. A 4 mL water sample is collected using a 20 mL syringe and injected into a 12 mL exetainer, which was evacuated and brought to atmospheric pressure. Prior to evacuation, 50 µL of 6.25% (v/v) mercuric chloride (HgCl2) solution was added to the exetainer, inactivating bacterial function and thus, halting further gas evolution. The dissolved N2O in the tile drainage water is measured by the headspace analysis. A trial performed determined that the water could be left in the bottles exposed to the atmosphere for up to three days previous to seeing any significant decrease in N2O concentrations.