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A recent study measured transfer factors for 49 elements in hunter-killed Whitetail deer (Odocoileus virginianus), using concentrations in the stomach content as the substrate/denominator to compute muscle/vegetation concentration ratios (CRm-stomach) and daily fractional transfer factors (Ff). Using the stomach content ensured an accurate representation of what the deer ate, except that it was limited in time to the vegetation selected by the animal just before it was killed. Here, two alternatives are considered, one where the feed is represented by samples of 21 different vegetation types that deer may have eaten in the area (CRm-plant), and the other is using soil concentration in the region as the denominator (CRm-soil). The latter is the formulation used in the ERICA tool, and other sources, for risk assessment to non-human biota. Across elements, (log) concentrations in all the media were highly correlated. The stomach contents had consistently higher ash and rare earth element concentrations than the sampled (and washed) vegetation and this was attributed to soil or dust ingestion. This lends credence to the use of soil-based CRm-soil values, despite (or more accurately because of) the inclusive yet gross simplicity of the approach. However, it was clear that variation of CRm-soil values was larger than for CRm-stomach or CRm-plant, even if soil load on vegetation was included in the latter values. It was also noted that the variation in CRm-soil computed from the product of CRm-plant and CRplant-soil (where CRplant-soil is the plant/soil concentration ratio) was somewhat larger than the variation inherent in CRm-soil data. Thus it is reasonable to estimate CRm-soil from CRm-plant and CRplant-soil if observed CRm-soil values are not available, but this introduces further uncertainty. © 2012 Elsevier Ltd. Source


Sheppard S.C.,ECOMatters Inc | Bittman S.,Agriculture and Agri Food Canada
Animal Feed Science and Technology | Year: 2011

National inventories of N emissions to the atmosphere from cattle depend on reliable information about husbandry practices, with appropriate spatial and temporal resolution. A survey of ∼1400 beef cattle farmers was used to quantify the prevalence of pasture and forage management practices that impact N intake and NH3 emissions, with implications for N2O emissions. These survey data were coupled to a mass balance model to inventory NH3 emissions by accounting for total ammoniacal (i.e., ammonia and ammonium) N (TAN) from excretion through to land spreading. As inputs, the model required excretion fractions, 2006 Canadian Census of Agriculture animal populations and detailed farm management practices from the survey. The N intake by grazing cattle was especially difficult to quantify. Early season grazing, when forages have elevated crude protein (>300gCP/kgdry matter), indicated potential for elevated emissions in May and June. Such exceptional CP concentrations during spring grazing may be important for N emissions, especially NH3. Additionally, beef cattle were reported by producers to spend 7-30%) of their time congregated, such as around water sources, feed or shade trees. This level of piosphere activity was attributed in the model to ∼20% increases in NH3 emissions relative to open pasture, and similar or higher effects would be expected for N2O emissions.This paper is part of the special issue entitled: Greenhouse Gases in Animal Agriculture-Finding a Balance between Food and Emissions, Guest Edited by T.A. McAllister, Section Guest Editors: K.A. Beauchemin, X. Hao, S. McGinn and Editor for Animal Feed Science and Technology, P.H. Robinson. © 2011 Elsevier B.V. Source


Sheppard S.C.,ECOMatters Inc | Bittman S.,Agriculture and Agri Food Canada
Agriculture, Ecosystems and Environment | Year: 2013

Manure nitrogen (N) includes what can be generalized as organic N, which includes undigested N from the feeds; ammoniacal and easily hydrolysable N, which includes urea and uric acid; and nitrate/nitrite species, which are the least abundant. From excretion to landspreading, the largest change in N concentration occurs because of volatilization of ammonia (NH3) from the ammoniacal and easily hydrolysable fraction. This process can be highly dependent on manure management, and some management strategies such as manure injection are largely designed to decrease NH3 loss. This paper utilizes recent models of NH3 emission from beef, dairy, swine and poultry production to estimate the net organic and ammoniacal N content of manure in Canadian Ecoregions before and after land spreading. Confinement versus grazing for beef is a major factor for overall net manure N application, and slurry versus solid manure is next most important. There are distinct differences among Ecoregions in the proportions of organic and ammoniacal N, so that generic assumptions are not appropriate. The estimates are mapped for all of Canada based on 2006 animal census. Several best management practices (BMPs) are evaluated using recent costing information (dollars per kg of NH3-N saved from emission). Relatively low-cost BMPs related to slurry manure applied nation-wide could save 16GgNH3-Nyear-1 for an estimated cost of $13M. Other low-cost BMPs could increase this to a saving of 79GgNH3-Nyear-1 or 26% of present emissions. © 2013 Elsevier B.V. Source


Sheppard S.C.,ECOMatters Inc | Herod M.,University of Ottawa
Journal of Environmental Radioactivity | Year: 2012

Assessment of the potential environmental impacts of nuclear fuel waste involves multiple lines of argument, one of which is an evaluation of the possible increments to background concentrations of certain radionuclides. This is especially relevant for radionuclides such as 3H, 36Cl and 129I where there is continuous cosmogenic or geogenic production. However, for 36Cl and 129I and certain U/Th-series radionuclides, data are scarce because the analysis methods are complex and costly. The present study used accelerator mass spectroscopy (AMS) to measure 36Cl and 129I in river waters throughout Canada. Radiochemical methods were used for 3H and the selected U/Th-series radionuclides, and stable element concentrations were also determined. There were distinct differences in concentrations among the sites. Stable Cl and I tended to be at higher concentrations near the ocean or population centres. The 3H was high in regions with power reactors. The 226Ra, 235U and 238U concentrations were high in areas with known U mineralizations, as expected. The 36Cl and 129I concentrations were generally homogenous in mid-latitudes, but the 129I concentration was lower in the one arctic site sampled. Because the stable and radioactive isotopes of Cl and I varied in response to different factors, the resulting specific activities were especially variable. Both Cl and I are homeostatically controlled in animals, thus it follows that dose from 36Cl and 129I will depend more closely on specific activity than concentration, and therefore the environmental increments of interest are in the specific activities rather than simply concentrations. © 2011 Elsevier Ltd. Source


Sheppard S.C.,ECOMatters Inc
Human and Ecological Risk Assessment | Year: 2011

Soil solid/liquid partition coefficients (Kd) are commonly used in quantitative environmental assessments as a means to predict retention of contaminant metals and radionuclides in soils. There are Kd data for most elements in the literature, and they can be measured for specific sites. However, there is also a need for robust, defensible relationships to predict the variation in Kd as a function of soil characteristics. This article reports relationships for As, Cd, Ce, Cl, Co, Cr, Cs, Cu, Fe, Ho, I, La, Mn, Mo, Nb, Nd, Ni, Np, Pa, Pb, Pu, Ra, Sb, Se, Sm, Sn, Sr, Tc, Th, Tl, Tm, U, W, and Yb, most based on a wide range of soil properties. Soil pH, clay content, and organic carbon content were the independent variables considered in all cases, and methodology variables were invoked for Cs, Mn, and Ni. The underlying Kd data were considered representative of steady state conditions: most were measured by desorption of the indigenous element at realistic field moisture contents. The equations, developed by forward or backward stepwise regression, were all statistically highly significant. Estimates from the equations were compared to data for seven site-specific soils and generally were within 95th percentile bounds. © Taylor & Francis Group, LLC. Source

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