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ESTIMATING DIFFUSE PHOSPHORUS LOADS TO LAKES: IMPLICATIONS FOR THE CALCULATION OF TOTAL MAXIMUM DAILY LOADS LH Defew Centre for Ecology and Hydrology, Bush Estate, Penicuik, Midlothian, EH26 0QB, UK, E-mail: ldef@ceh.ac.uk SUMMARY Nutrients and the concentrations in which they are present within a water body are important factors regulating the growth of phytoplankton and other plants. Problematic overgrowth of these is generally recognised as the biological manifestation of eutrophication and poor water quality, often resulting in hypoxia, loss of biodiversity, fish kills, and release of algal toxins in the water body. As many freshwater environments are considered to be phosphorus limited, controlling and regulating the input of this particular nutrient is often one of the targets set under the total maximum daily load (TMDL) management approach. A TMDL is the sum of the allowable loads of a single pollutant from all contributing point and non-point (diffuse) sources, including natural background levels. The major steps in the American TMDL initiative are: (1) to develop load calculations for nonpoint sources of pollution; (2) to calculate natural loads; (3) to calculate maximum total loads from all sources; and (4) to determine how to reduce the maximum load in order to meet water-quality standards. A key requirement of this approach is the determination of accurate and reliable pollutant loads to the receiving water from non-point sources. Many of the methods that are currently being developed in the UK to assess nutrient inputs to lakes from non-point sources are based on data collected at weekly, monthly or even quarterly intervals. Previous studies have shown that such infrequent data collection results in pollutant load estimates that are of low accuracy and precision (Webb et al., 1997; Soerens and Nelson, 2001). There is now mounting evidence (e.g. May et al., 2005) that calculations based on such data may underestimate the pollutant load to water bodies from diffuse sources by up to 80%. This is because they fail to take account of the influence of storm events on the mobilisation and transport of pollutants. The method used to estimate the nutrient loading to a lake will have important implications to the final TMDL that is calculated. To be reliable, TMDLs must take into account the impact of high intensity, low frequency rainfall events on nutrient loadings to water bodies. 205
REFERENCES May L, Place C, O’Hea B, Lee M, Dillane M and McGinnity P (2005). Modelling soil erosion and transport in the Burrishoole catchment, Newport, Co. Mayo, Ireland. Freshwater Forum 23, 139-154. Soerens TS and Neilson MA (2001). Designing Stream Sampling Schemes for Load Determination. In: Warwick, J. J. (Ed) AWRA Annual Spring Speciality Conference Proceedings. Water Quality Monitoring and Modelling. American Water Resources Association, Middleburg, Virginia, TPS-01, pp 71-76. Webb BW, Phillips JM, Walling DE, Littlewood IG, Watts CD and Leeks GJL (1997). Load estimation methodologies for British rivers and their relevance to the LOIS RACS programme. The Science of the Total Environment, 194-195, 379-389. 206
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International Water Association AGR
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2006 Conference Organising Committe
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Theme 2: Cost-effectiveness of Best
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Poster Presentations The Farm Soils
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viii
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managers need support in understand
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During the past 20 years, it became
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infiltration); and (4) capture, sto
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DOMINATING PARAMETERS OF IMPAIRMENT
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Using the results of the unsupervis
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Kohonen T (2001). Self-Organizing M
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WATER FRAMEWORK DIRECTIVE IMPLEMENT
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Table 1: Modelled total annual loss
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• It should be possible to apply
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Scottish Executive against 18 measu
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REFERENCES Anthony S, Betson M, Lor
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ased on the ‘drainage basin’ in
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management practices’ (BMPs) toge
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It is envisaged that these data wil
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testing (including climate change)
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Council of the European Communities
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DECREASING THE NITROGEN SOIL SURFAC
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Table 1: Overview of the measures c
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Table 2: Costs (C), effects (E) and
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Figure 2: Combination of ‘best av
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MATERIALS AND METHODS At the 5-km 2
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REFERENCES Jordan P, Menary W, Daly
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Although the TMDL programme origina
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grassland and heather moorland, sup
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Given that the release of P from th
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to the underlying causes, and thus
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All water body use attainment infor
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indicate the possible presence of p
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DEVELOPMENT AND IMPLEMENTATION OF M
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BMP is being implemented and the ap
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THE USE OF PONDS TO REDUCE POLLUTIO
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established pond/wetland for nutrie
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Table 1: Hydraulic load, mean water
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Comparable SS removals have been re
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Reddy GB, Hunt PG, Phillips R, Ston
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In general, the combinations of mea
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final word on the POMs selection an
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CONCLUSIONS The ERBD project team i
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Table 1: A summary of the measures
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Table 3: A summary of the represent
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cost (£'000/farm) or reduction in
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ECONOMIC IMPLICATIONS OF MINIMISING
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spread cattle slurry in the autumn
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£25,000. The investment in trailin
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Studies on a drained clay soil at B
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REFERENCES Anon (2000). Fertiliser
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(Haygarth and Jarvis, 1999). The vo
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Application Representative farm sys
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Table 2: Modelled cost-curve for th
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ASSESSING THE SIGNIFICANCE OF DIFFU
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In the absence of data on the sourc
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Magnitude of Impacts The magnitude
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D. Use relative area of farm and wh
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ADAS has developed a matrix for Def
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Dickson JW, Edwards T, Jeffrey WA,
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60% phosphorus and 50% nitrogen of
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RESULTS AND DISCUSSION Landscape St
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was contributed to the low vegetati
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iological uptake in a grassed area.
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Tim US, Jolly R and Liao HH (1995).
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to control SS and P loads from agri
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Total P inputs in fertilisers and m
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Within the Teme catchment, largest
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A RISK ASSESSMENT AND MITIGATION ST
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Environmental Monitoring The primar
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BMP measure 1 (exclusion of stock f
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(a) With reference to the increase
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ACKNOWLEDGEMENTS SAC acknowledges f
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The Environment Sensitive Farming (
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improved further as a result of att
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to do more to reduce pesticide impa
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MANAGING DIFFUSE POLLUTION FROM A F
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turbulent air mixing. The effect th
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Although nitrate leaching can be re
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infiltration of water sheeting off
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Nisbet TR, Orr H and Broadmeadow S
Page 163 and 164: anthropogenic activities are pollut
Page 165 and 166: monitoring is determined up front b
Page 167 and 168: (USEPA). Nevertheless, by applying
Page 169 and 170: • Sampling equipment •Laborator
Page 171 and 172: Reinert RE, Knuth BA, Kamrin MA and
Page 173 and 174: Tier 3 - Tier 3 of LMCs is planned
Page 175 and 176: policy literature, although this is
Page 177 and 178: Figure 1: Individual-collective spe
Page 179 and 180: • tailoring activities to local c
Page 181 and 182: ACKNOWLEDGEMENTS The support of the
Page 183 and 184: THE EFFECT OF DIFFUSE POLLUTION FRO
Page 185 and 186: equires the Minister to designate a
Page 187 and 188: protection and restoration, sustain
Page 189 and 190: expensive. One-to-one contact becom
Page 191 and 192: farmers. In England, recent policy
Page 193 and 194: practices but, hopefully, the chang
Page 195 and 196: A CASE STUDY: ADOPTION OF BEST MANA
Page 197 and 198: The approaches taken by Brittany to
Page 199 and 200: MANURE TREATMENT By January 2005, t
Page 201 and 202: REGULATORY OPTIONS FOR THE MANAGEME
Page 203 and 204: There are also measures that contro
Page 205 and 206: widely recognised as needing much a
Page 207 and 208: ploughed, of rivers and streams tha
Page 209 and 210: is the only mechanism identified fo
Page 211 and 212: PHOSPHORUS STORAGE IN FINE CHANNEL
Page 213: structure and minimum level of main
Page 217 and 218: LOUND CATCHMENT PROJECT: WORKING WI
Page 219 and 220: MINIMISING THE PRESSURES AND IMPACT
Page 221 and 222: Predicting Bathing Water Quality Vi
Page 223 and 224: Risk of illness percentages were ca
Page 225 and 226: Table 4: Expected lifetime benefits
Page 227 and 228: DETERMINATION OF THE VETERINARY ANT
Page 229 and 230: Thin Layer Chromatography The sampl
Page 231 and 232: Table 2: Regression functions and c
Page 233 and 234: OPPORTUNITIES AND CONSTRAINTS FOR U
Page 235 and 236: to land managers and agency staff t
Page 237 and 238: stakeholders, together with their i
Page 239 and 240: REFERENCES EC (2000). Directive 200
Page 241 and 242: A third scenario was applied to Clu
Page 243 and 244: Based on a detailed distribution of
Page 245 and 246: could be misleading. The results of
Page 247 and 248: TACKLING DIFFUSE NITRATE POLLUTION:
Page 249 and 250: AMMONIA VOLATILISATION FROM CATTLE
Page 251 and 252: and 27% of the soil surface at 80 m
Page 253 and 254: FIELD TESTING OF MITIGATION OPTIONS
Page 255 and 256: techniques can significantly reduce
Page 257 and 258: NITRATE CONTAMINATION OF GROUNDWATE
Page 259 and 260: MATERIALS AND METHODS At two UK sit
Page 261 and 262: ACKNOWLEDGEMENTS Funding of this wo
Page 263 and 264: y standard methods and fresh, end o
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comparable to those in water draini
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Results may be influential in deter
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• numbers and distribution of liv
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Using this method of classification
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Table 5: Results of land use scenar
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CONCLUSIONS As a decision support t
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types. This paper reports results f
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N Losses in Drainage Water Mean nit
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SOIL AND CROP MANAGEMENT EFFECTS ON
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treatments, typically 10 storm even
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Tramline Effects In both years, obs
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Notes 278
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