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Nutrient Source Apportionment in Irish Water Bodies – (Ph.D.)
University of Dublin Trinity College
School of Natural Sciences| Application Deadline: | July 31 | ||
| Location: | Dublin / Ireland / View location on map ▾ Hide location on map ▴ | ||
| Duration: | 48 months | Start Date: | October |
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| Languages: | English | ||
Location of University of Dublin Trinity College
Nutrient transfers from land to water, caused by combinations of phosphorus and nitrogen loss from agricultural and urban sources, are considered to be one of the most pervasive water quality problems in developed countries. These sources have predominant periods of mass transfers and impacts in specific water body types according to influences of current hydrology and landuse and past activities and conditions.
In Ireland, all water body types can be impacted by nutrient transfers; preventing these impacts from occurring requires a detailed understanding of dose-response issues at both low and high river flows and in standing water bodies. Building on ongoing catchment scale research into the delivery of nutrients to inland water bodies, this project aims to investigate the seasonal impacts of specific nutrient sources on a selection of rivers and lakes in Ireland.
Utilising state-of-the-art high resolution monitoring facilities established through the Agricultural Catchments Programme (ACP), the objectives of the project are to:
* use existing datasets of river discharge and nutrient concentration from meso- to macro-scale river catchments to develop nutrient load apportionment models;
* use the nutrient load apportionment models to compare with patterns and residence times from a series of high resolution discharge and water quality river stations in Ireland; and
* determine the water quality impacts of external and internal nutrient loading patterns in standing waters.
Contents
The aim of the research project is to develop a conceptual model of nutrient transfers,
residence times and potential impacts for catchments in Ireland and will be delivered via three main objectives:
1. Use existing instantaneous, low resolution discharge and nutrient concentration data
from meso- to macro-scale catchments and fit load apportionment models (LAMs)
2. Use this principle to establish patterns and residence times from a series of high
resolution discharge and water quality stations in the Agricultural Catchments
Programme (ACP)
3. Determine the eutrophic impacts of external and internal nutrient loading patterns at
high resolution in standing waters.
The major aim of this proposal is to develop a conceptual model of nutrient transfers,
residence times and potential impacts to investigate, for example, the extent to which river Qvalues are influenced by low magnitude, high frequency, non-agricultural P sources in surface water dominated rivers and not by high magnitude, low frequency diffuse sources from soils.
Two caveats need to be highlighted, however. First, where groundwater is the dominant
proportion of river flow and where measured groundwater P concentrations are high, then the long residence times afforded by eutrophic groundwater flowing into rivers negates the premise that point sources provide the only significant between-storm source.
Second, where a standing water body, such as a lake or reservoir, represents the end point of a river, then the trophic status of that water body is influenced by the river P load and/or the internal load and not the ambient P concentration of the inflowing river.
The boundaries of this proposal are therefore limited to rivers and lakes with significant
surface and near-surface pathways and to where P is assumed or observed to be the major nutrient transfer requiring mitigation.
Cognisance of the caveats will, therefore, be built into the final conceptual model of load apportionment. Nevertheless, surface pathway dominated rivers with influences from diffuse and point source P transfers represent the major river typology in Ireland and lake impacts from surface water sources. This is due to large areas of soils with impeded drainage and or impermeable geology that influence surface runoff and diffuse pollution, and also due to dispersed housing in the Irish landscape with small rural towns that influence point source pollution.
The research proposed will test the hypothesis that ambient P (or time-weighted)
concentrations in rivers are not primarily linked to predominant landuse but to dispersed point sources. The logical alternative hypothesis will be to test whether the river P load (or flowweighted concentration) is of more concern to the eutrophication of standing water-bodies that rivers drain into and to determine the seasonal role of internal loading. For sustainableagriculture this will be an extremely important premise as it is often accepted by catchment managers that the largest nutrient source in catchments (for example Smith et al., 2005) has a ubiquitously high risk of impairing water bodies - of all kinds. As further constraining measures are considered for agriculture for the protection of specific water bodies and/or habitats beyond those already prescribed under the Nitrates Directive, finding a metric or
series of metrics that appropriately follow the nutrient transfer continuum concept for the management of particular water bodies at risk is important.
It is clear that the mitigation of all point and diffuse sources require attention under programmes of measures in the main EU directives aimed at water protection. However, with limited resources for inspecting the success of mitigation measures, establishing the nutrient sources and timing responsible for individual water body impacts assumes an even greater importance than might otherwise have been the case.
With these considerations, five Tasks (workpackages) will deliver the three objectives, above:
i. Literature review and data compilation. This task will select river catchments with
established Q-value, discharge and P chemistry datasets from EPA and OPW
sources. Other suitable datasets in Northern Ireland will also be collated from
Environment Agency Northern Ireland (EANI) where inter-calibration with ecological
metrics has been established. As data on river chemistry are generally only collected
on a monthly basis, and there is some variation in quality - and in the type of data
collected - between collecting stations and over time, the careful examination and
quality assurance of several years of records of river data will be an important and
time-consuming component of this stage of the proposed research.
ii. Development of LAMs. Data compiled and quality assured in Task 1, above, will be
used in Load Apportionment Models (LAMs; Bowes et al., 2008; Neal et al., 2008;
Jarvie et al., 2010) to establish the relative influence of flow-independent, continuous
P point sources, and also from flow-dependent, episodic diffuse P sources. In these
models, at baseflows, point source P is diluted as baseflow increases and, during
runoff events, diffuse sources increase the concentration of P as flow increases. A Qe
parameter determines the flow where the predominant influence of point sources end
and where diffuse source predominance starts. The percentage time in a year that
river flows are below Qe determines both the load of point sources and also the
crucial period of time that this source and load influence ambient river P
concentrations. This Task will form a single chapter in the PhD thesis and a paper
submitted to an internationally regarded journal.
iii. Detailed River Study. The River Glyde at Tallanstown drains a 270km2 catchment in a region of drumlins in Counties Cavan, Meath, Monaghan and Louth. The local
hydrometric station was established in 1975. The catchment epitomises an extreme
example of surface pathway-dominated river landscapes, characterised by poorlydrained soils and a range of grassland based agricultural landuses with different
intensities of utilisation. Levels of human population are also relatively high, as the
catchment contains two towns, Carrickmacross, Co. Monaghan and Kingscourt, Co.
Cavan. There is a range of Q-value sampling points and a further two established
hydrometric stations upstream.
This workpackage will augment the EPA data with a targeted year of weekly and sub-weekly water chemistry sampling to include different
P fractions (TP, TSP, SRP, MRP) and ancillary chemistry to include boron (B). Boron
is a highly reliable indicator of point source inputs from Waste Water Treatment
Works as it is a major ingredient of modern detergents (Jarvie et al., 2006). These
data will help to validate the assumptions described above and should show an
increase in concentration at ambient low flows in conjunction with increases of
soluble P - if point sources are present and predominant below the Qe threshold.
This Task will form a single chapter in the PhD thesis and a paper submitted to an
internationally regarded journal.
iv. LAMs and High-Resolution Data. The fourth workpackage will be used to evaluate
critically the assumptions in tasks 2 and 3 and the LAMs. Data will be used from
several high resolution monitoring stations maintained by the ACP that are generating
sub-hourly TP and MRP (with similar NO3-N, turbidity, conductivity and temperature)
data with synchronous discharge measurements. These data series represent the
most complete determination of nutrient transfer dynamics in rivers (Jordan et al.,
2007), and data will be used ultimately to evaluate the Good Agricultural Practise
regulations in 6 mini-scale catchments. The assumption of the Qe parameter is
critical to LAM and only with a high resolution dataset can these assumptions be
validated. For example, the process of small storm events impacting channel beds
but below the annual Qe flow parameter may describe P transfer patterns ordinarily
associated with flow-independence, i.e. rain-induced but below Qe. This Task will
form a single chapter in the PhD thesis and a paper submitted to an internationally
regarded journal.
v. External and Internal Lake Nutrient Loading. The fifth workpackage will use in-situ
lake water quality probes monitoring Chl-a, DO, turbidity, temperature and pH to
investigate the role of internal loading events compared with external loading events
(Task 4) and the resulting eutrophic impacts. The role of lake stratification and
sediment P release, wind-induced sediment resuspension and pH controls of ligand
exchanges on resolubilised P during ecologically sensitive times will be established.
Data from high resolution water quality stations and meteorological stations will
provide ancillary data. This Task will form a single chapter in the PhD thesis and a
paper submitted to an internationally regarded journal.
The five tasks will result in at least four manuscripts submitted to peer-reviewed
internationally-regarded journals (e.g. Water Research, Journal of Hydrology, Science of the Total Environment) and the student candidate will be expected to present to at least one Irish and one international conference audience of scientific peers.
The two PIs (professors Taylor and Jordan) have a range of hydrology and limnology
experience to manage and guide the proposed project, including early development of LAMs on Lough Sheelin catchment data, establishing long term datasets using high resolution monitoring, and leading the science team of the Agricultural Catchments Programme (ACP).
The student candidate appointed to this project will be able to make use of state-of-the art facilities both in terms of access to field facilities in up to six highly instrumented catchments operated by the Teagasc ACP and also in terms of supervisory support and access to high specification laboratory facilities in TCD. In summary, the research will make good and effective use of high quality infrastructure that has recently been established, both in Teasgasc and TCD.
The student will be trained in a range of catchment science techniques including the use of spatial datasets in Geographical Information Systems, collection and analysis of hydrometric and hydrochemical data, boat handling, statistical analysis, analytical chemistry and the use of modern, bankside analysis equipment.
Expected outcomes:
There will be a series of outcomes from this project:
i. A fully validated conceptual model of P transfers from point and diffuse sources in
surface pathway dominated catchments with reference to potential impacts in both
flowing and standing water bodies
ii. A method for defining the load apportionment and predominance of P transfers in
river catchments
iii. Catchment management tool determining where P mitigation should be targeted
according to point or diffuse predominance on target water bodies
iv. A thesis submitted as published papers or submitted manuscripts (at least four) in
internationally regarded peer-reviewed journals (target journals include Water
Research, Journal of Hydrology, Science of the Total Environment).
v. A fully trained agri-environmental scientist with transferable skills in nutrient
hydrochemistry and catchment hydrology - and expertise in an area of agrienvironmental science that is traditionally contentious (definition of point verses
diffuse nutrient transfers).
IELTS
You are normally required to take an English Proficiency Test.
Most European Universities recognise the IELTS test.
Take testRequirements
Applicants should have a good primary degree (II1 or I) and a M.Sc. in an appropriate discipline (Geography, Earth Sciences, Environmental Sciences, Environmental Engineering, etc.).
The successful candidate will be highly self-motivated and prepared for extended periods of hydrological and limnological field work working with modern field-based analytical equipment. (S)he will also be keen to publish the results of their research in high impact journals in the field. A full EU driving licence is required.
Additional Requirements
| Minimal degree required: | Master's degree |
| Minimal amount of work experience | Not specified |
Faculty
Student will be enrolled in the School of Natural Sciences, Trinity College, University of Dublin, Ireland.
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You can contact Prof. David Taylor to ask a question about Nutrient source apportionment in Irish water bodies at University of Dublin Trinity College.
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