Dr. Carlos Rocha
Telephone: +353-(0)1 896 3871
Email: rochac@tcd.ie
Postal Address: Department of Geography, Museum Building, Trinity College Dublin
Graduate Research Projects
Project ID: Controls on sediment P release from temperate intertidal sediments (In collaboration with Dr Eric Epping, Royal Netherlands Institute for Sea Research)
Synopsis: Several recent analyses suggest that primary production in the Dutch western Wadden Sea is limited by phosphorus (P), as a consequence of effective reducing policies. However, the phytoplankton community has changed remarkably, but annual primary production remained unaffected. To reconcile these observations, we hypothesize that a substantial proportion of primary production following the spring bloom is supported by P regeneration, buffering the reduction in P loads since 1987. To test this hypothesis, we will study regenerative shunts of P cycling in the water column and sediment from the western Wadden Sea, including field work, laboratory experiments and diagenetic modeling. The obtained results can be compared with other ecosystems that are phosphorus limited. This work is expected to add significantly to the understanding of nutrient dynamics and its relations with primary production and with the ecosystems carrying capacity.
Funding: ESF-European Social Fund; FCT-National Foundation for Science and Technology, Portugal
Duration: 2008-2012
PhD student: Catarina de Freixo Leote
Project ID: Nitrogen reduction in marine systems: in-situ study of alternative metabolic pathways linked to Coastal Groundwater Discharge
Synopsis: The objectives of this proposal are to identify, quantify and parameterize key biogeochemical processes affecting Nitrogen (N) turnover inside permeable sediments and correlate these processes with in-situ flux measurements, while using selected representative N molecules as proxies. Laboratory investigations and field measurements will aim to describe N dynamics in sandy sediments locus of Coastal Groundwater Discharge (CGD). By using stable isotopes as tracers of competing metabolic pathways leading to nitrate reduction in laboratory assays, and complementing these studies with stoichiometric and diagenetic modelling, we will identify and quantify key process rates, thus elucidating the environmental parameters controlling the resulting sediment-water fluxes and mitigating capability of coastal tidal ecosystems over human-derived nitrogen inputs. The expected results will clarify the mediation role played by marine sandy sediments located on the borderline between continental nitrogen inputs and receiving coastal ecosystems. Ultimately, the derived modelling studies will allow the study of how projected environmental changes could affect nitrogen processing in these systems, filling a current gap in the knowledge of the present and future functioning of the coastal ecosystem.
Funding: ESF-European Social Fund; FCT-National Foundation for Science and Technology, Portugal
Duration: 2008-2012
PhD student: Juan Severino Pino Ibanhez
Other Research projects
NITROLINKS - NITROgen loading into the Ria Formosa through Coastal Groundwater Discharge (CGD) - Pathways, turnover and LINKS between land and sea in the Coastal Zone
Synopsis: NITROLINKS focuses on the least understood coastal ecotone: coastal sediments including groundwater discharge. Using the Ria Formosa (Southern Portugal) as a study site, our research includes mapping of groundwater discharge zones, evaluation of fluxes and seasonal discharge patterns, quantification of biogeochemical process rates at seepage sites, and tracing the transfer of groundwater-borne Nitrogen (N) to the autotrophic food-web. Results will clarify how CGD relates to the N cycle in the Ria Formosa, filling a current gap in the knowledge of the functioning of coastal lagoon ecosystems.
Funding: EU (FEDER), National Science and Technology Foundation (FCT) and the Portuguese Government
Calendar: 1-10-2008 to 30-09-2011
Development of Remote Sensing as a Tool for Detection, Quantification and Evaluation of Submarine Groundwater Discharge (SGD) to Irish Coastal Waters
Synopsis: Submarine Groundwater Discharge (SGD) is receiving considerable attention in the literature as a major pathway for anthropogenically derived pollutants to coastal waters. The specific goal of this research is to develop remote sensing as a tool in the identification, quantification and mapping of SGD. The principal means of the assessment will be via thermal infrared remote sensing for two case-study areas in Ireland – Galway Bay and Dublin Bay. A third site, the Ria Formosa, Portugal, will be used as a reference system for the tools developed. The thermal imagery will be used in combination with ground-based measurements of temperature, conductivity (salinity) and natural chemical tracers of groundwater discharge (222Rn) to assess the impact of SGD. The study aims to improve understanding of the pathways and discharge of contaminants via SGD into Irish coastal waters. This research project, to be led by Dr. Jean Wilson under Dr. Carlos Rocha’s supervision, aims to:
Evaluate the potential of thermal remote sensing in SGD assessment in Ireland using Galway Bay and Dublin Bay as case-studies
Validate the areas of SGD identified using thermal IR imagery in the field and calculate the anthropogenic component (using the NITROLINKS project for calibration and control)
Determine the significance of anthropogenically derived SGD to the nutrient load
Identify the geologic and anthropogenic controls on SGD through an analysis of available national offshore and onshore geological spatial datasets (e.g. INFOMAR and EPA) and available satellite imagery within a GIS
Funding: EPA (STRIVE)
Calendar: 1-03-2009 to 29-02-2012