ORCID Profile
0000-0002-5919-4116
Current Organisation
Université Laval
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Publisher: Copernicus GmbH
Date: 19-10-2020
Abstract: Abstract. The MALINA oceanographic c aign was conducted during summer 2009 to investigate the carbon stocks and the processes controlling the carbon fluxes in the Mackenzie River estuary and the Beaufort Sea. During the c aign, an extensive suite of physical, chemical and biological variables was measured across seven shelf–basin transects (south-north) to capture the meridional gradient between the estuary and the open ocean. Key variables such as temperature, absolute salinity, radiance, irradiance, nutrient concentrations, chlorophyll-a concentration, bacteria, phytoplankton and zooplankton abundance and taxonomy, and carbon stocks and fluxes were routinely measured onboard the Canadian research icebreaker CCGS Amundsen and from a barge in shallow coastal areas or for s ling within broken ice fields. Here, we present the results of a joint effort to tidy and standardize the collected data sets that will facilitate their reuse in further studies of the changing Arctic Ocean. The dataset is available at 0.17882/75345 (Massicotte2020b).
Publisher: Copernicus GmbH
Date: 28-02-2018
Abstract: Abstract. Groundwater-borne contaminants such as nutrients, dissolved organic carbon (DOC), coloured dissolved organic matter (CDOM) and pesticides can have an impact the biological quality of lakes. The sources of pollutants can, however, be difficult to identify due to high heterogeneity in groundwater flow patterns. This study presents a novel approach for fast hydrological surveys of small groundwater-fed lakes using multiple groundwater-borne tracers. Water s les were collected from the lake and temporary groundwater wells, installed every 50 m within a distance of 5–45 m to the shore, were analysed for tracer concentrations of CDOM, DOC, total dissolved nitrogen (TDN, groundwater only), total nitrogen (TN, lake only), total dissolved phosphorus (TDP, groundwater only), total phosphorus (TP, lake only), δ18O ∕ δ16O isotope ratios and fluorescent dissolved organic matter (FDOM) components derived from parallel factor analysis (PARAFAC). The isolation of groundwater recharge areas was based on δ18O measurements and areas with a high groundwater recharge rate were identified using a microbially influenced FDOM component. Groundwater discharge sites and the fractions of water delivered from the in idual sites were isolated with the Community Assembly via Trait Selection model (CATS). The CATS model utilized tracer measurements of TDP, TDN, DOC and CDOM from the groundwater s les and related these to the tracer measurements of TN, TP, DOC and CDOM in the lake. A direct comparison between the lake and the inflowing groundwater was possible as degradation rates of the tracers in the lake were taken into account and related to a range of water retention times (WRTs) of the lake (0.25–3.5 years in 0.25-year increments). These estimations showed that WRTs above 2 years required a higher tracer concentration of inflowing water than found in any of the groundwater wells around the lake. From the estimations of inflowing tracer concentration, the CATS model isolated groundwater discharge sites located mainly in the eastern part of the lake with a single site in the southern part. Observations from the eastern part of the lake revealed an impermeable clay layer that promotes discharge during heavy precipitation events, which would otherwise be difficult to identify using traditional hydrological methods. In comparison to the lake concentrations, high tracer concentrations in the southern part showed that only a smaller fraction of water could originate from this area, thereby confirming the model results. A Euclidean cluster analysis of δ18O isotopes identified recharge sites corresponding to areas adjacent to drainage channels, and a cluster analysis of the microbially influenced FDOM component C4 further identified five sites that showed a tendency towards high groundwater recharge rate. In conclusion, it was found that this methodology can be applied to smaller lakes within a short time frame, providing useful information regarding the WRT of the lake and more importantly the groundwater recharge and discharge sites around the lake. Thus, it is a tool for specific management of the catchment.
Publisher: Copernicus GmbH
Date: 04-10-2017
DOI: 10.5194/BG-2017-209
Abstract: Abstract. Groundwater borne contaminants such as e.g., nutrients, dissolved organic carbon (DOC), coloured dissolved organic matter (CDOM) and pesticides impact the biological quality of lakes. The sources of pollution can, however, be difficult to identify due to high heterogeneity in groundwater flow patterns. This study presents a novel approach for fast hydrological surveys of small groundwater-fed lakes using multiple groundwater-borne tracers. Water s les were collected from groundwater wells installed every 50 m within 5–45 m from the shore and were analysed for tracer concentrations of CDOM, DOC, total dissolved nitrogen (TDN), total dissolved phosphorus (TDP), 𝛿18O isotopes and fluorescent dissolved organic matter (FDOM) components derived from parallel factor analysis (PARAFAC). Based on tracer concentrations and degradation rates, the maximum WRT was estimated to 2 years. Isolation of groundwater recharge areas were based on 𝛿18O measurements and sites with high a degree of recharge was isolated using PARAFAC component C4. Groundwater discharge sites and the fractions of water delivered from the sites were isolated with the Community Assembly via Trait Selection model (CATS) for WRTs between 0.25 and 2 years. The identified recharge sites corresponded to areas adjacent to drainage channels and a cluster analysis of component C4 further identified five sites which showed a tendency of high groundwater recharge rates. Isolated groundwater discharge sites were located in the eastern part of the lake and a single site in the southern part. Observations from the eastern part of the lake revealed an impermeable clay layer that promotes discharge during short precipitation events, which would be difficult to identify using traditional hydrological methods. High tracer concentrations in the southern part in relation to lake concentrations showed that only a smaller fraction of water could originate from this area, thereby confirming the model results. The methodology used can be applied to smaller lakes yielding results within a short time frame with information related to the WRT of the lake.
Publisher: Copernicus GmbH
Date: 27-01-2020
Abstract: Abstract. The Green Edge initiative was developed to investigate the processes controlling the primary productivity and fate of organic matter produced during the Arctic phytoplankton spring bloom (PSB) and to determine its role in the ecosystem. Two field c aigns were conducted in 2015 and 2016 at an ice c located on landfast sea ice southeast of Qikiqtarjuaq Island in Baffin Bay (67.4797∘ N, 63.7895∘ W). During both expeditions, a large suite of physical, chemical and biological variables was measured beneath a consolidated sea-ice cover from the surface to the bottom (at 360 m depth) to better understand the factors driving the PSB. Key variables, such as conservative temperature, absolute salinity, radiance, irradiance, nutrient concentrations, chlorophyll a concentration, bacteria, phytoplankton and zooplankton abundance and taxonomy, and carbon stocks and fluxes were routinely measured at the ice c . Meteorological and snow-relevant variables were also monitored. Here, we present the results of a joint effort to tidy and standardize the collected datasets, which will facilitate their reuse in other Arctic studies. The dataset is available at 0.17882/59892 (Massicotte et al., 2019a).
Publisher: American Geophysical Union (AGU)
Date: 08-2019
DOI: 10.1029/2019JC015007
Publisher: Copernicus GmbH
Date: 15-04-2021
DOI: 10.5194/ESSD-13-1561-2021
Abstract: Abstract. The MALINA oceanographic c aign was conducted during summer 2009 to investigate the carbon stocks and the processes controlling the carbon fluxes in the Mackenzie River estuary and the Beaufort Sea. During the c aign, an extensive suite of physical, chemical and biological variables were measured across seven shelf–basin transects (south–north) to capture the meridional gradient between the estuary and the open ocean. Key variables such as temperature, absolute salinity, radiance, irradiance, nutrient concentrations, chlorophyll a concentration, bacteria, phytoplankton and zooplankton abundance and taxonomy, and carbon stocks and fluxes were routinely measured onboard the Canadian research icebreaker CCGS Amundsen and from a barge in shallow coastal areas or for s ling within broken ice fields. Here, we present the results of a joint effort to compile and standardize the collected data sets that will facilitate their reuse in further studies of the changing Arctic Ocean. The data set is available at 0.17882/75345 (Massicotte et al., 2020).
Publisher: Copernicus GmbH
Date: 04-10-2017
No related grants have been discovered for Philippe Massicotte.