Recent distribution, inventories and temporal trends of suspended particulate matter in the St. Lawrence Estuary, Canada

Lebeuf, Michel; Maltais, Domynick; Larouche, Pierre; Lavoie, Diane; Lefaivre, Denis; Starr, Michel; Scarratt, Michael

doi:10.1016/j.rsma.2019.100664

Cited by 4 publications

(14 citation statements)

References 24 publications

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“…The study area was divided in cells of 2.5 by 2.5 km (6.25 km 2 ) as in previous studies (Dutil et al, 2012;Lebeuf et al, 2019). Cells were fused to create 10 sectors that have at least two sampling sites for each month (Figure 1), including sites at the center of the LSLE (sectors 1-6) that were used in two adjacent sectors.…”

Section: Estuary Inventories and Concentrationsmentioning

confidence: 99%

“…The depth of each cell was calculated from the average bathymetric measurements and tidal levels provided by the Canadian Hydrographic Service. Considering vertical water stratification in the SLE, four distinctive water layers were considered: a warm surface layer (first 40 m), an intermediate layer (40-140 m), a deep layer (> 140 m down to 10 m above the bottom), and a 10 m bottom layer (Bewers and Yeats, 1979;Lebeuf et al, 2019). The latter was always kept in our calculations notwithstanding of total depth.…”

Section: Estuary Inventories and Concentrationsmentioning

confidence: 99%

“…Despite this importance, earlier studies in the SLE focused on a few chemical groups or localised sampling, preventing comprehensive understanding of organic matter dynamics, transport and fate. Recently, Hudon et al (2017) described the export of TSM, DOC and DON of the St. Lawrence River (SLR) to the estuary and Lebeuf et al (2019) estimated TSM and particulate inorganic matter (PIM) inventories and seasonality in the estuary. Overall, studies on organic matter biogeochemistry and inventories in the St. Lawrence Estuary based on comprehensive sampling of TSM, POM, POC, PON, DOC, and DON are still needed to provide a complete overview that could be fully integrated in biochemical models (Lavoie et al, 2021) and improve our knowledge of hypoxia and eutrophication.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Transport inventories and exchanges of organic matter throughout the St. Lawrence Estuary continuum (Canada)

Lévesque

Lebeuf²,

Maltais³

et al. 2023

Front. Mar. Sci.

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Hypoxia (O2 < 2 mg/L) driven by eutrophication in estuaries and shelves is a worldwide expanding problem. The role of organic matter (OM) inputs is emerging as an important contributor to this issue, beside the well-known implication of inorganic nutrients. The St. Lawrence Estuary, one of the largest and deepest estuarine system in the world is facing strong persistent and increasing hypoxia. In this context, transport and exchange of particulate and dissolved organic matter (POM and DOM, respectively) were investigated as a first step to understand their implication in hypoxia. Tributaries and Gulf contributions were compared to St. Lawrence Estuary inventories for the spring freshet (May), the summer low-flow (August), and the fall-mixing (October). Furthermore, changes in OM ratios were examined along the estuarine gradient from the upper St. Lawrence Estuary (USLE), downstream of the maximum turbidity zone, to the lower estuary (LSLE). For the USLE, net transport was always positive and net export/loading ratios suggested that 64–90% of POM and 30–63% of DOM were either retained or transformed during its course from tributaries to LSLE. Net transport from the USLE toward the LSLE was 3–13 fold more important in May than in August or October. For the LSLE, net transport to the Gulf was generally negative meaning that OM production was the dominating proces. The extremely high net export/loading ratios in August indicate that POM production was 28.8 to 41.4 times the combined inputs of tributaries and Gulf. Net export/loading ratios remained superior to one during May and October (1.7–9.4) for the LSLE. Changes along the upstream–downstream continuum were seen for POM, with a steady increase relative to total suspended matter from 7.3% to 50.2%, but they were not observed for DOM, for which no obvious trends were detected. Our results highlight the importance of explicitly considering OM in eutrophication monitoring programs of the St. Lawrence Estuary, as the mineralisation of a portion of the large OM pool size could influence our understanding of hypoxia and acidification of the deep waters of LSLE.

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Section: Estuary Inventories and Concentrationsmentioning

confidence: 99%

Section: Estuary Inventories and Concentrationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Transport inventories and exchanges of organic matter throughout the St. Lawrence Estuary continuum (Canada)

Lévesque

Lebeuf²,

Maltais³

et al. 2023

Front. Mar. Sci.

Self Cite

View full text Add to dashboard Cite

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“…As the main component of case-II water, suspended particulate matter (SPM) concentration is an important parameter used in the assessment of aquatic ecosystems and environmental impact of water [ 1 , 2 , 3 ]. It also plays a key biogeochemical role in aquatic ecosystems [ 4 ]. SPM transportation and accumulation have significant effects on aquatic ecosystems and human activities [ 5 ].…”

Section: Introductionmentioning

confidence: 99%

“…SPM transportation and accumulation have significant effects on aquatic ecosystems and human activities [ 5 ]. Therefore, monitoring the temporal and spatial variations in the SPM concentration in lakes is important since it allows to understand the dynamics of suspended particulates, as well as the structure and function of aquatic ecosystems, and in the management and protection of aquatic ecosystems [ 1 , 2 , 3 , 4 , 5 , 6 , 7 ].…”

Section: Introductionmentioning

confidence: 99%

Consistency of Suspended Particulate Matter Concentration in Turbid Water Retrieved from Sentinel-2 MSI and Landsat-8 OLI Sensors

Wang

Cui

et al. 2021

Sensors

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Research on the consistency of suspended particulate matter (SPM) concentration retrieved from multisource satellite sensors can serve as long-time monitoring of water quality. To explore the influence of the atmospheric correction (AC) algorithm and the retrieval model on the consistency of the SPM concentration values, Landsat 8 Operational Land Imager (OLI) and Sentinel 2 MultiSpectral Imager (MSI) images acquired on the same day are used to compare the remote sensing reflectance (Rrs) SPM retrieval values in two high-turbidity lakes. An SPM retrieval model for Shengjin Lake is established based on field measurements and applied to OLI and MSI images: two SPM concentration products are highly consistent (R2 = 0.93, Root Mean Squared Error (RMSE) = 20.67 mg/L, Mean Absolute Percentage Error (MAPE) = 6.59%), and the desired results are also obtained in Chaohu Lake. Among the four AC algorithms (Management Unit of the North Seas Mathematical Models (MUMM), Atmospheric Correction for OLI’lite’(ACOLITE), Second Simulation of Satellite Signal in the Solar Spectrum (6S), Landsat 8 Surface Reflectance Code & Sen2cor (LaSRC & Sen2cor), the two Rrs products, as well as the final SPM concentration products retrieved from OLI and MSI images, have the best consistency when using the MUMM algorithm in SeaWIFS Data Analyst System (SeaDAS) software. The consistency of SPM concentration values retrieved from OLI and MSI images using the same model or same form of models is significantly better than that retrieved by applying the optimal models with different forms.

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Using chlorophyllic organic matter degradation in the deep St. Lawrence Estuary as an indicator of water column remineralization

Lévesque,

Lebeuf,

Starr

2024

Front. Mar. Sci.

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Coastal hypoxia, driven by remineralization of chlorophyllic particulate organic matter (POM) in dark environments, poses a threat to deep estuarine and shelf ecosystems. To better understand the fate of POM along a depth gradient, we investigated the degradation of chloropigments, particulate organic carbon (POC), and nitrogen (PON) across the water column in the St. Lawrence Estuary, one of the largest and deepest estuarine system in the world that is facing strong persistent and increasing hypoxia. Our objectives were to establish causal relationships among suspended POM descriptors and assess the potential of a chlorophyll-based degradation index, known as the chlorin index (CI), in evaluating OM degradation within the water column. The CI, ranging from 0.2 for pure chlorophyll to almost 1 for highly degraded pigments, was initially developed for uses in the sediments. Water samples from multiple depths were collected, characterized, and statistically analyzed with a combination of variation partitioning, non-linear regressions and piecewise structural equation modeling (pSEM). We found that the combined influence of chloropigments and depth explained 84.0% of POC and 90.0% of PON variations; the pure fraction attributed to chloropigments accounted for 73.4% and 75.6% (R2adj, both with p< 0.001), respectively. The decline of chloropigments, PON, and POC with increasing depth was reflected by the concomitant increase in CI, whose rate decreases as particles sink resulting in reduced degradation due to less labile organic matter. The pSEM causal model indicated that CI increased with depth and POC concentration, while it decreased in the presence of elevated PON concentrations, known for their high reactivity. The direct effect of depth on CI could be linked to the distinct water column properties influencing particle residence time and thus the degradation potential by biotic and abiotic factors. Finally, CI explained 86% (R2) of the apparent oxygen utilization highlighting the strong connection between POM degradation and hypoxia of deep coastal ecosystems. Our study underscores the utility of the chlorin index as a simple yet robust tool for monitoring OM degradation in the water column, particularly in the St. Lawrence Estuary.

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Recent distribution, inventories and temporal trends of suspended particulate matter in the St. Lawrence Estuary, Canada

Cited by 4 publications

References 24 publications

Transport inventories and exchanges of organic matter throughout the St. Lawrence Estuary continuum (Canada)

Transport inventories and exchanges of organic matter throughout the St. Lawrence Estuary continuum (Canada)

Consistency of Suspended Particulate Matter Concentration in Turbid Water Retrieved from Sentinel-2 MSI and Landsat-8 OLI Sensors

Using chlorophyllic organic matter degradation in the deep St. Lawrence Estuary as an indicator of water column remineralization

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