• Energy Research

La chromatographie liquide à haute performance (HPLC) est une méthode qui permet de quantifier les concentrations de pigments phytoplanctoniques provenant d'échantillons d'eau en vrac. Les groupes d'espèces de phytoplancton (c'est-à-dire les diatomées, les dinoflagellés, etc.) contiennent généralement différents pigments et concentrations de pigments utilisés pour la photosynthèse. Ces différences permettent d'utiliser des méthodes statistiques (par exemple, analyse chimiotaxonomique, CHEMTAX) pour estimer les contributions à la biomasse au niveau du groupe de phytoplancton dans un échantillon d'eau en vrac. Ces méthodes fournissent des informations uniques et précieuses sur la dynamique des communautés phytoplanctoniques car elles quantifient le spectre granulométrique complet du phytoplancton, sont relativement rapides et rentables et sont directement liées à la télédétection (c'est-à-dire que les pigments entraînent les différences de lumière mesurées par les satellites). En outre, la HPLC est considérée comme la référence absolue pour quantifier les concentrations totales de chlorophylle a du phytoplancton (tchLA, indicateur de la biomasse phytoplanctonique en vrac) requises pour la validation par télédétection par satellite. L'institut Hakai collecte des échantillons HPLC dans le nord de la mer des Salish (NSS) à la station de recherche écologique à long terme (LTER) QU39 et dans diverses stations de la côte centrale de la Colombie-Britannique depuis 2015. Ces données sont utilisées pour surveiller la dynamique au niveau des groupes de phytoplancton, approfondir les connaissances sur les différentes conditions environnementales qui entraînent leur variabilité (Del Bel Belluz et al., 2021), étudier les liens entre le réseau trophique et le système carbonaté, évaluer les changements à long terme et créer des modèles de télédétection régionaux (Vishnu et al., 2022). Les données de la station QU39 du NSS sont collectées chaque semaine et de 2015 à 2019 à 5 m de profondeur, puis à 0, 5, 10 et 20 m de profondeur. Sur la côte centrale de la Colombie-Britannique, les données sont collectées tous les mois à 5 m de profondeur. Les échantillons sont analysés à l'Institut Baruch des sciences marines et côtières de l'Université de Caroline du Sud à l'aide de la méthode USC. Cette méthode a été évaluée et est détaillée dans la quatrième expérience d'analyse HPLC SeaWIFS de la NASA (SeaHarre-4, Hooker et al., 2010). Le phytoplancton constitue la base du réseau trophique marin et joue un rôle clé dans le cycle biogéochimique et la séquestration du carbone. Les taux de renouvellement élevés des espèces de phytoplancton en font des sentinelles idéales des changements environnementaux, car elles réagissent rapidement aux perturbations ; toutefois, le manque de données, notamment en termes de composition des communautés, existe dans les systèmes côtiers, ce qui empêche de déterminer les conditions de référence pour évaluer les changements. Ce manque de connaissances est particulièrement pertinent si l'on considère que les régions côtières sont confrontées à des changements climatiques rapides, notamment une augmentation de la température et de l'acidification, une réduction de l'oxygène et une modification de la dynamique de l'eau douce. La synergie de ces influences est susceptible de modifier la structure de la communauté et de la taille du phytoplancton, ce qui aurait d'importantes répercussions en aval sur la résilience des écosystèmes, la production alimentaire et la régulation du climat. High performance liquid chromatography (HPLC) is a method that quantifies concentrations of phytoplankton pigments from bulk water samples. Phytoplankton species groupings (i.e. diatoms, dinoflagellates, etc.) typically contain different pigments, and concentrations of pigments, used for photosynthesis. These differences make it possible to use statistical methods (e.g. chemotaxonomic analysis, CHEMTAX) to estimate phytoplankton group-level biomass contributions within a bulk water sample. These methods provide unique and valuable insight into phytoplankton community dynamics as they quantify the full phytoplankton size-spectrum, are relatively fast and cost-effective and, are directly relatable to remote sensing (i.e. pigments drive differences in light measured by satellites). Furthermore, HPLC is considered the gold-standard for quantifying phytoplankton total chlorophyll a concentrations (TChla, proxy for bulk phytoplankton biomass) required for satellite remote sensing validation. The Hakai institute has been collecting HPLC samples in the northern Salish Sea (NSS) at the QU39 long-term ecological research (LTER) station and at various stations on the central coast of British Columbia since 2015. These data are used to monitor phytoplankton group level dynamics, build knowledge of different environmental conditions driving their variability (Del Bel Belluz et al., 2021), investigate linkages to the food web and carbonate system, evaluate long-term change and, to build regional remote sensing models (Vishnu et al., 2022). Data from station QU39 within the NSS are collected weekly and from 2015-2019 at 5m depth and afterwards at 0, 5, 10 and 20m depth. On the central coast of British Columbia, data are collected monthly at 5m depth. Samples are analyzed at the University of South Carolina Baruch Institute for Marine and Coastal Sciences using the USC method. This method was evaluated and is detailed in the NASA Fourth SeaWiFS HPLC Analysis Round-Robin Experiment (SeaHARRE-4, Hooker et al., 2010). Phytoplankton form the base of the marine food web and play key roles in biogeochemical cycling and carbon sequestration. The high turnover rates of phytoplankton species make them ideal sentinels of environmental change as they quickly respond to perturbations; however, a paucity of data, notably in terms of community composition, exists across coastal systems hindering the derivation of baseline conditions to assess change. This knowledge gap is especially pertinent when considering that coastal regions are experiencing rapid climate-driven change including increased temperature and acidification, reduced oxygen and altered freshwater dynamics. The synergy of these influences has the potential to alter phytoplankton community and size structure having large downstream implications on ecosystem resiliency, food production and climate regulation.

Abstract. Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere in a changing climate – the “global carbon budget” – is important to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe and synthesize data sets and methodology to quantify the five major components of the global carbon budget and their uncertainties. Fossil CO2 emissions (EFOS) are based on energy statistics and cement production data, while emissions from land-use change (ELUC), mainly deforestation, are based on land use and land-use change data and bookkeeping models. Atmospheric CO2 concentration is measured directly and its growth rate (GATM) is computed from the annual changes in concentration. The ocean CO2 sink (SOCEAN) and terrestrial CO2 sink (SLAND) are estimated with global process models constrained by observations. The resulting carbon budget imbalance (BIM), the difference between the estimated total emissions and the estimated changes in the atmosphere, ocean, and terrestrial biosphere, is a measure of imperfect data and understanding of the contemporary carbon cycle. All uncertainties are reported as ±1σ. For the last decade available (2010–2019), EFOS was 9.6 ± 0.5 GtC yr−1 excluding the cement carbonation sink (9.4 ± 0.5 GtC yr−1 when the cement carbonation sink is included), and ELUC was 1.6 ± 0.7 GtC yr−1. For the same decade, GATM was 5.1 ± 0.02 GtC yr−1 (2.4 ± 0.01 ppm yr−1), SOCEAN 2.5 ± 0.6 GtC yr−1, and SLAND 3.4 ± 0.9 GtC yr−1, with a budget imbalance BIM of −0.1 GtC yr−1 indicating a near balance between estimated sources and sinks over the last decade. For the year 2019 alone, the growth in EFOS was only about 0.1 % with fossil emissions increasing to 9.9 ± 0.5 GtC yr−1 excluding the cement carbonation sink (9.7 ± 0.5 GtC yr−1 when cement carbonation sink is included), and ELUC was 1.8 ± 0.7 GtC yr−1, for total anthropogenic CO2 emissions of 11.5 ± 0.9 GtC yr−1 (42.2 ± 3.3 GtCO2). Also for 2019, GATM was 5.4 ± 0.2 GtC yr−1 (2.5 ± 0.1 ppm yr−1), SOCEAN was 2.6 ± 0.6 GtC yr−1, and SLAND was 3.1 ± 1.2 GtC yr−1, with a BIM of 0.3 GtC. The global atmospheric CO2 concentration reached 409.85 ± 0.1 ppm averaged over 2019. Preliminary data for 2020, accounting for the COVID-19-induced changes in emissions, suggest a decrease in EFOS relative to 2019 of about −7 % (median estimate) based on individual estimates from four studies of −6 %, −7 %, −7 % (−3 % to −11 %), and −13 %. Overall, the mean and trend in the components of the global carbon budget are consistently estimated over the period 1959–2019, but discrepancies of up to 1 GtC yr−1 persist for the representation of semi-decadal variability in CO2 fluxes. Comparison of estimates from diverse approaches and observations shows (1) no consensus in the mean and trend in land-use change emissions over the last decade, (2) a persistent low agreement between the different methods on the magnitude of the land CO2 flux in the northern extra-tropics, and (3) an apparent discrepancy between the different methods for the ocean sink outside the tropics, particularly in the Southern Ocean. This living data update documents changes in the methods and data sets used in this new global carbon budget and the progress in understanding of the global carbon cycle compared with previous publications of this data set (Friedlingstein et al., 2019; Le Quéré et al., 2018b, a, 2016, 2015b, a, 2014, 2013). The data presented in this work are available at https://doi.org/10.18160/gcp-2020 (Friedlingstein et al., 2020).

AbstractArctic outflow winds bring cold air from the continent to the coastline through mountain passes. Using observational data and a 2‐D model, we show that a February 2019 outflow event caused the upper 100 m in Bute Inlet, British Columbia (within the traditional territory of the Homalco Nation) to cool up to 1.9°C and gain up to 4.1 mLL−1 of oxygen. The cold, oxygenated water persisted for almost 1 year within the 1,023–1,023.5 kgm−3 isopycnal range (∼50–150 m). Atmospheric (from 1929 to 2022) and oceanographic (from 1951 to 2022) data showed a statistically significant relationship between continental air temperature at Tatlayoko Lake and temperature and oxygen in Bute Inlet. This local mechanism that counters some effects of climate change could create a biological refugium as surrounding waters warm and lose oxygen at a faster rate. The number of outflow events decreased from 1951 to 2018, and increased since.

Oceanic uptake of anthropogenic carbon dioxide (CO2) from the atmosphere has changed ocean biogeochemistry and threatened the health of organisms through a process known as ocean acidification (OA). Such large-scale changes affect ecosystem functions and can have impacts on societal uses, fisheries resources, and economies. In many large estuaries, anthropogenic CO2-induced acidification is enhanced by strong stratification, long water residence times, eutrophication, and a weak acid–base buffer capacity. In this article, we review how a variety of processes influence aquatic acid–base properties in estuarine waters, including coastal upwelling, river–ocean mixing, air–water gas exchange, biological production and subsequent aerobic and anaerobic respiration, calcium carbonate (CaCO3) dissolution, and benthic inputs. We emphasize the spatial and temporal dynamics of partial pressure of CO2 ( pCO2), pH, and calcium carbonate mineral saturation states. Examples from three large estuaries—Chesapeake Bay, the Salish Sea, and Prince William Sound—are used to illustrate how natural and anthropogenic processes and climate change may manifest differently across estuaries, as well as the biological implications of OA on coastal calcifiers.