Primary Production Export Research Articles

Stormwater Runoff and Tidal Flooding Transform Dissolved Organic Matter Composition and Increase Bioavailability in Urban Coastal Ecosystems

AbstractCoastal drainages contain multiple sources of dissolved organic matter (DOM) that influence OM transformation and fate along inland‐to‐marine gradients. Anthropogenic activities have altered DOM composition in urban drainages, thereby influencing in‐stream breakdown rates, primary productivity, and downstream export. Yet, it is uncertain how hydrologic conditions (i.e., rainfall, tides, shallow groundwater) interact with different sources of DOM to regulate the transformation and export of DOM through urban coastal drainages. We characterized how seasonal changes in hydrologic conditions influence DOM composition and bioavailability in tidally influenced drainages in Miami, FL, USA. We estimated the quality and bioavailability of DOM using compositional proxies based on fluorescence spectroscopy, including parallel‐factor analysis, and measured dissolved organic carbon degradation during laboratory incubations containing a local bacterial community. Interactions between stormwater runoff and tidal amplitude increased the bioavailability of DOM and were positively correlated with predominantly humic‐like components in the wet season and protein‐like components in the dry season. Further, increases in tryptophan fluorescence intensity corresponded with elevated concentrations of Escherichia coli and enterococci—likely from waste‐impacted groundwater—and contributed substantially to overall DOM bioavailability. Our results provide new evidence of an urban priming effect in which labile autochthonous DOM from anthropogenic sources facilitates microbial degradation of DOM that is driven by seasonal differences in stormwater runoff and tides. As hydrologic conditions in near‐shore aquatic ecosystems shift with urbanization and climate‐driven changes in sea‐level rise, increases in autochthonous sources of bioavailable DOM may impact ecosystem metabolism and affect the quality of DOM exported downstream.

Sinking Diatom Assemblages as a Key Driver for Deep Carbon and Silicon Export in the Scotia Sea (Southern Ocean)

Physical and biogeochemical processes in the Southern Ocean are fundamental for modulating global climate. In this context, a process-based understanding of how Antarctic diatoms control primary production and carbon export, and hence global-ocean carbon sequestration, has been identified as a scientific priority. Here we use novel sediment trap observations in combination with a data-assimilative ocean biogeochemistry model (ECCO-Darwin) to understand how environmental conditions trigger diatom ecology in the iron-fertilized southern Scotia Sea. We unravel the role of diatoms assemblage in controlling the biogeochemistry of sinking material escaping from the euphotic zone, and discuss the link between changes in upper-ocean environmental conditions and the composition of settling material exported from the surface to 1,000 m depth from March 2012 to January 2013. The combined analysis of in situ observations and model simulation suggests that an anomalous sea-ice episode in early summer 2012–2013 favored (via restratification due to sea-ice melt) an early massive bloom of Corethron pennatum that rapidly sank to depth. This event drove high biogenic silicon to organic carbon export ratios, while modulating the carbon and nitrogen isotopic signals of sinking organic matter reaching the deep ocean. Our findings highlight the role of diatom ecology in modulating silicon vs. carbon sequestration efficiency, a critical factor for determining the stoichiometric relationship of limiting nutrients in the Southern Ocean.

Counteracting Contributions of the Upper and Lower Meridional Overturning Limbs to the North Atlantic Nutrient Budgets: Enhanced Imbalance in 2010

AbstractThe North Atlantic Basin is a major sink for atmospheric carbon dioxide (CO2) due in part to the extensive plankton blooms which form there supported by nutrients supplied by the three‐dimensional ocean circulation. Hence, changes in ocean circulation and/or stratification may influence primary production and biological carbon export. In this study, we assess this possibility by evaluating inorganic nutrient budgets for 2004 and 2010 in the North Atlantic based on observations from the transatlantic A05‐24.5°N and the Greenland‐Portugal OVIDE hydrographic sections, to which we applied a box inverse model to solve the circulation and estimate the across‐section nutrient transports. Full water column nutrient budgets were split into upper and lower meridional overturning circulation (MOC) limbs. According to our results, anomalous circulation in early 2010, linked to extreme negative NAO conditions, led to an enhanced northward advection of more nutrient‐rich waters by the upper overturning limb, which resulted in a significant nitrate and phosphate convergence north of 24.5°N. Combined with heaving of the isopycnals, this anomalous circulation event in 2010 favored an enhancement of the nutrient consumption (5.7 ± 4.1 kmol‐P s−1) and associated biological CO2 uptake (0.25 ± 0.18 Pg‐C yr−1, upper‐bound estimate), which represents a 50% of the mean annual sea–air CO2 flux in the region. Our results also suggest a transient state of deep silicate divergence in both years. Both results are indicative of a MOC‐driven modulation of the biological carbon uptake (by the upper MOC limb) and nutrient inventories (by the lower MOC limb) in the North Atlantic.

Seasonal-to-decadal scale variability in primary production and particulate matter export at Station ALOHA

Station ALOHA (A Long-term Oligotrophic Habitat Assessment) was established in the North Pacific Subtropical Gyre (22°45′N, 158°W) as an oligotrophic ocean benchmark to improve our understanding of processes that govern the fluxes of carbon (C) into and from the surface ocean. At approximately monthly intervals, measurements of the primary production of particulate C (PC) using the 14C method, and the export of PC and particulate nitrogen (PN) using surface-tethered sediment traps deployed at 150 m have been made along with a host of complementary physical, biological, and biogeochemical measurements. Euphotic zone depth-integrated (0–200 m) primary production ranged from 220.2 (standard deviation, SD, 10.8) mg C m−2 d−1 in Feb 2018 to 1136.5 (SD = 17.1) mg C m−2 d−1 in Jun 2000, with a 30-yr (1989–2018) mean of 536.8 (SD = 135.0) mg C m−2 d−1 (n = 271). Although the monthly primary production climatology was fairly well constrained, we observed substantial sub-decadal variability and a significant 0–125 m depth-integrated increasing trend of 4.0 (p < 0.01; 95% confidence interval, CI, 2.1–5.9) (mg C m−2 d−1) yr−1 since 1989, displaying a large relative increase of 37% (CI = 18–55%) in the lower portion (75–125 m) of the euphotic zone. Chlorophyll (Chl) a and suspended PC and PN concentrations also displayed significant (p < 0.01) increases in the 75–125 m region of the euphotic zone. PC export at 150 m exhibited both short-term (monthly) and longer-scale variability with a 30-yr mean of 27.9 (SD = 9.7, n = 265) mg C m−2 d−1. PC and PN export exhibited extended, multi-year periods of significantly lower or higher values compared to the 30-yr mean. These multi-year periods of anomalously low and high particle export, in the absence of contemporaneous variations in primary production, probably reflect periodic changes in remineralization efficiencies. The PC export ratio (e-ratio; PC export at 150 m ÷ 0–150 m depth-integrated 14C-based primary production) was low, with a 30-yr mean of 0.054 (SD = 0.021, n = 248), and exhibited a significant (p < 0.01) long-term decreasing trend over the 30-yr observation period. The 30-yr long-term increases in primary production (~37%), Chl a, and suspended PC and PN concentrations (~17%, 8%, and 8%, respectively) in the 75–125 m portion of the water column are hypothesized to result from an enhanced supply of nutrients to the lower portion of the water column over the past three decades.

Cross‐Shore Flow and Implications for Carbon Export in the California Current Ecosystem: A Lagrangian Analysis

AbstractEastern Boundary Current Upwelling Systems are regions of elevated primary production and carbon export and thus play a central role in the global carbon cycle. In these regions, nutrient upwelling occurs in a narrow region close to the coast, but primary production and carbon export are typically observed across a broader region. The fact that productive waters reach the open ocean has important consequences for the biological carbon pump, because such transport connects nutrient sources close to the coast to the deep carbon sinks of the offshore ocean. However, many aspects of this offshore transport are still not known. Here we address seasonal and interannual variability of upwelling‐related cross‐shore flows in the California current ecosystem (CCE) by employing Lagrangian diagnostics of horizontal transport inferred from satellite data. We define an advective age as the time a water parcel flowed offshore of the 500 m isobath. We find that the offshore extension of high Chl‐a waters covaries with the age of a coastal water parcel, and is consistent with mesoscale circulation. Interannual variability in the offshore extent of older waters is primarily driven by mesoscale variability and covaries with large scale forcing by both ENSO and the NPGO. The measured ratio of in‐situ new production: carbon export also covaries with water age, and tends to be ≫ 1 in younger and more balanced in older waters. Our results may help to parameterize the role of the finescale on the export of carbon in upwelling regions for climate resolving models.

Factors controlling the competition between &amp;lt;i&amp;gt;Phaeocystis&amp;lt;/i&amp;gt; and diatoms in the Southern Ocean and implications for carbon export fluxes

Abstract. The high-latitude Southern Ocean phytoplankton community is shaped by the competition between Phaeocystis and silicifying diatoms, with the relative abundance of these two groups controlling primary and export production, the production of dimethylsulfide, the ratio of silicic acid and nitrate available in the water column, and the structure of the food web. Here, we investigate this competition using a regional physical–biogeochemical–ecological model (ROMS-BEC) configured at eddy-permitting resolution for the Southern Ocean south of 35∘ S. We improved ROMS-BEC by adding an explicit parameterization of Phaeocystis colonies so that the model, together with the previous addition of an explicit coccolithophore type, now includes all biogeochemically relevant Southern Ocean phytoplankton types. We find that Phaeocystis contribute 46±21 % (1σ in space) and 40±20 % to annual net primary production (NPP) and particulate organic carbon (POC) export south of 60∘ S, respectively, making them an important contributor to high-latitude carbon cycling. In our simulation, the relative importance of Phaeocystis and diatoms is mainly controlled by spatiotemporal variability in temperature and iron availability. In addition, in more coastal areas, such as the Ross Sea, the higher light sensitivity of Phaeocystis at low irradiances promotes the succession from Phaeocystis to diatoms. Differences in the biomass loss rates, such as aggregation or grazing by zooplankton, need to be considered to explain the simulated seasonal biomass evolution and carbon export fluxes.

Pandemics and Multiple Crises in Latin America.

The crisis caused by the Covid-19 pandemic is certainly one of the worst in recent Latin American history. Forecasts for 2020 show a drop in the exports sector of approximately 23%, and a 9% reduct ...

A circumpolar dust conveyor in the glacial Southern Ocean

The increased flux of soluble iron (Fe) to the Fe-deficient Southern Ocean by atmospheric dust is considered to have stimulated the net primary production and carbon export, thus promoting atmospheric CO2 drawdown during glacial periods. Yet, little is known about the sources and transport pathways of Southern Hemisphere dust during the Last Glacial Maximum (LGM). Here we show that Central South America (~24‒32°S) contributed up to ~80% of the dust deposition in the South Pacific Subantarctic Zone via efficient circum-Antarctic dust transport during the LGM, whereas the Antarctic Zone was dominated by dust from Australia. This pattern is in contrast to the modern/Holocene pattern, when South Pacific dust fluxes are thought to be primarily supported by Australian sources. Our findings reveal that in the glacial Southern Ocean, Fe fertilization critically relies on the dynamic interaction of changes in dust-Fe sources in Central South America with the circumpolar westerly wind system.

Energy consumption and export performance of sub-Sahara African Countries

Many SSA countries are low-Income countries with inadequate access to basic infrastructure including energy. According to IEA 2018, SSA has the least energy access rates globally. Thirteen countries in SSA, do not have up to 25% access, unlike developing Asia where there is only one country (World Bank, 2018). To this end, this empirical investigation focuses on the nexus between energy consumption and export performance of Sub-Sahara African countries. Generally, the study examines the contribution of energy consumption to real export of goods and services and specifically to the export of manufactured goods. This is very crucial as many countries in Sub-Saharan Africa heavily rely on the export of primary products. They trade on a small range of agricultural products and a small number of markets for their exports. To achieve this, Dumitrescu and Hurlin (2012) Granger causality procedure and Pooled Mean Group (PMG) were employed to determine the direction of causality and estimate the effect of energy consumption (renewable and non-renewable) on export performance. This estimation approach constrains the long run coefficients to be identical, but allows the short run coefficients and error variances to differ across groups. The estimated model in this study is constructed within the framework of multivariate panel analysis. Specifically, two models are specified with real export of goods and services and export of manufacturing goods as dependents variables. The study established that real export granger causes renewable energy, renewable energy, granger causes manufacturing export and manufacturing export granger causes non-renewable energy. More importantly, the study established the relative importance of renewable energy to export performance in SSA. The study, therefore, recommends that as sub-region is aspiring to move away from resource-based exports to manufacturing exports, it is critical that the countries in the region scale up access to energy and look more in the direction of renewable energy to bring this aspiration to reality.

Changing Biogeochemistry of the Southern Ocean and Its Ecosystem Implications

The Southern Ocean plays a critical role in regulating global climate as a major sink for atmospheric carbon dioxide (CO2), and in global ocean biogeochemistry by supplying nutrients to the global thermocline, thereby influencing global primary production and carbon export. Biogeochemical processes within the Southern Ocean regulate regional primary production and biological carbon uptake, primarily through iron supply, and support ecosystem functioning over a range of spatial and temporal scales. Here we assimilate existing knowledge and present new data to examine the biogeochemical cycles of iron, carbon and major nutrients, their key drivers and their responses to, and roles in, contemporary climate and environmental change. Projected increases in iron supply, coupled with increases in light availability to phytoplankton through increased near-surface stratification and longer ice-free periods, are very likely to increase primary production and carbon export around Antarctica. Biological carbon uptake is likely to increase for the Southern Ocean as a whole, whilst there is greater uncertainty around projections of primary production in the Sub-Antarctic and basin-wide changes in phytoplankton species composition, as well as their biogeochemical consequences. Phytoplankton, zooplankton, higher trophic level organisms and microbial communities are strongly influenced by Southern Ocean biogeochemistry, in particular through nutrient supply and ocean acidification. In turn, these organisms exert important controls on biogeochemistry through carbon storage and export, nutrient recycling and redistribution, and benthic-pelagic coupling. The key processes described in this paper are summarised in the graphical abstract. Climate-mediated changes in Southern Ocean biogeochemistry over the coming decades are very likely to impact primary production, sea-air CO2 exchange and ecosystem functioning within and beyond this vast and critically important ocean region.

Dissolved Domoic Acid Does Not Improve Growth Rates and Iron Content in Iron-Stressed Pseudo-Nitzschia subcurvata

Many regions of Antarctica are classified as high nutrient low chlorophyll (HNLC) areas. In these, iron availability is limiting primary productivity and subsequent carbon export. Domoic acid (DA) has previously been detected in the Southern Ocean and suggested to act as a ligand that facilitates iron assimilation for Pseudo-nitzschia spp., species that contribute to Antarctic diatom blooms. An incubation experiment using the Antarctic species Pseudo-nitzschia subcurvata was performed in Antarctic seawater at low and high iron concentrations. Dissolved DA was added to one set of each of the two treatments. This was done to verify whether DA positively affects the growth of the non-toxic species Pseudo-nitzschia subcurvata and increases its cellular iron content, particularly under low iron conditions. We hypothesize that (i) DA is taken up under low iron conditions (ii) that more iron is taken up if DA is available and (iii) that the growth rate increases in the presence of DA. We showed that P. subcurvata did not take up any added DA, even under low iron conditions. Additionally and contrary to our hypothesis, the cells were not positively influenced by the addition of dDA in terms of growth rate, cellular iron and carbon content. Hence, there was no significant difference in iron content between the different treatments. However, the cellular copper content increased under low iron conditions when DA was added. This study suggests that dissolved DA in naturally occurring concentrations does not increase bioavailability of iron to P. subcurvata and that only species producing DA might benefit from it.

Deep Ocean Particle Flux in the Northern South China Sea: Variability on Intra-Seasonal to Seasonal Timescales

Based on time-series sediment trap observation at 1003-m depth in the northern South China Sea from 2014 to 2015, we used sinking particle flux combined with remote sensing-derived environmental data to infer mechanisms of the biological carbon pump. Total particle flux, particulate organic carbon, CaCO3, and lithogenic (inorganic)fluxes peaked in winter and autumn but showed minima in summer, ranging from 59.7 to 413.2 mg m−2 d−1, 2.1 to 18.2 mg m−2 d−1, 32.9 to 197.9 mg m−2 d−1, and 12.0 to 73.6 mg m−2 d−1, respectively. Similarly, opal flux varied from 6.9 to 109.6 mg m−2 d−1, with a prominent peak in winter and minimum in summer. However, a secondary maximum of opal in autumn was barely noticeable compared with other components. A deeper mixed-layer depth related to the northeast monsoon and surface cooling, overlapping with the effect of cyclonic eddies, is responsible for the strong winter fluxes. When an anticyclonic eddy suppresses the subsurface nutrient supply, primary production and subsequent export flux in summer were reduced substantially. With respect to maximum lithogenic and CaCO3 fluxes in autumn, a large aerosol optical depth suggests the scavenging and mineral ballast effects as potential causes. This study highlights the importance of intra-seasonal physical processes (e.g., mesoscale eddies and aerosol deposition) to the deep particle flux in the South China Sea as well as monsoonal transition.

The Effect of Export Diversification on the Economic Growth of West-Asian Arab Countries

This paper examined the relationship between the patterns of export diversification and economic growth in west Asian Arab countries during the period (2000-2017) using World Bank, UNCTAD, and Pen World data. The study used the DX Diversification Index (UNCTAD). This index measures the country's export divergence from the world's diversification patterns. The OLS and FMOLS methods were used to estimate the study model coefficients. The study found that the exports diversification structures in this group diverged clearly from the world diversification pattern since the exports of group countries driven by a high degree of primary exports concentration. Moreover, the economic growth was influenced positively by human capital, primary products export growth, and the adoption of efficient anti-corruption policies, but, it negatively influenced by trade openness and population growth. The study disclosed a long-term relationship between economic growth and the interactions of explanatory variables in the model, while in the short run the relationship was weak and insignificant. Moreover, there was a reciprocal causality relationship between economic growth and the degree of exports diversification using (DX-index). The study recommends that Arab countries should reduce the reliance on the exports of primary products, enhancing the share of industrial-based exports to achieve sustainable growth and to reduce the impacts of primary export’s prices instability on their economies.

Pan-Arctic Ocean Primary Production Constrained by Turbulent Nitrate Fluxes

Arctic Ocean primary productivity is limited by light and inorganic nutrients. With sea ice cover declining in recent decades, nitrate limitation has been speculated to become more prominent. Although much has been learned about nitrate supply from general patterns of ocean circulation and water column stability, a quantitative analysis requires dedicated turbulence measurements that have only started to accumulate in the last dozen years. Here we present new observations of the turbulent vertical nitrate flux in the Laptev Sea, Baffin Bay, and Young Sound (North-East Greenland), supplementing a compilation of 13 published estimates throughout the Arctic Ocean. Combining all flux estimates with a Pan-Arctic database of in situ measurements of nitrate concentration and density, we found the annual nitrate inventory to be largely determined by the strength of stratification and by bathymetry. Nitrate fluxes explained the observed regional patterns and magnitudes of both new primary production and particle export on annual scales. We argue that with few regional exceptions, vertical turbulent nitrate fluxes can be a reliable proxy of Arctic primary production accessible through autonomous and large-scale measurements. They may also provide a framework to assess nutrient limitation scenarios based on clear energetic and mass budget constraints resulting from turbulent mixing and freshwater flows.

High Temporal Variability of Total Organic Carbon in the Deep Northeastern Pacific

The interseasonal and interannual variability of total organic carbon (TOC) was assessed in the deep northeastern Pacific Ocean, an area characterized by high primary production and organic matter export. Samples were collected from throughout the deeper water column (>250 m) seasonally in 2017 and 2018 along the Line P transect, as well as one distribution of dissolved organic carbon (DOC) in spring 2018. High heterogeneity was observed in TOC concentrations at depths greater than 1000 meters, both within seasons (concentration differences of ~2-6 µmol kg-1) and across seasons (~2-12 µmol kg-1), coinciding with changes in fluorescence in the overlying waters. Such observations suggest that biogenic particles sinking from the upper ocean are seasonally delivering observable TOC to depth. The presence of these particles also appeared to contribute to the DOC pool, as suggested by differences in the TOC and DOC distributions in spring 2018. Seasonal TOC net accumulation and removal rates differed between the years: 0.5 and 2.1 µmol kg-1 day-1 (accumulation) and 0.6 and 2.1 µmol kg-1 day-1 (removal) for 2017 and 2018, respectively. The rate estimates indicated that introduction of organic carbon to the bathypelagic occurred at approximately the same rate as removal post-bloom, demonstrating the efficient removal of seasonally-produced organic carbon. High abundances of gelatinous zooplankton in spring 2018, supported by higher abundances of phytoplankton, enhanced the export of organic carbon to the bathypelagic zone during the seasonal bloom, resulting in localized TOC concentrations up to 148 µmol kg-1 in the bathypelagic. These results indicate high variability in bathypelagic TOC concentrations at high latitude, unlike oligotrophic systems.

Impact of Changes to the Atmospheric Soluble Iron Deposition Flux on Ocean Biogeochemical Cycles in the Anthropocene

AbstractIron can be a growth‐limiting nutrient for phytoplankton, modifying rates of net primary production, nitrogen fixation, and carbon export ‐ highlighting the importance of new iron inputs from the atmosphere. The bioavailable iron fraction depends on the emission source and the dissolution during transport. The impacts of anthropogenic combustion and land use change on emissions from industrial, domestic, shipping, desert, and wildfire sources suggest that Northern Hemisphere soluble iron deposition has likely been enhanced between 2% and 68% over the Industrial Era. If policy and climate follow the intermediate Representative Concentration Pathway 4.5 trajectory, then results suggest that Southern Ocean (&gt;30°S) soluble iron deposition would be enhanced between 63% and 95% by 2100. Marine net primary productivity and carbon export within the open ocean are most sensitive to changes in soluble iron deposition in the Southern Hemisphere; this is predominantly driven by fire rather than dust iron sources. Changes in iron deposition cause large perturbations to the marine nitrogen cycle, up to 70% increase in denitrification and 15% increase in nitrogen fixation, but only modestly impacts the carbon cycle and atmospheric CO2concentrations (1–3 ppm). Regionally, primary productivity increases due to increased iron deposition are often compensated by offsetting decreases downstream corresponding to equivalent changes in the rate of phytoplankton macronutrient uptake, particularly in the equatorial Pacific. These effects are weaker in the Southern Ocean, suggesting that changes in iron deposition in this region dominates the global carbon cycle and climate response.

Suborbital Hydrological Variability Inferred From Coupled Benthic and Planktic Foraminiferal‐Based Proxies in the Southeastern Mediterranean During the Last 19 ka

AbstractWe present a high‐resolution study covering the past 19 ka from the southeastern Mediterranean Sea, based on benthic foraminiferal faunas and their stable oxygen and carbon isotopes. These data are integrated with previously published and newly acquired planktic foraminiferal data from the same sediment core in order to investigate the benthic‐planktic coupling and its response to past suborbital climate variability. On a millennial timescale, foraminiferal communities and their isotopic signatures vary following three main time periods (late glacial, sapropel S1 [~10.1–6.5 ka], and mid‐Holocene to Late Holocene). Within these intervals, we identified short‐timescale changes related to the carbon export and hydrological conditions. During the deglaciation, and except for the Younger Dryas, the coupled benthic‐planktic data indicate an overall poorly mixed water column with a low productivity. During S1 event, our data confirm the presence of a highly stratified water column, with enhanced primary productivity export to the deep sea, being associated to high Nile River activity. While the foraminiferal ecosystem is strongly driven by the combined influence of overturning circulation and the Nile River activity until the end of the African humid period, we suggest a more regional eastern Mediterranean climatic‐driven response of the foraminiferal community over the mid‐Holocene to Late Holocene. A strong multicentennial variability, probably associated to solar forcing, was found for both benthic and planktic records, and a supplementary 1,600‐year mode was found for the benthic data, suggesting a potential overturning circulation‐driven forcing for the latter.

Panel Discussion: Tropics and the export of primary products

Panel Discussion: Tropics and the export of primary products

A propriedade da terra no Uruguai: Formação social, politicas publicas, território e industria de celulose

Desde o ano 2005, com a chegada ao governo da força progressista da “Frente Ampla”, o Uruguai atravessa por um ciclo de estabilidade político- econômica e governabilidade que tem lhe permitido manter um ritmo de crescimento relativamente constante, em um contexto regional marcado pela arremetida do conservadorismo e a direita neoliberal. Durante este ciclo foram notórios os avanços em matéria de direitos individuais e laborais, na redução da pobreza e exclusão social, etc., em consonância com a consolidação de um modelo produtivo baseado na exportação em grande escala de produtos primários e caracterizado pela concentração e anonimato sobre a propriedade da terra. Isto, por sua vez, se apoia em políticas públicas que estabelecem um marco regulatório que garante grandes vantagens ás empresas (concessões, isenções fiscais, etc.), visando assim atrair investimentos (estrangeiros) como forma de inserção internacional. A indústria da celulose, que começou em 2007, baseada no monocultivo de eucalipto, é hoje um pilar fundamental deste modelo, com a particularidade de ser uma indústria conduzida por grandes empresas transnacionais, que produzem baixo o regime de Zonas Francas e que são as maiores proprietárias de terra no país. Com a iminente instalação de uma terceira fábrica de produção de celulose, abrem-se novas questões em relação à propriedade da terra, a forma de organização espacial das empresas, sob a relação entre estas e o Estado e sobre a capacidade de este de regular soberanamente o território nacional.&#x0D; &#x0D; Palavras–chave: Formação social - Políticas públicas – Território – Indústria de celulose

Sensitivity of ocean biogeochemistry to the iron supply from the Antarctic Ice Sheet explored with a biogeochemical model

Abstract. Iron (Fe) delivery by the Antarctic Ice Sheet (AIS) through ice shelf and iceberg melting enhances primary productivity in the largely iron-limited Southern Ocean (SO). To explore this fertilization capacity, we implement a simple representation of the AIS iron source in the global ocean biogeochemical model NEMO-PISCES. We evaluate the response of Fe, surface chlorophyll, primary production, and carbon (C) export to the magnitude and hypothesized vertical distributions of the AIS Fe fluxes. Surface Fe and chlorophyll concentrations are increased up to 24 % and 12 %, respectively, over the whole SO. The AIS Fe delivery is found to have a relatively modest impact on SO primary production and C export, which are increased by 0.063±0.036 PgC yr−1 and 0.028±0.016, respectively. However, in highly fertilized areas, primary production and C export can be increased by up to 30 % and 42 %, respectively. Icebergs are predicted to have a much larger impact on Fe, surface chlorophyll, and primary productivity than ice shelves in the SO. The response of surface Fe and chlorophyll is maximum in the Atlantic sector, northeast of the tip of the Antarctic Peninsula, and along the East Antarctic coast. The iceberg Fe delivery below the mixed layer may, depending on its assumed vertical distribution, fuel a non-negligible subsurface reservoir of Fe. The AIS Fe supply is effective all year round. The seasonal variations of the iceberg Fe fluxes have regional impacts that are small for annual mean primary productivity and C export at the scale of the SO.