The ocean's biological carbon pump transfers carbon from the surface ocean to the deep ocean by several distinct pathways, including gravitational settling of organic particles, mixing and advection ...of suspended organic carbon, and active transport by vertically migrating metazoans. Carbon exported by these pathways can be sequestered as respired CO2 in the deep ocean for years to centuries. However, the contribution of each pathway to carbon export and sequestration remains highly uncertain. Here, satellite and in situ ocean biogeochemical observations are assimilated in an ensemble numerical model of the biological pump to quantify global and regional carbon export and sequestration. The ensemble mean global carbon export is 10.2 Pg C yr−1 and the total amount of carbon sequestered via the biological pump is 1,300 Pg C. The gravitational pump is responsible for 70% of the total global carbon export, 85% of which is zooplankton fecal pellets and 15% is sinking phytoplankton aggregates, while migrating zooplankton account for 10% of total export and physical mixing is responsible for the remaining 20%. These pathways have different sequestration times, with an average of 140 years for the gravitational pump, 150 years for the migrant pump, and only 50 years for the mixing pump. Regionally, the largest sequestration inventories and longest sequestration times are found in the northern high latitudes, while the shortest sequestration times are found in the subtropical gyres. These results suggest that ocean carbon storage will weaken as the oceans stratify and the subtropical gyres expand due to anthropogenic climate change.
Plain Language Summary
Tiny organisms called phytoplankton help to reduce atmospheric CO2 levels by absorbing large amounts of carbon in the surface ocean during photosynthesis. Various biological and physical processes, or pathways, then work together to transfer some of this carbon to the deep ocean where it can be stored for potentially hundreds of years. In this study, we examined these pathways using computer models that are consistent with data from satellite‐based sensors and ocean observations. Our model shows that the most important pathways for carbon storage are transport by sinking particles and swimming zooplankton, while transport by ocean currents is the least important pathway. The North Atlantic and North Pacific oceans have the greatest carbon storage power, while the subtropical oceans have the least. These results imply that ocean carbon storage may decrease in the future, because subtropical regions will expand in a warming climate.
Key Points
Carbon export and sequestration pathways are quantified with a data‐assimilated global ocean ecosystem and biogeochemistry model
Gravitational and migrant pumps are the most important biological pump pathways for carbon storage and mixing pump is the least important
Longest sequestration times in the subarctic and shortest in the subtropics, implying a future weakening of biological carbon sequestration
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The ocean's ability to sequester carbon away from the atmosphere exerts an important control on global climate. The biological pump drives carbon storage in the deep ocean and is thought to function ...via gravitational settling of organic particles from surface waters. However, the settling flux alone is often insufficient to balance mesopelagic carbon budgets or to meet the demands of subsurface biota. Here we review additional biological and physical mechanisms that inject suspended and sinking particles to depth. We propose that these 'particle injection pumps' probably sequester as much carbon as the gravitational pump, helping to close the carbon budget and motivating further investigation into their environmental control.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Despite growing attention to the role of social context in determining political participation, the effect of the structure of social networks remains little examined. This article introduces a model ...of interdependent decision making within social networks, in which individuals have heterogeneous motivations to participate, and networks are defined via a qualitative typology mirroring common empirical contexts. The analysis finds that some metrics for networks' influence-size, the prevalence of weak ties, the presence of elites-have a more complex interaction with network structure and individual motivations than has been previously acknowledged. For example, in some contexts additional network ties decrease participation. This presents the potential for selection bias in empirical studies. The model offers a fuller characterization of the role of network structure and predicts expected levels of participation across network types and distributions of motivations as a function of network size, weak and strong ties, and elite influence.
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BFBNIB, FZAB, GIS, IJS, INZLJ, KILJ, NLZOH, NMLJ, NUK, ODKLJ, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK, ZRSKP
Chromophoric dissolved organic matter (CDOM) is a ubiquitous component of the open ocean dissolved matter pool, and is important owing to its influence on the optical properties of the water column, ...its role in photochemistry and photobiology, and its utility as a tracer of deep ocean biogeochemical processes and circulation. In this review, we discuss the global distribution and dynamics of CDOM in the ocean, concentrating on developments in the past 10 years and restricting our discussion to open ocean and deep ocean (below the main thermocline) environments. CDOM has been demonstrated to exert primary control on ocean color by its absorption of light energy, which matches or exceeds that of phytoplankton pigments in most cases. This has important implications for assessing the ocean biosphere via ocean color-based remote sensing and the evaluation of ocean photochemical and photobiological processes. The general distribution of CDOM in the global ocean is controlled by a balance between production (primarily microbial remineralization of organic matter) and photolysis, with vertical ventilation circulation playing an important role in transporting CDOM to and from intermediate water masses. Significant decadal-scale fluctuations in the abundance of global surface ocean CDOM have been observed using remote sensing, indicating a potentially important role for CDOM in ocean-climate connections through its impact on photochemistry and photobiology.
A behavioral theory of elections Bendor, Jonathan; Diermeier, Daniel; Siegel, David A ...
2011., 20110220, 2011, 2011-01-17, 20110101
eBook
Most theories of elections assume that voters and political actors are fully rational. While these formulations produce many insights, they also generate anomalies--most famously, about turnout. The ...rise of behavioral economics has posed new challenges to the premise of rationality. This groundbreaking book provides a behavioral theory of elections based on the notion that all actors--politicians as well as voters--are only boundedly rational. The theory posits learning via trial and error: actions that surpass an actor's aspiration level are more likely to be used in the future, while those that fall short are less likely to be tried later.
By adapting the concept of epitaxy to two-dimensional space, we show the growth of a single-atomic-layer, in-plane heterostructure of a prototypical material system—graphene and hexagonal boron ...nitride (h-BN). Monolayer crystalline h-BN grew from fresh edges of monolayer graphene with atomic lattice coherence, forming an abrupt one-dimensional interface, or boundary. More important, the h-BN lattice orientation is solely determined by the graphene, forgoing configurations favored by the supporting copper substrate.
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Abstract
Background
The American Cancer Society, Centers for Disease Control and Prevention, National Cancer Institute, and North American Association of Central Cancer Registries provide annual ...updates on cancer occurrence and trends by cancer type, sex, race, ethnicity, and age in the United States. This year’s report highlights the cancer burden among men and women age 20–49 years.
Methods
Incidence data for the years 1999 to 2015 from the Centers for Disease Control and Prevention- and National Cancer Institute–funded population-based cancer registry programs compiled by the North American Association of Central Cancer Registries and death data for the years 1999 to 2016 from the National Vital Statistics System were used. Trends in age-standardized incidence and death rates, estimated by joinpoint, were expressed as average annual percent change.
Results
Overall cancer incidence rates (per 100 000) for all ages during 2011–2015 were 494.3 among male patients and 420.5 among female patients; during the same time period, incidence rates decreased 2.1% (95% confidence interval CI = −2.6% to −1.6%) per year in men and were stable in females. Overall cancer death rates (per 100 000) for all ages during 2012–2016 were 193.1 among male patients and 137.7 among female patients. During 2012–2016, overall cancer death rates for all ages decreased 1.8% (95% CI = −1.8% to −1.8%) per year in male patients and 1.4% (95% CI = −1.4% to −1.4%) per year in females. Important changes in trends were stabilization of thyroid cancer incidence rates in women and rapid declines in death rates for melanoma of the skin (both sexes). Among adults age 20–49 years, overall cancer incidence rates were substantially lower among men (115.3 per 100 000) than among women (203.3 per 100 000); cancers with the highest incidence rates (per 100 000) among men were colon and rectum (13.1), testis (10.7), and melanoma of the skin (9.8), and among women were breast (73.2), thyroid (28.4), and melanoma of the skin (14.1). During 2011 to 2015, the incidence of all invasive cancers combined among adults age 20–49 years decreased −0.7% (95% CI = −1.0% to −0.4%) among men and increased among women (1.3%, 95% CI = 0.7% to 1.9%). The death rate for (per 100 000) adults age 20–49 years for all cancer sites combined during 2012 to 2016 was 22.8 among men and 27.1 among women; during the same time period, death rates decreased 2.3% (95% CI = −2.4% to −2.2%) per year among men and 1.7% (95% CI = −1.8% to −1.6%) per year among women.
Conclusions
Among people of all ages and ages 20–49 years, favorable as well as unfavorable trends in site-specific cancer incidence were observed, whereas trends in death rates were generally favorable. Characterizing the cancer burden may inform research and cancer-control efforts.
One pathway of the biological pump that remains largely unquantified in many export models is the active transport of carbon from the surface ocean to the mesopelagic by zooplankton diel vertical ...migration (DVM). Here, we develop a simple representation of zooplankton DVM and implement it in a global export model as a thought experiment to illustrate the effects of DVM on carbon export and mesopelagic biogeochemistry. The model is driven by diagnostic satellite measurements of net primary production, algal biomass, and phytoplankton size structure. Due to constraints on available satellite data, the results are restricted to the latitude range from 60°N to 60°S. The modeled global export flux from the base of the euphotic zone was 6.5 PgC/year, which represents a 14% increase over the export flux in model runs without DVM. The mean (± standard deviation, SD) proportional contribution of the DVM‐mediated export flux to total carbon export, averaged over the global domain and the climatological seasonal cycle, was 0.16 ± 0.04 and the proportional contribution of DVM activity to total respiration within the twilight zone was 0.16 ± 0.06. Adding DVM activity to the model also resulted in a deep local maximum in the oxygen utilization profile. The model results were most sensitive to the assumptions for the fraction of individuals participating in DVM, the fraction of fecal pellets produced in the euphotic zone, and the fraction of grazed carbon that is metabolized.
Key Points
A novel satellite-driven model of ocean carbon export was developed, including the role of diel vertical migration
Diel vertical migration is a significant contributor to carbon export out of the euphotic zone, especially in the subtropics
The export flux mediated by diel vertical migration significantly impacts mesopelagic biogeochemistry
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Cancer continues to be the leading disease-related cause of death among children and adolescents in the United States. More current information is needed to describe recent cancer trends and identify ...demographic and geographic variations.
We analyzed data from the National Program of Cancer Registries and Surveillance, Epidemiology, and End Results statewide registries representing 94.2% of the US population to identify cancers diagnosed among persons aged 0 to 19 years during 2001-2009. Age-adjusted rates and annual percentage change for trends were calculated. Data were stratified by age, gender, race, ethnicity, and geography.
We identified 120,137 childhood and adolescent cancer cases during 2001-2009 with an age-adjusted incidence rate of 171.01 per million. The overall rate of all cancers combined remained stable over time (annual percent change APC, 0.3%; 95% confidence interval CI, -0.1 to 0.7). There was an increase in the overall cancer trend among African American children and adolescents (APC, 1.3%; 95% CI, 0.2 to 2.5). An increasing trend for thyroid cancer was observed among both genders (APC, 4.9%; 95% CI, 3.2 to 6.6) and specifically among adolescents and those in the Northeast, South, and West regions of the United States. Renal carcinoma incidence was increasing significantly overall (APC, 5.4%; 95% CI, 2.8 to 8.1). Extracranial and extragonadal germ cell tumors and melanoma were both significantly decreasing.
This study reports the novel finding that renal carcinoma rates are increasing among children and adolescents. This study confirms that thyroid cancer rates are increasing and further describes rising cancer rates among African Americans.
The ocean's biological carbon pump (BCP) affects the Earth's climate by sequestering CO2 away from the atmosphere for decades to millennia. One primary control on the amount of carbon sequestered by ...the biological pump is air‐sea CO2 disequilibrium, which is controlled by the rate of air‐sea CO2 exchange and the residence time of CO2 in surface waters. Here, we use a data‐assimilated model of the soft tissue BCP to quantify carbon sequestration inventories and time scales from remineralization in the water column to equilibration with the atmosphere. We find that air‐sea CO2 disequilibrium enhances the global biogenic carbon inventory by ∼35% and its sequestration time by ∼70 years compared to identical calculations made assuming instantaneous air‐sea CO2 exchange. Locally, the greatest enhancement occurs in the subpolar Southern Ocean, where air‐sea disequilibrium increases sequestration times by up to 600 years and the biogenic dissolved inorganic carbon inventory by >100% in the upper ocean. Contrastingly, in deep‐water formation regions of the North Atlantic and Antarctic margins, where biological production creates undersaturated surface waters which are subducted before fully equilibrating with the atmosphere, air‐sea CO2 disequilibrium decreases the depth‐integrated sequestration inventory by up to ∼150%. The global enhancement of carbon sequestration by air‐sea disequilibrium is particularly important for carbon respired in deep waters that upwell in the Southern Ocean. These results highlight the importance of accounting for air‐sea CO2 disequilibrium when evaluating carbon sequestration by the biological pump and for assessing the efficacy of ocean‐based CO2 removal methods.
Plain Language Summary
In the surface ocean, tiny organisms called phytoplankton convert CO2 to organic matter, a portion of which is transferred to the deep ocean where it then releases CO2. This regenerated CO2 can be stored for hundreds to thousands of years before it is brought back to the surface ocean and reenters the atmosphere. Through this transfer of carbon from the surface to the depth, the “biological carbon pump” helps the ocean take up more CO2 from the atmosphere. In this study, we used computer models to determine how the rate of CO2 exchange between the ocean and the atmosphere impacts the amount of time CO2 can be stored in the ocean. Since the air‐sea exchange of CO2 is slow, the amount of carbon stored by the biological pump is about 35% greater than it would be if the exchange happened instantly. The slow air‐sea exchange rate also increases the length of time this carbon will be stored in the ocean. It is important to take this effect into account when assessing methods for deliberately storing CO2 in the ocean.
Key Points
Impact of air‐sea CO2 disequilibrium on biogenic carbon inventories and sequestration times is quantified using an ocean biogeochemical model
Air‐sea CO2 disequilibrium enhances global sequestration time by ∼70 years and biogenic dissolved inorganic carbon inventory by ∼35%
Disequilibrium effect is the strongest in the Southern Ocean and North Atlantic and weakest in the Pacific Ocean
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