17 research outputs found
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Atmospheric methanol budget and ocean implication
Methanol is a biogeochemically active compound and a significant component of the volatile organic carbon in the atmosphere. It influences background tropospheric photochemistry and may serve as a tracer for biogenic emissions. The mass of methanol in the atmospheric reservoir, the annual mass flux of methanol from sources to sinks, and the estimated atmospheric lifetime of methanol in the free troposphere, marine boundary layer, continental boundary layer, and in-cloud, are evaluated. The atmosphere contains approximately 4 Tg (terragrams, 1012 g) of methanol. Estimates of global methanol sources and sinks total 340 and 270 Tg methanol yr-1, respectively, and are in balance given their estimated precision. Sink terms were evaluated using observed methanol distributions; the total loss is approximately a factor of 5 larger than prior estimates. The adopted source is a factor of 3 larger than its prior estimate. Recent net flux observations and the magnitude of the estimated sink suggest biogenic methanol emissions to be near their current estimated upper limit, >280 Tg methanol yr-1, and this value was adopted. The methanol source will be larger with the inclusion of an argued for oceanic gross emission of 30 Tg methanol yr-1, but a major uncertainty concerns whether the oceans are a major net sink or source of methanol, an issue which will not be resolved without new measurements. Other large uncertainties are the estimates of primary biogenic emissions and gas surface deposition. The first loss estimates of methanol by in-cloud chemistry and precipitation are presented. They are approximately equal at 10 Tg methanol yr-1, each. These are small in comparison to the surface loss and gas phase photochemical loss estimated here but would be significant additional losses in earlier budgets. Surface exchange processes dominate the atmospheric budget of methanol and its distribution. The atmospheric deposition of methanol and the argued for methanol produced in the upper ocean are ubiquitous sources of C1 substrate capable of sustaining methylotrophic organisms throughout the surface ocean
Recommended from our members
Atmospheric methanol budget and ocean implication
Methanol is a biogeochemically active compound and a significant component of the volatile organic carbon in the atmosphere. It influences background tropospheric photochemistry and may serve as a tracer for biogenic emissions. The mass of methanol in the atmospheric reservoir, the annual mass flux of methanol from sources to sinks, and the estimated atmospheric lifetime of methanol in the free troposphere, marine boundary layer, continental boundary layer, and in-cloud, are evaluated. The atmosphere contains approximately 4 Tg (terragrams, 1012 g) of methanol. Estimates of global methanol sources and sinks total 340 and 270 Tg methanol yr-1, respectively, and are in balance given their estimated precision. Sink terms were evaluated using observed methanol distributions; the total loss is approximately a factor of 5 larger than prior estimates. The adopted source is a factor of 3 larger than its prior estimate. Recent net flux observations and the magnitude of the estimated sink suggest biogenic methanol emissions to be near their current estimated upper limit, >280 Tg methanol yr-1, and this value was adopted. The methanol source will be larger with the inclusion of an argued for oceanic gross emission of 30 Tg methanol yr-1, but a major uncertainty concerns whether the oceans are a major net sink or source of methanol, an issue which will not be resolved without new measurements. Other large uncertainties are the estimates of primary biogenic emissions and gas surface deposition. The first loss estimates of methanol by in-cloud chemistry and precipitation are presented. They are approximately equal at 10 Tg methanol yr-1, each. These are small in comparison to the surface loss and gas phase photochemical loss estimated here but would be significant additional losses in earlier budgets. Surface exchange processes dominate the atmospheric budget of methanol and its distribution. The atmospheric deposition of methanol and the argued for methanol produced in the upper ocean are ubiquitous sources of C1 substrate capable of sustaining methylotrophic organisms throughout the surface ocean
Evolution of cetacean osmoregulation
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62665/1/381379b0.pd
On the Response of pH to Inorganic Nutrient Enrichment in Well-Mixed Coastal Marine Waters
Recent concerns about declining pH in the surface ocean in response to anthropogenic increases of carbon dioxide (CO2) in the atmosphere have raised the question of how this declining baseline of oceanic pH might interact with the much larger diel and seasonal variations of pH in coastal marine ecosystems. Nutrient enrichment, which can amplify both production and respiration, has the potential to reduce or exacerbate the impacts of ocean acidification in coastal waters. Here, we present results from a multi-year experiment in which replicate phytoplankton-based mesocosms with a 5-m deep well-mixed water column (salinity = 27–31) and intact benthic community were exposed to a gradient in daily inorganic nitrogen (N), phosphorous (P), and silica (Si) addition. We show that the response of water column pH to nutrient enrichment was the greatest during the autotrophic winter-spring period, and there was no significant decline in pH across treatments during the heterotrophic summer-fall period. We believe that the differences in response lie in the seasonal cycles of production and respiration, where spring production peaks are large and discrete, and respiration is more temperature-driven but occurs diffusely throughout the year. The observed basification associated with enhanced nutrient inputs may have consequences for phytoplankton community structure, some species of submersed aquatic vegetation, cycling of Si, and perhaps other ecological processes