Seagrass beds are important coastal habitats that are diminishing globally. Nitrogen, a key nutri... more Seagrass beds are important coastal habitats that are diminishing globally. Nitrogen, a key nutrient, often limits seagrass growth. Nitrogen fixation provides new, bioavailable nitrogen to the plants. This study explores its importance and factors controlling rates in sediments colonized by two dominant taxa in Northwest Florida, Thalassia testudinum and Halodule wrightii, compared to unvegetated sediments. We hypothesized that nitrogen fixation rates would be greater in seagrass colonized sediments, particularly during high growth periods. We expected to observe a positive relationship between rates and porewater sulfide concentrations because sulfate reducers were the dominant diazotrophs in similar studies. Rates were higher in vegetated areas. In H. wrightii beds, nitrogen fixation was driven by the decreased availability of porewater ammonium relative to phosphorus. In T. testudinum beds, rates were highest during winter. Organic matter may be a controlling factor in all substr...
Estuaries and coasts : journal of the Estuarine Research Federation, 2018
Seasonal responses in estuarine metabolism (primary production, respiration, and net metabolism) ... more Seasonal responses in estuarine metabolism (primary production, respiration, and net metabolism) were examined using two complementary approaches. Total ecosystem metabolism rates were calculated from dissolved oxygen time series using Odum's open water method. Water column rates were calculated from oxygen-based bottle experiments. The study was conducted over a spring-summer season in the Pensacola Bay estuary at a shallow seagrass-dominated site and a deeper bare-bottomed site. Water column integrated gross production rates more than doubled (58.7 to 130.9 mmol O m d) from spring to summer, coinciding with a sharp increase in water column chlorophyll-a, and a decrease in surface salinity. As expected, ecosystem gross production rates were consistently higher than water column rates, but showed a different spring-summer pattern, decreasing at the shoal site from 197 to 168 mmol O m d and sharply increasing at the channel site from 93.4 to 197.4 mmol O m d. The consistency amon...
Event based atmospheric deposition of mercury, trace metals and major ions has been monitored in ... more Event based atmospheric deposition of mercury, trace metals and major ions has been monitored in the Pensacola Bay (Florida) watershed over the last three years at three locations to evaluate the temporal and spatial patterns in atmospheric wet deposition. A goal of this project is to evaluate the contribution of local sources (coal fired power plant and paper mill) to
ABSTRACT Event-based (24-hour integrated) rainfall deposition of mercury, trace metals, and major... more ABSTRACT Event-based (24-hour integrated) rainfall deposition of mercury, trace metals, and major ions has been monitored over the last 6 years at 3 inland locations and at a "Beach" site close to the coast over the past 2 years in the Pensacola Bay watershed to evaluate the temporal and spatial patterns in atmospheric wet deposition. Samples were analyzed for total mercury and a suite of 50 other trace elements. One goal of this project was to attempt to quantify the contribution of local emission sources to atmospheric deposition of mercury and other heavy metals. There were no significant differences in the rainfall Hg flux between the three inland sites or between nearby Mercury Deposition Network monitoring sites along the Gulf Coast. However, the inland sites saw Hg fluxes in the range of 20-46% greater than that of the Beach site for the year 2010 and two of the nearby MDN sites saw a range of 35-71% greater over the first half of 2010 compared to the Beach site. We seek to explain these differences for sites that are relatively close together geographically. Mercury deposition during the summer months is higher than other months due to higher concentrations in the rainfall and higher summer-time rainfall rates throughout the region. Multivariate statistical analysis was used to sort these trace elements into factors that represent potential sources that contribute to the rainfall chemistry. Four significant factors were identified: (1) crustal dust factor (Al, Ba, Co, Cs, Fe, Li, Si), (2) sea-salt factor (Cl, Na, Mg, Sr), (3) Cd/Zn factor (Cd, Cr, Zn, P), and (4) a "pollution" factor (acidity, nitrate, excess-sulfate, ammonia, As, Bi, Hg, Pb, Sb, Se, Sn). Using ratios of Hg to volatile trace elements and excess sulfate, we can estimate that 22-33% of the rainfall mercury fluxes could be the result of emissions from coal combustion in the region while factor analysis suggests slightly over 40%. However, we cannot definitively distinguish the impacts from local vs. regional or distant sources on wet deposition of Hg. We also conduct a positive matrix factorization to account for source variations and percent contributions between seasons.
International Journal of Sustainable Society, 2012
ABSTRACT The need to track and analyse the atmospheric deposition of mercury and trace metals in ... more ABSTRACT The need to track and analyse the atmospheric deposition of mercury and trace metals in the Pensacola (Florida) Bay Watershed in recent years has resulted in the need for a data management system that will allow data to be efficiently stored, checked for errors, manipulated, retrieved for analysis and shared within the research community. In this paper, we describe a relational database that was developed as a data management tool to address the needs of those maintaining and using atmospheric deposition of mercury and trace metal data in the Pensacola Bay Watershed area. We present the overall design of the database and show useful queries that can be used to clean and maintain the integrity of the data, perform calculations on the data, join and union tables and retrieve the data for presentation and analysis.
IntroductIon Grand Bay National Estuarine Research Reserve (GB-NERR) is nitrogen-limited (Blackbu... more IntroductIon Grand Bay National Estuarine Research Reserve (GB-NERR) is nitrogen-limited (Blackburn 2000, Amacker 2013, Baine 2017) and adjacent to a phosphate fertilizer production facility (Mississippi Phosphates Corporation, MPC, Figure 1). The MPC produced diammonium phosphate (DAP) fertilizer from the 1960s until late 2014. Calcium sulfate, or phosphogypsum, a byproduct of this process, was stored in large stacks as waste. Phosphogypsum is rich in phosphorus, highly acidic (pH ~2 .4), and contains several impurities such as radionuclides, heavy metals, fluoride, and sulfide (
Nitrate and water quality parameters (temperature, salinity, dissolved oxygen, turbidity, and dep... more Nitrate and water quality parameters (temperature, salinity, dissolved oxygen, turbidity, and depth) were measured continuously with in situ NO 3 analyzers and water quality sondes at two sites in Elkhorn Slough in Central California. The Main Channel site near the mouth of Elkhorn Slough was sampled from February to September 2001. Azevedo Pond, a shallow tidal pond bordering agricultural fields further inland, was sampled from December 1999 to July 2001. Nitrate concentrations were recorded hourly while salinity, temperature, depth, oxygen, and turbidity were recorded every 30 min. Nitrate concentrations at the Main Channel site ranged from 5 to 65 M. The propagation of an internal wave carrying water from ϳ100 m depth up the Monterey Submarine Canyon and into the lower section of Elkhorn Slough on every rising tide was a major source of nitrate, accounting for 80-90% of the nitrogen load during the dry summer period. Nitrate concentrations in Azevedo Pond ranged from 0-20 M during the dry summer months. Nitrate in Azevedo Pond increased to over 450 M during a heavy winter precipitation event, and interannual variability driven by differences in precipitation was observed. At both sites, tidal cycling was the dominant forcing, often changing nitrate concentrations by 5-fold or more within a few hours. Water volume flux estimates were combined with observed nitrate concentrations to obtain nitrate fluxes. Nitrate flux calculations indicated a loss of 4 mmol NO 3 m Ϫ2 d Ϫ1 for the entire Elkhorn Slough and 1 mmol NO 3 m Ϫ2 d Ϫ1 at Azevedo Pond. These results suggested that the waters of Elkhorn Slough were not a major source of nitrate to Monterey Bay but actually a nitrate sink during the dry season. The limited winter data at the Main Channel site suggest that nitrate was exported from Elkhorn Slough during the wet season. Export of ammonium or dissolved organic nitrogen, which we did not monitor, may balance some or all of the NO 3 flux.
Measurements of denitrification using the acetylene inhibition, 15N isotope tracer, and N2 flux m... more Measurements of denitrification using the acetylene inhibition, 15N isotope tracer, and N2 flux methods were carried out concurrently using sediment cores from Vilhelmsborg sø, Denmark, in an attempt to clarify some of the limitations of each technique. Three ...
Seagrass beds are important coastal habitats that are diminishing globally. Nitrogen, a key nutri... more Seagrass beds are important coastal habitats that are diminishing globally. Nitrogen, a key nutrient, often limits seagrass growth. Nitrogen fixation provides new, bioavailable nitrogen to the plants. This study explores its importance and factors controlling rates in sediments colonized by two dominant taxa in Northwest Florida, Thalassia testudinum and Halodule wrightii, compared to unvegetated sediments. We hypothesized that nitrogen fixation rates would be greater in seagrass colonized sediments, particularly during high growth periods. We expected to observe a positive relationship between rates and porewater sulfide concentrations because sulfate reducers were the dominant diazotrophs in similar studies. Rates were higher in vegetated areas. In H. wrightii beds, nitrogen fixation was driven by the decreased availability of porewater ammonium relative to phosphorus. In T. testudinum beds, rates were highest during winter. Organic matter may be a controlling factor in all substr...
Estuaries and coasts : journal of the Estuarine Research Federation, 2018
Seasonal responses in estuarine metabolism (primary production, respiration, and net metabolism) ... more Seasonal responses in estuarine metabolism (primary production, respiration, and net metabolism) were examined using two complementary approaches. Total ecosystem metabolism rates were calculated from dissolved oxygen time series using Odum's open water method. Water column rates were calculated from oxygen-based bottle experiments. The study was conducted over a spring-summer season in the Pensacola Bay estuary at a shallow seagrass-dominated site and a deeper bare-bottomed site. Water column integrated gross production rates more than doubled (58.7 to 130.9 mmol O m d) from spring to summer, coinciding with a sharp increase in water column chlorophyll-a, and a decrease in surface salinity. As expected, ecosystem gross production rates were consistently higher than water column rates, but showed a different spring-summer pattern, decreasing at the shoal site from 197 to 168 mmol O m d and sharply increasing at the channel site from 93.4 to 197.4 mmol O m d. The consistency amon...
Event based atmospheric deposition of mercury, trace metals and major ions has been monitored in ... more Event based atmospheric deposition of mercury, trace metals and major ions has been monitored in the Pensacola Bay (Florida) watershed over the last three years at three locations to evaluate the temporal and spatial patterns in atmospheric wet deposition. A goal of this project is to evaluate the contribution of local sources (coal fired power plant and paper mill) to
ABSTRACT Event-based (24-hour integrated) rainfall deposition of mercury, trace metals, and major... more ABSTRACT Event-based (24-hour integrated) rainfall deposition of mercury, trace metals, and major ions has been monitored over the last 6 years at 3 inland locations and at a "Beach" site close to the coast over the past 2 years in the Pensacola Bay watershed to evaluate the temporal and spatial patterns in atmospheric wet deposition. Samples were analyzed for total mercury and a suite of 50 other trace elements. One goal of this project was to attempt to quantify the contribution of local emission sources to atmospheric deposition of mercury and other heavy metals. There were no significant differences in the rainfall Hg flux between the three inland sites or between nearby Mercury Deposition Network monitoring sites along the Gulf Coast. However, the inland sites saw Hg fluxes in the range of 20-46% greater than that of the Beach site for the year 2010 and two of the nearby MDN sites saw a range of 35-71% greater over the first half of 2010 compared to the Beach site. We seek to explain these differences for sites that are relatively close together geographically. Mercury deposition during the summer months is higher than other months due to higher concentrations in the rainfall and higher summer-time rainfall rates throughout the region. Multivariate statistical analysis was used to sort these trace elements into factors that represent potential sources that contribute to the rainfall chemistry. Four significant factors were identified: (1) crustal dust factor (Al, Ba, Co, Cs, Fe, Li, Si), (2) sea-salt factor (Cl, Na, Mg, Sr), (3) Cd/Zn factor (Cd, Cr, Zn, P), and (4) a "pollution" factor (acidity, nitrate, excess-sulfate, ammonia, As, Bi, Hg, Pb, Sb, Se, Sn). Using ratios of Hg to volatile trace elements and excess sulfate, we can estimate that 22-33% of the rainfall mercury fluxes could be the result of emissions from coal combustion in the region while factor analysis suggests slightly over 40%. However, we cannot definitively distinguish the impacts from local vs. regional or distant sources on wet deposition of Hg. We also conduct a positive matrix factorization to account for source variations and percent contributions between seasons.
International Journal of Sustainable Society, 2012
ABSTRACT The need to track and analyse the atmospheric deposition of mercury and trace metals in ... more ABSTRACT The need to track and analyse the atmospheric deposition of mercury and trace metals in the Pensacola (Florida) Bay Watershed in recent years has resulted in the need for a data management system that will allow data to be efficiently stored, checked for errors, manipulated, retrieved for analysis and shared within the research community. In this paper, we describe a relational database that was developed as a data management tool to address the needs of those maintaining and using atmospheric deposition of mercury and trace metal data in the Pensacola Bay Watershed area. We present the overall design of the database and show useful queries that can be used to clean and maintain the integrity of the data, perform calculations on the data, join and union tables and retrieve the data for presentation and analysis.
IntroductIon Grand Bay National Estuarine Research Reserve (GB-NERR) is nitrogen-limited (Blackbu... more IntroductIon Grand Bay National Estuarine Research Reserve (GB-NERR) is nitrogen-limited (Blackburn 2000, Amacker 2013, Baine 2017) and adjacent to a phosphate fertilizer production facility (Mississippi Phosphates Corporation, MPC, Figure 1). The MPC produced diammonium phosphate (DAP) fertilizer from the 1960s until late 2014. Calcium sulfate, or phosphogypsum, a byproduct of this process, was stored in large stacks as waste. Phosphogypsum is rich in phosphorus, highly acidic (pH ~2 .4), and contains several impurities such as radionuclides, heavy metals, fluoride, and sulfide (
Nitrate and water quality parameters (temperature, salinity, dissolved oxygen, turbidity, and dep... more Nitrate and water quality parameters (temperature, salinity, dissolved oxygen, turbidity, and depth) were measured continuously with in situ NO 3 analyzers and water quality sondes at two sites in Elkhorn Slough in Central California. The Main Channel site near the mouth of Elkhorn Slough was sampled from February to September 2001. Azevedo Pond, a shallow tidal pond bordering agricultural fields further inland, was sampled from December 1999 to July 2001. Nitrate concentrations were recorded hourly while salinity, temperature, depth, oxygen, and turbidity were recorded every 30 min. Nitrate concentrations at the Main Channel site ranged from 5 to 65 M. The propagation of an internal wave carrying water from ϳ100 m depth up the Monterey Submarine Canyon and into the lower section of Elkhorn Slough on every rising tide was a major source of nitrate, accounting for 80-90% of the nitrogen load during the dry summer period. Nitrate concentrations in Azevedo Pond ranged from 0-20 M during the dry summer months. Nitrate in Azevedo Pond increased to over 450 M during a heavy winter precipitation event, and interannual variability driven by differences in precipitation was observed. At both sites, tidal cycling was the dominant forcing, often changing nitrate concentrations by 5-fold or more within a few hours. Water volume flux estimates were combined with observed nitrate concentrations to obtain nitrate fluxes. Nitrate flux calculations indicated a loss of 4 mmol NO 3 m Ϫ2 d Ϫ1 for the entire Elkhorn Slough and 1 mmol NO 3 m Ϫ2 d Ϫ1 at Azevedo Pond. These results suggested that the waters of Elkhorn Slough were not a major source of nitrate to Monterey Bay but actually a nitrate sink during the dry season. The limited winter data at the Main Channel site suggest that nitrate was exported from Elkhorn Slough during the wet season. Export of ammonium or dissolved organic nitrogen, which we did not monitor, may balance some or all of the NO 3 flux.
Measurements of denitrification using the acetylene inhibition, 15N isotope tracer, and N2 flux m... more Measurements of denitrification using the acetylene inhibition, 15N isotope tracer, and N2 flux methods were carried out concurrently using sediment cores from Vilhelmsborg sø, Denmark, in an attempt to clarify some of the limitations of each technique. Three ...
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Papers by Jane Caffrey