B41C-01
Transboundary air Pollution in Peruvian Amazonia
Biomass burning in the tropics is an important source of pollution to the atmosphere with different and not well understood consequences to the climate and the atmospheric chemistry. Burning over Amazonia is related mainly to land use cover change. During the dry season (May to November) high amount of fires are produced in Amazonia. The resulting pollutants under some conditions could produce tropospheric ozone, which reaches long distances far from the sources, the same occurs with aerosols, both could be detected by ground and satellite measurements. The work focused on the transboundary air pollution between Brazil and Peru during the last years. In this sense, this research determines the seasonal variations and the spatial coverage of this pollution in Peruvian Amazonia. We used satellite data and ground measurements to make a detailed evaluation of the transport and production of pollutants (tropospheric ozone and aerosols) related to biomass burning in order to quantify the levels of pollution based on tropospheric ozone and aerosol index and optical depth. Also, we evaluate the climatology of fires detected by satellites. It is expected that the results will provide basic information to policy makers about possible effects of this pollution in the natural resources of Peru. Also, we will provide the scientific basis for the National Program for Prevention of Forest Fires.
B41C-02
Uncertainty Assessment for the Vegetated Filter Strip Performance with Respect to Manure- Borne Pathogens
Vegetated filter strips (VFS) separate fields and pastures from streams and other water bodies and can serve as barriers that prevent sediment and agricultural chemicals from entering waterways and spoiling them. Growing concern about the manure-borne pathogens as water pollutants defines the need to evaluate efficiency of VFSs with respect to pathogens. Selecting locations for the VFS placement can be done with the SWAT model allows for a comprehensive description of agricultural practices, and has proven to be efficient in applications to watershed with a substantial agricultural component. Functioning of VSF as barriers for manure-borne pathogens to the large extent depends on vegetation status, soil infiltration capacity in VFS, and rainfall intensity and duration. The effect of these factors on the pathogen breakthrough in VFS needs to be researched at the time scales smaller than the computation interval of one day that SWAT uses. The downscaling is necessary which creates an unavoidable uncertainty that cannot be ignored and has to be factored into the VFS efficiency estimates. We have developed the model STIR to simulate the overland transport and loss to infiltration of manure-borne pathogens in VFS. This model was used in Monte Carlo simulations in which the input parameters of vegetation, soil, rainfall, and pathogen load were drawn from probability distribution functions. The result of such simulations was also the probability distribution of the VFS efficiency. For the example of our experimental 6-m long VFS at the 20% slope, the VFS efficiency was less than 100% in 5% of cases, and less than 75% in 2.5% of cases. Relatively long high-intensity rainfalls, low hydraulic conductivities, high soil moisture contents before the rainfall, and high spread of surface water velocities were the main sources of the strip partial failure. Similar simulations can be done for any other VFS with site-specific soil and weather properties, and the results on terms of efficiency probabilities can be used in making decisions on VFS placement with respect to manure-borne pathogens.
B41C-03
Association of Drought with Typhus Epidemics in Central Mexico
Typhus is an acute infectious disease caused by the bacteria Rickettsia prowazekii, which is transmitted among humans by the body lice (Pediculus humanus corporis). The disease is highly contagious and transmission is favored in populations living in crowded conditions. Under these circumstances, typhus transmission is facilitated by factors that favor the colonization and proliferation of body lice such as absence of personal hygiene and wearing the same clothes for long periods of time. Historically, periods of war and famine were associated with devastating epidemics with high mortality rates in many parts of the world. Central Mexico has a long record of typhus epidemics. In this region, at > 2000 meters above sea level, the disease was endemic and occurred with a seasonal pattern in winter, with occasional large epidemics. Recently, we completed a chronology of epidemics in Mexico. A total of 22 well-defined major typhus epidemics were identified between 1650 and 1920. All of them caused periods of increased mortality that lasted 2 - 4 years (more than one standard deviation from the previous ten year period). The record of typhus epidemics was evaluated against the tree-ring record of Cuauhtmoc La Fragua, Puebla. This chronology, based on Douglas fir, has demonstrated to be a faithful record of precipitation in central Mexico. The results indicate that a statistically significant drought (t test, p < .05) prevailed during the first year of all 22 large outbreaks of typhus in recent Mexican history. No distinction is made between times of peace and war. This indicates that drought alone was capable of inducing the social conditions for increased transmission of typhus in pre-industrial central Mexico.
B41C-04
Anammox Coupled With Nitrification Impacts a Saline, High Ammonia Groundwater
High amounts of ammonia (130 to 2200 mg-N/l) in a saline environment (TDS = 10-20 g/l) are present in a groundwater plume adjacent to the Colorado River near Moab, Utah. Ammonia levels sufficient to affect aquatic life have been observed in limited sections of the river adjacent to the site, which has prompted interim treatment efforts. Microcosm studies were performed to assess the potential for microbial transformations of ammonia in the hyporheic zone sediment and the effect of ground/river-water mixing on transformations. Experiments were conducted using sub-riverbed sediment and mixtures of groundwater (290 mg-N/L ammonia) and river water (100%, 50% and 10% plume water) in anaerobic and aerobic environments. Aqueous NH4+, NO2-, NO3-, pH, dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC) were monitored over 38 days. Interestingly, the ammonia concentration decreased in all microcosms (29% to 100%) with the highest removal occurring in the oxic microcosms. Total nitrogen removal ranged from 27% to 83%. Three lines of evidence suggest that anammox occurred in the anaerobic microcosms: 1) NH4+ concentrations decreased, 2) little change in DOC occurred and 3) DIC decreased. DIC should increase if denitrification were the dominant process. It is possible that small amounts of O2 diffused into the microcosms, driving some nitrification that supplied NO2- for anammox. In the aerobic microcosms, denitrification or anammox occurred in addition to nitrification because nitrate did not accumulate in general. Again, we believe anammox occurred because of DOC and DIC trends. In the aerobic 10% groundwater microcosm, NO3- accumulated once the ammonia concentration became low and the nitrate level stabilized after the ammonia was gone. This also indicated that anammox was the dominant process because denitrification should not stop due to ammonia depletion. The aerobic microcosms were only agitated twice per week, which would allow the sediments to become anoxic. Concurrent nitrification and anammox has been observed in aerobic wastewater treatment and sediment environments due to anaerobic microenvironments.
B41C-05
Immediate Impact of Elevated Nitrogen Input on Trace Gases Emissions in an old-Growth Lowland Forest in Panama
In tropical areas, nitrogen (N) emission, transport and deposition are projected to increase rapidly in the next decades. In this study, the consequences of elevated N input on trace gases emissions from a tropical lowland forest soil were evaluated. The study site is located in Gigante Peninsula, Panama, which included control and N addition treatments each with four replicate plots. Urea-N was applied twice in 2006 (April 28 and June 6) at a rate of 31.25 kg N ha-1 each application. Nitrous oxide (N2O), nitric oxide (NO), carbon dioxide (CO2) and methane (CH4) fluxes were intensively measured prior to and until one month after the second N application; this measurement period was within the beginning of the rainy season. We observed significantly higher NO emissions from the N-fertilized than the control plots, but N2O, CO2 and CH4 fluxes did not differ. The increased NO fluxes were largely observed during the first week after the second fertilization, when water-filled pore space (WFPS) has increased as the rainy season progressed. N2O emissions could possibly increase with N addition when soil moisture further increase into the rainy season. The significant correlation between N2O + NO fluxes and NH4+ levels and the range of WFPS (40-60%) indicated that N trace gases were possibly predominantly produced by nitrification. The fertilizer- induced N oxide emission was 3% of the applied N. The CO2 and CH4 fluxes indicated that initial N addition did not bring detectable change in microbial decomposition and root respiration for CO2 emissions and in CH4 consumption and production for CH4 fluxes, at least during the early rainy season covered in our measurement.
B41C-06
Methane and Nitrous Oxide in the Central and Eastern Black Sea
Methane (CH4) and nitrous oxide (N2O) are two major greenhouse gases whose concentrations have risen significantly since 1750. The Black Sea has been identified as a source for both of these greenhouse gases. The methane emitted is thought to origin from the anoxic deep waters or from bubble transport bypassing the oxic/anoxic boundary, while the nitrous oxide stems from nitrification and denitrification in low oxygen and suboxic zones. Data availability for both gases is best for the Western and North-Western area of the basin, and scarce for the Eastern part. In this study we wanted to enlarge the data base by collecting samples from the Central and Eastern Black Sea. We measured concentration and isotopic composition of CH4 and N2O every five meters across the oxic/anoxic boundary, as well as about every twenty meters in the surface water. This way we tried to distinguish between methane from the anoxic deep waters and methane produced in the surface waters, as well as to determine the amount of methane oxidized aerobically compared to anaerobically. For N2O we could distinguish zones of production and consumption, as well as surface water concentrations not influenced by the nutrient inputs of the Danube or other major rivers.
B41C-07
Increases of riverine dissolved inorganic carbon fluxes over the Mississippi River Basin: The role of changing water-throughput and watershed H+ inputs.
Previously about 50% of alkalinity flux increase over the last 50 years from the North America's largest river, the Mississippi was reported. The mechanism for this initial finding was determined to be an increase in water throughput. Extending the research, we investigated spatial variation on riverine alkalinity fluxes from the Mississippi River basin using US Geological Survey Water Data and a variety of GIS layers including yearly precipitation. Since flux is estimated by multiplying concentration and discharge, the increase in alkalinity flux can be due to increase of both concentration and discharge. Results demonstrate that increases in both precipitation and the discharge normalized concentration contributed significantly to changes in alkalinity flux and demonstrate that the relative contributions of the both on the flux was greatly dependent on different hydrologic regions, indicating the importance of spatial variation on riverine alkalinity flux.