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Project Progress

We investigate an analog of a biosphere and focus on hind-casting its biogeochemical cycles. The carbon cycle is most important in the biosphere and is reflected by the Net Primary Production (NPP). NPP varies with climate and life variables. We reconstruct the history of NPP in South America over the last 2,500 years at 8-km spatial resolution and 1-year time resolution in order to understand past ecosystem process and provide larger time windows for future prediction. Our model is formulated to circumvent the shortcomings of the fossil record and adjusted for prediction as the major drivers of climate vary.

Paleo NPP = {LGS [(PET/ Paleo-NDVI)*Paleo-NDVI] * [N in soil]}*[V.O.S.]

LGS = temperature-controlled length of the growing season; PET / Paleo-NDVI = potential evapotranspiration trimmed by the inferred vegetation index, [N in soil] = available nutrients, V.O.S. (volcanic, orbital, solar) are data of the drivers of Holocene climate.

Accomplishments: databases, remote sensing studies and ground-truth stations in South America, fieldwork, pollen analysis of Patagonia, model testing, effects of increased solar ultraviolet radiation on human skin, and EPO work.

1. 
   We completed databases for LGS, PET, N in soil, and V.O.S., needed to run the model, developed databases for tree-rings (2,500 years), volcanic eruptions recorded in ice cores, orbital eccentricity, precession, ecliptic angle at 1-year resolution for the last 2,500 years, solar databases, satellite data showing solar output variation, and surface measurements of solar radiation to include atmospheric influence, ice core proxy data for the last 2,500 years, gases and isotopes trapped in fossil ice, methane, carbon dioxide, Talos δ Deuterium, Dome δ Deuterium, δ ¹⁸Oxygen, Deuterium excess. We used non-linear math and neural networks for our calculations.
2. In remote sensing we measured spectral changes in South American plant cover linked to “El Niño” Southern Oscillation over the period of 1982-2000, created 160 calibration stations, each with 20-year data, and monthly resolution to capture maximum variation, for model calibration. We tested correlation between Sea Surface Temperature (SST) the vegetation index. Consequently, we improved our reconstruction of past SST at 1-year resolution for the last 750 years treating tree-ring data with neural networks (D’Antoni and Mlinarevic 2002) and are extending it to 2,500 years in order to use it as one of the predictors of past NDVI.

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3. We developed a ground-truth program with monitoring stations in the Atuel Wetlands (Altolaguirre), in Balcarce (Magnoni), and in the riparian forest of Buenos Aires, where Dr. Madanes is already producing a continuous stream of quality data.

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4. Fieldwork: In December 2005, D’Antoni measured chlorophyll absorbance, solar radiation, and soil moisture in several transects around lakes Nahuel Huapi and Argentino (Patagonia), and in Tierra del Fuego, at the sites of our main proxy records in the subantarctic forests.

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   For fieldwork we assembled a portable, computer-controlled laboratory to measure, solar radiation in the 250-750 nm range, at 1-nm resolution*, chlorophyll absorbance, chlorophyll concentration, soil moisture* and concentration of nitrogen (NO₃^-), sodium (Na), and potassium (K), pH, and soil temperature to 12”. We added a digital photo camera*, a digital movie camera*, a digital microscope, and a GPS receiver*. (* = used in 2005 fieldwork).

5. Given the relatively short span of the tree-ring record, we made new efforts in pollen analysis that are yielding further detail (Burry et al. 2005), a larger time window [present to -9300] for our research in Patagonia (Trivi et al. 2005) and Tierra del Fuego (Burry et al. 2005) [present to -10,000]. Despite its lower time resolution, the pollen record is the next source of proxy data for our modeling work.
6. In model testing we calibrated and used available and reliable proxy data, and hosted the model in a spreadsheet for easy operation. Predictions are compared with those of Potter’s NASA-CASA. The model was tested over 200 years in the Lago Agrio calibration site (Ecuador).

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7. In effects of increased solar ultraviolet radiation on human skin, results of our joint research effort with minority-serving University of Puerto Rico-Mayagüez and Ponce School of Medicine were published (2005). We established a threshold dose of 24-28 KJ/m², equivalent to 19’ exposure to UV-A and 23’ to UV-B to produce apoptosis and necrosis of skin fibroblasts. Dose and exposures are relatively low and hence important for humans on Earth as well as for those involved in NASA’s exploration enterprise. Other aspects of our research on solar UV-radiation link with Project 7 (Rothschild) of the Ames Team. We also collaborate with R. Amils (from NAI member, Centro de Astrobiología, Madrid) on spectroscopy of the bacteria from Rio Tinto.

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8. In EPO work, we trained three graduate students and one undergraduate and, due to their performance, made them coauthors of our presentations. Leveraging on SBIRs and MURED projects, we performed joint research on the effects of UV-A and B radiation on human skin with the Ponce School of Medicine using NASA sponsored technology (GeneEngine, only used at the schools of medicine at Harvard, UCSF, and Ponce) for DNA research. We started collaboration with the National Park Service, and gave papers and a few invited speeches at science conferences and meetings in the US and overseas. D’Antoni has been interviewed by specialized press (biochemistry) and newspapers in Argentina and Spain, and also in the Spanish television.