Browsing by Subject "photosynthesis"

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Developing a microfluidic device for in situ water column profiling of phototrophic sulfur bacteria
    (Office of the Vice Chancellor for Research, 2015-04-17) Kellogg, Austin; East, Zachary
    Phototrophic purple sulfur bacteria are crucial to study in Biogeochemistry because they are thought to be one of the first organisms to utilize photosynthesis. In the early atmosphere, there was very little oxygen present. Sulfur bacteria use light and sulfides as energy in anoxic conditions. Conditions suitable for sulfur bacteria can be found in anoxic lakes, which many are located in northern Indiana and the Pacific Northwest. The main goal of this project was to design and create a device that could record data and abstract samples of purple sulfur bacteria in anoxic lakes. In order to create this device, we first had to test the purple sulfur bacteria’s light absorbance using a spectrophotometer. The data collected about the sulfur bacteria’s absorbance was used by us to optimize our design for the circuit which incorporated the LED and Photo-detector components. Also, a Thermosensor component was added in an attempt to determine the optimal temperature sulfur bacteria lives in. Overall, six Op-amps were used in order to limit the amount of noise and to convert current into voltage so temperature and light absorbance can be measured.
  • Thumbnail Image
    Item
    From remotely-sensed solar-induced chlorophyll fluorescence to ecosystem structure, function, and service: Part II—Harnessing data
    (Wiley, 2023-06) Sun, Ying; Wen, Jiaming; Gu, Lianhong; Joiner, Joanna; Chang, Christine Y.; van der Tol, Christiaan; Porcar-Castell, Albert; Magney, Troy; Wang, Lixin; Hu, Leiqiu; Rascher, Uwe; Zarco-Tejada, Pablo; Barrett, Christopher B.; Lai, Jiameng; Han, Jimei; Luo, Zhenqi; Earth and Environmental Sciences, School of Science
    Although our observing capabilities of solar-induced chlorophyll fluorescence (SIF) have been growing rapidly, the quality and consistency of SIF datasets are still in an active stage of research and development. As a result, there are considerable inconsistencies among diverse SIF datasets at all scales and the widespread applications of them have led to contradictory findings. The present review is the second of the two companion reviews, and data oriented. It aims to (1) synthesize the variety, scale, and uncertainty of existing SIF datasets, (2) synthesize the diverse applications in the sector of ecology, agriculture, hydrology, climate, and socioeconomics, and (3) clarify how such data inconsistency superimposed with the theoretical complexities laid out in (Sun et al., 2023) may impact process interpretation of various applications and contribute to inconsistent findings. We emphasize that accurate interpretation of the functional relationships between SIF and other ecological indicators is contingent upon complete understanding of SIF data quality and uncertainty. Biases and uncertainties in SIF observations can significantly confound interpretation of their relationships and how such relationships respond to environmental variations. Built upon our syntheses, we summarize existing gaps and uncertainties in current SIF observations. Further, we offer our perspectives on innovations needed to help improve informing ecosystem structure, function, and service under climate change, including enhancing in-situ SIF observing capability especially in “data desert” regions, improving cross-instrument data standardization and network coordination, and advancing applications by fully harnessing theory and data.
  • Thumbnail Image
    Item
    Improved understanding of the spatially-heterogeneous relationship between satellite solar-induced chlorophyll fluorescence and ecosystem productivity
    (Elsevier, 2021-10) Song, Yang; Wang, Lixin; Wang, Jing; Earth Science, School of Science
    Satellite solar-induced chlorophyll fluorescence (SIF) is deemed as a good proxy for vegetation photosynthesis. To date, SIF has been shown to correlate strongly with gross primary productivity (GPP) at ecosystem scale and perform well in monitoring the impacts of extreme climate events on ecosystem productivity. However, the SIF-GPP relationship exhibits a spatially-heterogeneous pattern across ecosystems and produces both linear and nonlinear results at different spatiotemporal scales. Understanding of the different spatiotemporal SIF-GPP relationships is still incomplete and somewhat controversial in previous studies. Here, based on the light-use efficiency (LUE) models, this study investigated the spatially-heterogeneous SIF-GPP relationships across the conterminous United States (CONUS), and examined the possible drivers and mechanisms. Our results showed that SIF and GPP exhibited similar spatiotemporal patterns but responded differently to environmental factors (i.e., soil moisture, precipitation, photosynthetically active radiation, air temperature, and atmospheric vapor pressure deficit). The correlation analysis showed that the SIF-GPP relationships were spatially-heterogeneous across the CONUS both at monthly and annual scales. Moreover, our findings also indicated that different biome types could partly explain the spatial heterogeneity of SIF-GPP relationship. Different canopy structures and vegetation coverages across biomes could be primary drivers of the spatially-heterogeneous SIF-GPP relationship. In addition, the SIF-GPP relationships under the baseline and drought scenarios appeared to be similar and consistent. It implies that there could be an invariant SIF-GPP relationship under both drought and non-drought conditions, leading to a weak effect of interannual drought on the spatial heterogeneity. In summary, our results highlight that the effects of biome characteristics (Ωbiome) and environmental stresses (Φstress) on spatially-heterogeneous SIF-GPP relationship and further explore possible mechanisms of the linkage between SIF and GPP.