Browsing by Subject "Dew"

Now showing 1 - 5 of 5
  • Thumbnail Image
    Item
    Dew formation characteristics in the gravel desert ecosystem and its ecological roles on Reaumuria soongorica
    (Elsevier, 2021-12) Zhuang, Yanli; Zhao, Wenzhi; Luo, Lihui; Wang, Lixin; Earth Sciences, School of Science
    As an additional source of water to plants besides rainfall, dew may have a positive impact on vegetation in the arid ecosystems. Knowledge regarding dew formation characteristics and its ecological effects on vegetation water status and photosynthetic performance in the gravel desert ecosystem is still lacking. In this study, the dew variability and formation frequency on a gravel desert were measured by microlysimeters. We quantified dew formation characteristics, investigated vegetation water response to dew events in the gravel desert ecosystem at the edge of a desert oasis, Northwestern China. The results showed water adsorption was a primary pathway of dew formation in such system, and the average daily amount of dew is 0.06 mm. Dew occurred on 36% of growing season days, the number of days with dew amounts >0.03 mm accounted for 82% of the total dew events, and the cumulative amount of dew for those days was 3.41 mm. Relative humidity, air temperature, wind speed, the difference between air temperature and soil surface temperature had significant effects on dew formation. A threshold of RH ≥30% is taken to mark possible condensation in the gravel desert ecosystem. A significant positive correlation between dew amounts and the relative moisture in the near-surface air was found when RH ≥30%. The moderate wind velocity (1–1.8 m/s) was favorable to dew formation, and when wind speed >5.47 m/s, there was no dew formation. Because of the water-absorbing scales on the leaves of Reaumuria soongorica, dew events significantly improved their relative water content, water potential, and photosynthetic performance in the early morning and ameliorating the adverse effects of plants exposed to prolonged drought. The study highlights dew is an important supplementary source of water in the gravel desert ecosystem. Although the absolute dew amounts were found not high, it can be a frequent and stable water resource. Furthermore, this study provides a comprehensive understanding of the effects of dew on plant water status in the gravel desert ecosystem.
  • Thumbnail Image
    Item
    Fog and Dew as Potable Water Resources: Maximizing Harvesting Potential and Water Quality Concerns
    (Wiley, 2018) Kaseke, Kudzai F.; Wang, Lixin; Earth Sciences, School of Science
    Fog and dew are often viewed as economic nuisances causing significant financial losses in the transportation industry and agricultural sector. However, they are also critical components of the hydrological cycle, especially in water scarce environments. Water scarcity is one of the major threats to mankind in the 21st century, and this can be due to development pressures, pollution, and/or expanding populations. In water scarce environments, fog and dew represent potentially exploitable ancillary water resources that could ameliorate the water scarce situation, if efficiently harvested. However, two important issues are often overlooked in relation to fog and dew harvesting and potability. First, current fog and dew harvesting technologies are low yielding with great potential for improvements. Second and more importantly, the potability of these water resources is often based on simple analyses that often omit trace metal and biological analyses. The few studies that report trace metal or biological measurements suggest elevated trace metal concentrations or biological contamination that could be of concern to public health. We discuss the potential for fog and dew harvesting technologies and the need for trace metal and biological analyses of these waters before use.
  • Thumbnail Image
    Item
    A Stable Isotope Approach to Investigative Ecohydrological Processes in Namibia
    (2018-12) Kaseke, Kudzai Farai; Wang, Lixin; Jacinthe, Pierre Andre; Gilhooly, William P.; Wilson, Jeffrey; Soderberg, Keir
    Drylands cover 40% of the earth’s terrestrial surface supporting over 2 billion people, the majority of whom reside in developing nations characterised by high population growth rates. This imposes pressure on the already limited water resources and in some dryland regions such as southern Africa, the origins and dynamics of rainfall are not well understood. Research has also tended to focus on factors limiting (e.g., rainfall) than sustaining productivity in drylands. However, non-rainfall water (NRW) e.g., fog and dew can supplement and/or exceed rainfall in these environments and could potentially be exploited as potable water resources. Much remains unknown in terms of NRW formation mechanisms, origins, evolution, potability and potential impact of global climate change on these NRW dependent ecosystems. Using Namibia as a proxy for drylands and developing nations, this dissertation applies stable isotopes of water (δ2H, δ18O, δ17O and d-excess), cokriging and trajectory analysis methods to understand ecohydrological processes. Results suggest that locally generated NRW may be a regular occurrence even in coastal areas such as the Namib Desert, and that what may appear as a single fog event may consist of different fog types co-occurring. These results are important because NRW responses to global climate change is dependent on the source, groundwater vs. ocean, and being able to distinguish the two will allow for more accurate modelling. I also demonstrate, that fog and dew formation are controlled by different fractionation processes, paving the way for plant water use strategy studies and modelling responses to global climate change. The study also suggests that current NRW harvesting technologies could be improved and that the potability of this water could raise some public health concerns related to trace metal and biological contamination. At the same time, the dissertation concludes that global precipitation isoscapes do not capture local isotope variations in Namibia, suggesting caution when applied to drylands and developing nations. Finally, the dissertation also reports for the first time, δ17O precipitation results for Namibia, novel isotope methods to differentiate synoptic from local droughts and suggests non-negligible moisture contributions from the Atlantic Ocean due to a possible sub-tropical Atlantic Ocean dipole.
  • Thumbnail Image
    Item
    Stable isotope variations of dew under three different climates
    (Springer Nature, 2022-02-14) Tian, Chao; Du, Kun; Wang, Lixin; Zhang, Xiao; Li, Fadong; Jiao, Wenzhe; Beysens, Daniel; Kaseke, Kudzai Farai; Medici, Marie-Gabrielle; Earth Sciences, School of Science
    As a supplementary or the only water source in dry regions, dew plays a critical role in the survival of organisms. The new hydrological tracer 17O-excess, with almost sole dependence on relative humidity, provides a new way to distinguish the evaporation processes and reconstruct the paleoclimate. Up to now, there is no published daily dew isotope record on δ2H, δ18O, δ17O, d-excess, and 17O-excess. Here, we collected daily dew between July 2014 and April 2018 from three distinct climatic regions (i.e., Gobabeb in the central Namib Desert with desert climate, Nice in France with Mediterranean climate, and Indianapolis in the central United States with humid continental climate). The δ2H, δ18O, and δ17O of dew were simultaneously analyzed using a Triple Water Vapor Isotope Analyzer based on Off-Axis Integrated Cavity Output Spectroscopy technique, and then d-excess and 17O-excess were calculated. This report presents daily dew isotope dataset under three climatic regions. It is useful for researchers to use it as a reference when studying global dew dynamics and dew formation mechanisms.
  • Thumbnail Image
    Item
    The water of life: Where does desert fog come from?
    (Futurum, 2021) Wang, Lixin; Earth and Environmental Sciences, School of Science
    The lack of rainfall in desert environments means that many plants and animals rely on fog and dew to provide their water. But where does this fog come from? And what will happen to these ecosystems as the climate changes? Professor Lixin Wang, a hydrologist at Indiana University-Purdue University Indianapolis in the US, has been looking for the answers to these questions.