Exposure to Light Elicits a Spectrum of Chemical Changes in Soil

Abstract

The significance of photochemically active solar radiation is well substantiated in Earth's air and water environments, but no broad connection has yet been ascertained between sunlight and the chemical properties of land surfaces. Since it is obvious that sunlight strikes Earth every day, an inquiry into this connection was made in a simple experiment with a diverse group of 20 soils. Light‐induced alteration of most of the major elements in soil was evident, including significant changes in dissolved organic carbon, inorganic nitrogen, pH, phosphorus availability and sorption capacity, and soluble and mineral forms of iron, manganese, aluminum, silicon, and calcium. In many instances the extent of these changes could be predicted from initial values. This broad response to light attests to the vivid photochemistry of soils and has both pedological and edaphological implications that reach beyond the surface. The phenomena reported here affirm the opportunity for novel inquiries into the chemistry of soils and land surfaces in general.

Interactive effects of vegetation and water table depth on belowground C and N mobilization and greenhouse gas emissions in a restored peatland

“…Higher temperature (Lou et al 2014;Dieleman et al 2016), exposure to light (Doane et al 2019), oxygen concentrations, enzyme production and overall microbial activity, foster the increase in organic matter decomposition rates (Holden 2005), leading to increased DOC production (Strack et al 2011) and increased CO2 efflux from soils (Leiber-Sauheitl et al 2014). Nevertheless, the lower microbial biomass and respiration observed in dry bare plots as compared to wet bare plots, suggest that DOC mineralization and CO2 efflux could be limited, presumably by moisture availability.…”

Iron (III) doped titanium dioxide coated dimensionally stable graphite anode electrode for electro-chemical treatment of domestic wastewater

“…Sample 1 had the least reduction (contact) time resulting to the least concentration of iron while sample 6 had the highest due to high reaction time hence more iron leached in the solution that the other samples. The observation was due to the fact that iron and manganese are the two main metals in the soil and organic matter that exist in oxidized and reduced forms capable form organic complexes with biomass ( Doane1 et al., 2019 ). The results show that the oxidation of dissolved organic matter releases labile form of iron from the bio material ( Doane1 et al., 2019 ).…”

“…The observation was due to the fact that iron and manganese are the two main metals in the soil and organic matter that exist in oxidized and reduced forms capable form organic complexes with biomass ( Doane1 et al., 2019 ). The results show that the oxidation of dissolved organic matter releases labile form of iron from the bio material ( Doane1 et al., 2019 ). This suggests that the different samples analyzed by the CV had different concentrations of dissolved (leached) iron due to the difference in the concentrations of the dissolved matter (complexing agent) was being depleted with time.…”

Organic Matter Preservation in Ancient Soils of Earth and Mars

“…Recently, there has been increasing consideration of the abiotic pathways of pedogenesis (soil creation) on planets other than Earth. These include chemical alteration through leaching of layered sedimentary rocks in subaerial settings on Mars [ 14 , 15 , 16 ] and a variety of photochemical reactions that create soil minerals [ 17 , 18 ]. If life does not define soil, then the key questions now are when and how did life appear in soils, and what evidence for life can be preserved in paleosols?…”