Human Appropriation of the Calcium Cycle: From Rain, Land, Food, to Water
11th RCC Lecture at ZUG Wien
31.01.2019
Speaker: John Kim
Location: Universität für Bodenkultur Wien, Schottenfeldgasse 29, 1070 Wien
Conversion of natural forests and grasslands to croplands has been one of the biggest contributors to anthropogenic greenhouse gas emissions, much of which stems from the decomposition of organic carbon in plant biomass and soils. However, as agriculture expands into more arid ecosystems where large amounts of carbon (in its inorganic form, caliche) are stored in the soils, the impact of agricultural conversion on this calcium carbonate mineral and its implications on climate regulation are becoming focal points of scientific inquiry.
Using historical data on river chemistry, agricultural land acreage, and agricultural inputs from the 1900s to present, Kim outlines his approach to reconstruct how much calcium has moved through the large river systems in the United States Southern Great Plains. He uses calcium in the rivers as a proxy for carbon to trace carbon movements from the atmosphere to soil and water. A key player in this story is the limestone, which is made of the same calcium carbonate as the caliche and has long been a crucial component in construction and metalworking—and more recently in mitigating the effects of environmental issues such as acid rain, residential wastewater, and agricultural soil acidification.