The carbon pools of biomass,littering,and SOC wre studied with regards to carbon cycles in epikarst zone,taking an example of Yaji Karst Experiemnt Site in Guilin.This study was focused on SOC and its lability,SOC dec...The carbon pools of biomass,littering,and SOC wre studied with regards to carbon cycles in epikarst zone,taking an example of Yaji Karst Experiemnt Site in Guilin.This study was focused on SOC and its lability,SOC decomposition rate,CO 2 regime in the soils. 13 ctracing was used to persua the relation of bicarbonate in karst water to soil carbon.The results indicated sufficient carbon pool in SOC for the driveing CO 2 in the karst system.It was revealed that about 60percent of carbon in epi-karst springs resulted from SOC during spring and summer.Thus,the CO 2,driving the karstification,was not simply due to adsorption of atmospheric CO 2 but due to carbon transfer through the pathway of air-plant-soil-water.The driving force should not be overlooked for the epi-karst formation by soil as an interface of carbon environmental geochemistry.展开更多
Karst aquifers supply a significant fraction of the world's drinking water. These types of aquifers are alsohighly susceptible to pollution from the surface with recharge usually occurring through fractures and so...Karst aquifers supply a significant fraction of the world's drinking water. These types of aquifers are alsohighly susceptible to pollution from the surface with recharge usually occurring through fractures and solution openings at the bedrock surface. Thickness of the protective soil cover, macropores and openings within the soil cover, and the nature of the weathered bedrock surface all influence infiltration. Recharge openings at the bedrock surface, however, are often covered by unconsolidated sediments, resulting in the inadvertent placement of landfills, unregulated dump sites, tailing piles, waste lagoons and septic systems over recharge zones. In these settings surface geophysical surveys, calibrated by a few soil cores, could be employed to identify these recharge openings, and qualitatively assess the protection afforded by the soil cover. In a test of this hypothesis, geophysical measurements accurately predicted the thickness of unconsolidated deposits overlying karstic dolomite at a site about 100 km south of Chicago, Illinois. Zones of elevated electrical conductivity and high ground-penetrating radar (GPR) attenuation within the sediments coincided with subcropping solutionally-enlarged hydraulically active bedrock fractures. These fractures extend to over 12-m depth, as shown by 2-D inverted resistivity sections and soil coring. Anomalous electromagnetic (EM) conductivity and GPR response may be due to higher soil moisture above these enlarged fractures. An epikarstal conduit at 2.5-m depth was directly identified through a GPR survey. These results suggest that surface geophysical surveys are a viable tool for assessing the susceptibility of shallow karst aquifers to contamination.展开更多
文摘The carbon pools of biomass,littering,and SOC wre studied with regards to carbon cycles in epikarst zone,taking an example of Yaji Karst Experiemnt Site in Guilin.This study was focused on SOC and its lability,SOC decomposition rate,CO 2 regime in the soils. 13 ctracing was used to persua the relation of bicarbonate in karst water to soil carbon.The results indicated sufficient carbon pool in SOC for the driveing CO 2 in the karst system.It was revealed that about 60percent of carbon in epi-karst springs resulted from SOC during spring and summer.Thus,the CO 2,driving the karstification,was not simply due to adsorption of atmospheric CO 2 but due to carbon transfer through the pathway of air-plant-soil-water.The driving force should not be overlooked for the epi-karst formation by soil as an interface of carbon environmental geochemistry.
文摘Karst aquifers supply a significant fraction of the world's drinking water. These types of aquifers are alsohighly susceptible to pollution from the surface with recharge usually occurring through fractures and solution openings at the bedrock surface. Thickness of the protective soil cover, macropores and openings within the soil cover, and the nature of the weathered bedrock surface all influence infiltration. Recharge openings at the bedrock surface, however, are often covered by unconsolidated sediments, resulting in the inadvertent placement of landfills, unregulated dump sites, tailing piles, waste lagoons and septic systems over recharge zones. In these settings surface geophysical surveys, calibrated by a few soil cores, could be employed to identify these recharge openings, and qualitatively assess the protection afforded by the soil cover. In a test of this hypothesis, geophysical measurements accurately predicted the thickness of unconsolidated deposits overlying karstic dolomite at a site about 100 km south of Chicago, Illinois. Zones of elevated electrical conductivity and high ground-penetrating radar (GPR) attenuation within the sediments coincided with subcropping solutionally-enlarged hydraulically active bedrock fractures. These fractures extend to over 12-m depth, as shown by 2-D inverted resistivity sections and soil coring. Anomalous electromagnetic (EM) conductivity and GPR response may be due to higher soil moisture above these enlarged fractures. An epikarstal conduit at 2.5-m depth was directly identified through a GPR survey. These results suggest that surface geophysical surveys are a viable tool for assessing the susceptibility of shallow karst aquifers to contamination.
