16:00 〜 16:15
[AHW22-18] Hydrochemical Dynamics in an Intensive Citrus Cultivation Island: Deciphering Natural and Anthropogenic Influences Amidst Depopulation and Population Aging
キーワード：Fertilizer , Denitrification, Groundwater contamination, Nitrogen stable isotopes, Sewage treatment, Seto Inland Sea
As the global agricultural landscape undergoes transformative shifts, understanding the intricate interplay between natural processes, anthropogenic activities, and demographic changes becomes imperative. This study delves into the hydrochemical dynamics of groundwater in an intensive citrus cultivation island experiencing the dual challenges of depopulation and population aging. Through comprehensive field investigations and utilizing stable nitrogen isotopes along with a Bayesian isotope mixing model, we examine the complex relationships between land-use practices, demographic shifts, and the resulting impacts on groundwater quality.
We compared two neighbouring villages with differences in their social aspects despite similar land-use pattern. The northern village (Kubi) has a slightly higher average farmer age of 76 years and a decreasing rate of farmland over the last 10 years (2005 to 2015) of 46%, compared to the eastern village (Ocho) with an average farmer age of 73 years and a decreasing rate of 37% during the same period. Despite a population of 830 in Ocho, twice that of Kubi, higher mean concentrations of Nitrate-nitrogen were recorded in Kubi village than in the Ocho area. Nitrate contamination sources were associated with land use practices and social aspects such as aging and depopulation, with Kubi experiencing higher leaching due to the substantial use of chemical fertilizers by more aged farmers.
Insights gained from this study contribute to a broader understanding of sustainable land and water management in regions facing demographic transitions, offering valuable guidance for policymakers, environmental scientists, and agricultural stakeholders alike.
We compared two neighbouring villages with differences in their social aspects despite similar land-use pattern. The northern village (Kubi) has a slightly higher average farmer age of 76 years and a decreasing rate of farmland over the last 10 years (2005 to 2015) of 46%, compared to the eastern village (Ocho) with an average farmer age of 73 years and a decreasing rate of 37% during the same period. Despite a population of 830 in Ocho, twice that of Kubi, higher mean concentrations of Nitrate-nitrogen were recorded in Kubi village than in the Ocho area. Nitrate contamination sources were associated with land use practices and social aspects such as aging and depopulation, with Kubi experiencing higher leaching due to the substantial use of chemical fertilizers by more aged farmers.
Insights gained from this study contribute to a broader understanding of sustainable land and water management in regions facing demographic transitions, offering valuable guidance for policymakers, environmental scientists, and agricultural stakeholders alike.