5:15 PM - 6:30 PM
[HTT16-P02] Identification of regional characteristics of the basin using elemental components as tracers
Keywords:Elemental component, Tracer, Regional characteristics, Land cover
1.Introduction
1.1 background
Changes in the environmental dynamics of the basin are expected in response to "land use development due to human modification" and "extreme temperature rise and precipitation due to climate change", and research on the impact assessment of eutrophication is being developed especially in closed water areas. Has been done. Along with internal production, it is necessary to understand the inflow effect of external load on the drastic environmental changes. Predicting the future image of water quality can be evaluated more precisely based on detailed information on both internal production according to the shape scale of each basin and external load according to regional characteristics.
1.2 Research purpose
In this research, as part of the purpose of developing an external load database that can be used for land cover and current conditions, and for assessing the water environment impact of climate change, the Abukuma River basin, which is a first-class river in the Tohoku region, was set as the target area and numerical geography. Based on the information, we attempted to compare and examine the relationship between regional characteristics (vegetation, land cover, soil, geology) and sampled and analyzed chemical outflow components (chemical component content due to multiple elements) for each small basin. ,
In the basin condition analysis, the types of basin conditions of the basin were classified using cluster analysis. We decided to compare the characteristics of the global region with the values obtained from chemical analysis (content of elements).
2.Main subject
2.1. Results of multi-element analysis using ICP-MS
Inductively coupled plasma mass spectrometry (ICP-MS) was used for analysis to determine the amount of elements contained in the Abukuma River basin (Na, Mg, Al, Si, K, Ca, Mn, Fe, P).
The chemical composition (element content) of the Abukuma River main river increases from the upstream to the middle basin, with the confluence with the Ose River at its maximum and decreasing toward the downstream.
In addition, in the results of this analysis, the value of Arakawa was the largest among the main river and tributary points. Above all, the concentration of Mg was more than twice as high as that of other tributaries.
At each concentration, Na and Ca varied at each point, so it is considered that there are some regional characteristics.
2.2 Results of Regional Characteristics Analysis
2.2.1 Classification results by cluster analysis
For the sake of convenience, the classification by cluster analysis was integrated, and the integration numbers were shown as equivalent values in the relative positional relationship, and a total of three groups were shown. Vegetation in the Abukuma River basin was divided into 5 groups, 5 categories for land cover, 4 categories for soil, and 5 categories for geology. The classification categories of "4334 (Fujita River, Sasahara River)", "5112 (Suwon River, Yashiro River)", and "2113 (Kitasu River, Yui River)" have overlapping basin characteristics. Depending on the conditions, there is a high possibility that similar chemical component outflow will occur.
2.2.2 Comparison with multi-element analysis results
As basin conditions that are considered to contribute to the outflow of chemical components, vegetation includes deciduous and evergreen broad-leaved forests in the Yabutsubaki class area, land cover includes basins that occupy a high proportion of urban areas, and soil includes Andosols. In terms of humus and geology, the basin has a high occupation ratio related to volcanic ejecta. From the transition of the material outflow component (element content) as the material circulation route in the Abukuma River basin, it became clear that it changes depending on the basin where the outflow is artificially high due to the urban area and the regional characteristics due to the contribution of forests and volcanoes. ..
3.Conclusion
From the chemical analysis (content of elements) and the comparative study of the basin conditions, the elements of deciduous / evergreen broadleaf forest zone, urban area, humus, and volcanic ejecta were shown as basin conditions that contribute to the formation of water quality in the Abukuma River basin.
Furthermore, it is shown that classification by natural factors and social factors is necessary as a pattern of load increase due to basin conditions.
This time, the analysis was performed without considering the item of estimated population as the basin condition, so we plan to add some conditions in the future and work on the elucidation of the chemical composition and its material cycle.
1.1 background
Changes in the environmental dynamics of the basin are expected in response to "land use development due to human modification" and "extreme temperature rise and precipitation due to climate change", and research on the impact assessment of eutrophication is being developed especially in closed water areas. Has been done. Along with internal production, it is necessary to understand the inflow effect of external load on the drastic environmental changes. Predicting the future image of water quality can be evaluated more precisely based on detailed information on both internal production according to the shape scale of each basin and external load according to regional characteristics.
1.2 Research purpose
In this research, as part of the purpose of developing an external load database that can be used for land cover and current conditions, and for assessing the water environment impact of climate change, the Abukuma River basin, which is a first-class river in the Tohoku region, was set as the target area and numerical geography. Based on the information, we attempted to compare and examine the relationship between regional characteristics (vegetation, land cover, soil, geology) and sampled and analyzed chemical outflow components (chemical component content due to multiple elements) for each small basin. ,
In the basin condition analysis, the types of basin conditions of the basin were classified using cluster analysis. We decided to compare the characteristics of the global region with the values obtained from chemical analysis (content of elements).
2.Main subject
2.1. Results of multi-element analysis using ICP-MS
Inductively coupled plasma mass spectrometry (ICP-MS) was used for analysis to determine the amount of elements contained in the Abukuma River basin (Na, Mg, Al, Si, K, Ca, Mn, Fe, P).
The chemical composition (element content) of the Abukuma River main river increases from the upstream to the middle basin, with the confluence with the Ose River at its maximum and decreasing toward the downstream.
In addition, in the results of this analysis, the value of Arakawa was the largest among the main river and tributary points. Above all, the concentration of Mg was more than twice as high as that of other tributaries.
At each concentration, Na and Ca varied at each point, so it is considered that there are some regional characteristics.
2.2 Results of Regional Characteristics Analysis
2.2.1 Classification results by cluster analysis
For the sake of convenience, the classification by cluster analysis was integrated, and the integration numbers were shown as equivalent values in the relative positional relationship, and a total of three groups were shown. Vegetation in the Abukuma River basin was divided into 5 groups, 5 categories for land cover, 4 categories for soil, and 5 categories for geology. The classification categories of "4334 (Fujita River, Sasahara River)", "5112 (Suwon River, Yashiro River)", and "2113 (Kitasu River, Yui River)" have overlapping basin characteristics. Depending on the conditions, there is a high possibility that similar chemical component outflow will occur.
2.2.2 Comparison with multi-element analysis results
As basin conditions that are considered to contribute to the outflow of chemical components, vegetation includes deciduous and evergreen broad-leaved forests in the Yabutsubaki class area, land cover includes basins that occupy a high proportion of urban areas, and soil includes Andosols. In terms of humus and geology, the basin has a high occupation ratio related to volcanic ejecta. From the transition of the material outflow component (element content) as the material circulation route in the Abukuma River basin, it became clear that it changes depending on the basin where the outflow is artificially high due to the urban area and the regional characteristics due to the contribution of forests and volcanoes. ..
3.Conclusion
From the chemical analysis (content of elements) and the comparative study of the basin conditions, the elements of deciduous / evergreen broadleaf forest zone, urban area, humus, and volcanic ejecta were shown as basin conditions that contribute to the formation of water quality in the Abukuma River basin.
Furthermore, it is shown that classification by natural factors and social factors is necessary as a pattern of load increase due to basin conditions.
This time, the analysis was performed without considering the item of estimated population as the basin condition, so we plan to add some conditions in the future and work on the elucidation of the chemical composition and its material cycle.