17:15 〜 18:30
[HTT16-P04] Seasonal variations and trends of dissolved elements in rainwater and stream water in forest catchment area of central Japan
キーワード：微量元素、森林集水域、同位体比分析
Metal elements released into the atmosphere by human activities such as fossil fuel combustions flow into forest ecosystems by wet deposition (precipitation) and dry deposition (particulate matters), and some of them flow out of the system via mountainous stream water. Some elements are essential for lives, but excessive intake is harmful. It is important to grasp the concentration level of dissolved metal elements, because they are easily taken into the living organisms.
The Kajikawa catchment site in Niigata Prefecture, which is located on the continental side of central Japan, has been suffering to a large amount of acidic substances deposited due to its geographical conditions and meteorological seasonality, and is affected by transboundary air pollution originating from the Asian continent. In this study, concentrations of trace elements dissolved in rainfall (RF) and mountain stream water (SW) were clarified in order to evaluate the effects of transboundary air pollution in forest ecosystems more comprehensively. In addition, stable isotope ratio analysis was used to analyze the dynamic mechanism in more detail.
RF were collected by using bulk samplers at the end of each month, and SW were also collected on the same day during the period from 2014 to 2018. Trace element concentrations were quantified by ICP-MS and major inorganic ion concentrations by using ion chromatography. At the same time, pH, electrical conductivity, precipitation amount and flow rate were measured. In this study, we focus on Al, V, Cr, Zn, As, Sr, and Pb as trace elements. In addition, stable isotope ratios were measured for Sr and Pb.
Concentrations of trace elements and major inorganic ions in RF tended to be high in winter and low in summer. Fluxes of many trace elements also increased in winter, reflecting the high amount of precipitation in winter. The enrichment factors (EFs) calculated based on Al (as an index of earth crust) was high in winter and low in summer. The EFs for many elements were found to be above 10, suggesting that they are derived from anthropogenic sources, such as fossil fuel combustion. The EFs of many elements showed an upward trend, while that of Pb showed a downward trend.
The isotopic ratio of Sr increased over the years, especially in the spring, possibly due to the influence of the Asian dust (yellow sand). At the time of poster presentation, we will compare and discuss the change in the isotope ratio of Pb.
This work was supported by grants from the Japan Society for the Promotion of Science (JSPS) KAKENHI Grant Numbers JP19H00955 and JP18K11616.
The Kajikawa catchment site in Niigata Prefecture, which is located on the continental side of central Japan, has been suffering to a large amount of acidic substances deposited due to its geographical conditions and meteorological seasonality, and is affected by transboundary air pollution originating from the Asian continent. In this study, concentrations of trace elements dissolved in rainfall (RF) and mountain stream water (SW) were clarified in order to evaluate the effects of transboundary air pollution in forest ecosystems more comprehensively. In addition, stable isotope ratio analysis was used to analyze the dynamic mechanism in more detail.
RF were collected by using bulk samplers at the end of each month, and SW were also collected on the same day during the period from 2014 to 2018. Trace element concentrations were quantified by ICP-MS and major inorganic ion concentrations by using ion chromatography. At the same time, pH, electrical conductivity, precipitation amount and flow rate were measured. In this study, we focus on Al, V, Cr, Zn, As, Sr, and Pb as trace elements. In addition, stable isotope ratios were measured for Sr and Pb.
Concentrations of trace elements and major inorganic ions in RF tended to be high in winter and low in summer. Fluxes of many trace elements also increased in winter, reflecting the high amount of precipitation in winter. The enrichment factors (EFs) calculated based on Al (as an index of earth crust) was high in winter and low in summer. The EFs for many elements were found to be above 10, suggesting that they are derived from anthropogenic sources, such as fossil fuel combustion. The EFs of many elements showed an upward trend, while that of Pb showed a downward trend.
The isotopic ratio of Sr increased over the years, especially in the spring, possibly due to the influence of the Asian dust (yellow sand). At the time of poster presentation, we will compare and discuss the change in the isotope ratio of Pb.
This work was supported by grants from the Japan Society for the Promotion of Science (JSPS) KAKENHI Grant Numbers JP19H00955 and JP18K11616.