In order to investigate the isotopic and chemical characteristics of lagoon waters in Niigata Prefecture in recent years, oxygen and hydrogen stable isotope ratios （i.e., 8180 and 6D）, the concentrations of DOC （di...In order to investigate the isotopic and chemical characteristics of lagoon waters in Niigata Prefecture in recent years, oxygen and hydrogen stable isotope ratios （i.e., 8180 and 6D）, the concentrations of DOC （dissolved organic carbon）, DO （dissolved oxygen） and pH, etc. in water samples of Sakata and Toyanogata were measured. Samples were generally taken monthly at the fixed sampling points from these lagoons. Consequently, the following matters have been mainly clarified： （1） ~D value of water samples in Sakata was generally larger than that in Toyanogata similarly to the case of ~180, though remarkable large difference among samples was not found; （2） the pH value of lagoon water samples is almost 6.5-8.5 （which is generally larger than that of river water）, and pH at the spot of SI （downstream point of Lower Lagoon （Shitakata）） is remarkably high （9.0-9.5）; （3） Lagoon water has the chemical characteristics contrasting to groundwater with a focus on river water from the viewpoint of pH （acidity or alkalinity） and DO. These matters can be closely related to the biological activity such as photosynthesis due to aquatic plant and phytoplankton and the activity of Crustacea plankton etc. in lagoon.展开更多
文摘In order to investigate the isotopic and chemical characteristics of lagoon waters in Niigata Prefecture in recent years, oxygen and hydrogen stable isotope ratios （i.e., 8180 and 6D）, the concentrations of DOC （dissolved organic carbon）, DO （dissolved oxygen） and pH, etc. in water samples of Sakata and Toyanogata were measured. Samples were generally taken monthly at the fixed sampling points from these lagoons. Consequently, the following matters have been mainly clarified： （1） ~D value of water samples in Sakata was generally larger than that in Toyanogata similarly to the case of ~180, though remarkable large difference among samples was not found; （2） the pH value of lagoon water samples is almost 6.5-8.5 （which is generally larger than that of river water）, and pH at the spot of SI （downstream point of Lower Lagoon （Shitakata）） is remarkably high （9.0-9.5）; （3） Lagoon water has the chemical characteristics contrasting to groundwater with a focus on river water from the viewpoint of pH （acidity or alkalinity） and DO. These matters can be closely related to the biological activity such as photosynthesis due to aquatic plant and phytoplankton and the activity of Crustacea plankton etc. in lagoon.
