Fecal Pollution of the Riverwaters in the Matsuyama Plain, using Coprostanol as an Indicator

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Fecal pollution of the riverwaters in the Matsuyama Plain (Fig.1 and 2) was investigated by using coprostanol (5β-cholestan-3β-ol) as an indicator. Coprostanol in the riverwaters was extracted by hexane and silylated by BSTFA. The silylated Coprostanol was determined by using a gas chromatograph-mass spectrometer equipped with a multi-ion detector (GC-MS-MID). In the waters of the rivers which flow through residential districts without sewer system, the concentration of coprostanol increased from 0.8ng/l to 8100ng/l continuously downstream (Table 2-(1) and Fig.3). This fact suggests that fecal drain, which comes from the insufficiently functioning septic tanks, flows into the rivers. In Ishite River, one of the main rivers in the Matsuyama Plain, the fecal sources were the outflows from Oku-Dogo hotspring town and hog farms, but not from the septic tank systems (Table 2-(2) and Fig.4). In the Matsuyama Plain, fecal pollution of waters of the tributary streams was severer than that of the main rivers (Table 2-(3) and Fig.2). In particular, the concentration of coprostanol in the waters of Miyamae River, whose upper reaches has a municipal sewage treatment plant along the bank (Fig.1), was the highest in the Matsuyama Plain (24000ng/l). The concentration level of coprostanol in the aquatic environment, which is not polluted severely with feces, is postulated to be below 500 ng/l.
日本陸水学会の論文