The invention provides an online automatic
monitoring system of
total nitrogen and
total phosphorus in
seawater and a monitoring method thereof. The
system comprises an automatic
seawater liquid feedcontroller, an
ultraviolet microwave digestor, a
total nitrogen measuring flow passage, a
total phosphorus measuring flow passage and a spectrophotometer, wherein the automatic
seawater liquid feed controller is connected with the
ultraviolet microwave digestor by a liquid feed pipeline; digested sample flows into an electronic cooler from a liquor drainage pipeline of the
ultraviolet microwave digestor to be cooled and respectively enters into the
total nitrogen measuring flow passage and the
total phosphorus measuring flow passage; the total
nitrogen measuring flow passage comprises a
nitrate ion reducing device, a sample reaction pipeline is connected with the spectrophotometer, and the front end of the sample reaction pipeline is provided with a
nitrite color
reagent injecting valve; and the total
phosphorus measuring flow passage comprises the structure that the sample reaction pipeline is connected with the spectrophotometer, and the front end of the sample reaction pipeline is provided with an orthophosphate color
reagent injecting valve. The invention can complete work procedures such as automatically sampling seawater, digesting, reducing, washing, measuring, and the like,at one time.