Application Research On Microbial Source Tracking Technology In Dalian Beach Watershed

With the increase of animals and human population in our nation, nonpoint pollution has been a serious water environmental problem as it degrades water quality and restricts its use. Microbial source tracking technology has developed rapidly in many countries around the world because the emering discipline can be used to identify contamination origins of polluted waters. With the aim of promoting the technology in our nation, a study was conducted in Dalian chosed to be the expermental area. As a method of being wildly used in the technology, antibiotic resistance analysis was performed on an antibiotic resistance fingerprint database genetated from potential onshore sources (human, dog, chicken, cattle, pig). Resubstitution test, cross-validation test and sample test were carred out to verify the accuracy and reliability of the database. Afield test of the predictive practicability of the technology was conducted by sampling in two watersheds. The results showed that:(1) The average rate of correct classification(ARCC) of the fingerprint database for the five-way split (human, dog, chicken, cattle, pig) was 52.9% by resubstitution test and 52.2% by cross-validation test. The ARCC for the two-way split (human and nonhuman) by resubstitution test and cross-validation test were both 69.9%. The fingerprint database can be considered accuracy because the ARCC differences between resubstitution test and cross-validation test were both small (less than 5%),0.7% and 0% respectively in five-way split and in two-way split.(2) When the sample test was conducted, the fingerprint database had an average correct classification rate of 48.0% for five-way split, and 68.8% for two-way split. The ARCC difference between sample test and cross-validation test was both small (less than 5%),4.2% in five-way split and 1.1% in two-way split, which showed that the fingerprint database can be considered reliability.(3) Field tests were conducted in Xinghai Beach and Jinzhou Beach simultaneously. The ARA results showed that human were the major source of pollution in Xinghai Beach, and the percentages of other sources were insignificant. When enterococci isolated from the seawater of Jinzhou Beach were classified using the ARA database, it was evident that cattle were the major source of this watershed, followed by human and dog. The results were coincident with prospective investigation conclusions, which showed that the technology is practicable. The results suggested that the ARA fingerprint database can be considered accuracy and reliability, and the technology is practicable. Antibiotic resistance analysis method based microbial source tracking technology can be used to identify sources of nonpoint pollution in our nation, which enables the application of appropriate management plans for prevention of further contamination.