팔당호에 설치된 인공식물섬 식생기반재 내에서 세균의 생태학적 기능을 파악하기 위하여 식생기반재 내의 공극수와 호숫물에서 총인(TP), 용존인(DIP), 총질소(TN), 질산성질소$(NO_3)$총세균수, 활성세균수와 체외효소활성도를 측정하였다. 인공식물섬 식생기반재의 공극수에서 TN과 $NO_3$농도는 각각 $4.4sim7.5mg;L^{-1}$, $1.2sim3.8mg;L^{-1}$ 범위로 호숫물보다 약 2배 높게 나타났으며, TP와 DIP값도 식생기반재 공극수에서 각각 $1.4sim4.1mg;L^{-1}$, $0.003sim0.137mg;L^{-1}$ 범위로 TP 값은 호숫물보다 약 $4sim25$배, DIP값은 5.3배 높은 값이었다. 총세균수와 활성세균수는 호숫물보다 10배 이상 값을 보였다. 또한 phosphatase 및 $eta$-glucosidase 활성도도 인공식물섬 공극수에서 호숫물보다 10배 이상의 높은 결과를 보여 식생기반재 내부에서 세균에 의한 영양염류의 농축과 왕성한 유기물질분해가 일어나고, 이 과정에서 수초의 성장, 동물플랑크톤의 증식 등 새로운 수생태계가 조성된 것으로 사료된다.
To evaluate the functions of vegetation mat of artificial floating island (AFI) installed in Lake Paldang, nutrients, such as total phosphorus (TP), dissolved inorganic phosphorus (DIP), total nitrogen (TN) and nitrate $(NO_3)$ and microbial factors such as total bacterial numbers, active bacterial numbers and exoenzymatic activities of $eta$-glucosidase and phosphatase in pore water of medium and bulk lake water were analyzed. The concentration of TN and $NO_3$ in pore water ranged from 4.4 to 7.5mg $L^{-1}$ from 1.2 to 3.8mg $L^{-1}$ respectively, which were ca. 2 times higher than those of lake water. The ranges of TP and DIP of were $1.4sim4.1mg;L^{-1}$ and $0.003sim0.137mg;L^{-1}$ in pore water of media which were $4sim25$ and 5 times higher than those of lake water, respectively. The numbers of total bacteria and active bacteria in pore waterwere about 10 times higher than those of laker water. Also, both phosphatase and $eta$-glucosidase activities of pore water were on an average 10 times higher than those of lake water. These results suggest that the bacteria were playing important role for nutrients concentrating and cycling in media of artificial floating island. And the medium of artificial floating island contained newly created microbial ecosystem, which is responsible for sustaining the growth of macrophytes and the creation of new aquatic ecosystem.
