Numerical experiments of HAB inducement in Qingdao adjacent coastal area
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Numerical experiments of HAB inducement in Qingdao adjacent coastal area LIU Xuehai1,2,3∗ , LI Ruixiang2 , YUAN Yeli2,3 1 2 3
College of Physical and Environmental Oceanography, Ocean University of China, Qingdao 266100, China First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, China Key Laboratory of Marine Science and Numerical Modeling, State Oceanic Administration, First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, China
Received 2 September 2008; accepted 30 October 2009 ©The Chinese Society of Oceanography and Springer-Verlag Berlin Heidelberg 2010
Abstract A three-dimension ecological dynamic model was established to numerically study the relationship of HAB and environmental conditions. The numerical experiments showed that the growth of diatom, the dominant HAB specie, was mainly restricted by phosphate and silicate. If the concentrations of phosphate and silicate reach 17–25 µg/L and 300–375 µg/L respectively, the water is in a state of eutrophication. When phosphate and silicate up to 26–32 µg/L and 350–500 µg/L respectively, HAB could be induced. The major regions of HAB occurrence are Jiaozhou Bay mouth, coastal bays, and coastal area from Maidao to Shilaoren. To avoid HAB occurrence, concentration of phosphate and silicate should not exceed 17–20 µg/L and 300 µg/L as a whole. Reasonable control of pollutant discharge is a key point to prevent water eutrophication and HAB occurrence. Key words: HAB, numerical model, marine ecosystem dynamics, environmental condition
1 Introduction As an ecological disaster, HAB is caused by abnormal proliferation and aggregation of HAB organism. It affects sea sight, environmental quality and normal ecosystem, damages fishery resources, and threatens human health and life security (Kifle et al., 1993). In recent years, Qingdao adjacent coastal area has become a HAB-prone region, and even there is upward trend in frequency, duration and area of HABs. They usually happen in summer when tourism is vigorous, which damages tourism image. Besides, HAB organisms can harm human health directly. For example, biotoxin could be accumulated in shellfish’ body and result in seafood poisoning; HAB of some species could lead to swimmers’ allergic response (Wang et al., 2008). Moreover, the monitorings showed that diatom, Skeletonema costatum as an important HAB specie, has an absolute preponderance among phytoplankton from July to September (Li et al., 2004). The direct causes of HAB increase are marine eu-
trophication and environmental quality degradation. In recent years the volume of pollutant discharge into Qingdao coastal sea had been raised constantly, and the pollution degree was aggravated, especially in scenic regions such as Fushan Bay, Huiquan Bay and Qingdao Bay (Chen et al., 2006; Shi et al., 2007). In this study, an ecological dynamic model for Qingdao adjacent coastal area is established, and the environmental conditions inducing HAB are obtained by numerical experiments. 2 Model setup and verification Considerin
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