ISSN : 1225-3480
피조개 양식장의 해수 수온, 염분, pH, DO, 영양염, COD의 조사결과 해역별 편차가 적게 나타났다. 그리고 엽록소 a 농도는 7-8월에 부영양화 기준인 <TEX>$7{\mu}g/L$</TEX> 보다 높게 나타났지만 8월 이후 부영양화 기준보다 낮은 농도를 보였다. 따라서 피조개 양식장에서 서식환경에 의한 생존율의 급감은 여름철 고수온, 낮은 용존산소량과 먹이원인 클로로필의 감소로 인하여 발생되는 것으로 사료된다. 퇴적물의 강열감량 (IL) 과 산휘발성화합물 (AVS) 및 함수율 (WC) 은 유사한 양상을 보이며 큰 차이가 나타나지 않았으며 화학적산소요구량 (COD) 은 거제만의 조사 정점에서 월별 변화가 심하게 나타났다. 퇴적물의 평균입도 (Mz) 는 8.07-8.33 범위를 보였고 분급도는 1.66-2.13 범위로 피조개 양식에 적합한 지역으로 나타났다. 퇴적물의 C/N 비는 양식장에서 5-10 사이의 값을 나타내어 해양기원의 유기물에 의한 것으로 추정되며, C/S 비는 지역에서 2.8 이상으로 유기물이 분해되기 전에 유기물의 급속한 퇴적이 이루어졌을 환경으로 조사 되었다. 중금속에 대한 농집지수 (Igeo) 의 결과는 연구지역이 Igeo class가 0에서 4 사이로 분포되어 있어 오염되지 않았거나 약간오염된 수준으로 (practically unpolluted / moderately polluted) 나타났다.
To assess the effects of environmental factors on the sustainability of cultured ark shell Scapharca broughtonii production, we investigated the habitat characteristics of shellfish-farming bays (Gangjin Bay, Yeoja Bay, Keoje Bay and Deukryang Bay). We measured the physiochemical parameters (temperature, salinity, dissolved oxygen, nutrients, chemical oxygen demand and Chlorophyll a) and the geochemical characteristics (chemical oxygen demand, ignition loss, C/N ratio and C/S ratio). Surface sediments were collected from several shellfish-farming bays to examine the geochemical characteristics of both the benthic environment and heavy metal pollution. The grain sizes for Gangjin Bay, Yeoja Bay and Keoje Bay were similar, at the ratio of silt and clay in comparison with Deukryang bay of it. The C/N ratio was more than 5.9, reflecting the range arising from the mix of marine organisms and organic matter. The C/S ratio (more than 4.2) showed that the survey area had anoxic or sub-anoxic bottom conditions. The index of accumulation rate (Igeo) of the metals showed that those research areas can be classified as heavily polluted, heavily to moderately polluted, or more or less unpolluted, respectively. We suggested that the growth of ark shell Scapharca broughtonii in the shellfish-farming bay was effected by the various environmental conditions.
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