水体中钉螺耗氧量测定方法研究

STUDY ON DETERMINATION OF OXYGEN DEMAND OF ONCOMELANIA SNAILS IN WATER

目的 探索一种简便、可靠的钉螺耗氧量测定方法。方法 根据水质溶解氧测定的原理 ,测定钉螺在不同数量 /密度、不同时间情况下 ,在水中耗氧量的变化情况 ,评价耗氧测定钉螺适宜数选择性试验和耗氧测定适宜时间选择性试验的效果。结果 6、13℃水环境温度下每笼 10、5 0只钉螺分别与每笼 2 0、30只钉螺耗氧测定的每螺每小时耗氧量两两比较 ,差异均有非常显著性 (P<0 .0 1)。每笼 2 0、30、4 0只钉螺耗氧测定的每螺每小时耗氧量两两比较 ,差异无显著性 (P>0 .0 5 ) ;6、13、2 8℃水环境温度下 3、6、9、12 h耗氧测定的每螺每小时耗氧量两两比较差异均无显著性 (P>0 .0 5 ) ;6、13、2 8℃水环境温度下 3、6、9、12 h分别与 2 4、36 h耗氧测定的每螺每小时耗氧量两两比较差异均有非常显著性 (P<0 .0 1)。 18h后耗氧测定的每螺每小时耗氧量开始呈下降趋势。结论 本方法是一种简便、可靠的水体钉螺耗氧量的测定方法 ,但每次耗氧测定的钉螺数应在 30只左右 ,耗氧测定时间应控制在 6～ 12 h。

Objective To develop a simple and reliable method for determination of oxygen demand of Oncomelania snails in water. Methods By using the principle of determination of dissolved oxygen demand, the variation of the oxygen demand of the snail in different number, density and time was determined, and the effect of the selective number and time was evaluated. Results There were significant differences among 10- or 50-snail groups and 20- or 30-snail groups in 6 ℃ and 13 ℃, respectively (P<0.01). There were no significant differences between 20- and 30- and 40-snail groups (P>0.05). There were no significant differences among 3- ,6- and 9-hour groups in 28 ℃(P>0.05). There were significant differences among 3- or 6- or 9- or 12-hour groups and 24- or 36-hour groups in 6, 13 ℃ and 28 ℃ respectively (P<0.01). There was a decline trend of oxygen demand after 18 hours. Conclusion The method is simple and reliable. The suitable number of snails was about 30 and the suitable time was between 6 and 12 hours.