The effect of total dissolved gas （TDG） supersaturation on fish living downstream of dams is one of the main ecological risks of high dam construction. A strategy for mitigating the negative effects is needed urgent...The effect of total dissolved gas （TDG） supersaturation on fish living downstream of dams is one of the main ecological risks of high dam construction. A strategy for mitigating the negative effects is needed urgently since many high dams are under construction in the upper reaches of the Yangtze River in China. Experiments on the hatching process of David＇s schizothoracin were carried out and the results show that the hatching rate decreased with increasing TDG levels, and that most eggs hatched within a very short time in the higher TDG saturation groups. By using a stereomicroscope, damages to the head, yolk sac, body, anus, etc. were found in larvae which hatched in TDG supersaturated water. Results show that the lesion rate increased with increasing TDG levels. Furthermore, 7-d-old David＇s schizothoracin were exposed to TDG supersaturated water levels of 100%, 105%, 110%, 115%, 120%, 125%, 130%, 135%, and 140% for testing their tolerance to TDG supersaturation. We found that the median lethal concentrations （LC50） for 13, 14, 20, 35, 52, 73, and 96 h exposure were 138%, 138%, 134%, 130%, 129%, 128%, and 126%, respectively. The median lethal times （LTs0） were 7.49, 11.04, 19.25, and 35.38 h for exposure to water with TDG levels of 145%, 140%, 135%, and 130%, respectively.展开更多
文摘用浓度为(0~90)m L/m^3的臭氧在实验仓内进行熏蒸杀虫实验,分别得出不同臭氧浓度下5种主要储粮害虫的致死时间。实验发现,玉米象的致死时间最短,其次是谷蠹、长角扁谷盗和锈赤扁谷盗,赤拟谷盗的致死时间最长,可能跟害虫的活动习性和生理构造有关。在臭氧浓度为40m L/m^3条件下测定各害虫的杀灭情况,得知粮仓中心点下层位置的杀虫效果最好,外围点上层位置的杀虫效果稍差,总体来说,杀虫效果理想。在臭氧浓度为40 m L/m^3条件下测定各害虫不同虫态的致死时间发现,幼虫最容易杀灭,其次是成虫,最难杀灭的是虫卵和蛹,但只要保证熏蒸的时间和臭氧的浓度最终也能将虫卵和蛹一起杀死。
基金Project (No. 50979063) supported by the National Natural Science Foundation of China
文摘The effect of total dissolved gas （TDG） supersaturation on fish living downstream of dams is one of the main ecological risks of high dam construction. A strategy for mitigating the negative effects is needed urgently since many high dams are under construction in the upper reaches of the Yangtze River in China. Experiments on the hatching process of David＇s schizothoracin were carried out and the results show that the hatching rate decreased with increasing TDG levels, and that most eggs hatched within a very short time in the higher TDG saturation groups. By using a stereomicroscope, damages to the head, yolk sac, body, anus, etc. were found in larvae which hatched in TDG supersaturated water. Results show that the lesion rate increased with increasing TDG levels. Furthermore, 7-d-old David＇s schizothoracin were exposed to TDG supersaturated water levels of 100%, 105%, 110%, 115%, 120%, 125%, 130%, 135%, and 140% for testing their tolerance to TDG supersaturation. We found that the median lethal concentrations （LC50） for 13, 14, 20, 35, 52, 73, and 96 h exposure were 138%, 138%, 134%, 130%, 129%, 128%, and 126%, respectively. The median lethal times （LTs0） were 7.49, 11.04, 19.25, and 35.38 h for exposure to water with TDG levels of 145%, 140%, 135%, and 130%, respectively.
