敌百虫对两种赤潮微藻生长的毒性效应研究

敌百虫是使用最为广泛的有机磷农药之一,在水产养殖中主要用于防治甲壳类寄生虫。本文研究了72 h的急性暴露以及25 d的亚慢性暴露下,敌百虫对两种赤潮微藻海洋卡盾藻和锥状斯氏藻生长的影响,以了解敌百虫对海洋微藻的毒性及海洋初级生产力的影响。在急性暴露下,高质量浓度敌百虫能明显抑制两种藻细胞的生长,而低质量浓度则对藻细胞的生长影响不明显,敌百虫对海洋卡盾藻和锥状斯氏藻生长的72 h EC50分别为32.1 mg/L和22.1 mg/L。在亚慢性暴露下,两种藻细胞对敌百虫的敏感性相近,高质量浓度组(25 mg/L)的藻细胞在暴露的第7~9天就全部死亡;1 mg/L的低质量浓度组,藻细胞的生长状况与对照组相近;5 mg/L和10 mg/L质量浓度组在暴露初期对藻细胞生长具有抑制作用,但在暴露后期则明显刺激了藻细胞的生长。本研究说明水环境背景质量浓度下的敌百虫不会抑制浮游植物的生长,但施药一段时间后,可刺激藻细胞的生长,从而增加了引发赤潮的风险。

Toxic effects of trichlorfon on the growth of two microalgae, Chattonella marina and Scrippsiella trochoidea

Trichlorfon is an important organophosphate insecticide and has been widely used for treating various parasitic infestations in aquaculture. This study analyzed the effects of trichlorfon on the growth of Chattonella marina and Scrippsiella trochoidea through 72-h and 25-d growth tests. The aim was to estimate the toxic effects of trichlorfon on marine phytoplankton. Results showed that high concentrations of trichlorfon significantly inhibited the growth of both microalgae in the 72-h test. However, low concentrations had no significant influence on the growth of the microalgae. The 72-h EC₅₀ values of trichlorfon for C. marina and S. trochoidea were 32.1 and 22.1 mg/L, respectively. In the 25-d test, the algal cells were not able to survive at trichlorfon concentrations >25 mg/L after 7 - to 9-d exposure, while the growth under 1 mg/L was comparable with that of the control. At moderate concentrations (5 and 10 mg/L), the growth was enhanced during the late period of exposure in the 25-d test. These results suggest that background concentrations of trichlorfon in aquatic environments would not inhibit the growth of phytoplankton; however, the growth might be stimulated after a period of application, which might thus increase the risk of algal blooms.