Aida Miki, Ikeda Hiroaki, Itoh Kazuyuki, Usui Kenji
Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba 305-8572, Japan.
Ecotoxicol Environ Saf. 2006 Mar;63(3):463-8. doi: 10.1016/j.ecoenv.2005.02.010.
The effects of five rice herbicides bensulfuron methyl, mefenacet, quinoclamine, simetryn, and thiobencarb on the growth of two threatened aquatic ferns Azolla japonica and Salvinia natans were tested using 12-day exposure experiments at 0.1-100 nM which are expected to be present in drainages and rivers in Japan. As a reference species, Lenma minor was also used to examine the toxicity of bensulfuron methyl. Bensulfuron methyl had the most pronounced effect on the relative growth rate (RGR) of A. japonica, S. natans, and L. minor with an EC50 of 5.0, 0.54, and 10 nM, respectively. The other herbicides reduced the RGR of the aquatic ferns only at the highest concentration (100 nM) or not at all. S. natans showed the highest susceptibility to bensulfuron methyl among the three species, and the EC50 for this species was comparable to or below the maximum concentration (0.49-5.6 nM) that had been previously detected in 7 of 11 rivers in Japan. These results suggest that bensulfuron methyl runoff in drainages and rivers in Japan is expected to have adverse effects on the growth of threatened aquatic ferns in some cases, and that no or small effects occur for the other four herbicides tested.
使用12天暴露实验，在0.1 - 100纳摩尔的浓度下测试了五种水稻除草剂（苄嘧磺隆、苯噻酰草胺、二氯喹啉酸、西草净和杀草丹）对两种受威胁水生蕨类植物日本满江红和槐叶苹生长的影响，这些浓度预计存在于日本的排水系统和河流中。作为参考物种，还使用了小浮萍来检测苄嘧磺隆的毒性。苄嘧磺隆对日本满江红、槐叶苹和小浮萍的相对生长率（RGR）影响最为显著，其半数有效浓度（EC50）分别为5.0、0.54和10纳摩尔。其他除草剂仅在最高浓度（100纳摩尔）时才降低水生蕨类植物的相对生长率，或者根本没有影响。在这三个物种中，槐叶苹对苄嘧磺隆的敏感性最高，该物种的EC50与之前在日本11条河流中的7条河流中检测到的最大浓度（0.49 - 5.6纳摩尔）相当或低于该浓度。这些结果表明，日本排水系统和河流中的苄嘧磺隆径流在某些情况下预计会对受威胁水生蕨类植物的生长产生不利影响，而测试的其他四种除草剂则不会产生影响或影响较小。
