Despite the higher diversity of amphibians and the increasing use of agrochemicals in tropical countries, knowledge on the ecotoxicity of such compounds to tropical amphibians remains very limited. The aim of this study was, therefore, to assess the acute lethal toxicity of three nitrogen salts (ammonium sulphate, sodium nitrate and sodium nitrite) to tadpoles of five tropical frog species: Rhinella ornata, Boana faber, B. pardalis, Physalaemus cuvieri, and P. olfersii. The order of sensitivity to the nitrogen salts for all five species was sodium nitrite > ammonium sulphate > sodium nitrate. There was not a single most sensitive species to all three nitrogen salts. However, differences in generated 4-d LC50 values between the most and least sensitive test species were small (a factor 2 to 6). A comparison with published toxicity values does not suggest an intrinsic higher, or lower, sensitivity of the tropical species tested as compared to their temperate counterparts. Reported nitrogen concentrations in sugarcane fields do not indicate a lethal risk to the amphibian species tested. Chronic-exposure and field studies are recommended to evaluate amphibian sensitivity under environmental-realistic multiple-stressor conditions.

尽管两栖动物的多样性更高，并且在热带国家中农用化学品的使用越来越多，但是关于此类化合物对热带两栖动物的生态毒性的知识仍然非常有限。本研究的目的是，因此，要评估的三个氮盐急性致死毒性（硫酸铵，硝酸钠和亚硝酸钠）至五个热带蛙种蝌蚪：Rhinella姬蛙，Boana费伯，B. pardalis，Physalaemus cuvieri，和P. olfersii。所有五个物种对氮盐的敏感度顺序为亚硝酸钠>硫酸铵>硝酸钠。没有一个对所有三种氮盐最敏感的物种。但是，在最敏感和最不敏感的测试物种之间生成的4-d LC50值的差异很小（2到6倍）。与已公布的毒性值进行比较，并不表明与温带对等物种相比，所测试的热带物种固有的更高或更低的敏感性。报道的甘蔗田中的氮浓度并不表明对测试的两栖动物具有致命的危险。建议进行长期暴露和田间研究，以评估环境逼真的多应激条件下的两栖动物敏感性。