State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China; University of Chinese Academy of Sciences, Beijing, China.
State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China; Institute for Ecological Research and Pollution Control of Plateau Lakes, School of Ecology and Environmental Science, Yunnan University, Kunming, China.
Ecotoxicol Environ Saf. 2021 Dec 20;227:112933. doi: 10.1016/j.ecoenv.2021.112933. Epub 2021 Oct 23.
Along with a steady increasing use of artificial nitrogen fertilizer, concerns have been raised about the effects that high nitrogen loading may have on ecosystems. Due to the toxicity of unionized ammonia (NH), tolerance criteria have been proposed for ambient water management in many countries; however, these are mainly based on acute or chronic tests carried out under lab conditions run with purified water. Aiming at understanding the responses of organisms to natural exposure to high ammonia concentrations, a Viviparidae gastropod, Bellamya aeruginosa, was tested at three experimental scales: standard 96-h lab test, one-month cage test in 6 experimental ponds with continuous nitrogen inputs, and intensive investigation of the B. aeruginosa from these ponds in spring and winter. The results were: 1) 96-h LC in the standard lab test was 0.56 mg NH-N/L and 343.3 mg TAN/L (total ammonia expressed as N, standardized at pH 7 and 20 ℃). 2) In the one-month cage test, the survival rate was 97% when NH-N was 0.61 mg/L (i.e., a higher concentration than the lab 96-h LC) and the body size of the gastropods actually increased with increasing NH-N concentrations. 3) In the winter-spring investigation, little effect of ammonia on the standing crops of gastropods was found, and the body size of the gastropods tended to increase with increasing ammonia concentrations (NH-N concentration range of 0.05 ~ 2.06 mg/L). Thus, B. aeruginosa showed higher tolerance to ammonia exposure (NH-N concentration < 0.81 mg/L) in the field than under laboratory conditions. Our study points to the necessity of considering the relevant scale when determining criteria for ammonia toxicity in water management.
随着人工氮肥使用量的稳步增加，人们对高氮负荷可能对生态系统造成的影响表示担忧。由于非离子氨（NH）的毒性，许多国家都提出了环境水体管理的耐受标准；然而，这些标准主要基于在实验室条件下使用纯化水进行的急性或慢性测试。为了了解生物体对高氨浓度自然暴露的反应，测试了一种圆田螺科腹足纲动物——铜锈环棱螺（Bellamya aeruginosa），在三个实验规模上进行：标准的 96 小时实验室测试、在 6 个有连续氮输入的实验池塘中进行为期一个月的笼式测试，以及对这些池塘中的 B. aeruginosa 在春季和冬季进行密集调查。结果如下：1）标准实验室测试的 96 小时 LC 为 0.56mg NH-N/L 和 343.3mg TAN/L（总氨以 N 表示，在 pH 7 和 20°C 下标准化）。2）在一个月的笼式测试中，当 NH-N 为 0.61mg/L 时，存活率为 97%（即比实验室 96 小时 LC 更高的浓度），并且腹足类动物的体型实际上随着 NH-N 浓度的增加而增加。3）在冬季-春季调查中，发现氨对腹足类动物的现存量几乎没有影响，并且腹足类动物的体型随着氨浓度的增加而增大（NH-N 浓度范围为 0.05~2.06mg/L）。因此，B. aeruginosa 在野外对氨暴露（NH-N 浓度<0.81mg/L）的耐受性高于实验室条件下。我们的研究表明，在确定水管理中氨毒性标准时，必须考虑相关的尺度。
