Nitrate Toxicity in Florida Springs and Spring-Run Streams: A Review of the Literature and It's Implications

摘要

The global nitrogen cycle has been altered substantially by human activity over the last century. This alteration has resulted in increased loads of nitrogen to surface and groundwater. Considerable research attention has been given to the ecological effects of nitrogen enrichment on primary producers and the concurrent effects on aquatic food webs. An emerging body of research data suggests that, in addition, there are toxic effects of nitrogen enrichment on aquatic fauna, not only from ammonia and nitrite (which have been well-established), but also from nitrate. Here, the current literature of nitrate toxicity is reviewed and the implications for Florida's springs are discussed. Nitrate toxicity thresholds down to 0.23 mg/L NO3-N were reported for invertebrates, down to 1.1 mg/L NO3-N were reported for fishes, and down to 5 mg/L NO3-N were reported for amphibians. A number of springs in Florida display nitrate concentration levels above these thresholds, which suggests there may be toxic effects on springs' fauna.