Nitrogen fixation (acetylene reduction) and denitrification (acetylene block) data from streams across ecoclimatic domains in the United States, 2017-2019

We conducted a cross-ecoregion study to test the hypothesis that N-fixation and denitrification would co-occur in streams and rivers across a range of reactive N concentrations. Between 2017 and 2019, we sampled 30 streams in 13 ecoregions, using chambers to quantify N-fixation using acetylene reduction and denitrification using acetylene block. 25 of the study streams were part of the National Ecological Observatory Network or the StreamPULSE network, which provided data on water temperature, light, nutrients, discharge and metabolism. Although N-fixation and denitrification occur under contrasting environmental conditions, we found that they co-occurred in ca. 40% of stream ecosystems surveyed, and microbes capable of carrying out each process were found in all surveyed streams. This dataset includes the chamber data used to calculate nitrogen fixation and denitrification rates, stream substrate information used to scale rates from substrate to whole-reach scale, and a variety of reach-to-landscape scale covariates used to evaluate predictors of rates across the study streams.

我们开展了一项跨生态区研究，旨在验证以下假设：在不同活性氮（reactive N）浓度范围内，溪流与河流中会同时发生固氮（N-fixation）和反硝化（denitrification）过程。2017至2019年间，我们在13个生态区的30条溪流中采样，通过箱式装置（chambers）分别采用乙炔还原法（acetylene reduction）测定固氮速率、乙炔抑制法（acetylene block）测定反硝化速率。其中25条研究溪流属于国家生态观测网络（National Ecological Observatory Network）或StreamPULSE网络，这两个网络提供了水温、光照、营养盐、流量及代谢等数据。尽管固氮和反硝化发生在截然不同的环境条件下，但我们发现约40%的受调查溪流生态系统中两者同时存在，且所有受调查溪流中均检测到能执行这两种过程的微生物。本数据集包含用于计算固氮和反硝化速率的箱式装置数据、用于将速率从基质尺度扩展至全河段尺度的溪流基质信息，以及用于评估跨研究溪流速率预测因子的多种河段至景观尺度协变量。