Assessing the Impact of Recreational Activities on Streams: A Colorado Case Study

Water-based recreational activities
can impact freshwater
systems,
but the resulting anthropogenic alterations to the chemical and microbial
composition of natural streams remain poorly understood. Utilizing
state-of-the-art analytical approaches, including liquid chromatography-high-resolution
mass spectrometry (LC-HRMS), inductively coupled plasma mass spectrometry
(ICP-MS), and 16S rRNA gene sequencing, we investigated changes in
stream chemistry and microbiology resulting from recreational activities
in Clear Creek (Golden, Colorado). Spatial and temporal sampling was
conducted for 3 days over a summer holiday weekend when a large influx
of recreational float tubing activity occurred. Nontarget LC-HRMS
analysis demonstrated substantial differences in the organic fingerprint
on days and locations with high recreational use compared to that
of low use. Similarly, increases in the total suspended solids were
correlated with suspended particulate metal concentrations (Al, Cu,
Ti, Pb, and Zn). Element ratios suggest recreation-induced resuspension
of streambed sediments as the metal source rather than other anthropogenic
inputs (e.g., Ti/Zn-containing sunscreens). Gene sequencing revealed
significant shifts in the stream microbial community, supporting an
input of human-associated enteric microbiota during high recreation
periods. However, the overall results indicate that recreational activities
have a short-lived effect on the stream. In this work, we established
a first-of-its-kind holistic assessment of the impact of anthropogenic
activity on a natural stream by simultaneously considering changes
in the organic, inorganic, and microbial fingerprints.

基于水体的休闲活动可能对淡水生态系统产生影响，然而，人类活动对自然溪流的化学和微生物组成所造成的特定人工改变仍缺乏深刻理解。本研究运用了先进的分析技术，包括液相色谱-高分辨质谱（LC-HRMS）、电感耦合等离子体质谱（ICP-MS）以及16S rRNA基因测序，对科罗拉多州金市清晰溪因休闲活动导致的溪流化学和微生物变化进行了研究。在夏季假期周末的三天时间里，当大量休闲漂流活动发生时，我们进行了空间和时间采样。非目标LC-HRMS分析显示，与低使用率相比，在休闲活动频繁的日期和地点，有机指纹存在显著差异。同样，总悬浮固体的增加与悬浮颗粒金属浓度（铝、铜、钛、铅和锌）的增加相关。元素比率表明，休闲活动引起的溪流底泥悬浮是金属来源，而非其他人为输入（例如，含钛/锌的防晒霜）。基因测序揭示了溪流微生物群落发生显著变化，支持了在高休闲时期存在与人类相关肠道的微生物输入。然而，总体结果表明，休闲活动对溪流的影响是短暂的。在本研究中，我们首次建立了一种综合评估人类活动对自然溪流影响的体系，该方法同时考虑了有机、无机和微生物指纹的变化。