The importance of time and space in biogeochemical heterogeneity and processing along the reservoir ecosystem continuum
The importance of time and space in biogeochemical heterogeneity and processing along the reservoir ecosystem continuum
复制标题
DOI：
10.1007/s00027-023-00959-7
复制
发表时间：
2023-04
期刊：
影响因子：
2.4
通讯作者：
W. Woelmer;A. Hounshell;M. Lofton;H. Wander;Abigail S. L. Lewis;D. Scott;C. Carey
中科院分区：
文献类型：
--
作者：
W. Woelmer;A. Hounshell;M. Lofton;H. Wander;Abigail S. L. Lewis;D. Scott;C. Carey
全球每年有大量的碳（C）、氮（N）和磷（P）进入淡水水库。这些输入物可以埋藏在沉积物中、呼吸、被生物体吸收、排放到大气中或向下游输出。虽然对水库尺度的水地球化学过程了解很多，但对水库内水地球化学的时空变异性知之甚少，沿着从流入河流到大坝的连续体。为了解决这个差距，我们研究了纵向变化的地表水地球化学（C，N和P）在两个小水库在整个热分层的季节。我们采样的总和溶解组分的C，N和P，以及叶绿素a从每个水库的主要流入大坝。我们发现，在地球化学浓度的异质性更大，随着时间的推移比空间。然而，溶解的营养物和有机碳的浓度有很高的网站到网站的变化，在这两个水库，可能是由于不断变化的生物活动或环境条件。当考虑空间显式处理，我们发现，在水库内的某些位置，最常见的是流-水库界面，作为“热点”的变化，地球化学浓度。我们的研究表明，空间上明确的指标的地球化学处理可以帮助限制水库的作用，在景观中的C，N和P循环。最后，我们的研究结果强调，在小型水库的地球化学异质性可能会随着时间的变化比空间，水库内的一些网站发挥至关重要的作用，在整个生态系统的地球化学处理。
Globally significant quantities of carbon (C), nitrogen (N), and phosphorus (P) enter freshwater reservoirs each year. These inputs can be buried in sediments, respired, taken up by organisms, emitted to the atmosphere, or exported downstream. While much is known about reservoir-scale biogeochemical processing, less is known about spatial and temporal variability of biogeochemistry within a reservoir along the continuum from inflowing streams to the dam. To address this gap, we examined longitudinal variability in surface water biogeochemistry (C, N, and P) in two small reservoirs throughout a thermally stratified season. We sampled total and dissolved fractions of C, N, and P, as well as chlorophyll-a from each reservoir’s major inflows to the dam. We found that heterogeneity in biogeochemical concentrations was greater over time than space. However, dissolved nutrient and organic carbon concentrations had high site-to-site variability within both reservoirs, potentially as a result of shifting biological activity or environmental conditions. When considering spatially explicit processing, we found that certain locations within the reservoir, most often the stream–reservoir interface, acted as “hotspots” of change in biogeochemical concentrations. Our study suggests that spatially explicit metrics of biogeochemical processing could help constrain the role of reservoirs in C, N, and P cycles in the landscape. Ultimately, our results highlight that biogeochemical heterogeneity in small reservoirs may be more variable over time than space, and that some sites within reservoirs play critically important roles in whole-ecosystem biogeochemical processing.