Buzzard Vanessa, Thorne Dana, Gil-Loaiza Juliana, Cueva Alejandro, Meredith Laura K
School of Natural Resources and the Environment, University of Arizona, Tucson, Arizona, United States.
Biosphere2, University of Arizona, Oracle, Arizona, United States.
PeerJ. 2022 Mar 17;10:e12966. doi: 10.7717/peerj.12966. eCollection 2022.
The North American Monsoon season (June-September) in the Sonoran Desert brings thunderstorms and heavy rainfall. These rains bring cooler temperature and account for roughly half of the annual precipitation making them important for biogeochemical processes. The intensity of the monsoon rains also increase flooding in urban areas and rely on green infrastructure (GI) stormwater management techniques such as water harvesting and urban rain gardens to capture runoff. The combination of increased water availability during the monsoon and water management provide a broad moisture regime for testing responses in microbial metabolism to natural and managed soil moisture pulses in drylands. Soil microbes rely on atmospheric hydrogen (H) as an important energy source in arid and semiarid landscapes with low soil moisture and carbon availability. Unlike mesic ecosystems, transient water availability in arid and semiarid ecosystems has been identified as a key limiting driver of microbe-mediated H uptake. We measured soil H uptake in rain gardens exposed to three commonly used water harvesting practices during the monsoon season in Tucson AZ, USA. static chamber measurements were used to calculate H uptake in each of the three water harvesting treatments (stormwater runoff), (stored rooftop runoff), and (used laundry water) compared to an unaltered treatment to assess the effects of water management practices on soil microbial activity. In addition, soils were collected from each treatment and brought to the lab for an incubation experiment manipulating the soil moisture to three levels capturing the range observed from field samples. H fluxes from all treatments ranged between -0.72 nmol m s and -3.98 nmol m s over the monsoon season. Soil H uptake in the greywater treatment was on average 53% greater than the other treatments during pre-monsoon, suggesting that the increased frequency and availability of water in the greywater treatment resulted in higher H uptake during the dry season. H uptake was significantly correlated with soil moisture (r = -0.393, = 0.001, df = 62) and temperature (r = 0.345, = 0.005, df = 62). Our findings suggest that GI managed residential soils can maintain low levels of H uptake during dry periods, unlike unmanaged systems. The more continuous H uptake associated with GI may help reduce the impacts of drought on H cycling in semiarid urban ecosystems.
北美季风季节（6月至9月）期间，索诺兰沙漠会迎来雷暴和强降雨。这些降雨带来了较低的温度，且年降水量中约有一半是由它们贡献的，这使得它们对生物地球化学过程至关重要。季风降雨的强度也加剧了城市地区的洪水泛滥，因此需要依靠绿色基础设施（GI）雨水管理技术，如集水和城市雨水花园来截留径流。季风期间可用水量的增加与水管理措施相结合，为测试旱地微生物代谢对自然和人为管理的土壤湿度脉冲的响应提供了广泛的湿度条件。在土壤湿度和碳可用性较低的干旱和半干旱地区，土壤微生物将大气中的氢气（H）作为重要的能量来源。与中生生态系统不同，干旱和半干旱生态系统中短暂的可用水量已被确定为微生物介导的氢吸收的关键限制驱动因素。我们在美国亚利桑那州图森市的季风季节，测量了暴露于三种常用集水措施下的雨水花园中的土壤氢吸收情况。使用静态箱测量法计算三种集水处理（雨水径流）、（储存的屋顶径流）和（使用过的洗衣水）与未改变处理相比的氢吸收量，以评估水管理措施对土壤微生物活性的影响。此外，从每个处理中采集土壤并带回实验室进行培养实验，将土壤湿度控制在三个水平，以涵盖田间样本中观察到的范围。在整个季风季节，所有处理的氢通量在-0.72 nmol m² s⁻¹ 和-3.98 nmol m² s⁻¹ 之间。在季风前，中水（灰水）处理中的土壤氢吸收量平均比其他处理高53%，这表明中水（灰水）处理中增加的水频率和可用性导致旱季氢吸收量更高。氢吸收与土壤湿度（r = -0.393，p = 0.001，df = 62）和温度（r = 0.345，p = 0.005，df = 62）显著相关。我们的研究结果表明，与未管理的系统不同，GI管理的住宅土壤在干旱时期可以保持较低的氢吸收水平。与GI相关的更持续的氢吸收可能有助于减少干旱对半干旱城市生态系统中氢循环的影响。
