测量实验室微量微生物中的磷释放,用于水质评估
Summary
在饱和土壤和沉积物中准确定量磷(P)解吸电位对P建模和运输缓解工作非常重要。为了更好地解释在长期饱和条件下的原位土壤-水氧化还原动力学和P动员,在实验室缩微图反复取样的基础上,开发了一种简单的方法。
Abstract
磷(P)是农业生态系统中一种关键的营养物质,需要谨慎管理,以减少对水生环境的运输风险。P生物利用度的常规实验室测量基于在氧化条件下对干燥样品进行的化学提取。这些测试虽然有用,但相对于在长期水饱和条件下的P释放特征而言是有限的。与氧化铁和其他金属结合的甲氧乙酸磷可以迅速解灭溶液,减少环境,增加地表径流和地下水的P动员风险。为了更好地量化P解吸电潜力和在延长饱和期间的流动性,基于对孔隙和覆盖洪水的反复取样,开发了实验室微观方法。该方法可用于量化土壤和沉积物中具有物理化学性质变化的P释放潜力,并通过更好地描述水文活动区域的P释放风险,改进现场特定的P缓解工作。该方法的优点包括能够模拟原位动力学、简单性、低成本和灵活性。
Introduction
磷(P)是作物和水生生物量生产力的关键限制营养素。地表水水文是P命运和运输的主要驱动力,因为它控制着沉积物和P的物理运输,同时也影响径流和洪水/池塘事件期间的再动员潜力。各种基于实验室的提取方法通常用于在氧化条件下估计场尺度的P释放。虽然不同的机制可以促进P释放,但铁磷酸盐的还原溶解是一种成熟的反应机制,可导致对水1、2、3的大正磷-P通量。 4.在湿地P生物地球化学控制机制的综述中,将氧化还原状态假设为控制土壤和浅层地下水P释放的主要变量5。因此,传统的P测试可能不是长期饱和下P释放的可靠预测变量。
鉴于水停留时间和氧化还原状态对P命运和运输的重要性,旨在更好地模拟原位条件的实验室方法可改善农业和湿地生态系统的P运输风险指数。可变饱和度。由于正磷酸盐是可立即生物可利用的,饱和期间解吸率和范围可作为非点源P污染风险的指标。我们的方法旨在量化P解吸水(PW)和动员覆盖洪水(FW),这是在源区水文变化地区的典型情况(例如,被淹的农田、湿地、排水沟和河岸/近流区域)。该方法最初用于描述美国纽约北部季节性淹没土壤中的P释放潜力,最近用于量化佛蒙特州西北部尚普兰湖盆地6的河岸土壤的P解吸潜力。.在这里,我们为实验室微缩方法提供一个协议,并重点介绍了最近发表的一项研究的结果,该研究展示了其量化P解吸潜力的能力。我们还演示了P释放潜力与常规土壤测试(可提取P,pH)的可靠性之间的关系,以预测不同地点的释放。
实施该方法需要进入具有适当气候控制、通风、水和适当酸废物处理系统的分析实验室。该方法假定使用常规化学试剂和实验室设备(水槽、罩、玻璃器皿等)。除了常规实验室需求外,还需要一个膜过滤(± 0.45 μm)系统和一个紫外分光光度计来测量P。也推荐使用 pH 计或多参数水质探头,但不是必需的。实验室温度是一个重要因素,除非温度本身作为实验因子加以研究(建议为 20°C),否则应保持不变。能够畅通无阻地使用适当的分析实验室和适当的设备,是正确执行该方法并产生有意义的结果的先决条件。
Protocol
Representative Results
Discussion
微观方法的一个主要技术优势是能够模拟原位条件,使饱和的土壤或沉积物立即被FW覆盖,在氧化还原和P状态上可能有很大差异。具有可变源区水文的景观,如排水沟、被淹没的农田、湿地和河岸/近流区,都是通过更氧化的水而周期性地过度利用的、Pi浓度较低的水减少 PW 的示例。这些氧化还原梯度可以强烈地影响 Pi 吸附/解吸,因此可移动到地表和地下水…
Disclosures
The authors have nothing to disclose.
Acknowledgements
佛蒙特州水资源和湖泊研究中心通过与美国地质调查局达成协议,提供了资金。结论和意见是作者的结论和意见,而不是佛蒙特州水资源和湖泊研究中心或美国地质调查局。
Materials
| 1.25 cm plastic hose barbs | numerous | NA | |
| Chemical reagents for phosphorus determination | numerous | NA | P analysis capability is assumed; refer to cited references for details on method |
| Chordless or electric drill with 1.25 cm bit | numerous | NA | |
| Graduated plastic beakers (1L) | numerous | NA | |
| Laboratory with fume hoods, temperature control, and acid waste disposal system | NA | NA | |
| Nylon mesh filter screen (100um) | numerous | NA | |
| Silicone | numerous | NA | |
| UV Spectrophotometer | numerous | NA |
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