High-frequency nutrient monitoring to infer seasonal patterns in catchment source availability, mobilisation and delivery
High-frequency nutrient monitoring to infer seasonal patterns in catchment source availability, mobilisation and delivery
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DOI：
10.1007/s10661-013-3246-8
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发表时间：
2013-11-01
影响因子：
3
通讯作者：
Cresswell, Hamish P.
中科院分区：
文献类型：
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作者：
Bende-Michl, Ulrike;Verburg, Kirsten;Cresswell, Hamish P.
为了探索高频监测对解释河流营养盐浓度动态的价值，在澳大利亚塔斯马尼亚州西北部的鸭河，对一个369 km（2）的混合土地利用集水区进行了为期2年的总磷（TP）、活性磷（RP）、铵（NH 4-N）和硝酸盐（NO3-N）浓度的逐小时测量。在相同的位置和频率观测到河流流量，跨越各种水文条件。营养物浓度变化迅速，高于先前观察到的浓度。最大营养浓度分别为2，577 μ g L-1 TP、1，572 μ g L-1 RP、972 μ g L-1 NH 4-N和1，983 μ g L-1 NO3-N。不同的营养响应模式是明显的，在季节性，个别事件和昼夜时间尺度的模式，在以前不太频繁的水质采样，在很大程度上未被发现。解释这些模式的营养源的可用性，动员和交付流允许开发的概念模型集水区营养动态。确定了鸭河集水区养分释放的功能阶段，并得到聚类分析的支持，聚类分析证实了水文事件序列引起的养分响应的相似性和差异：（1）水文活动较低时期营养物质的积累，（2）高流量时期开始时现成营养源的冲刷，其次是（3）从运输到供应限制的转变，（4）随着流域湿度和水文连通性的增加，新营养源的可获得性，以及（5）当新资源变得容易动员并迅速重建水文连通性时，出现高营养峰值。日变化可能受到河流过程和/或局部点源的影响，也被确定为阶段（1）的一部分，并在后期衰退的一些冬季高流量事件。从鸭河研究的例子说明，我们表明，使用高频监测，以确定和监测功能阶段的集水区养分释放是一个建设性的方法，为信息和支持集水区管理和未来的养分监测战略。
To explore the value of high-frequency monitoring to characterise and explain riverine nutrient concentration dynamics, total phosphorus (TP), reactive phosphorus (RP), ammonium (NH4-N) and nitrate (NO3-N) concentrations were measured hourly over a 2-year period in the Duck River, in north-western Tasmania, Australia, draining a 369-km(2) mixed land use catchment area. River discharge was observed at the same location and frequency, spanning a wide range of hydrological conditions. Nutrient concentrations changed rapidly and were higher than previously observed. Maximum nutrient concentrations were 2,577 mu g L-1 TP, 1,572 mu g L-1 RP, 972 mu g L-1 NH4-N and 1,983 mu g L-1 NO3-N, respectively. Different nutrient response patterns were evident at seasonal, individual event and diurnal time scales-patterns that had gone largely undetected in previous less frequent water quality sampling. Interpretation of these patterns in terms of nutrient source availability, mobilisation and delivery to the stream allowed the development of a conceptual model of catchment nutrient dynamics. Functional stages of nutrient release were identified for the Duck River catchment and were supported by a cluster analysis which confirmed the similarities and differences in nutrient responses caused by the sequence of hydrologic events: (1) a build-up of nutrients during periods with low hydrologic activity, (2) flushing of readily available nutrient sources at the onset of the high flow period, followed by (3) a switch from transport to supply limitation, (4) the accessibility of new nutrient sources with increasing catchment wetness and hydrologic connectivity and (5) high nutrient spikes occurring when new sources become available that are easily mobilised with quickly re-established hydrologic connectivity. Diurnal variations that could be influenced by riverine processes and/or localised point sources were also identified as part of stage (1) and during late recession of some of the winter high flow events. Illustrated by examples from the Duck River study, we demonstrate that the use of high-frequency monitoring to identify and characterise functional stages of catchment nutrient release is a constructive approach for informing and supporting catchment management and future nutrient monitoring strategies.