Uncertainty in the Estimation of Stream Metabolism from Open-Channel Oxygen Concentrations
Uncertainty in the Estimation of Stream Metabolism from Open-Channel Oxygen Concentrations
复制标题
根据开放通道氧气浓度估计流代谢的不确定性
DOI：
--
复制
发表时间：
1998
影响因子：
--
通讯作者：
James III. F. Saunders
中科院分区：
文献类型：
--
作者：
J. H. McCutchan;W. Lewis;James III. F. Saunders
明渠氧法估算溪流代谢避免了许多与室技术相关的问题，但其不确定性尚未得到严格量化。光合作用（P）和呼吸作用（R）的明渠估算值的不确定性可以通过使用蒙特卡罗方法进行估算，该方法将影响P和R估算值误差的每个项（复氧率系数、温度振荡范围、中点温度、旅行时间、代谢率和仪器校准精度）的不确定性结合起来。从蒙特卡罗模拟中推导出的分布为P和R的估计提供了置信限。沿着这种方法并模拟一系列水流条件表明：1）在同等代谢率和物理条件下，R的估计值比P的估计值具有更大的不确定性，特别是在高梯度水流中; 2）通过特别注意影响氧饱和浓度的因素的测量精度，可以使不确定性最小化。合理的置信限（95%CL平均值的30%内），可以实现的估计P日光合速率超过L-1d-1，但在湍流（k20 =100/d），R率必须接近15毫克L-1d-1，以达到类似的精度。
The open-channel oxygen method for estimating stream metabolism avoids many of the problems associated with chamber techniques, but its uncertainty has not been rigorously quantified. Uncertainty in open-channel estimates of photosynthesis (P) and respiration (R) can be estimated by use of a Monte Carlo approach incorporating uncertainty in each of the terms (reaeration rate coefficient, range of temperature oscillation, midpoint temperature, travel time, metabolic rate, and precision of instrument calibration) affecting error in estimates of P and R. The distributions derived from the Monte Carlo simulations provide confidence limits for estimates of P and R. Use of this approach along with simulation of a range of stream conditions indicates that: 1) given equivalent metabolic rates and physical conditions, estimates of R are subject to greater uncertainty than are estimates of P, especially in high-gradient streams, and 2) uncertainty can be minimized by special attention to the precision of measurement for factors affecting the saturation concentration of oxygen. Reasonable confidence limits (95% CL within 30% of mean) can be achieved for estimates of P where daily photosynthetic rates exceed L-1d-1, but in turbulent streams (k20⚬=100/d), rates of R must be nearly 15 mg L-1d-1 to achieve similar precision.