Calibration of turbidity meter and acoustic doppler velocimetry (Triton‐ADV) for sediment types present in drained peatland headwaters: Focus on particulate organic peat

Abstract

Suspended sediments have a clear impact on fluvial water quality and aquatic habitats. As the concentrations are highly variable, continuous measurement offers a good way to provide accurate and precise values of sediment concentration and yield. However, there is a lack of information regarding the effect of organic peat particles, which typically appear in boreal fluvial systems. In the present study, the effect of different types of suspended sediments on calibration of a turbidity meter and an acoustic Doppler velocimetry (Triton-ADV) was studied in laboratory conditions. The measurements were performed using particulate organic peat, clay and silt with several concentrations ranging from clear water to 3500 mg L À1. The present study primarily provides organic peat sediment calibration data for used sensors. Regression equations were developed for the different sediment. The results indicate that particle size, shape, concentration and sediment type have an effect on calibration. When the turbidity and the ADV calibration were performed for different particle size groups, sediment types and concentrations, the calibration and suspended solids calculation error was reduced. For the turbidity sensor used, the reliable upper continuous measurement limit for clay, peat and silt sediments was found to be at 1000, 2500 and 3500 mg L À1 , respectively. The ADV-sensor was noticed to be reliable only with fine particles. The results enable easy and first step calibration and error assessment for automatic turbidity and acoustic monitoring of the suspended sediment quality typically present in headwater fluvial systems. This study can be used to evaluate the effect of different sediments on turbidity and ADV-measuring error and reliability during changing particles size distributions, characteristics and concentrations. The laboratory-based approach used in this study indicates that the shape of organic peat particles has an influence on sensor calibration, especially when suspended sediment concentrations are high.

Spatial and temporal variation in particle size and particulate organic matter content in suspended particulate matter from peatland‐dominated catchments in Finland

“…However, in these systems, it is more probable that transport of organic matter and formation of humus‐iron colloids caused these high values. Furthermore, especially in headwater areas, part of the SPM was formed from poorly decomposed plant and peat fragments (Figure ), as has been observed previously (Marttila and Kløve, ; Marttila et al ., ). Inorganic and organic materials form rather tight aggregates, especially if the material has been dried or is fragile and contains easily disintegrated flocs.…”

Storage, properties and seasonal variations in fine‐grained bed sediment within the main channel and headwaters of the River Sanginjoki, Finland

“…In general, local characteristics in terms of channel morphology, structure and texture, local water velocity and depth, pool and riffle sequences and also macrophytes affect sediment storage conditions (Sear, ; Wood and Armitage, ; Marttila et al ., ). In addition, the properties of the transported organic suspended sediment (Marttila et al ., ) and organic bed sediment (Marttila and Kløve, ) affect settling and re‐suspension. These effects were especially apparent during summer months, when the highest fine‐grained bed sediment storage was observed, in the present study.…”

Erosion in peatlands: Recent research progress and future directions

“…However, their application in peatland catchments should be treated with caution and calibration is required since turbidity is sensitive to variations in particle size distribution, water colour and the proportion of organic and inorganic contents (Lewis, 1996;Marttila et al, 2010).…”