摘要:SSC (Suspended Solid Concentration) measurements in rivers
are a complex scientific issue. Many questions arise on the spatial and
temporal distribution of particles throughout a cross-section, on the
properties of particles and grain-size, and also on the sediment transport
capacity of streams and rivers. In this study, we focused on the SSC and
grain size distribution measured from river samples, automatically or
manually acquired. Many agencies suggested slightly different methods for
measuring SSC: The European standard NF EN 872, which related to the
US EPA 160.2 requires sub-sampling using shake-and-pour aliquot
selection. The APHA 2540D requires sub-sampling by pipetting at middepth
in the original sample shaken with a magnetic stirrer. These methods
lead to significant uncertainty when particles larger than 63 µm are present
in the samples. The ASTM D3977 analysis method, endorsed by the USGS
is more accurate to capture and quantify particles larger than 63 µm. In this
study we confirm the sub-sampling problem in a large concentration range
using a set of samples from an alpine river.
其他摘要:SSC (Suspended Solid Concentration) measurements in rivers are a complex scientific issue. Many questions arise on the spatial and temporal distribution of particles throughout a cross-section, on the properties of particles and grain-size, and also on the sediment transport capacity of streams and rivers. In this study, we focused on the SSC and grain size distribution measured from river samples, automatically or manually acquired. Many agencies suggested slightly different methods for measuring SSC: The European standard NF EN 872, which related to the US EPA 160.2 requires sub-sampling using shake-and-pour aliquot selection. The APHA 2540D requires sub-sampling by pipetting at middepth in the original sample shaken with a magnetic stirrer. These methods lead to significant uncertainty when particles larger than 63 μm are present in the samples. The ASTM D3977 analysis method, endorsed by the USGS is more accurate to capture and quantify particles larger than 63 μm. In this study we confirm the sub-sampling problem in a large concentration range using a set of samples from an alpine river.