Water Chemistry Field Sampling
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2.3.3 On-Site Measurements
2.3.3.1 Evaluation of Site Characteristics
The field notebook and all field forms should be filled in while personnel are
at the sampling location so the sample can be accurately linked to field data
and observations. A sample field form is shown in Appendix D. Field notebooks
are helpful at sites used for LTM to provide easy access to locational information and maps, historical information on site characteristics, and field data collected during previous years.
Observations and impressions made by the field teams at the sampling location and elsewhere on the target stream or lake are extremely useful for ecological value assessment, evaluation of general water body condition, and data
verification and validation. Thus, it is important that observations made by the
field team about lake, stream, or watershed characteristics and condition be
recorded while the field personnel are in the field. Field data forms are available, and field notebooks should be provided for this purpose. The forms are
designed as a guide for recording pertinent field observations. Field data entry
forms are never considered to be comprehensive. Any additional observations
made by the field crew that might eventually be useful in making a site condition assessment should be recorded in the “Comments” section of the field
notebook. Team members complete the form at the end of the sampling, taking
into account all observations made while on site.
2.3.3.2 Stream Stage and Discharge and Lake Level
2.3.3.2.1 Stream Stage and Discharge
The most valuable nonchemical measurement for interpreting stream chemistry data is often stream flow, which is measured as volume of water per unit
time (also referred to as discharge). Variations in stream flow reflect precipitation and the different pathways water takes to reach the stream channel.
During low-flow conditions, water discharging into the stream channel has
usually had opportunity to pass well below the surface soil into deeper soils,
till, or bedrock. Such deeper flow paths provide greater contact between water
and the soils and geologic materials in the watershed. As a consequence, base
flow commonly receives larger quantities of weathering products that can buffer acidity, raise pH, and increase concentrations of BC in solution. During
high-flow periods, some water enters the stream channel through shallow flow
paths that more clearly reflect the chemistry of upper soil horizons. Shallow
flow paths tend to result in lower concentrations of BC in drainage water, less
acid neutralization (sometimes increased acidity), and higher concentrations
of DOC than deeper flow paths.
The USGS is the recognized leader in development and implementation
of flow measurements. USGS protocols and recommended equipment for
66
2.3.3 On-Site Measurements
2.3.3.1 Evaluation of Site Characteristics
The field notebook and all field forms should be filled in while personnel are
at the sampling location so the sample can be accurately linked to field data
and observations. A sample field form is shown in Appendix D. Field notebooks
are helpful at sites used for LTM to provide easy access to locational information and maps, historical information on site characteristics, and field data collected during previous years.
Observations and impressions made by the field teams at the sampling location and elsewhere on the target stream or lake are extremely useful for ecological value assessment, evaluation of general water body condition, and data
verification and validation. Thus, it is important that observations made by the
field team about lake, stream, or watershed characteristics and condition be
recorded while the field personnel are in the field. Field data forms are available, and field notebooks should be provided for this purpose. The forms are
designed as a guide for recording pertinent field observations. Field data entry
forms are never considered to be comprehensive. Any additional observations
made by the field crew that might eventually be useful in making a site condition assessment should be recorded in the “Comments” section of the field
notebook. Team members complete the form at the end of the sampling, taking
into account all observations made while on site.
2.3.3.2 Stream Stage and Discharge and Lake Level
2.3.3.2.1 Stream Stage and Discharge
The most valuable nonchemical measurement for interpreting stream chemistry data is often stream flow, which is measured as volume of water per unit
time (also referred to as discharge). Variations in stream flow reflect precipitation and the different pathways water takes to reach the stream channel.
During low-flow conditions, water discharging into the stream channel has
usually had opportunity to pass well below the surface soil into deeper soils,
till, or bedrock. Such deeper flow paths provide greater contact between water
and the soils and geologic materials in the watershed. As a consequence, base
flow commonly receives larger quantities of weathering products that can buffer acidity, raise pH, and increase concentrations of BC in solution. During
high-flow periods, some water enters the stream channel through shallow flow
paths that more clearly reflect the chemistry of upper soil horizons. Shallow
flow paths tend to result in lower concentrations of BC in drainage water, less
acid neutralization (sometimes increased acidity), and higher concentrations
of DOC than deeper flow paths.
The USGS is the recognized leader in development and implementation
of flow measurements. USGS protocols and recommended equipment for