Water Chemistry Field Sampling
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are presented here. The detailed step-by-step procedures that you will follow
are provided in the standard operating procedures (SOPs). Example SOPs are
given in Appendices B (stream sampling) and C (lake sampling).
2.2 WHERE, WHAT, AND WHEN TO SAMPLE
Data that provide information on the quality of surface water can be used to
evaluate the following kinds of issues:
• short-term episodic changes (scale of hours to days) in water quality
• long-term chronic changes (scale of years to decades) in water quality
• types of water quality changes
• likely causes of water quality changes
• longitudinal variation of water quality along streams or depth variation within lakes
• status and extent of chemical and biological condition across populations of lakes and streams
• biological effects of water quality changes
The ability to assess these issues will be limited largely by the extent and
intensity of the sampling effort. Three of the most critical aspects of water quality sampling design (cf., Green 1979) are the following:
• concisely and precisely stating the questions to be addressed,
• conducting a preliminary pilot sampling if existing data are not available, and
• replicating sampling in time and in space.
The questions to be addressed will arise from the project objectives; these
should be agreed on in advance of field sampling.
Sampling can be conducted at different intensity levels depending on study
design, questions to be addressed, and the intended use of the resulting data.
The level of intensity will influence decisions about how, where, what, and when
to sample and will affect associated quality assurance (QA), laboratory analysis, and data analysis objectives and SOPs. For example, if the objective is to
gain a general understanding of the distribution of potentially acid-sensitive
streams within a particular wilderness, then a low level of sampling intensity
may be perfectly acceptable. This may, for example, entail only a summer survey of specific conductance, pH, or acid-neutralizing capacity (ANC), with no
additional measurements. If, however, the objective is to more fully characterize the acid-base chemistry of one or more streams or lakes or to quantify longterm trends in water chemistry, then a higher level of intensity will be required.
Sampling that is intended to support regulatory decision making or that will
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are presented here. The detailed step-by-step procedures that you will follow
are provided in the standard operating procedures (SOPs). Example SOPs are
given in Appendices B (stream sampling) and C (lake sampling).
2.2 WHERE, WHAT, AND WHEN TO SAMPLE
Data that provide information on the quality of surface water can be used to
evaluate the following kinds of issues:
• short-term episodic changes (scale of hours to days) in water quality
• long-term chronic changes (scale of years to decades) in water quality
• types of water quality changes
• likely causes of water quality changes
• longitudinal variation of water quality along streams or depth variation within lakes
• status and extent of chemical and biological condition across populations of lakes and streams
• biological effects of water quality changes
The ability to assess these issues will be limited largely by the extent and
intensity of the sampling effort. Three of the most critical aspects of water quality sampling design (cf., Green 1979) are the following:
• concisely and precisely stating the questions to be addressed,
• conducting a preliminary pilot sampling if existing data are not available, and
• replicating sampling in time and in space.
The questions to be addressed will arise from the project objectives; these
should be agreed on in advance of field sampling.
Sampling can be conducted at different intensity levels depending on study
design, questions to be addressed, and the intended use of the resulting data.
The level of intensity will influence decisions about how, where, what, and when
to sample and will affect associated quality assurance (QA), laboratory analysis, and data analysis objectives and SOPs. For example, if the objective is to
gain a general understanding of the distribution of potentially acid-sensitive
streams within a particular wilderness, then a low level of sampling intensity
may be perfectly acceptable. This may, for example, entail only a summer survey of specific conductance, pH, or acid-neutralizing capacity (ANC), with no
additional measurements. If, however, the objective is to more fully characterize the acid-base chemistry of one or more streams or lakes or to quantify longterm trends in water chemistry, then a higher level of intensity will be required.
Sampling that is intended to support regulatory decision making or that will