Autonomous underwater vehicle provides high-resolution observations of water quality and much more. Photo (c) Peter Berrini, HDR, Inc., used by permission.

Noteworthy

National & Regional Science:

• Fact Sheet: Integrated Synoptic Surveys Using an Autonomous Underwater Vehicle and Manned Boats
• Press Release: Decades-old Nitrate Found to Affect Stream Water Quality
• Circular 1383-G: USGS Water Science Strategy – Observing, Understanding, Predicting, and Delivering Water Science to the Nation
• OFR 2013-1054: User's Manual for the National Water Information System of the USGS
• Press Release: New water-quality test for preventing unnecessary beach closures

Local Science Features:

• New Hampshire: Concentrations of Chloride and Sodium in Groundwater in New Hampshire From 1960 Through 2011
• Arkansas:
  • –Press Release: No Contamination from Fayetteville Shale Exploration Found in Sampled Wells
  • –USGS Report: Shallow Groundwater Quality and Geochemistry in the Fayetteville Shale Gas-Production Area, North-Central Arkansas, 2011
  • –Journal Article: Geochemical and isotopic variations in shallow groundwater in areas of the Fayetteville shale development, north-central Arkansas 

Past listings...

Water Quality Data

National Water Information System (NWIS)

NWIS provides current and historical water-quality data.

Today's Water Conditions

Water-Quality Watch provides continuous real-time water-quality measurements.

Water-Quality Web Services

Web services automate the sharing of USGS and USEPA water-quality monitoring data.

For More Data

Additional water-quality data resources are available.

USGS in Your Area

USGS Water Science Centers are located in each state.

Chapter A6. Field Measurements

National Field Manual for the Collection of Water-Quality Data (TWRI Book 9)

6.4 pH, Version 2.0 dated 10/2008

Revised By G.F. Ritz and J.A. Collins

This section of Chapter 6 is available as a pdf file:
6.4, Version 2.0 (dated 10/2008) [195KB PDF]

Download a copy of Adobe Acrobat Reader for free.

Abstract

Measurement of pH is critical to the understanding of the viability and vulnerability of environmental waters and is considered a master variable in determining the aqueous geochemistry of an aqueous system. pH is a measure that represents the hydrogen-ion concentration (activity) of a solution. This section of the National Field Manual (NFM) describes U.S. Geological Survey (USGS) guidance and protocols for measurement of pH in ground and surface waters.

Contents

6.4 - pH

6.4.1 Equipment and supplies

6.4.2 Maintenance of pH instruments

6.4.3 Calibration of the pH instrument system

6.4.4 Measurement

6.4.5 Troubleshooting

6.4.6 Reporting

6.4.7 Selected References

6.4.8 Acknowledgments

Return to Chapter A6 Contents Page

Return to Field Manual Table of Contents

Section 6.4 Archived versions:

• Archive: 6.4, Version 1.3, dated 1/2006 (296KB PDF)
• Archive: 6.4, Version 1.2, dated 7/2003 (165KB PDF)
• Archive: 6.4, dated 4/98 (95KB PDF)