Specifications.docx

Specifications Project: Field rugged and portable optical multi parameter water probe High-frequency, Multi-parameter Measurement of Agricultural Waters

GENERAL INFORMATION

1.0 Scope of Work: We will conduct high-frequency sampling with two different strategies (Lagrangian, Eulerian) in order to quantify NO3- export from an agricultural watershed and identify locations and times that are biogeochemically important for influencing watershed scale processing of NO3-. We also study processing and export of additional water constituents such as dissolved carbon and suspended solids.

2.0 Background: Agricultural landscapes in the Upper Midwest can be responsible for export of excess sediment and nutrients to streams and rivers which leads to water quality problems at local and national scales. Loss of fertilizer from agricultural fields represents an economic loss to the farmer. Research to minimize farm inputs helps to increase farm profitability while also improving water quality. Reduction in nutrient losses can be achieved by installing edge-of-field practices that intercept and treat tile drainage effluent via denitrification prior to discharge into surface waters. Denitrification requires a carbon source; monitoring both nitrate and carbon concentrations in the influent and effluent of these practices is necessary to understand processes and optimize performance. Using advanced instrument technology to simultaneously measure nitrate and carbon concentrations (and other water parameters) at fine timescales (sub-minute) would greatly enhance our research capabilities.

CONTRACTOR REQUIREMENTS

3.0 Salient Characteristics - Technical Requirements:

We require a multi-parameter water quality probe that can conduct high-frequency measurements in a laboratory or field setting.

· The probe must be able to measure NO3- as well as additional water parameters including: organic carbon, turbidity, and temperature as well as additional data about light transmittance across multiple wavelengths (200-720 nm) with the ability for data retrieval and in-house development of additional calibration curves.

· The probe must show long-term stability with minimal to no maintenance.

· The multi-parameter probe must be able to communicate wirelessly with common mobile devices and have on-board memory capable of logging data from potentially extended deployments (up to 6 months).

· The sensor must have an optical path length and calibration parameters suitable for measuring NO3- concentration ranges suitable for agricultural landscapes (up to 50 ppm).

· The sensor, software to drive it, and all data produced by it, must be compatible with sensors that are currently in use by scientists in our unit. More specifically, we need a multi-parameter water quality probe that matches our current in-house lineup of Spectrolyser_V3 sensors produced by s::can (owned by Badger Meter).

4.0 Deliverables / Schedule: Equipment should be delivered to: USDA-ARS, Soil and Water Management Research Unit, 1991 Upper Buford Circle, Rm 439 Borlaug Hall., St. Paul, MN 55108; Delivery within 90 days of award.