Low-Cost Temperature Profiling - micro-T Mooring System

Project Overview

Water temperature has many important effects on the biological, chemical, and physical aspects of aquatic environments. Temperature is dependent on air temperature, sunlight, wind, and water depth. During the summer, the sun warms surface layers of water, while deeper layers remain cool. Wind is important for mixing warmer surface water with deeper, cooler water.

Factories and power plants generate tremendous volumes of hot water, which is typically released into streams and estuaries. If the water has not been cooled to safe levels before being discharged, dissolved oxygen levels will decrease, but the biological oxygen demand (BOD) of aquatic organisms will increase. In short, organisms may not receive enough oxygen to survive.

A small factory was looking for a cost-effective temperature profiling solution for a nearby lake. Managers wanted to monitor temperature at various depths to ensure the effluent they release is not affecting the aquatic ecosystem. Based on site conditions and budget constraints, NexSens applications engineers recommended the micro-T mooring system, which is an ideal solution for cost-effective temperature profiling studies.

System Description

Mooring System Diagram

The NexSens micro-T mooring system consists of micro-T temperature loggers with underwater housings mounted on a line to create a temperature string. micro-T loggers are accurate to +/-0.5 degrees Celsius and can operate for many years (depending on sample interval). The memory chip stores up to 4,096 readings per deployment.

micro-T software allows users to configure each logger's sampling options, such as log interval, start time, and data rollover. For consistent temperature profiling, the loggers are programmed to start collecting temperature data at the same time. The loggers will be deployed for three months at a time while storing temperature readings every hour.

The application consists of multiple underwater housings attached to a 3/16-inch stainless steel mooring line at specified intervals. The line is connected to a 12-inch-diameter buoy, made of extremely durable marine-grade PVC. The buoy is moored to the bottom with an anchor, chain, and shackles. A 15-pound pyramid anchor and 10 feet of bottom chain are designed to withstand water level fluctuations while keeping the line in place.

This system allows factory workers to map the temperature readings over an extended period of time. The user-friendly software simplifies data management. Customized reports can be converted to PDF, exported to Microsoft Excel, sent to colleagues via e-mail, uploaded to a web server, and more. Management of factory effluent may change depending on the results of this study.