The Different Types of Sampling Protocols Used in Water Quality Sensing
Water quality is essential for maintaining the health of the environment and living organisms. Nowadays, technological advances allow us to detect water quality easily and accurately. However, before the water quality can be determined, the water needs to be sampled in the first place. There are multiple sampling protocols available, each with its advantages and disadvantages. In this article, we will discuss the different types of sampling protocols used in water quality sensing.
Types of Sampling Protocols
1. Grab sampling
Grab sampling is the most common and straightforward method used to collect water samples. Usually, a container is used to collect water from a specific location in the water body, whether it is a river, lake, or the ocean's coastal waters. The sample collected is instantaneous and not representative of the water body's overall quality, as a single water sample only represents the water at that moment in time. Furthermore, grab sampling is subject to bias from the person collecting the sample, as they can vary the amount of water collected and the location of the sample taken.
2. Composite Sampling
Composite sampling, unlike grab sampling, gives an overall qualitative analysis of the water body. A series of water samples are taken over a specific period, and these are mixed to form a single sample to be analyzed at the lab later. Composite sampling gives a better overall view of the water quality over time. This method's downside is that the quality of the water fluctuates over time, and sample collection times may not coincide with the worst-case scenarios of water quality.
3. In-line Sampling
In-line sampling employs probes or sensors that are inserted into the water body to measure the water's quality in situ or online. This method provides real-time data that is immediately available at the push of a button, and allows for continuous monitoring of the water quality. In-line sampling is ideal for remote water sources, where accessing the location to collect grab samples could be challenging and dangerous. The downside is that in-line sampling is costly and requires specialized equipment to achieve accurate results.
4. Passive Sampling
Passive sampling is a new method of collecting water samples that involves the use of devices that can capture contaminants and pollutants that accumulate over prolonged exposure. The sample is not analyzed in real-time but is taken to the lab and analyzed later. The advantage of passive sampling is that it can capture a large range of pollutants and contaminants that would be missed by grab sampling. This technique is often used in detecting pollutants like pesticides, PCBs, and other persistent organic pollutants.
5. Portable or Field Analyzers
Portable or filed analyzers are an alternative to conducting laboratory analyses of water sources. This method involves bringing the analytical instruments to the sample source and conducting the analysis on-site. Portable analyzers are more efficient in determining water quality than grab sampling, and can give almost real-time measurements. This method is advantageous for remote water sources or during environmental emergencies where time is of the essence.
Conclusion
Each of these methods has its advantages and limitations, and the choice of the most appropriate one depends on several factors like cost, location, and the contaminants present. The type of sampling protocol selected determines the accuracy and reliability of the data collected. As technology continues to develop, new and better sampling techniques are developing, and with them come more accurate water analyses. Whether it is grab sampling, composite sampling, in-line sampling, passive sampling or portable analyzers, detecting water quality has become increasingly necessary to maintain water bodies' purity, and it is crucial to know which method is best-suited for each scenario.
