In the study and monitoring of aquatic environments, water sampling is one of the crucial steps to understand water quality, biota distribution, and ecosystem dynamics. One instrument that is often used to take water samples with high precision is the Nansen Sampler. It has become the first choice for researchers in a wide range of disciplines, from marine science to environmental science, thanks to its ability to collect water samples from various depths with accurate representation.
Developed by Fridtjof Nansen in the early 20th century, the Nansen Sampler was originally designed for oceanographic research purposes. However, along with its technological development and scientific applications, it has become a versatile tool in understanding aquatic ecology from shallow to deep waters. Its working principle is based on a sampling principle consisting of water bottles that can be automatically closed at a certain depth, allowing sampling of various water layers with high precision.
The Nansen Sampler is a water sampling device used in aquatic environmental research. The instrument is designed to take water samples from various depths with high precision, allowing researchers to obtain comprehensive information on water quality, biota distribution, and aquatic ecosystem dynamics.
The working principle of the Nansen Sampler is based on the use of water bottles that can be automatically closed at a certain depth. The instrument consists of a series of bottles connected by ropes or cables. When the instrument is lowered into the water, the bottles open passively. When the instrument reaches the desired depth, the researcher can trigger the bottle closing mechanism manually or by using an automatic setting system, depending on the model and design of the instrument used. Once the bottles are closed, the water sample from that depth is trapped inside the bottle with a strong seal, maintaining the integrity of the sample throughout the collection process.
The main advantage of the Nansen Sampler is its ability to sample vertically from various depths with high precision. This allows researchers to obtain a comprehensive picture of water conditions from the surface to the bottom of the ocean or river. Information obtained from samples collected with the Nansen Sampler includes physicochemical parameters such as temperature, salinity, dissolved oxygen, pH, and nutrient and pollutant concentrations.
The Nansen Sampler is frequently used in various research fields, including oceanography, limnology, hydrology, and aquatic biology. The instrument is also important in water quality monitoring, understanding aquatic ecology, and research on the impact of environmental change on aquatic ecosystems.
While the Nansen Sampler has become one of the most popular and reliable water sampling tools, its use still requires expertise and careful attention to ensure the integrity and representativeness of the samples collected. In addition, recent technological developments continue to introduce improvements and innovations to the design and function of this instrument, enhancing its ability to collect accurate and relevant data for better understanding of the aquatic environment.
Parts of the Nansen Sampler:
- Sample bottle: made of glass or plastic and fitted with a watertight cap. It has two valves: an upper valve to fill the bottle with seawater and a lower valve to prevent seawater from escaping.
- Ballast: to help lower the Nansen Sampler to the desired depth. The ballast is usually made of metal and is attached to the bottom of the Nansen Sampler.
- Thermometer: to measure the seawater temperature at the sample depth. The thermometer is usually attached to the outside of the sample bottle.
- Messenger: a small weight used to trigger the release of the sample bottle. The messenger is dropped onto the cable of the Nansen Sampler to trigger the release mechanism.
- Cable: for lowering and raising the Nansen Sampler. The cable is usually made of steel and has a length that corresponds to the sea depth to be measured.
How Nansen Work
The Nansen Sampler works on the principle of taking water samples from various depths in the water. Here are the general steps of how it works:
- Instrument Preparation: Before use, the Nansen Sampler must be properly prepared. This includes checking the condition of the sampling bottles, ensuring all parts of the instrument are functioning properly, and calibrating the sensors or gauges built into the instrument, if any.
- Lowering the Instrument into Water: Once prepared, the Nansen Sampler is run into the water using a boat or vessel. The instrument is usually dropped slowly into the water or lowered using a cable or rope connected to a towing system or pulley.
- Setting the Sampling Depth: Researchers determine the depth at which they want to sample the water. This can be done by monitoring the depth using electronic devices such as sonar or by referring to a visual estimation or map of the water depth.
- Bottle Cap Triggering: Once the instrument reaches the desired depth, researchers trigger the bottle cap mechanism. This can be done manually by pulling a cable or lever connected to the bottle, or using a pre-set automated system.
- Removal of the Instrument from the Water: Once the sampling bottles are filled with water from the specified depth, the instrument is pulled back to the surface. This process is usually done carefully to ensure that the collected water samples remain intact and are not contaminated during removal.
- Sampling from Bottles: After the instrument is lifted to the surface, the sampling bottles are carefully opened to remove the water samples. These samples are then taken for further analysis in the laboratory or directly in the field, depending on the purpose of the research or monitoring application.
- Cleaning and Maintenance: Once sampling is complete, the instrument needs to be properly cleaned and maintained to keep its performance. This includes cleaning the sampling bottles, checking the mechanical and electronic systems, and replacing or repairing any damaged or worn parts.
Nansen Strengths and Weaknesses
Nansen Strengths:
- Vertical Sampling Precision: The Nansen Sampler enables water sampling from various depths with high precision, allowing researchers to obtain a comprehensive picture of water conditions from the surface to the bottom of the sea or river.
- Representative Sampling: The instrument can sample water from multiple layers simultaneously, resulting in samples that are vertically representative of water conditions. This enables more accurate analysis of the distribution of physicochemical parameters, nutrients, plankton and pollutants in the water column.
- Versatility: The Nansen Sampler can be used in a variety of aquatic environments, including rivers, lakes and the ocean. This makes it a versatile tool in oceanographic, limnological, hydrological, and aquatic biological research.
- Reliability: This instrument has been used extensively by researchers over the years and has proven to be reliable in taking good quality water samples. It’s simple and tested design also makes it relatively easy to operate and maintain.
Nansen Weaknesses:
- Manual Operation: Some Nansen Sampler models still require manual operation to trigger the sampling bottle cap. This can require skill and careful attention from the operator, especially in poor weather or water conditions.
- Limited Sampling Capacity: The sample capacity that can be taken by the Nansen Sampler depends on the number of sampling bottles installed. This may be a limitation to sampling in situations where the number of samples required is very large or when sampling must be done repeatedly.
- Depth Limitations: While the Nansen Sampler can be used for sampling from various depths, some models have specific depth limitations. This may limit its use in studies that require sampling from great depths.
- Potential for Contamination: As with all water sampling instruments, the Nansen Sampler is susceptible to contamination from external sources. Extra care should be taken to ensure that the instrument and sampling bottles are well cleaned before use to avoid cross-contamination between samples.
Writer : Muhammad Farhan
