A precise water sampling process is crucial in environmental research and monitoring, especially in open waters that are susceptible to factors such as contamination and temperature changes. In this context, tools such as the Van Dorn water sampler offer an effective solution with their specialized design to minimize contamination and enable accurate sampling, even in environments with solid particles or other contaminants. Therefore, understanding the features and capabilities of these tools can provide valuable insights in understanding the dynamics of aquatic environments and maintaining the sustainability of the associated ecosystems.
The Van Dorn water sampler, designed specifically for open water sampling, comprises a horizontal water bottle along with a falling weight, 30 meters of polyester rope, and a carrying case. It can be further enhanced with a CTD Driver, enabling temperature, vertical water depth, and optionally, conductivity monitoring.
Due to its material composition, this sampler is well-suited for coastal water sampling and heavy metal analysis. Its design allows for uninterrupted horizontal water flow, minimizing contamination risks, even in shallow waters. Hence, it is effective for measuring parameters in water containing solid particles or other constituents, potentially in substantial quantities. Holding up to 2.2 litres, the sampler ensures that the sample remains free from contact with metal components.
How Van Dorn Work
Here are the general steps for using the Van Dorn water sampler:
- Tool Preparation: Ensure that all parts of the Van Dorn water sampler are properly prepared. This includes checking the physical state of the device, ensuring that all components are well connected, and checking the availability of additional equipment such as CTD Driver if required.
- Rope Length Adjustment: Adjust the length of the polyester rope by about 30 meters to match the water depth where the sampling will take place. Ensure that the rope is securely attached to the towing device.
- Lowering the Tool: Slowly lower the Van Dorn water sampler into the water using the rope. Ensure the device is fully submerged in the water to avoid sampling errors.
- Tool Opening: Use the rope to carefully pull the tool puller so that the horizontal tool opens wide. This will allow water to enter the sample bottle freely.
- Sampling: Once the tool is fully open, leave the tool in the open position for a few seconds to ensure representative sampling. Make sure to sample from the desired depth by holding the rope steady.
- Tool Closure: Once the sample is taken, gently pull the rope to close the tool again. Ensure the tool is completely closed before raising it back to the surface.
- Recalling the Tool: Carefully lift the Van Dorn water sampler back to the water surface using the rope. Be sure to observe the device as it is being pulled up to ensure there are no leaks or other issues.
- Sample Storage and Analysis: Once sampling is complete, be sure to properly store the sample in a suitable container for further analysis as needed. Evaluate the analysis results to gain a better understanding of the water quality at the sampling site.
Van Dorn Strengths and Weaknesses
The Van Dorn water sampler has several advantages that distinguish it from other water sampler instruments:
- Specialized Design for Open Water: The Van Dorn water sampler is designed specifically for water sampling in open environments. Its horizontal design allows for accurate sampling even in open waters that are prone to flow disturbances and contamination.
- Minimal Contamination: Compared to some other water sampler instruments that may have limitations in preventing contamination, the Van Dorn water sampler ensures that water flows freely through the sample bottle without obstruction, so the risk of contamination is minimized.
- Ability for Sampling at Various Depths: With an adjustable polyester rope of up to 30 meters, the Van Dorn water sampler can be used for sampling at various water depths, providing greater flexibility in environmental research.
- Suitability for Heavy Sampling: The Van Dorn water sampler’s ability to cope with environments with solid particles or other contaminants, even in large quantities, makes it an ideal choice for sampling that requires high precision in analysis.
- Maximum Sample Capacity: With a sample capacity of up to 2.2 liters, the Van Dorn water sampler allows for sampling large enough for more in-depth analysis without compromising sample quality.
Although the Van Dorn water sampler is an effective tool in sampling water in open environments, it has some drawbacks compared to other water sampler instruments:
- Limitations in Water Depth: Van Dorn water samplers are typically used in shallow to medium water due to the limited length of the rope (usually around 30 meters). This limits its ability to be used for sampling in deeper waters.
- Sample Capacity Limitations: Despite having a fairly large sample capacity (typically around 2.2 liters), the Van Dorn water sampler cannot sample very large quantities like some other water sampler instruments that may have a larger capacity.
- Limitations on Specific Applications: It may be less suitable for certain applications, such as sampling in environments with very strong currents or in locations that are difficult to access. Other water sampler instruments may be more suitable for these conditions.
- Difficulty in Handling: Operating the Van Dorn water sampler requires skill and care to allow accurate sampling. The process of opening and closing the device and pulling it back to the surface can be difficult especially in unfavorable weather or environmental conditions.
- Functionality Limitations: Although it can be upgraded by using a CTD Driver, the Van Dorn water sampler is not intrinsically equipped with additional parameter measurement capabilities such as salinity or water turbidity, which may be available in other water sampler instruments.
Overall, the Van Dorn water sampler stands out as a reliable and effective tool in water sampling in open environments. Nonetheless, with a good understanding of its advantages and disadvantages, and with the application of proper usage procedures, the Van Dorn water sampler remains an invaluable tool in environmental research and surveillance.
Writer : Ignatia Feronica Sinaga
