Abstract:
Quality concerns drive many water studies and practices, but obtaining samples from water bodies over time and space for quality determination is often difficult and expensive. We present a low-cost approach that allows integration of water samples over timescales of days to months to allow more widely distributed acquisition of time-integrated samples than possible with previous technology. The device is simply a submerged bottle with a small hole in the lid. In an alternative design the submerged bottle is connected by a tube to a second bottle located outside of the water. In either case, pressure changes inside the sampler arising from natural fluctuations in temperature and atmospheric pressure lead to an accumulation of water in the bottle. For example, when the sampler warms, air escapes the hole, and when it cools, water enters the hole, so with daily variation of 6°C per day the bottle will half fill in 1 month. Laboratory and environmental tests confirm the concept's function. Variants of the design for well sampling and use in deep water are also presented.
