Water fluctuations

Water fluctuations in Mediterranean rivers seriously affect fish production and droughts put important selective forces on fish communities [73] by reducing population density and species richness [58], Fish also suffer from chemical and organic pollution affecting their physiological abilities [90],... 

It is desirable to determine the chemical properties of irrigation water, paddy water in the field, and adjacent streams and rivers. Since especially the pH of the paddy water fluctuates diurnally (high in daytime and low at night), this may affect the water solubility of certain chemicals, e.g., sulfonylureas, which have dissociation constants (p/fa) in an environmentally relevant range. 

The pH of the lake water fluctuates when not replenished by the alkaline river water in the tributary rivers. In fact, the pH of the lake water drops significantly each time it rains (i.e. when more H2CO3 enters the lake). If the amounts of acid and alkali in the water remain relatively low, then the slight fluctuations in water pH wifi not be great enough to kill life forms in the lake. 

Responsibility for mine water quality and quantity From time to time, the quality and flow rate of the mine water fluctuate significantly, and this may cause overloading of the entire system and subsequent non-compliance with permitted discharge concentrations, which can be only be buffered by the reactive filter materials. In this respect, contractual questions must be resolved between the operator of the wetland (WISUTEC) and the owner of the mine water (WISMUT) as to who is responsible for treatment and discharge. 

We recently developed a systematic method that uses the intrinsic tryptophan residue (Trp or W) as a local optical probe [49, 50]. Using site-directed mutagenesis, tryptophan can be mutated into different positions one at a time to scan protein surfaces. With femtosecond temporal and single-residue spatial resolution, the fluorescence Stokes shift of the local excited Trp can be followed in real time, and thus, the location, dynamics, and functional roles of protein-water interactions can be studied directly. With MD simulations, the solvation by water and protein (residues) is differentiated carefully to determine the hydration dynamics. Here, we focus our own work and review our recent systematic studies on hydration dynamics and protein-water fluctuations in a series of biological systems using the powerful intrinsic tryptophan as a local optical probe, and thus reveal the dynamic role of hydrating water molecules around proteins, which is a longstanding unresolved problem and a topic central to protein science. 

Figure 44. Solvation dynamics from constrained MD simulations, (a) Comparison of indole-water relaxation with and without frozen protein structure for isomer 1. The slow component of the water response nearly disappears, which indicates that slow water relaxation needs protein fluctuations, (b) Comparison of indole—protein relaxation with and without frozen water for isomer 2. Similarly, the slow component of the indole—protein disappears, which indicates that the protein relaxation also requires water fluctuations.

Monolayer of water covers surface. Interaction with charged and polar surface groups selects locally ordered arrangements of hydration water. Fluctuation between many instantaneous arrangements, as in liquid water. 

Finally, the climatic conditions and local factors must also be clarified in advance Is water available How much does the temperature of the water fluctuate in the course of a year Even oil-operated vacuum pumps have to be designed differently for service in, say, Saudi Arabia than in Sweden. 

---