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Research
at the Fernando
Cobo Gradín and other biologists from the Data
pH, conductivity and turbidity of fountains of the district of Santiago of
Compostela pH and conductivity of different points
from send your data to the following electronic mail: Data of some points of the region of Santiago of Compostela, in the course 2007-08 In the present activity we are only going to work with two of the fisico-chemistries parameters to investigate in the basic analysis to be made which term according to the effective norm:
· Conductivity · pH · Turbidity
The conductivity gives a measurement of the amount of salts ionized in a watery dissolution, being therefore important at the time of cataloguing a water or its possible use for irrigation or human consumption. An overexploited water-bearing can be discovered by his greater content in salts than the normal one, being therefore the conductivity a reference for the monitoring of the state of water-bearing and the overoperation of these at certain times of the year such as in the months of tourist season in the coast. Indeed, in the coast many of the water-bearing ones, due to the overexploitation, could be undergoing a progressive salinization. A data to consider is the following one: in the coastline by each meter that descends the phreatic level from fresh water, the water-bearing rises forty meters in depth, invading the saline water the lost volume. In fact, the conductivity measured with conductivimeter is called "specific conductivity", whereas the one that more would be adapted to compare the capacity to produce electrical current of a certain number of loads of an electrolyte, to different concentrations, it would be the equivalent conductivity ( ), that is the equivalent conductivity by solute.
PH also is important because it is an indicator of the different types of earth and the possible changes that can suffer when they are put under contaminators, like for example acid rain caused by the nitric and sulfuric acids that fall diluted with rain, forming both acids in the atmosphere from gases emitted by the industry, the traffic and the heatings, like main causes. In order to make these analyses and to determine the potability of the water we must follow the specified techniques in Real Decree 1138/1990, modified first by Real Decree 781/1998 and finally by the more recent Real Decree 1074/2002 that collects the norm emanated of European Directorate 98/83/CE on waters packaged for the human consumption. For this activity, really single pHmeter is necessary and conductivimeter of hand, of small cost both of them, whose maintenance only usually consists of maintaining the electrodes humid, being recommendable that pHmeter has a sensitivity of one tenth of unit of pH, and the conductivimeter has a minimum sensitivity of miliSiemens . The unit of measurement adopted by Standard ISO is to FTU (Unit of Turbidity of the Formazina) that is identical to the NTU (Unit of Turbidity of Nefelometric). In the case of having a turbidimeter or in addiction another that makes measures of pH and conductivity and also does it of turbidity; it is interesting to also measure this residual parameter that indicates to us the amount of material in suspension in the water, as a result of contributions of an excess of particles of earth, sediments, waters or plancton. If the turbidity of the water is high, there will be many particles suspended in it. These solid particles will block the solar light and avoid that the aquatic plants obtain the solar light that they need for the photosynthesis.The plants will produce less oxygen and with it they will lower the Levels of Dissolved Oxygen (DO). The plants will die and they will be more easily disturbed by the bacteria in the water, which will reduce the DO levels still more. The particles suspended in the water also will absorb additional heat of the solar light what will cause that the water is hotter. The hot water is not able to keep so oxygen as the cold water, so the DO levels will lower, specially near the surface. The suspended particles are also destructive for many aquatic organisms such as macroinvertebrate ones which are in the water. They can obstruct gills of the fish and interfere in his ability to obtain food. Also they can bury their creatures who live in the sea bed and their eggs. The suspended particles can transport contaminators in the water. The turbidity unit has been defined "as the optical obstruction of the light, caused by one part per million of silica in the distilled water", 1 nefelometric unit of turbidity (7.5 NTU) = ppm of SiO2. At the moment the used unit is the NTU, Nefelometric Unit of Turbidity, that is equivalent to: 1 nefelometric unit of turbidity (NTU) = 1 ppm of standard formazina The other two methods used to measure the turbidity and its units of measurement are the JTU (Unit of Jackson Turbidity) and the Silica unit (mg/l SiO2). Next the tables of conversion of these methods and their units as reference can be observed.
Although until
recently the parametric number was of
ten nefelometric units, in Real Decree 140/2003, of 7 of February (BOE, 21 of
February of 2003), for which the sanitary criteria of the quality of the
water of human consumption are settled down and 1 UNF in the exit of the
purifying Station or deposit and of 5 UNF in the distribution network is
determined as the maximum number of allowed turbidity.
Waters will be classified using the following tables:
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