Comparison between aquifer solute concentration and monitoring wells

Disparities between solute concentration in the aquifer and that in monitoring wells have been observed. It is important to be able to relate concentrations between monitoring well and aquifer solute concentration for design of remediation systems. Reported that solute concentrations in a monitoring well may underestimate the corresponding aquifer concentration by over an order of magnitude (Martin-Hayden et al., 1991, Chiang et al., 1995). Contributing factors such as well screen length, purging procedure, vertical solute concentration profile in the formation and the hydrogeological characteristics of the aquifer were cited. Factors such as chemical reactions, biological processes, adsorption phenomena and vertical groundwater flow combined with vertical and longitudinal dispersion also reported to cause the disparities between monitoring well and aquifer concentration (Barcelona and Herfrich 1986, Herzog et al., 1988) Groundwater sampling is conducted to provide accurate information of subsurface water resources. The reliable detection and assessment of groundwater contamination require minimal or no disturbance of geochemical and hydrogeological conditions during sampling. Validity of comparison between aquifer solute concentration and monitoring wells based to representative or error free sampling procedure. In this paper our effort focused to compare solute concentration of extracted mixed-water from a partially penetrating monitoring well and calculated aquifer solute concentration as a result of numerical methods. The aquifer solute concentration calculated as a combination of a finite element method for the flow and transport simulation in a vertical section aligned with principal direction of flow and an analytical solution for describing the potential ? and the velocity field around a pumping well. On the other hand, groundwater samples are collected from partially penetrating monitoring wells and are mixed-water samples. These groundwater samples were analyzed in the laboratory using the standard methods (Hem 1995). It must be noted that this work focused to nitrate pollution control and nitrate concentration in collected samples were measured with a portable equipment of type Eijkelkamp (Marckoquant 10020) and sporadically verified using analytical methods. The nitrate pollution is the non-point pollution problem, a significant part of which is the contamination of groundwater resources, has its main origin in agricultural practices. The use of fertilizers to supply plan nutrients has caused nitrate contamination of groundwater in numerous rural areas of the world. The increased fertilizers for the increased agricultural production must combine detrimental effect on the environment. Suggestively note that in Greece the nitrogen fertilizers increased from 4.4 Kg/ha to 100 Kg/ha in the period 1950-1990 (Ministry of Environment, Planning and Public Works 1995).

Związek pomiędzy stężeniem substancji rozpuszczonych w studniach monitoringowych a w warstwie wodonośnej ma duże znaczenie przy szacowaniu wielkości zanieczyszczenia zasobów wód gruntowych. Co ważniejsze, aby ocenić wpływ odcieków z nawadnianych obszarów rolniczych, na których występuje intensywne nawożenie na studnie pobierające wodę do picia, należy skorelować stężenia azotanów w warstwie wodonośnej ze stężeniami w wodzie do picia, tak aby poprawnie ocenić realne ryzyko. Do obliczeń przepływu i prędkości wody w pobliżu częściowo penetrującej studni zastosowano dwu wymiarowy model elementów skończonych przepływu itransportu w połączeniu z rozwiązaniem analitycznym. Zaprezentowano porównanie obliczonych stężeń azotanów i zmierzonych w studniach monitoringowych. Stwierdzono różnice pomiędzy stężeniem azotanów w warstwie wodonośnej a w studniach monitoringowych. Związek pomiędzy stężeniem azotanów w studniach monitoringowych a w warstwie wodonośnej zależy od dostępnych danych. Azotany jako zanieczyszczenie nie punktowe lub obszarowe musi być traktowane bardzo poważenie z wielu punktów widzenia.