CONCENTRATION OF IRON AND MAGNESIUM IN GROUND WATERAT NORTH BELA OF DARBHANGA DISTRICT (BIHAR)

Excessive levels of Fe, Mg and TDS are the main factors affecting groundwater quality at North Bela, Darbhanga. However, there are few studies on the source and effect of Fe, Mg and TDS concentration in the groundwater. This study takes at North Bela of Darbhanga city in Bihar state as an example, where the source and effect of Fe, Mg and TDS concentration in groundwater in the study area were analyzed. The results show that the source of Fe and Mg in the groundwater of the platformis the iron and Magnesium nodules in the soil layer. The TDS, fluctuation in groundwater levelsarethe important factors affecting the content of Fe and Mg in groundwater.This studyprovides a basis for the rational utilization of groundwater and protection of people’s health in these areaswith high iron, magnesium and TDS concentrations.


…………………………………………………………………………………………………….... Introduction:-
North Bela is one of the important developing areas in Darbhanga city. Because it is located in a humid subtropical climate region, it has enough surface water. Groundwater sediments is the main source of drinking water for local residents. However, excessive levels of Fe,Mg and TDS are the main factors affecting groundwater quality behind R. B. Jalan College Bela, Darbhanga.Groundwater used as a source of drinking water containing excessive levels of Iron, Magnesium and TDS affects only certain area of North Bela, Darbhanga but not any other points. Iron and Magnesium ions can cause staining of laundry clothes, dirty stained patches on wall &plumbing fixtures and leadto the accumulation of sediment in the water delivery system. They can also raise the color, TDS andturbidity of the groundwater. The deleterious effect of Fe and Mg on health is known to include chronicintoxication, lung embolism, bronchitis, impotence, nerve damage and parkinsonism [1]. The national standard for drinkingwater qualities in India are 0.3 mg/L, 30 mg/L and 500mg/L for Fe, Mg and TDS. The WHO recommends a health-based value of 30 mg/L for Mg and 500 mg/L for TDS. Iron and Magnesium are widely found in soils and aquifers, which have similar geochemical behavior. To investigate the influence of Fe, Mg and TDS. Studies show that high Iron, Magnesium and TDS water is distributed mostly in the environment. The North Bela , located in Darbhanga city of Bihar, is a typical area with high Iron and Magnesium content in groundwater. Though some domestic studies focus on the treatment of Iron and Magnesium groundwater. Above all, This study systematically investigated the hydrogeochemical characteristics of groundwater with high Iron, Magnesium and TDS in Bela, Darbhanga city. The relationship between Iron, Magnesium and TDS and their source were investigated. The relationship between the concentration of Iron and Magnesium in groundwater and the character of the aquifer (thickness of clay and groundwater level fluctuation) and TDS is discussed quantitatively. In addition, a good correlation between the concentration of Fe/Mg was found in the study area. This study provides a 853 basis for the rational utilization of groundwater and protection of local people's health.

Physico-Chemical Parameters
A summary of the values obtained from laboratory and fieldwork are presented in Table 1. Fe, Mg and TDS in the groundwater seriously exceed the standard in the study area. The pH of groundwater is neutral-to-weak alkaline, the anion is mainly bicarbonate, and the TDS is high.
The parameters analysis for the platform shows that three parameters account for the variation in the data (Table-1). Fe accounts for 26.44% of the variation. This factor shows the inorganic sources of Iron in groundwater. pH explains 18.85% of the variation. This factor indicates the effect of fluctuations in groundwater level. This suggests that changes in pH and redox state caused by seasonal groundwater level fluctuations dissolve Mg complexes and release TDS adsorbed on them into groundwater [4]. TDS, which accounts for 40.60% of the variation, is the positive loading of borewell depth and turbidity. This factor is related to geology.

Source of Fe and Mg
Several main factors affect the content of Iron and Magnesium groundwater at Bela in Darbhanga city is Fe and Mg substances and organic matter deposited. It has been observed in field investigation that once colorless groundwater is extracted from borewells, it will appear red or yellow after a short time of contact with air. This indicates that the groundwater is in a reduced state [5]. A microbially mediated redox process, controlled by organic matter, can lead to the mobilization of Fe and Mg into groundwater [6]. This reduction environment is fostered by the combination of fine-grained sediments and organic matter [7]. Iron and Magnesium from soil will be released into groundwater under these conditions [8]. The lithology of platforms at North Bela in Darbhanga city is Quaternary deposits. The oxidation of organic matter causes iron and manganese minerals to dissolve in ground water. Thus, the source of Fe and Mg in groundwater is not only clay, but the other. There are also soil sources of Fe and Mg in the groundwater. This area has a history of rice cultivation along with deposition of garbage outside the fields. Paddy soils are widely distributed in rice-growing areas. Under the condition of artificial periodic submerging and draining, paddy soil was kept in the process of redox alternation for a long time, and underwent a series of unique biochemical changes [9]. Long-term submerged conditions are favorable for soil organic matter deposition. The input of inorganic and organic fertilizers continuously increases the organic content of soil. The iron and Magnesium oxides in the ploughing layer were reduced to low valence iron and Magnesium compounds under submerging conditions and entered the groundwater with the water under the action of gravity [10].

Effect of Groundwater Level Fluctuation on Fe and Mg
At present, it is generally accepted that there are four ways for oxygen to enter shallow groundwater: vertical infiltration of oxygen-containing precipitation, infiltration of oxygen-containing surface water, diffusion of air in the vadose zone, and gas capture caused by fluctuation of groundwater level caused by intermittent operation of exploitation borewells [11]. The dynamic of groundwater in the study area is mainly influenced by precipitation and human activities (mostly irrigation and exploitation). Different groundwater dynamic types represent different ways in which oxygen enters shallow groundwater. According to the formation mechanism, the groundwater dynamics in the study area can be divided into four types, that is, the upland field without irrigation, the upland field irrigated by groundwater, the paddy field irrigated by surface water and the paddy field irrigated by groundwater. However, the lower plain is irrigated by groundwater and the groundwater table depth is deeper (usually 4-8 m).

Effect of TDS on Fe and Mg
The TDS in the study area was high, with an average of 585 mg/L. Under the influence of pH effect, the increase in TDS leads to an increase in ionic strength and a decrease in activity coefficient, which will dissolve more Fe and Mg in groundwater. Fe and Mg ions can also form inorganic complexes with anions in water (such as Cl -, SO 2 ) The hydro-chemistry data of water samples with TDS close to the mean value were selected for calculation, and the results showed that Fe 2+ /TFe 2+ . This indicates that the concentration of Fe and Mg can be significantly increased under the effect of inorganic complexes.