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Dissolved organic matter (DOM) is linked to the heterogeneous distribution of elevated arsenic (As) in groundwater used for drinking and irrigation purposes, but the relationship between DOM characteristics and arsenic mobility has yet to be fully understood. Here, DOM from groundwater sampled in the Bengal Basin region was characterized using both conventional bulk emission-excitation (EEM) spectroscopy and high-performance size exclusion chromatography coupled to spectroscopy (HPSEC-EEM). Notably, application of the novel HPSEC-EEM approach permitted the total fluorescence of individual samples to be independently resolved into its underlying components. This allowed the external validation of the bulk-sample fluorescence decomposition and offered insight into the molecular size distribution of fluorescent DOM. Molecular size distributions were similar for the UVA fluorescent (C 310 , C 340) as well as the three visible fluorescent (C 390 , C 440 C 500) components. There was a greater visible fluorescence in shallow aquifer samples (10-33 m) with high As (SH, up to 418µg/L) than in samples from the same depth with lower As (up to 40µg/L). This indicated a link between DOM quality and As mobility within the shallow aquifer. The deep aquifer samples (170-200 m) revealed DOM characteristics similar to SH samples but had low As concentrations (<4µg/L), signifying that the deep aquifer is potentially vulnerable to As contamination. These findings pave the way for a more comprehensive assessment of the susceptibility of drinking water aquifers, thereby supporting the management of groundwater resources.

The Gaza Strip is one of the most densely populated areas in the world, 4505 people per km² and the only source of water is represent by groundwater. The water quality in Gaza is very poor and the groundwater is affected by many different contaminants sources including soil/water interaction in the unsaturated zone due to recharge and return flows, mobilization of deep brines, sea water intrusion or upcoming and disposal of domestic and industrial wastes into the aquifer. Previous reports on the water quality in Gaza discussed the high levels of major ions (especially of chloride, nitrate and fluoride) in the drinking water. Moreover, little or no information is available for trace elements in the groundwater of the Gaza Strip. The sources of trace elements in groundwater could be natural and anthropogenic. 58 wells were sampled during July 2010, and were analyzed major ions and trace elements to check if the water quality is improving from the previous report. This study has revealed that no groundwater in Gaza Strip meets all WHO drinking water standards. The contaminants which affected the Gaza Strip are of different types and they originate from different sources. The environmental conditions are no safe for the population and some actions to improve the groundwater conditions are necessary to safeguard the population.