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2 One of the reasons the processes resulting in arsenic release to groundwater in southern Asia remain poorly understood is the high degree of spatial variability of physical and chemical properties in shallow aquifers. In an attempt to overcome this difficulty, a simple device that collects groundwater and sediment as a slurry from precisely the same interval was developed in Bangladesh. We augment here recently published results from Bangladesh and India relying on the needle-sampler with new data from 37 intervals of grey aquifer material of likely Holocene age in Vietnam and Nepal. We compare a total of 145 samples ranging in depth from 3 to 36 m that were analyzed for As (1-1000 µg/L), Fe (0.01-40 mg/L), Mn (0.2-4 mg/L) and S (0.04-14 mg/L) in filtered groundwater. The P-extractable (0.01-36 mg/kg) and HCl-extractable As (0.04-36 mg/kg) content of the particulate phase was determined in the same suite of samples, in addition to Fe(II)/Fe ratios (0.2-1.0) in the acid-leachable fraction of the particulate phase. Needle-sampler data from Bangladesh indicated a relationship between dissolved As in groundwater and P-extractable As in the particulate phase that wa