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Fig. 4. Carbonate mineral precipitates from the Fe0 permeable reactive barrier (PRB) sampled 30 mo after operation: (a) scanning electron microscopy (SEM) photomicrograph of clusters of needle-shaped aragonite crystals from the deep down-gradient portion of Core 1 at 5.8 to 6.1 m; (b) energy dispersive X-ray (EDX) analysis of the aragonite from (a); (c) SEM photomicrograph of cube-shaped siderite crystals from the shallow cemented interface from Core 2 at the up-gradient interface at 4.6 to 4.9 m; (d) EDX of the siderite from (c); (e) SEM photomicrograph of the euhedral hexagonal-shaped carbonate form of green rusts from the deep down-gradient interface from Core 2 at 7.9 to 8.2 m; and (f) EDX analysis of the green rusts from (e).
