Sentence:  The fate processes and transport rates of each contaminant that is released at initial but time-variable concentration, Ca, into the surrounding <WSD>geomedia</WSD> are affected by the homogeneity, isotropy, and continuity of the <WSD>geomedium</WSD>. 
Meaning of the word marked with <WSD> tags:  A geological medium or substrate such as soil, sediment, or rocks.