release of organisms(The release of organisms in the environment creates the risk that once released they may exhibit some previously unknown pathogenicity, might take over from some naturally occurring bacteria or pass on some unwanted trait to such indigenous bacteria)
relief(The physical shape, configuration or general unevenness of a part of the Earth's surface, considered with reference to variation of height and slope or to irregularities of the land surface; the elevation or difference in elevation, considered collectively, of a land surface; land)