Leukocyte Esterase. Leukocyte esterase is an enzyme present in most white blood cells (WBCs). A few white blood cells are normally present in urine and usually give a negative chemical test result. When the number of WBCs in urine increases significantly, this screening test will become positive.
Land subsidence occurs when large amounts of groundwater have been withdrawn from certain types of rocks, such as fine-grained sediments. The rock compacts because the water is partly responsible for holding the ground up. When the water is withdrawn, the rocks falls in on itself.
A drop in the elevation of the surface of the land is called land subsidence, and can be caused by a collapse of underground mining shafts or naturally occurring underground c â¦ ave system collapses, commonly called sinkholes.   . 6 people found this useful. drop in the elevation of the surface of the land is called land subsidence, and can be caused by a collapse of underground mining shafts or naturally occurring underground c â¦ ave system collapses, commonly called sinkholes.    . 6 people found this useful.