The Allied Chemical Corporation contributed greatly to the chemical pollution of Onondaga Lake. The surface water was found to be contaminated with mercury whereas the sediments are contaminated with polychlorinated biphenyls (PCBs), pesticides, creosotes, heavy metals (lead, cobalt, and mercury), polycyclic aromatic hydrocarbons (PAHs), chlorinated benzenes, and BTEX compounds (benzene, ethylbenzene, toluene, xylene). In Onondaga Lake the chlorinated benzenes are located in the southwest portion, in the form of a dense oily liquid that has settled into the sediments. These chemicals were intentionally dumped into the lake or unintentionally seeped in from upland toxic waste sites or from the Solvay wastebeds located at the southwest end of Onondaga Lake. Approximately 6 million pounds of salty wastes made up of chloride, sodium, and calcium were dumped into the lake before Allied Chemical closed in 1986.