Geography of Kazakhstan the water in Kazakhstan is polluted by industrial effluents, pesticide and fertilizer residue, and, in some places, radioactive elements. The most visible damage has been to the Aral Sea, which as recently as the 1970s was larger than any of the Great Lakes of North America save Lake Superior. The sea began to shrink rapidly when sharply increased irrigation and other demands on the only significant tributaries, the Syr Darya and the Amu Darya (the latter reaching the Aral from neighboring Uzbekistan), all but eliminated inflow. During the Soviet Era, Kazakhstan received water from Tajikistan and Kyrgyzstan, and Uzbekistan, Turkmenistan,
Science and technology in Uzbekistan 14.1 "Note: PhD graduates in science cover life sciences, physical sciences, mathematics and statistics, and computing; PhDs in engineering also cover manufacturing and construction. For Central Asia, the generic term of PhD also encompasses Candidate of Science and Doctor of Science degrees. Data are unavailable for Turkmenistan." In 2014, Uzbekistan had a population of 29.3 million, compared to 16.6 million for Kazakhstan. The two most populous countries of Central Asia logically count the most researchers: just over 30 000 for Uzbekistan and 17 000 for Kazakhstan (in head counts), compared to a little over 2 000 for each of Kyrgyzstan