Molybdenum in Natural Surface Waters: Content and Forms of Occurrence (a Review)

Results of long-term investigations of molybdenum in various water bodies of Ukraine (rivers, reservoirs, and small lakes) and in surface waters of other regions of the world are given in the paper. In the water of the studied water bodies and watercourses, the total content of the metal accounted for 0.7−19.1 µg/L. The exception was the contaminated section of the Stugna River, where its maximal concentration was 91.8 µg/L. Molybdenum occurs mainly in the dissolved form − on the average 73.5−91.3% Mototal. In many water bodies, the concentration of molybdate-anion (MoO42−) as one of the form of its occurrence is lower than the degree of its detection by catalytic method. Only in the section of the Stugna River contaminated by molybdenum, the content of MoO42− was 26.5−73.0% Modis. The major portion of Modis was found in the composition of various groups of organic compounds. However, its maximal content (62.4−83.3 Mobound) was registered in the composition of the acidic group with a predominance of humic substances. In lake systems of Kiev, the major portion of Modis was observed in the composition of the neutral group of organic compounds (41.4−58.3% Mobound). Results of the study of the kinetics of molybdenum binding by humic substances and organic compounds of natural water are also discussed in the paper.