Ra. Charter et al., ARSENIC, MOLYBDENUM, SELENIUM, AND TUNGSTEN CONTENTS OF FERTILIZERS AND PHOSPHATE ROCKS, Communications in soil science and plant analysis, 26(17-18), 1995, pp. 3051-3062
Contamination of soils with trace metals or semi-metals has become a m
ajor public concern in recent years. Potential sources of these contam
inants include commercial phosphorus (P) fertilizers and the phosphate
rocks used in production of the P fertilizers. Solid commercial P fer
tilizers marketed in Iowa and phosphate rock samples (PRs) obtained fr
om deposits around the world were analyzed for arsenic (As), molybdenu
m (Mo), selenium (Se), and tungsten (W). The fertilizer materials incl
uded 24 samples of triple superphosphate (TSP), 23 samples of monoammo
nium phosphate (MAP), and 25 samples of diammonium phosphate (DAP). Tw
elve PRs from different PR deposits in Africa, United States, and Peru
were also analyzed. The concentrations of As and Mo were greater and
more variable than those of Se and W in TSP, MAP, DAP, and PRs. The ra
nges and median values of As, expressed in mg/kg, were: TSP (2.4-18.5,
10.1), MAP (8.1-17.8, 12.4), DAP (6.8-15.6, 12.4), and PR (3.2-32.1,
9.6). The range and median values for Mo contents of TSP, MAP, DAP, an
d PR were: 8-17, 13; 12-17, 15; 10-21, 14; and 2-21, 6, mg/kg, respect
ively. The median values for the Se and W contents were: TSP (1.1 and
2.7), MAP (0.3 and 2.1), DAP (0.1 and 2.4), and PR (1.0 and 1.9). One
each of the TSP and PRs contained much higher concentrations of Se tha
n the other samples analyzed. The concentrations of As, Mo, Se, and W
in the fertilizer materials and PRs analyzed were generally greater th
an those found in Iowa surface soils.