ABSTRACT
Large quantities of anthropogenic cyanide are continuously introduced into the oceans of the world. The most significant source of cyanide input to the oceans is the atmosphere. Biomass burning introduces 1.4 to 2.9 Tg N yr−1 HCN to the atmosphere, much of which (1.1 to 2.6 Tg N yr−1) is estimated to be taken up by the oceans [1]. This represents a significant fraction of the estimated 30 Tg N yr−1 total input of atmospheric fixed N to the oceans [2]. There are no reported measurements of HCN/CN− in the open ocean [1]. It is estimated that free cyanide transferred to ocean water from the atmosphere is biodegraded rapidly, and has a lifetime in ocean water of a few months or less [1]. It would be difficult to detect measurable free cyanide in the oceans, as an annual accumulation of 2.9 Tg HCN as N in the top 1 m of the world oceans (approximately 3.6× 1014 m3) corresponds to a concentration of 8 µg/l. This represents an unattainable upper-bound concentration, considering that free cyanide is readily biodegraded under aerobic conditions and will have a residence time of much less than one year. Thus, the actual concentration in ocean water from atmospheric input at a particular time and ocean location is likely to be considerably less than 1 µg/l, the lowest detection limit attainable with conventional analytical methods (Chapter 7).
