The Proceedings of the Eighth International Conference on Creationism (2018)

which makes the environment far more reducing in nature (Henke 2009a). It also produces bicarbonate that drives As off of the iron oxyhydroxides (Majumder et al. 2016). The result is the reduction of the iron oxyhydroxides and the release of arsenic, initially asAs 5+ but under these conditions a substantial amount will convert toAs 3+ (Meng et al. 2016; Molinari et al. 2015). Studies have shown the key role of microbes in this process; adding glucose as a feedstock for them can effectively double the arsenic released (Meng et al. 2016). This is the mechanism by which much of the modern arsenic-contamination of drinking water in South East Asia occurs; an influx of organic carbon leads to reducing conditions for waters in contact with As-rich iron oxyhydroxides. These minerals then undergo reductive dissolution to release the arsenic (Biswas et al. 2014; Nickson et al. 2000; Xie et al. 2014). During the Flood this could have happened as well. The decay of the abundant organic material could have led to oxygen depleted reducing areas where the majority of the sorbed arsenic would then be liberated. So, while oxidizing conditions would lead to the release of arsenic from sulfide minerals to join dissolved arsenic from other sources in the Flood waters, they would also generate iron oxyhydroxides and similar minerals that would sorb the arsenic and remove it from solution. However, if the water subsequently became reducing, this could remobilize the sorbed arsenic. Reductive conditions would be encouraged by organic material and organic material would certainly be available during the Flood. However, there are several factors that mitigate the seriousness of this problem. As waters become more reducing, they soon reach a point in which not only iron and arsenic are being reduced but also sulfates by sulfate reducing bacteria. This generates sulfides, which in turn remove arsenic from solution (Harvey et al. 2002; Meng et al. 2016; Saunders et al. 2008). The primary mechanism for arsenic removal seems to be the formation of pyrite when the sulfide combines with the Fe 2+ generated by the reduction of the iron. Arsenic sorbs to the surface of developing pyrite and is then incorporated into its structure as it continues to form (Saunders et al. 2008). This is essentially the reaction whose occurrence in hydrothermal waters we discussed at the beginning of this section. It does not occur to a great extent in most of the areas of South East Asia experiencing arsenic poisoning today because the arsenic-contaminated waters are low in sulfate; in fact, the addition of sulfate to those waters has been suggested as a remediation method (Saunders et al. 2008). However, one would expect some sulfate to be present in much of the Flood waters. As already mentioned, the SO 2 released from the volcanoes would have generated acid rain that would contribute a relatively small amount of sulfate to the Flood waters. More significantly, the oxidative weathering of any sulfides on the surface during the Flood would generate sulfate. Oxidative dissolution of arsenic sulfides and arsenic rich pyrite, which has been discussed as a source of arsenic in the water, would also generate sulfate. So in at least some of these environments we would expect a significant amount of sulfate which could be converted to sulfide and precipitate the arsenic. Even if sulfate is not available, research has shown that reductive dissolution of iron oxyhydroxides does not result in as high a concentration of arsenic in groundwater as might be predicted. This is because, rather than all becoming truly dissolved, some of the Fe 2+ will form new, undissolved, minerals such as magnetite, siderite, and vivanite. Some arsenic can sorb on to these, resulting in less than half of the arsenic released by reductive dissolution being truly dissolved in the water (Neidhardt et al. 2014). Even that amount of mobilization has proved catastrophic in Southeast Asia, but it obviously greatly lowers the potential for arsenic to remain soluble in the Floodwaters. Of course, the most significant factor in mitigating issues related to the reductive dissolution of iron oxyhydroxides is simply the extremely rapid rate of sedimentation during the Flood. The iron oxyhydroxides and their associated arsenic were being buried very swiftly. This does not permanently protect them from encountering groundwater and being remobilized, this is in fact what we will argue is the source of the arsenic contamination problems today, but it would remove them from the immediate proximity of the surface and surface waters. To summarize, during the Flood arsenic would have been brought near the surface in hydrothermal fluids and volcanos, and released by the rapid weathering of arsenic-containing rock and volcanic ash. Much of this arsenic would have been precipitated with sulfur and under reducing conditions would remain stable, not leaching into the surrounding waters. Much of it would have been precipitated subsurface or been rapidly buried in this form and so have posed no danger to the post-Flood world. Some, however, would have come in contact with oxidizing waters, which would dissolve these minerals and liberate the arsenic. Nevertheless, oxidizing conditions promote the formation of iron oxyhydroxides and arsenic will sorb to these (as well as to carbonates and clays), effectively removing it from water. Other dissolved substances will also sorb, creating some competition for binding sites, but under acidic-conditions sorbtion would still be expected to remove most of the arsenic from the water. Once again, rapid sedimentation would bury many of these minerals before the arsenic could be remobilized off of them. However, organic carbon can promote reducing conditions, which leads to reductive dissolution of the iron minerals in water if they are not buried quickly enough or deeply enough, freeing the arsenic again. This occurs today and is a primary factor in the current arsenic crisis. While the sheer speed at which sedimentary layers were being laid down during the Flood would have worked against this process, presumably some arsenic would have been remobilized this way. However, although they change form, some iron minerals will persist and continue to sorb arsenic, so no more than 50% of the sorbed toxin is likely to be freed. Furthermore, reductive dissolution requires reducing waters. If sulfate is also present in those waters, it can be reduced to sulfide and the arsenic will once again be sequestered in pyrite or arsenic sulfides. Meanwhile, the rapid deposition of sedimentary layers during the Flood was constantly burying the sorbed or mineralized arsenic, largely removing the opportunity for that arsenic to redissolve. These are the chemical processes which would govern the behavior of arsenic during Noah’s Flood (Figure 1). They are highly complex, but two trends stand out. Under virtually all conditions a significant amount of arsenic will not actually be dissolved in water, but will rather be sorbed or associated with some solid substance. Furthermore, the very processes that could free the Hutchison and Bortel ◀ Fate of Arsenic in the Flood ▶ 2018 ICC 233