A Flood of Arsenic

The phrase “arsenic poisoning” likely brings up memories of old mystery films or Agatha Christie novels. For over a century, arsenic has been a favorite poison for fictional murders. And for good reason. Not only is arsenic rapidly lethal in high doses, but this toxic element is extremely dangerous when consumed in low doses over an extended period, leading to cardiovascular disease, liver disease, and cancer. Arsenic poisoning is even more grim than mere fiction.

Arsenic is a common groundwater contaminant in many parts of the world, especially Southeast Asia. A World Health Organization study in 2012 suggested that in Bangladesh alone, nearly 43,000 people died as a result of arsenic that was naturally found in their drinking water.1 The arsenic was not planted there by some murderous villain but by the geochemistry of a region still bearing effects of the worldwide flood of Noah’s day.

Arsenic Chemistry

Arsenic has a complex chemistry in the environment and is generally found in nature not as a neutral atom but as a charged ion, either As³⁺ or As⁵⁺. In either case, it combines in water with oxygen atoms to form negatively charged ions: the arsenite ion for As³⁺ and the arsenate ion for As⁵⁺. Both ions can have one to three hydrogen atoms attached to them. The formation of these ions both increases their ability to dissolve in water and makes it possible for arsenic compounds to mimic the phosphates that are naturally found in living things.

In general, As³⁺ is more associated with low-oxygen waters (what chemists call reducing conditions), and As⁵⁺ is more associated with more oxygen-rich waters (called oxidizing conditions). In the ground, arsenic is generally found either in sulfide minerals (As³⁺ favors sulfides) or as oxides (usually As⁵⁺) bound to iron oxides. While As³⁺ is considered the most dangerous form, both As³⁺ and As⁵⁺ are highly toxic. Sulfide or oxide arsenic minerals both pose a significant hazard to people.

However, the minerals only pose a hazard if people ingest their arsenic. Since we do not eat rocks, the arsenic must either be dissolved in the water that people drink or be taken up (often from water) into the plants or animals that people eat. So the greatest environmental danger of arsenic comes from arsenic dissolved in water.

Arsenic sulfide minerals will only dissolve in water to a significant degree if conditions are oxidizing. When the water has a relatively high oxygen content, a process known as oxidative dissolution causes the arsenic to become dissolved in water and generally transform from As³⁺ to As⁵⁺.

However, the same conditions will also dissolve and oxidize iron sulfides, which will soon form insoluble iron oxides, essentially rust and rust-like compounds. These iron oxides sometimes give streambeds, especially near old mines, an orangish color. Arsenic (especially As⁵⁺) will bind to those iron compounds and fall out of the water with them. In fact, one of the primary methods of purging arsenic from waters is to run the water through a filter of iron oxides (sometimes this is as simple as pouring it through a mass of rusty nails). Much of the arsenic leaves the water to adhere to the iron.

When the water over the iron compounds becomes depleted of oxygen, reductive dissolution will occur. The iron oxides will then start to dissolve, returning some of the arsenic into the water.

How Does Arsenic Get Into the Environment?

Today, arsenic moves into the environment in several ways. Arsenic is often deposited in the soil from hydrothermal fluids (hot mineral-rich waters that come from under the earth). In fact, the most common arsenic-containing minerals today are sulfides formed from these hydrothermal fluids when they cool at or near the earth’s surface.

Volcanic eruptions also release arsenic into the atmosphere. It returns to the earth in ash or rain. However, the majority of volcanic arsenic is in gasses, and most of that arsenic (possibly as much as 90%) ends up deposited as arsenic sulfides below the earth’s surface in the area surrounding the volcano.

Finally, arsenic moves through the environment when water flows over and through arsenic-containing rocks, dissolving some of the toxic element into the water.

What About Arsenic During Noah’s Flood?

If groundwater running through some rock formations today picks up dangerous concentrations of this toxic element, how were Noah and his family not poisoned by the arsenic contamination of the global flood?2

At the onset of the flood, the “fountains of the deep” burst open (Genesis 7:11), likely referring to the release of massive amounts of hydrothermal fluids from beneath the earth’s surface. If these fluids were anything like modern hydrothermal fluids, a significant amount of arsenic would have been among the elements in these superheated waters. Most of that arsenic would not have dissolved into the floodwaters; however, as the fluids cooled, the arsenic would have immediately precipitated as sulfides, leading to a buildup of arsenic compounds near the fountains.

Meanwhile, the catastrophic volcanic activity during the flood would have spewed arsenic in both ash and gas into the atmosphere. The arsenic then returned to the surface in the rain. However, the majority of the arsenic from the volcanoes would have deposited as sulfides below the surface around the volcanos. So tremendous amounts of arsenic were moved from deep in the earth to near the surface, but most of that would not have dissolved in the floodwaters.

As the flood progressed, the waters scoured the surface of the earth (Genesis 7:19). This erosion of the continental crust could have moved some of the arsenic in those rocks into the floodwaters. However, the same process would have freed up iron, which is much more common in the earth than arsenic, to create insoluble iron compounds which would bind the arsenic (just as arsenic is pulled out when going through the rusty nails).

Meanwhile, according to the catastrophic plate tectonics model (a common flood model accepted by many creationists), essentially the entire pre-flood oceanic crust sank into the earth’s mantle, where some of it melted and released its arsenic (including many of the arsenic sulfides from the fountains of the deep) in either volcanoes or hydrothermal fluids. In both cases that arsenic would have mainly precipitated as sulfides. So throughout the flood, arsenic was being moved from deeper in the earth toward the surface, but rather than dissolving in the floodwaters themselves, it was scavenged from them by solid compounds, either attached to iron oxides or as arsenic sulfides that are not very soluble in water.

Simultaneously, as the floodwaters ravaged the earth’s surface, they rapidly deposited massive amounts of sediment to form the sedimentary rock layers that currently cover the earth. As a result, much of the arsenic was buried almost as soon as it precipitated.

Yet, all that arsenic did not stay buried. The flood continued and the mountain ranges rose to expose some of this arsenic closer to the surface. The tectonic processes (accompanied by volcanoes and increased hydrothermal activity) that created mountains likely continued to deposit arsenic in the surrounding sediments. As those sediments were pushed upward, arsenic sulfides were exposed to oxygenated water running off the mountains. That arsenic would have been oxidized and become attached to iron oxides.

Finally, as water ran off the newly risen mountains, it eroded sediments and created sedimentary basins in the shadow of the mountains. These basins became relatively enriched in arsenic. Today we find some of the greatest concentrations of arsenic in sedimentary basins below the Rocky Mountains, the Andes, and most of all the Himalayas.

This concentration of arsenic would not have been a threat to life reestablishing on the earth after the flood because the toxic element was still buried in the basins.

This concentration of arsenic would not have been a threat to life reestablishing on the earth after the flood because the toxic element was still buried in the basins. But over time, groundwater has run through those arsenic-containing sediments. That groundwater often undergoes a seasonal cycle between oxidizing and reducing. During the oxidizing phase, arsenic sulfides can dissolve, while during the reducing phase (when the iron oxides dissolve) trapped arsenic can be freed. Either way, the arsenic can enter shallow groundwaters that do not contain enough sulfur to form solid arsenic sulfides, so the arsenic remains dissolved and eventually works its way into the water supply. That is the source of the catastrophic arsenic poisoning that occurs today, particularly in Southeast Asia.

Scars from the Flood

When we read about those affected by this poison, we should help when we can. But we should also be reminded of the holiness of our God. The world still bears the scars of his awesome judgment on Adam’s sin in Genesis 3, as well as the global watery catastrophe of Noah’s day.

Environmental arsenic poisoning is one of those scars, an ongoing reminder of the terrible fury of the flood. But along with his judgment, God showed mercy by designing the chemistry of the flood so that the concentration of arsenic was not high enough in the floodwaters to threaten Noah’s family and the animals on the ark.

Similarly, God offers mercy from the coming judgment for those who will put their faith in his son, Jesus Christ. He promises that, though the world now groans under a curse, he will one day make all things new.