Humic acid is the component of soil that is produced in the process of decomposition. It comes about from the breakdown over time of the components of soil. As one could expect, humic acid comes from humus (organic matter that has become stable in that it will not break down further, and can remain in the same state for a millennia or more) and, when added to sea water, can have the same effect as adding fertilizers directly into the body of water.
All of these additional nutrients into the water may not seem like it would be very detrimental at first. After all, many of the nutrients added by humic acid are the nutrients needed by plants and animals in order to flourish, or reproduce, within their environment. However, because any given environment produces enough nutrients to support a given amount of life that will not cause undue stress on the environment, the introduction of additional nutrients can cause problems within the environment.
The problems arise as the flora and fauna populations increase, resulting in a strain on the environment. The space available for healthy growth becomes diminished and there is an increase in competition between species for space. There may also be room for more invasive species to grow, as one species may reproduce faster than another species can consume the first, resulting in an environment that is no longer responsive to the needs of all species involved, but to the few who profit most, or fastest from the added nutrients.
While at first it may not be apparent that damage is occurring, the increase in populations will eventually strain the environment to so great an extent that it will no longer be able to support life adequately.
But more than this, the release of humic acid into seawater has even more disastrous effects. Whenever humic acid is introduced into seawater, it causes the supply of nitrogenous and phosphorous compounds to increase. This leads to nitrification, which is the process of how ammonia becomes oxidized through using oxygen. This leads to an increase in demand for oxygen within the environment, causing an increase in the growth of algae. This reduction of available oxygen gas can cause toxic un-ionized ammonia to form.
Because algae is the plant that benefits the fastest, its growth increases exponentially, causing the surface of the water to become cloudy, blocking the penetration of sunlight into the depths of the water. This can lead to the decreased growth of other organisms that require sunlight to survive. The continual depletion of oxygen within the water can also lead to the death of oxygen dependent organisms within the environment.
