I've another quite diverse ...

I've another quite diverse suggestion to offer; assuming your wetlands are located in a "warm climate" zone of the world: There's a very, very unique floating plant, called the "Water Hyacinth" - that fishing cultures & hydro-electric back-bay people detest - but that possesses some very, very powerful positive attributes; especially applicable to your situation. This Amazon basin origins plant totally floats (i.e, does NOT attach itself to the bottom or anything else): But as it does so, its tendrils are absorbing/feeding off of any & all suspended effluvia in the water. It can thereby "clean up" even the most polluted water; and will absorb even dissolved "heavy metals". The dirtier/more polluted the water, the faster it grows; having the capacity to replicate its entire "floating mattress mass" every 3>5/days. But one of its most interesting - & positive - features, besides just being a "renewable resource" - is it's harvested use as a very effective composting/mulching source; particularly valuable to the restoration of semi-arid/sandy &/or otherwise "depleted" soils. It's so versatile, in fact, it can even be mixed with other fodder & used for livestock feed. Footnote: An entire new industry, involving the growth/harvesting/multiple uses of this once hated "Devil" plant, was generated on the shores of Lake Victoria; and the once desperate people of Malawi, living & depending on their splendorous Lake & Rivers system learned to harvest & use it to restore growing vitality to their Colonial-period abused lands. Bottom Line: "Mother Nature" is, in the final analysis, most often a far, far more valuable/reliable resource than anything our chem industry can offer!