Arsenic in irrigation water
I have very high arsenic in my water, and have been using a reverse osmosis system to bring it down. Apparently the aquifer changed and the level of arsenic overwhelmed the unit's ability so last summer I have been irrigating my landscaping with water of 144 ppm. Most of my japanese maples, especially those in containers either died or are doing very poorly and I suspect the arsenic. With our wet winters, will the arsenic leach out? Would changing the soil in the containers make sense? It seems some species are much more tolerant than others.
Changing the soil may help in the short term, but that level of arsenic in groundwater is not recommended to be used on any landscape plant/tree or garden. The arsenic can build up in the soil, and accumulate in the plant as well. The arsenic doesn't leach out very quickly, it moves very slow in the soil environment. Here is our in depth publication http://water.oregonstate.edu/sites/default/files/arsenic_in_well_water.pdf
If you have the ability to use some rain catchment to collect and store water for drier season use, that may help the long term health of the trees, where they aren't getting overloaded with arsenic laden water continuously.