Interactions between sulfide and reproductive phenology of an annual aquatic plant, wild rice (Zizania palustris)

Mercury sulfur initiative

“…In Minnesota soils, the pore water concentration of sulfate can be as high as 3350 milligrams per liter, several magnitudes higher than the 10 milligrams per liter limit related to Manoomin production (Berndt et al 2016a). Both sulfate and sulfide are known to have negative effects on Manoomin, an important cultural resource and commodity in the Great Lakes region (LaFond-Hudson et al 2020, Pastor et al 2017. The Minnesota Pollution Control Agency (MPCA) estimates that 19 to 27 percent of waterbodies containing Manoomin are downstream from a permitted discharger of sulfate, and nearly 130 dischargers are located 25 miles or less upstream of a Manoomin water (Governor's Task Force on Wild Rice 2019).…”

“…Minnesota is home to 11 sovereign Tribal Nations, and much of the Manoomin in Minnesota exists on Tribal reservations and treaty ceded territories(Minnesota Tribal Wild Rice Task Force 2018).State and federal projects and programs have broad impacts on Tribal communities and businesses, and state and federal agencies engage with Tribes both in a formal consultation process and in less formal contexts.How Sulfate Affects Manoomin and CommunitiesSulfate in water is converted to sulfide by microbes in the stream or lake sediment in which Manoomin is rooted. Most researchers agree that as sulfide levels in the sediment increase, the abundance of Manoomin decreases(LaFond-Hudson et al 2020, Pastor et al 2017, Pollman et al 2017. The rate and geochemical conditions at which sulfate is converted to sulfide and how Manoomin is affected is an active area of scientific discussion.…”

Sulfur Geochemistry Destabilizes Population Oscillations of Wild Rice (Zizania palustris)

“…However, iron sulfide can precipitate on roots of mature plants and is associated with impaired nitrogen uptake and inhibited seed production (LaFond‐Hudson et al., 2018, 2020a). Plant‐mediated gas transport of oxygen from the atmosphere into the rhizosphere allows formation of iron oxides on root surfaces, and oxygen fluxes are typically highest when plants are photosynthetically active (Blossfeld et al., 2011; Han et al., 2018; Marzocchi et al., 2019).…”

“…We have imaged iron sulfide plaques and quantified plaque iron and sulfide concentrations from plants grown in mesocosms with 300 mg L −1 sulfate (Pastor et al, 2017) and have visually observed black root plaques in the field at lower sulfate concentrations (unpublished data). Plants that accumulate greater concentrations of iron sulfide plaques have lower seed nitrogen mass (LaFond-Hudson et al, 2018, 2020a. There are, therefore, complex and as yet poorly understood couplings among biomass and litter cycles, nitrogen availability, sulfide inhibition of seed production, control of sulfide concentrations in sediments by iron and litter, and precipitation of iron sulfide on roots during seed production.…”

Use of Wild Rice (Zizania palustris L.) in Paddy-Scale Bioassays for Assessing Potential Use of Mining-Influenced Water for Irrigation

“…Use of WR in aquatic bioassays has increased in recent years in an effort to better understand how exposures of SO 4 (> 10 mg L −1 ; current MN WR water quality criterion) may influence phenology, distribution, and productivity. Laboratory, and small-scale field, investigations have focused on measuring responses of WR to well-defined exposures of SO 4 and hydrogen sulphide (H 2 S) associated with mining-influenced waters (Fort et al 2014 , 2017 ; Pastor et al 2017 ; LaFond-Hudson et al 2018 , 2020 ). Development and use of these paddy-scale bioassays was critical to better understanding larger-scale and longer-term in-situ responses of WR to exposures of elevated SO 4 (≈350 and 1350 mg L −1 ) in mining-influenced waters under a more realistic scenario.…”