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Jeff Perez

@jeffperez.bsky.social

DAAD PRIME Fellow, TU Berlin 🇩🇪 + Aarhus Uni 🇩🇰, currently studying OC-Fe cycling in polar wetlands 🇮🇸🇬🇱 | Envi Mineralogy & Biogeochem | #firstgen 🇵🇭 | he/they/siya 🌈

9 Posts117 Follower74 Folgt
David Olefeldt@olefeldt.bsky.social · last yr.

I have a fully funded PhD position open for start in Jan or May 2026. Field work in peatlands of the Northwest Territories, with lab work to understand potential downstream mobilization of carbon, nutrients, mercury after thaw or wildfire. Reach out for more information, and please send on!

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Jeff Perez@jeffperez.bsky.social · last yr.

Excited to share our new collaborative paper with @vanvillegas.bsky.social! 🧪 Proud to have contributed through the Envi Mineralogy & Biogeochemistry Labs @lianegbenning.bsky.social & @forjanes.bsky.social.

Vanderville Villegas@vanvillegas.bsky.social · last yr.

Just published my first paper from my PhD project! 🔬 Here, we show that nanoplastics—those tiny, pervasive pollutants—can alter the microbiome of Daphnia, a keystone freshwater organism. Check it out here kwnsfk27.r.eu-west-1.awstrack.me/L0/https:%2F...

Jeff Perez@jeffperez.bsky.social · last yr.

Big thanks to @mimilovesmilo.bsky.social for a great collab during her @daadworldwide.bsky.social RISE internship at @gfz.bsky.social! And grateful to @diamondlightsource.bsky.social for beamtime at I20-scanning that allowed us to "look" inside the crystal structure of these minerals. 💡💠

Jeff Perez@jeffperez.bsky.social · last yr.

New paper out! 🎉 How does #phosphate, a common nutrient in fertilizers, influence the behavior of toxic #arsenic in soils and groundwater? We show that phosphate levels affect how well arsenate can be locked inside iron minerals, controlling its toxicity and mobility. 🔗: tinyurl.com/3k254ebf

Jeff Perez@jeffperez.bsky.social · last yr.

New paper out! 🎉 How does #phosphate, a common nutrient in fertilizers, influence the behavior of toxic #arsenic in soils and groundwater? We show that phosphate levels affect how well arsenate can be locked inside iron minerals, controlling its toxicity and mobility. 🔗: tinyurl.com/3k254ebf

Coexisting Phosphate Controls Arsenate Speciation and Partitioning during Fe(II)-Catalyzed Ferrihydrite Transformation

Arsenic immobilization in soils and sediments is primarily controlled by its sorption onto or incorporation into reactive soil minerals, such as iron (oxyhydr)oxides. However, coexisting ions (e.g., dissolved bicarbonate, phosphate, silica, and organic matter) can negatively impact the interaction of the toxic arsenate species with iron (oxy)hydroxides. Of special note is inorganic phosphate, which is a strong competitor for sorption sites due to its analogous chemical and structural nature to inorganic arsenate. Much of our understanding of this competing nature between phosphate and arsenate focuses on the impact on mineral sorption capacities and kinetics. However, we know very little about how coexisting phosphate will alter the stability and transformation pathways of arsenate-bearing Fe (oxyhydr)oxides. In particular, the long-term fate and behavior regarding arsenate immobilization are unknown under anoxic conditions. Here, we document, through mineral transformation reactions, the immobilization of both phosphate (P) and arsenate [As(V)] in secondary mineral products and characterize their changing compositions during the transformations. We did this while controlling the initial P/As(V) ratios. Our results document that, in the absence or at low P/As(V) ratios, the initial ferrihydrite rapidly transforms to green rust sulfate (GRSO4), which further transforms into magnetite after 180 days. Meanwhile, high P/As(V) ratios resulted in a mixture of GRSO4 and vivianite, with magnetite as a minor fraction. Invariably, the speciation and partitioning of As(V) were also affected by the P/As(V) ratio. A higher P/As(V) ratio also led to a faster partial reduction of mineral-bound As(V) to As(III). The most important finding is that the initial ferrihydrite-bound As(V) became structurally incorporated into magnetite [low P/As(V) ratio] or vivianite [high P/As(V) ratio] and was thus immobilized and not labile. Overall, our results highlight the influence of coexisting phosphate in controlling the toxicity and mobility in anoxic, Fe2+-rich subsurface settings, such as contaminated aquifers.

pubs.acs.org

Pablo Forjanes@forjanes.bsky.social · last yr.

Very excited to share my first 100% @gfz.bsky.social paper on mineral pseudomorphism with my Interface Geochemistry fantastic team! @lianegbenning.bsky.social @jeffperez.bsky.social

EAG@eageo.bsky.social · last yr.

New in #GPLetters: Pseudomorphism, one of the most prominent features of mineral replacement phenomena, can survive several successive mineral transformations, as experimentally demonstrated for the 1st time by Forjanes et al ➡️ buff.ly/FbNFwXw @forjanes.bsky.social @jeffperez.bsky.social

Jeff Perez@jeffperez.bsky.social · last yr.

First day back at work after my #PH holidays 🌴🌞 and going through hundreds of emails 😵 Despite a fellowship rejection, we had a couple of manuscripts accepted, and the reviewer comments on my last manuscript were all quite positive! 🤞 What a great start to the month!

Jeff Perez@jeffperez.bsky.social · 2y ago

📣 Researchers wanted! 3x #PhD and 1x #PostDoc positions available in the #EnviChem group @lthomasarrigo.bsky.social at UniNeuchâtel CH. The topics are interesting + Laurel is an amazing mentor. Come and join their lab! #geochem #soil #mineralogy #carbon More info below 👇

Laurel ThomasArrigo@lthomasarrigo.bsky.social · 2y ago

📢The Environmental Chemistry group at University of Neuchâtel (CH) is hiring 💥3 PhD students and 💥1 Postdoc to work on mineral-organic carbon interactions in a @snsf-ch.bsky.social -funded Starting Grant. More information here: www.unine.ch/envchem/open...