Michelle L Hladik, PhD
(She/her)I am an environmental organic chemist whose current research focuses on the fate and transport of current-use pesticides and other organic contaminants in aquatic and terrestrial environments.
Much of my research is focused on pesticides but also includes other organic contaminants. I direct a research laboratory that is focused on developing new methods to measure pesticides and their degradates in water, sediment, and biota. My laboratory specializes in small samples sizes, complex matrices, and non-standard procedues. Additionally, I also work on developing methods and measuring disinfection by-products in treated water (especially those that are not-currently regulated and are understudied) with a focus on wastewater discharges.
Professional Experience
Research Chemist, USGS, California Water Science Center, Sacramento, 2006 to present
Chemist, USGS, California Water Science Center, Sacramento, 2005-2006
Graduate Fellow/Research and Teaching Assistant, Deparment of Geography and Environmental Engineering, Johns Hopkins University, 1999-2005
Undergraduate Research Summer Institute, Department of Chemistry, Vassar College, 1997,1998
Undergraduate Research and Teaching Assistant, Department of Chemistry, Vassar College ,1997,1998
Education and Certifications
Ph.D. 2005, Environmental Engineering and Chemistry, Johns Hopkins University, Baltimore, Maryland
B.A. 1999, Chemistry, Vassar College, Poughkeepsie, New York
Science and Products
Herbicide safeners and associated stream flow for water samples collected across Iowa and Illinois (2016-2017).
Sediment chemistry and sediment toxicity in wadable streams across the Midwestern United States, 2013
Bifenthrin causes trophic cascade and altered insect emergences in mesocosms: implications for small streams
Pilot-scale expanded assessment of inorganic and organic tapwater exposures and predicted effects in Puerto Rico, USA
Cross-ecosystem fluxes of pesticides from prairie wetlands mediated by aquatic insect emergence: Implications for terrestrial insectivores
Field-level exposure of bumble bees to fungicides applied to a commercial cherry orchard
Prevalence of neonicotinoids and sulfoxaflor in alluvial aquifers in a high corn and soybean producing region of the Midwestern United States
Public and private tapwater: Comparative analysis of contaminant exposure and potential risk, Cape Cod, Massachusetts, USA
Exploring biophysical linkages between coastal forestry management practices and aquatic bivalve contaminant exposure
Salinity changes the dynamics of pyrethroid toxicity in terms of behavioral effects on newly hatched delta smelt larvae
Environmental and anthropogenic drivers of contaminants in agricultural watersheds with implications for land management
Widespread use of the nitrification inhibitor nitrapyrin: Assessing benefits and costs to agriculture, ecosystems, and environmental health
Beyond neonicotinoids – Wild pollinators are exposed to a range of pesticides while foraging in agroecosystems
Differences in neonicotinoid and metabolite sorption to activated carbon are driven by alterations to the insecticidal pharmacophore
Spatiotemporal variation in occurrence and co-occurrence of pesticides, hormones, and other organic contaminants in rivers in the Chesapeake Bay Watershed, United States
Science and Products
- Science
Filter Total Items: 17
- Data
Filter Total Items: 39
Herbicide safeners and associated stream flow for water samples collected across Iowa and Illinois (2016-2017).
Four dichloroacetamide herbicide safeners (AD-67, benoxacor, dichlormid, and furilazole) and two co-applied herbicides (acetochlor and metolachlor) were measured in water samples from 7 streams across Iowa and Illinois. Iowa water samples were collected from March 2016 to June 2017, and Illinois water samples were collected from September 2016 to June 2017. The compounds studied are applied to corSediment chemistry and sediment toxicity in wadable streams across the Midwestern United States, 2013
These data present chemistry and toxicity results from freshwater stream sediments collected from 99 wadable stream sites across eleven states in the Midwestern U.S. as one component of a larger USGS study in the summer of 2013. This data presents a selected suite of chemistry collected at these sites (PAHs, Organochlorines, PCBs, Trace Elements, and current use pesticides) used in calculating a PBifenthrin causes trophic cascade and altered insect emergences in mesocosms: implications for small streams
Direct and indirect ecological effects of the widely used insecticide bifenthrin on stream ecosystems are largely unknown. To investigate such effects, a manipulative experiment was conducted in stream mesocosms that were colonized by aquatic insect communities and exposed to bifenthrin-contaminated sediment; implications for natural streams were interpreted through comparison of mesocosm results - Multimedia
- Publications
Filter Total Items: 113
Pilot-scale expanded assessment of inorganic and organic tapwater exposures and predicted effects in Puerto Rico, USA
A pilot-scale expanded target assessment of mixtures of inorganic and organic contaminants in point-of-consumption drinking water (tapwater, TW) was conducted in Puerto Rico (PR) to continue to inform TW exposures and corresponding estimations of cumulative human-health risks across the US. In August 2018, a spatial synoptic pilot assessment of than 524 organic, 37 inorganic, and select microbioloAuthorsPaul M. Bradley, Ingrid Y. Padilla, Kristin M. Romanok, Kelly Smalling, Michael J. Focazio, Sara E. Breitmeyer, Mary C. Cardon, Justin M. Conley, Nicola Evans, Carrie E Givens, James L. Gray, L. Earl Gray, Phillip C. Hartig, Michelle Hladik, Christopher P. Higgins, Luke R. Iwanowicz, Rachael F. Lane, Keith Loftin, R. Blaine McCleskey, Carrie A. McDonough, Elizabeth Medlock-Kakaley, Shannon M. Meppelink, Christopher P. Weis, Vickie S. WilsonCross-ecosystem fluxes of pesticides from prairie wetlands mediated by aquatic insect emergence: Implications for terrestrial insectivores
Contaminants alter the quantity and quality of insect prey available to terrestrial insectivores. In agricultural regions, the quantity of aquatic insects emerging from freshwaters can be impacted by insecticides originating from surrounding croplands. We hypothesized that, in such regions, adult aquatic insects could also act as vectors of pesticide transfer to terrestrial food webs. To estimateAuthorsJohanna M. Kraus, Kathryn Kuivila, Michelle Hladik, Neil Shook, David M. Mushet, Kelen Dowdy, Rachel HarringtonField-level exposure of bumble bees to fungicides applied to a commercial cherry orchard
Bumble bees, Bombus spp. (Apidae), are important native pollinators; however, populations of some species are declining in North America and agricultural chemicals are a potential cause. Fungicides are generally not highly toxic to bees, but little is known about sublethal or synergistic effects. This study evaluates bumble bee exposure to fungicides by quantifying concentrations of boscalid and pAuthorsKathryn M. Kuivila, Houston Judd, Michelle Hladik, James P. StrangePrevalence of neonicotinoids and sulfoxaflor in alluvial aquifers in a high corn and soybean producing region of the Midwestern United States
Neonicotinoids have been previously detected in Iowa surface waters, but less is known regarding their occurrence in groundwater. To help fill this research gap, a groundwater study was conducted in eastern Iowa and southeastern Minnesota, a corn and soybean producing area with known heavy neonicotinoid use. Neonicotinoids were studied in alluvial aquifers, a hydrogeologic setting known to be vulnAuthorsD.A. Thompson, Dana W. Kolpin, Michelle Hladik, Kimberlee K. Barnes, J.D. Vargo, R.W. FieldPublic and private tapwater: Comparative analysis of contaminant exposure and potential risk, Cape Cod, Massachusetts, USA
BackgroundHumans are primary drivers of environmental contamination worldwide, including in drinking-water resources. In the United States (US), federal and state agencies regulate and monitor public-supply drinking water while private-supply monitoring is rare; the current lack of directly comparable information on contaminant-mixture exposures and risks between private- and public-supplies underAuthorsPaul M. Bradley, Denis R. LeBlanc, Kristin M. Romanok, Kelly Smalling, Michael J. Focazio, Mary C. Cardon, Jimmy Clark, Justin M. Conley, Nicola Evans, Carrie E Givens, James L. Gray, L. Earl Gray, Phillip C. Hartig, Christopher P. Higgins, Michelle Hladik, Luke R. Iwanowicz, Keith Loftin, R. Blaine McCleskey, Carrie A. McDonough, Elizabeth Medlock-Kakaley, Christopher P. Weis, Vickie S. WilsonByEcosystems Mission Area, Water Resources Mission Area, Contaminant Biology, Environmental Health Program, Toxic Substances Hydrology, California Water Science Center, Eastern Ecological Science Center, New England Water Science Center, New Jersey Water Science Center, South Atlantic Water Science Center (SAWSC), Upper Midwest Water Science Center, National Water Quality LaboratoryExploring biophysical linkages between coastal forestry management practices and aquatic bivalve contaminant exposure
Terrestrial land use activities present cross-ecosystem threats to riverine and marine species and processes. Specifically, pesticide runoff can disrupt hormonal, reproductive, and developmental processes in aquatic organisms, yet non-point source pollution is difficult to trace and quantify. In Oregon, U.S.A., state and federal forestry pesticide regulations, designed to meet regulatory water quaAuthorsKaegan Scully-Engelmeyer, Elise F. Granek, Max Nielsen-Pincus, Andy Lanier, Steven S Rumrill, Patrick W. Moran, Elena Nilsen, Michelle Hladik, Lori PillsburySalinity changes the dynamics of pyrethroid toxicity in terms of behavioral effects on newly hatched delta smelt larvae
Salinity can interact with organic compounds and modulate their toxicity. Studies have shown that the fraction of pyrethroid insecticides in the aqueous phase increases with increasing salinity, potentially increasing the risk of exposure for aquatic organisms at higher salinities. In the San Francisco Bay Delta (SFBD) estuary, pyrethroid concentrations increase during the rainy season, coincidingAuthorsAmelie Segarra, Florian Mauduit, Nermeen Amer, Felix KJ Biefel, Michelle Hladik, Richard E Connon, Susanne M. BranderEnvironmental and anthropogenic drivers of contaminants in agricultural watersheds with implications for land management
If not managed properly, modern agricultural practices can alter surface and groundwater quality and drinking water resources resulting in potential negative effects on aquatic and terrestrial ecosystems. Exposure to agriculturally derived contaminant mixtures has the potential to alter habitat quality and negatively affect fish and other aquatic organisms. Implementation of conservation practicesAuthorsKelly L. Smalling, Olivia H. Devereux, Stephanie Gordon, Patrick J. Phillips, Vicki S. Blazer, Michelle Hladik, Dana W. Kolpin, Michael T. Meyer, Adam Sperry, Tyler WagnerByEcosystems Mission Area, Water Resources Mission Area, Contaminant Biology, Environmental Health Program, Toxic Substances Hydrology, California Water Science Center, Central Midwest Water Science Center, Chesapeake Bay Activities, Eastern Ecological Science Center, Kansas Water Science Center, New Jersey Water Science Center, New York Water Science Center, Pennsylvania Water Science CenterWidespread use of the nitrification inhibitor nitrapyrin: Assessing benefits and costs to agriculture, ecosystems, and environmental health
Agricultural production and associated applications of nitrogen (N) fertilizers have increased dramatically in the last century, and current projections to 2050 show that demands will continue to increase as the human population grows. Applied in both organic and inorganic fertilizer forms, N is an essential nutrient in crop productivity. Increased fertilizer applications, however, create the poteAuthorsEmily Woodward, Thea Margaret Edwards, Carrie E Givens, Dana W. Kolpin, Michelle HladikBeyond neonicotinoids – Wild pollinators are exposed to a range of pesticides while foraging in agroecosystems
Pesticide exposure is a growing global concern for pollinator conservation. While most current pesticide studies have specifically focused on the impacts of neonicotinoid insecticides toward honeybees and some native bee species, wild pollinators may be exposed to a broader range of agrochemicals. In 2016 and 2017 we collected a total of 637 wild bees and butterflies from the margins of cultivatedAuthorsA.R. Main, Michelle Hladik, Elisabeth B. Webb, K. W. Goyne, D. MengelDifferences in neonicotinoid and metabolite sorption to activated carbon are driven by alterations to the insecticidal pharmacophore
Widespread application of neonicotinoids has led to their proliferation in waters. Despite low neonicotinoid hydrophobicity, our prior studies implicated granular activated carbon (GAC) in neonicotinoid removal. Based on known receptor binding characteristics, we hypothesized that the insecticidal pharmacophore influences neonicotinoid sorption. Our objectives were to illuminate drivers of neonicoAuthorsDanielle T. Webb, Matthew R. Nagorzanski, Megan M Powers, David M. Cwiertny, Michelle Hladik, Gregory H. LeFevreSpatiotemporal variation in occurrence and co-occurrence of pesticides, hormones, and other organic contaminants in rivers in the Chesapeake Bay Watershed, United States
Investigating the spatiotemporal dynamics of contaminants in surface water is crucial to better understand how introduced chemicals are interacting with and potentially influencing aquatic organisms and environments. Within the Chesapeake Bay Watershed, USA, there are concerns about the potential role of contaminant exposure on fish health. Evidence suggests that exposure to contaminants in surfacAuthorsCatherine M. McClure, Kelly Smalling, Vicki S. Blazer, Adam Sperry, Megan K. Schall, Dana W. Kolpin, Patrick J. Phillips, Michelle Hladik, Tyler Wagner - News