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
Bifenthrin causes trophic cascades and alters insect emergence in mesocosms: implication for small streams
Increasing neonicotinoid use and the declining butterfly fauna of lowland California
Storm-event-transport of urban-use pesticides to streams likely impairs invertebrate assemblages
Dairy-impacted wastewater is a source of iodinated disinfection byproducts in the environment
Exposure of native bees foraging in an agricultural landscape to current-use pesticides
Effects of 2 fungicide formulations on microbial and macroinvertebrate leaf decomposition under laboratory conditions
Impact of wastewater infrastructure upgrades on the urban water cycle: Reduction in halogenated reaction byproducts following conversion from chlorine gas to ultraviolet light disinfection
First national-scale reconnaissance of neonicotinoid insecticides in streams across the USA
Pesticide concentrations in frog tissue and wetland habitats in alandscape dominated by agriculture
Dissolved pesticide concentrations entering the Sacramento-San Joaquin Delta from the Sacramento and San Joaquin Rivers, California, 2012-13
Characterization of selected bed-sediment-bound organic and inorganic contaminants and toxicity, Barnegat Bay and major tributaries, New Jersey, 2012
Widespread occurrence of neonicotinoid insecticides in streams in a high corn and soybean producing region, USA
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Bifenthrin causes trophic cascades and alters insect emergence in mesocosms: implication 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 resultsAuthorsHolly Rogers, Travis S. Schmidt, Brittanie L. Dabney, Michelle Hladik, Barbara Mahler, Peter C. Van MetreIncreasing neonicotinoid use and the declining butterfly fauna of lowland California
The butterfly fauna of lowland Northern California has exhibited a marked decline in recent years that previous studies have attributed in part to altered climatic conditions and changes in land use. Here, we ask if a shift in insecticide use towards neonicotinoids is associated with butterfly declines at four sites in the region that have been monitored for four decades. A negative association beAuthorsMatthew L. Forister, Bruce Cousens, Joshua G. Harrison, Kayce Anderson, James H. Thorne, Dave Waetjen, Chris C. Nice, Matt De Parsia, Michelle Hladik, Robert Meese, Heidi van Vliet, Arthur M. ShapiroStorm-event-transport of urban-use pesticides to streams likely impairs invertebrate assemblages
Insecticide use in urban areas results in the detection of these compounds in streams following stormwater runoff at concentrations likely to cause toxicity for stream invertebrates. In this 2013 study, stormwater runoff and streambed sediments were analyzed for 91 pesticides dissolved in water and 118 pesticides on sediment. Detections included 33 pesticides, including insecticides, fungicides, hAuthorsKurt D. Carpenter, Kathryn Kuivila, Michelle Hladik, Tana Haluska, Michael B. ColeDairy-impacted wastewater is a source of iodinated disinfection byproducts in the environment
Iodinated disinfection byproducts (DBPs) are among the most toxic DBPs, but they are not typically measured in treated water. Iodinated DBPs can be toxic to humans, and they also have the potential to affect aquatic communities. Because of the specific use of iodine and iodine-containing compounds in dairies, such livestock operations can be a potential source of iodinated DBPs in corresponding reAuthorsMichelle Hladik, Laura E. Hubbard, Dana W. Kolpin, Michael J. FocazioExposure of native bees foraging in an agricultural landscape to current-use pesticides
The awareness of insects as pollinators and indicators of environmental quality has grown in recent years, partially in response to declines in honey bee (Apis mellifera) populations. While most pesticide research has focused on honey bees, there has been less work on native bee populations. To determine the exposure of native bees to pesticides, bees were collected from an existing research areaAuthorsMichelle Hladik, Mark W. Vandever, Kelly L. SmallingEffects of 2 fungicide formulations on microbial and macroinvertebrate leaf decomposition under laboratory conditions
Aquatic fungi contribute significantly to the decomposition of leaves in streams, a key ecosystem service. However, little is known about the effects of fungicides on aquatic fungi and macroinvertebrates involved with leaf decomposition. Red maple (Acer rubrum) leaves were conditioned in a stream to acquire microbes (bacteria and fungi), or leached in tap water (unconditioned) to simulate potentiAuthorsAdria Elskus, Kelly L. Smalling, Michelle Hladik, Kathryn KuivilaImpact of wastewater infrastructure upgrades on the urban water cycle: Reduction in halogenated reaction byproducts following conversion from chlorine gas to ultraviolet light disinfection
The municipal wastewater treatment facility (WWTF) infrastructure of the United States is being upgraded to expand capacity and improve treatment, which provides opportunities to assess the impact of full-scale operational changes on water quality. Many WWTFs disinfect their effluent prior to discharge using chlorine gas, which reacts with natural and synthetic organic matter to form halogenated dAuthorsLarry B. Barber, Michelle Hladik, Alan M. Vajda, Kevin C. Fitzgerald, Chris DouvilleFirst national-scale reconnaissance of neonicotinoid insecticides in streams across the USA
To better understand the fate and transport of neonicotinoid insecticides, water samples were collected from streams across the United States. In a nationwide study, at least one neonicotinoid was detected in 53 % of the samples collected, with imidacloprid detected most frequently (37 %), followed by clothianidin (24 %), thiamethoxam (21 %), dinotefuran (13 %), acetamiprid (3 %) and thiaclopridAuthorsMichelle Hladik, Dana W. KolpinPesticide concentrations in frog tissue and wetland habitats in alandscape dominated by agriculture
Habitat loss and exposure to pesticides are likely primary factors contributing to amphibian decline in agricultural landscapes. Conservation efforts have attempted to restore wetlands lost through landscape modifications to reduce contaminant loads in surface waters and providing quality habitat to wildlife. The benefits of this increased wetland area, perhaps especially for amphibians, may be neAuthorsKelly L. Smalling, Rebecca Reeves, Erin L. Muths, Mark W. Vandever, William A. Battaglin, Michelle Hladik, Clay L. PierceDissolved pesticide concentrations entering the Sacramento-San Joaquin Delta from the Sacramento and San Joaquin Rivers, California, 2012-13
Surface-water samples were collected from the Sacramento and San Joaquin Rivers where they enter the Sacramento–San Joaquin Delta, and analyzed by the U.S. Geological Survey for a suite of 99 current-use pesticides and pesticide degradates. Samples were collected twice per month from May 2012 through July 2013 and from May 2012 through April 2013 at the Sacramento River at Freeport, and the San JoAuthorsJames L. Orlando, Megan McWayne, Corey Sanders, Michelle HladikCharacterization of selected bed-sediment-bound organic and inorganic contaminants and toxicity, Barnegat Bay and major tributaries, New Jersey, 2012
A study of bed-sediment toxicity and organic and inorganic contaminants was conducted by the U.S. Geological Survey (USGS) in cooperation with the New Jersey Department of Environmental Protection (NJDEP). Bed-sediment samples were collected once from 22 sites in Barnegat Bay and selected major tributaries during August–September 2012 and analyzed for toxicity and a suite of organic and inorganicAuthorsKristin M. Romanok, Timothy J. Reilly, Anthony R. Lopez, John J. Trainor, Michelle Hladik, Jacob K. Stanley, Daniel FarrarWidespread occurrence of neonicotinoid insecticides in streams in a high corn and soybean producing region, USA
Neonicotinoid insecticides are of environmental concern, but little is known about their occurrence in surface water. An area of intense corn and soybean production in the Midwestern United States was chosen to study this issue because of the high agricultural use of neonicotinoids via both seed treatments and other forms of application. Water samples were collected from nine stream sites during tAuthorsMichelle Hladik, Dana W. Kolpin, Kathryn Kuivila - News