Jean Macrae

University of Maine | UM · Department of Civil and Environmental Engineering

The American lobster, Homarus americanus , is an economically valuable and ecologically important crustacean along the North Atlantic coast of North America. Populations in southern locations have declined in recent decades due to increasing ocean temperatures and disease, and these circumstances are progressing northward. We monitored 57 adult fem...

Recirculating aquaculture systems (RAS) have grown in popularity in recent years due to their potential to provide a high-quality protein source in a contained environment. With increased production comes the need for RAS wastewater treatment to remove waste products such as phosphorus, which can harm other aquatic life in the area by causing algae...

State law requires the adoption of a maximum contaminant level (MCL) for PFAS contamination in drinking water by June 1, 2024. While discussion of mitigation options has included the degree of risk reduction and the cost of treatment, indirect environmental effects are missing from the conversation. Until other technologies are developed, water tre...

The Microbes and Social Equity working group was formed in 2020 to foster conversations on research, education, and policy related to how microorganisms connect to personal, societal, and environmental health, and to provide space and guidance for action. In 2021, we designed our first virtual symposium to convene researchers already working in the...

Recent disruptions in waste management, including the COVID-19 pandemic and China’s decision to limit waste imports from the United States, have shocked materials management systems across the United States. In Maine, these disruptions have been exacerbated by significant disturbances in the state’s waste management infrastructure. These shocks, em...

Food waste recycling is needed to create a more sustainable, circular food system; however, the process must be carefully managed to avoid the introduction and build-up of contaminants. We collected and screened source-separated food waste for five classes of contaminants (physical contaminants, heavy metals, halogenated organics, pathogens and ant...

Despite decades of research on lobster species’ biology, ecology, and microbiology, there are still unresolved questions about the microbial communities which associate in or on lobsters under healthy or diseased states, microbial acquisition, as well as microbial transmission between lobsters and between lobsters and their environment. There is an...

Microplastic formation in aqueous systems is among the inevitable consequences of plastic pollution, which has cascading environmental and health implications. As the microplastic sizes get smaller over time, their surface areas increase, which creates an implicit, dynamic, and inflating new domain, called the microplastisphere. This study summariz...

Nanobubbles have the potential to curtail loss of oxygen during activated sludge aeration due to their extensive surface areas and lack of buoyance in solution. In this study, nanobubbles aeration was explored as a novel approach to enhance aerobic activated sludge treatment and benchmarked against coarse bubble aeration at the lab scale. Nanobubbl...

Drawing on research with food waste recycling facilities in New England, this paper explores a fundamental tension between the eco-modernist logics of the circular economy and the reality of contemporary waste streams. Composting and digestion are promoted as key solutions to food waste, due to their ability to return nutrients to agricultural soil...

Northeastern North America has been experiencing warmer winters with reduced snow accumulation, with more frequent winter freeze–thaw cycles. We conducted a laboratory experiment to investigate how increased frequency of freeze–thaw cycles (FTC) would alter soil C and N availability. Organic (O) and mineral (B) horizon soils were collected from a c...

The necromenic nematode Pristionchus entomophagus has been frequently found in nests of the invasive European ant Myrmica rubra in coastal Maine, United States, and may contribute to ant mortality and collapse of colonies by transferring environmental bacteria. Paenibacillus and several other bacterial species were found in the digestive tracts of...

A circular food system is one in which food waste is processed to recover plant nutrients and returned to the soil to enable the production of more food, rather than being diverted to landfill or incineration. The approach may be used to reduce energy and water use in food production and contribute to the sustainability of the system. Anaerobic dig...

The vernal transition represents the seasonal transition to spring, occurring as temperatures rise at the end of winter. With rapid snowmelt, microbial community turnover, and accelerated nutrient cycling, this is a critical but relatively under-studied period of ecosystem function. We conducted a study over two consecutive winters (2015–2016) at t...

Background: Necromenic nematode Pristionchus entomophagus has been frequently found in nests of the invasive European ant Myrmica rubra in coastal Maine, United States. The nematodes may contribute to ant mortality and collapse of colonies by transferring environmental bacteria. M. rubra ants naturally hosting nematodes were collected from collapse...

In the northeastern United States, flooding arising from wave overtopping poses a constant threat to coastal communities during storm events. The purpose of this study is to construct a novel integrated atmosphere-ocean-coast and overtopping-drainage modeling framework based on the coupled tide, surge and wave model, SWAN+ADCIRC, to assess risk and...

Climate change in northeastern North America is resulting in warmer winters with reduced snow accumulation. Soils under a thin snowpack are more likely to experience freeze-thaw cycles, disrupting carbon (C) and nitrogen (N) transformations. We conducted a 2 year snow removal experiment in Maine to study the effects of soil freezing on soil C and N...

Increased N inputs through chronic atmospheric deposition has enriched temperate forest ecosystems, altering critical ecosystem functions such as decomposition and potentially resulting in a shift to P limitation. We used a combination of microbial biomass stoichiometry and enzymatic activity analyses to evaluate the potential for microbial nutrien...

Snowpack produces a thermal layer that protects soil from freezing and provides a pulse of nutrient-rich water in spring. Climate forecasts for Maine indicate 20–60% reduction in snowfall by 2050. In January 2015, we initiated a snow-removal experiment in Old Town, ME to investigate the impact of snow loss on forest soil conditions. Snow removal si...

One of the environmental risks associated with use of hydraulic fracturing stimulation technologies for oil and natural gas recovery is the potential release of used fluids into surface waters, soils, and groundwater that could contaminate drinking water resources. To better characterize biodegradability of organic additives, we developed a synthet...

Hydraulic fracturing is the industry standard for extracting hydrocarbons from shale formations. Attention has been paid to the economic benefits and environmental impacts of this process, yet the biogeochemical changes induced in the deep subsurface are poorly understood. Recent single-gene investigations revealed that halotolerant microbial commu...

Microorganisms play several important roles in unconventional gas recovery, from biodegradation of hydrocarbons to souring of wells and corrosion of equipment. During and after the hydraulic fracturing process, microorganisms are subjected to harsh physicochemical conditions within the kilometer-deep hydrocarbon-bearing shale, including high pressu...

Land use and cover conversions as well as climatic factors drive current and future threats to freshwater systems. Research from the United States and across the globe has focused on already threatened and degraded freshwater systems, whose recovery requires significant investments. Attention must also be directed to monitoring freshwater systems t...

Michelle Jordan, Stephanie Burnett, and Jean MacRae Determining the potential for Penstemon barbaris and Canna glauca in horizontal sub-surface flow wastewater treatments Constructed wetlands offer communities, companies and homeowners aesthetically pleasing and effective treatment possibilities for their wastewater. Plant choices play a large...

High arsenic concentrations occur naturally in groundwater in some locations and can result in serious health effects when the groundwater is used as a drinking water supply. The effects have been well documented in Bangladesh, where millions of people have been exposed to unacceptably high arsenic concentrations since the 1970s and serious health...

Parts of New England have naturally high arsenic concentrations in groundwater. High arsenic correlates broadly with bedrock type, but levels are patchy, so other conditions must affect arsenic mobilization. Microorganisms capable of arsenate (As(V)) respiration, if present, could affect arsenic speciation and mobility in groundwater. An arsenate-r...

Arsenic is known to cause serious health effects when consumed in drinking water. In the state of Maine, approximately half of the population relies on private groundwater wells for their drinking water. Of those wells, as many as 13% may contain arsenic levels above the current EPA maximum contaminant level of 10 microgl(-1). Microorganisms can po...

Polybrominated diphenyl ethers (PBDEs) are one class of flame retardants commonly used in textiles, foams and plastics. They are similar in behavior to the well-studied polychlorinated biphenyls and growing evidence suggests they are widespread global environmental pollutants that are capable of bioaccumulation. Fish tissue samples were collected f...

This study describes the synthesis and characterization of thiol-grafted chitosan beads for use as mercury (Hg) adsorbents. Chitosan flakes were dissolved and formed into spherical beads using a phase inversion technique, then crosslinked to improve their porosity and chemical stability. Cysteine was grafted onto the beads in order to improve the a...

Crushed crab shells were chemically treated to transform the chitin present into chitosan. Three particle sizes with average diameters of 0.65, 1.43 and 3.38 mm, average pore diameters ranging from approximately 300 to 540 A, and a specific surface area of approximately 30 m2/g were obtained. Batch experiments were performed to study the uptake equ...

Polycyclic Aromatic Hydrocarbons (PAH) are common environmental pollutants that have been linked to cancerous lesions in bottom fish. In this research, the feasibility of using nitrate as an alternative electron acceptor to stimulate PAH-degradation in anoxic marine sediment was investigated. PAH could be degraded under denitrifying conditions as l...

Semipermeable membrane devices (SPMDs), Tenax TA, and a polyethylene tube dialysis (PTD) methods were used to estimate the “available” fraction of PAH in marine sediment slurries. The polyethylene membrane used in the SPMD and PTD methods mimics a biomembrane. The PAH must diffuse through the membrane into triolein or pentane, respectively. The Ten...

Caulobacters are generally assumed to be found only in environments of low organic content; however, we readily isolated strains from a variety of sewage treatment system designs and locations, and 33 distinct strains were characterized. Most were morphologically similar, having the crescent-shaped cell body, short stalk, and hexagonally packed, pa...

Arsenic at elevated concentrations in drinking water affects the health of millions of people worldwide from Bangladesh to New Zealand to the USA. Keratosis, skin cancer, lung and bladder cancers, and diseases of the vascular system have all been linked to arsenic exposure through drinking water (Hopenhayn, 2006). To understand the factors that con...