Research gaps and priorities for quantitative microbial risk assessment (QMRA).

The coronavirus disease 2019 pandemic highlighted the need for more rapid and routine application of modeling approaches such as quantitative microbial risk assessment (QMRA) for protecting public health. QMRA is a transdisciplinary science dedicated to understanding, predicting, and mitigating infectious disease risks. To better equip QMRA researchers to inform policy and public health management, an Advances in Research for QMRA workshop was held to synthesize a path forward for QMRA research. We summarize insights from 41 QMRA researchers and experts to clarify the role of QMRA in risk analysis by (1) identifying key research needs, (2) highlighting emerging applications of QMRA; and (3) describing data needs and key scientific efforts to improve the science of QMRA. Key identified research priorities included using molecular tools in QMRA, advancing dose-response methodology, addressing needed exposure assessments, harmonizing environmental monitoring for QMRA, unifying a divide between disease transmission and QMRA models, calibrating and/or validating QMRA models, modeling co-exposures and mixtures, and standardizing practices for incorporating variability and uncertainty throughout the source-to-outcome continuum. Cross-cutting needs identified were to: develop a community of research and practice, integrate QMRA with other scientific approaches, increase QMRA translation and impacts, build communication strategies, and encourage sustainable funding mechanisms. Ultimately, a vision for advancing the science of QMRA is outlined for informing national to global health assessments, controls, and policies.

Changing Flows: Sociotechnical Tinkering for Adaptive Water Management.

The Western United States is experiencing historic drought, increasing pressure on water management systems. Agricultural production that relies on surface water flows is therefore imperiled, requiring new innovations and partnerships in order to adapt and survive. In Arizona, some agriculture continues to rely on historic, low-tech irrigation infrastructure such as hand-dug open ditches that divert river water to flood fields. These ditch systems are managed through both formal ditch companies and informal associations. To address changing water availability and needs, ditch users regularly "tinker" with water infrastructure, experimenting and making changes beyond the original infrastructure plans. Such changes are informed and driven by local social relationships and realities of the physical infrastructure. These dynamics are critical to understanding the adaptive capacity and flexibility of the water system; however, they are challenging to recognize and record. In this paper, we apply the emerging conceptualization of sociotechnical tinkering to examine the adaptive management of irrigation ditches in the Verde Valley of Arizona. We find evidence that water users frequently tinker with their water delivery and monitoring infrastructure to respond to and anticipate changes in water availability. Viewed through the lens of sociotechnical tinkering, these interactions are understood as the material manifestations of situated practice and actor agency within a water management system. This case study contributes to literature on adaptive environmental management and the hydrosocial cycle.

Micro(nano)plastic pollution in terrestrial ecosystem: emphasis on impacts of polystyrene on soil biota, plants, animals, and humans.

Pollution with emerging microscopic contaminants such as microplastics (MPs) and nanoplastics (NPs) including polystyrene (PS) in aquatic and terrestrial environments is increasingly recognized. PS is largely used in packaging materials and is dumped directly into the ecosystem. PS micro-nano-plastics (MNPs) can be potentially bioaccumulated in the food chain and can cause human health concerns through food consumption. Earlier MP research has focused on the aquatic environments, but recent researches show significant MP and NP contamination in the terrestrial environments especially agricultural fields. Though PS is the hotspot of MPs research, however, to our knowledge, this systematic review represents the first of its kind that specifically focused on PS contamination in agricultural soils, covering sources, effects, and ways of PS mitigation. The paper also provides updated information on the effects of PS on soil organisms, its uptake by plants, and effects on higher animals as well as human beings. Directions for future research are also proposed to increase our understanding of the environmental contamination of PS in terrestrial environments.

Assessment of Soil to Mitigate Antibiotics in the Environment Due to Release of Wastewater Treatment Plant Effluent.

With low levels of human antibiotics in the environment due to release of wastewater treatment plant (WWTP) effluent, concern is rising about impacts on human health and antibiotic resistance development. Furthermore, WWTP effluent may be released into waterways used as drinking water sources. The aim of this study was to analyze three antibiotics important to human health (sulfamethoxazole, ofloxacin, and trimethoprim) in soil and groundwater at a long-term wastewater reuse system that spray irrigates effluent. Soil samples were collected (i) at a site that had not received irrigation for 7 mo (approximate background concentrations), and then at the same site after (ii) one irrigation event and (iii) 10 wk of irrigation. Water samples were collected three times per year to capture seasonal variability. Sulfamethoxazole was typically at the highest concentrations in effluent (22 ± 3.7 µg L) with ofloxacin and trimethoprim at 2.2 ± 0.6 and 1.0 ± 0.02 µg L, respectively. In the soil, ofloxacin had the highest background concentrations (650 ± 204 ng kg), whereas concentrations of sulfamethoxazole were highest after continuous effluent irrigation (730 ± 360 ng kg). Trimethoprim was only quantified in soil after 10 wk of effluent irrigation (190 ± 71 ng kg). Groundwater concentrations were typically <25 ng L with high concentrations of 660 ± 20 and 67 ± 7.0 ng L for sulfamethoxazole and ofloxacin, respectively. Given that antibiotics interacted with the soil profile and groundwater concentrations were frequently about 1000-fold lower than effluent, soil may be an adequate tertiary treatment for WWTP effluent leading to improved water quality and protection of human health.

Nitrogen Management Affects Nitrous Oxide Emissions under Varying Cotton Irrigation Systems in the Desert Southwest, USA.

Irrigation of food and fiber crops worldwide continues to increase. Nitrogen (N) from fertilizers is a major source of the potent greenhouse gas nitrous oxide (NO) in irrigated cropping systems. Nitrous oxide emissions data are scarce for crops in the arid western United States. The objective of these studies was to assess the effect of N fertilizer management on NO emissions from furrow-irrigated, overhead sprinkler-irrigated, and subsurface drip-irrigated cotton ( L.) in Maricopa, AZ, on Trix and Casa Grande sandy clay loam soils. Soil test- and canopy-reflectance-based N fertilizer management were compared. In the furrow- and overhead sprinkler-irrigated fields, we also tested the enhanced efficiency N fertilizer additive Agrotain Plus as a NO mitigation tool. Nitrogen fertilizer rates as liquid urea ammonium nitrate ranged from 0 to 233 kg N ha. Two applications of N fertilizer were made with furrow irrigation, three applications under overhead sprinkler irrigation, and 24 fertigations with subsurface drip irrigation. Emissions were measured weekly from May through August with 1-L vented chambers. NO emissions were not agronomically significant, but increased as much as 16-fold following N fertilizer addition compared to zero-N controls. Emission factors ranged from 0.10 to 0.54% of added N fertilizer emitted as NO-N with furrow irrigation, 0.15 to 1.1% with overhead sprinkler irrigation, and <0.1% with subsurface drip irrigation. The reduction of NO emissions due to addition of Agrotain Plus to urea ammonium nitrate was inconsistent. This study provides unique data on NO emissions in arid-land irrigated cotton and illustrates the advantage of subsurface drip irrigation as a low NO source system.

Uptake of Three Antibiotics and an Antiepileptic Drug by Wheat Crops Spray Irrigated with Wastewater Treatment Plant Effluent.

With rising demands on water supplies necessitating water reuse, wastewater treatment plant (WWTP) effluent is often used to irrigate agricultural lands. Emerging contaminants, like pharmaceuticals and personal care products (PPCPs), are frequently found in effluent due to limited removal during WWTP processes. Concern has arisen about the environmental fate of PPCPs, especially regarding plant uptake. The aim of this study was to analyze uptake of sulfamethoxazole, trimethoprim, ofloxacin, and carbamazepine in wheat ( L.) plants that were spray-irrigated with WWTP effluent. Wheat was collected before and during harvest, and plants were divided into grain and straw. Subsamples were rinsed with methanol to remove compounds adhering to surfaces. All plant tissues underwent liquid-solid extraction, solid-phase extraction cleanup, and liquid chromatography-tandem mass spectrometry analysis. Residues of each compound were present on most plant surfaces. Ofloxacin was found throughout the plant, with higher concentrations in the straw (10.2 ± 7.05 ng g) and lower concentrations in the grain (2.28 ± 0.89 ng g). Trimethoprim was found only on grain or straw surfaces, whereas carbamazepine and sulfamethoxazole were concentrated within the grain (1.88 ± 2.11 and 0.64 ± 0.37 ng g, respectively). These findings demonstrate that PPCPs can be taken up into wheat plants and adhere to plant surfaces when WWTP effluent is spray-irrigated. The presence of PPCPs within and on the surfaces of plants used as food sources raises the question of potential health risks for humans and animals.

Vadose Zone Transport of Natural and Synthetic Estrogen Hormones at Penn State's "Living Filter" Wastewater Irrigation Site.

The increase in endocrine-disrupting compounds in the environment has generated research focused on the behavior of these compounds in natural soil and water ecosystems. To understand how estrogens behave in the soil environment as a result of 25+ yr of wastewater irrigation, soils from Penn State's "Living Filter" wastewater irrigation site were extracted and analyzed for two natural estrogens (17ß-estradiol and estrone) and one synthetic estrogen (17α-ethynylestradiol). Soil estrogen concentrations were compared for two independent variables: type of land cover and sampling time. Soils were sampled from cropped and forested land areas, and soils were sampled 2 d and 3 wk after a single 12-h effluent irrigation event. A nonirrigated control site was sampled to provide natural background data. For 17ß-estradiol, the nonirrigated mean concentration was 0.68 ± 0.11 ng cm, and the irrigated values, including samples from both land areas and time frames, ranged from 0.99 ± 0.11 to 1.82 ± 0.69 ng cm. For estrone, the nonirrigated mean concentration was 2.36 ± 0.22 ng cm, and the irrigated values, including samples from both land areas collected and time frames, ranged from 2.18 ± 0.20 to 6.24 ± 3.14 ng cm. The 17α-ethynylestradiol nonirrigated mean concentration was 0.47 ± 0.40 ng cm. The irrigated values, including samples from both land areas and time frames, ranged from 0.25 ± 0.06 to 1.37 ± 0.39 ng cm. This study found that time of sampling, land cover, and irrigation can affect estrogen concentrations in soils, resulting in levels that exceed natural background and require improvements in management practices.

An analysis of culture-based methods used for the detection and isolation of Salmonella spp., Escherichia coli, and Enterococcus spp. from surface water: A systematic review.

Identification of methods for the standardized assessment of bacterial pathogens and antimicrobial resistance (AMR) in environmental water can improve the quality of monitoring and data collected, support global surveillance efforts, and enhance the understanding of environmental water sources. We conducted a systematic review to assemble and synthesize available literature that identified methods for assessment of prevalence and abundance of bacterial fecal indicators and pathogens in water for the purposes of monitoring bacterial pathogens and AMR. After screening for quality, 175 unique publications were identified from 15 databases, and data were extracted for analysis. This review identifies the most common and robust methods, and media used to isolate target organisms from surface water sources, summarizes methodological trends, and recognizes knowledge gaps. The information presented in this review will be useful when establishing standardized methods for monitoring bacterial pathogens and AMR in water in the United States and globally.

A one health approach for monitoring antimicrobial resistance: developing a national freshwater pilot effort.

Antimicrobial resistance (AMR) is a world-wide public health threat that is projected to lead to 10 million annual deaths globally by 2050. The AMR public health issue has led to the development of action plans to combat AMR, including improved antimicrobial stewardship, development of new antimicrobials, and advanced monitoring. The National Antimicrobial Resistance Monitoring System (NARMS) led by the United States (U.S) Food and Drug Administration along with the U.S. Centers for Disease Control and U.S. Department of Agriculture has monitored antimicrobial resistant bacteria in retail meats, humans, and food animals since the mid 1990's. NARMS is currently exploring an integrated One Health monitoring model recognizing that human, animal, plant, and environmental systems are linked to public health. Since 2020, the U.S. Environmental Protection Agency has led an interagency NARMS environmental working group (EWG) to implement a surface water AMR monitoring program (SWAM) at watershed and national scales. The NARMS EWG divided the development of the environmental monitoring effort into five areas: (i) defining objectives and questions, (ii) designing study/sampling design, (iii) selecting AMR indicators, (iv) establishing analytical methods, and (v) developing data management/analytics/metadata plans. For each of these areas, the consensus among the scientific community and literature was reviewed and carefully considered prior to the development of this environmental monitoring program. The data produced from the SWAM effort will help develop robust surface water monitoring programs with the goal of assessing public health risks associated with AMR pathogens in surface water (e.g., recreational water exposures), provide a comprehensive picture of how resistant strains are related spatially and temporally within a watershed, and help assess how anthropogenic drivers and intervention strategies impact the transmission of AMR within human, animal, and environmental systems.

Fixed bed column experiments using cotton gin waste and walnut shells-derived biochar as low-cost solutions to removing pharmaceuticals from aqueous solutions.

Acetaminophen (ACT), sulfapyridine (SPY), ibuprofen (IBP) and docusate (DCT) are pharmaceuticals with widespread usage that experience incomplete removal in wastewater treatment systems. While further removal of these pharmaceuticals from wastewater effluent is desired prior to beneficial reuse, additional treatment technologies are often expensive and energy intensive. This study evaluated the ability of biochar produced from cotton gin waste (CG700) and walnut shells (WS800) to remove four pharmaceuticals (ACT, SPY, IBP, and DCT) from aqueous solution. Physico-chemical properties of the biochars were characterized by Brunauer-Emmett-Teller (BET) analysis, scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FT-IR), and zeta potential. The increased pyrolysis temperature during the production of WS800 led to an increase in the specific surface area and increased dehydration of the biochar represented by the loss of the OH-group. Fixed-bed column experiments were performed to determine the difference in removal efficiency between the biochars and elucidate the effects of biochar properties on the adsorption capacity for the pharmaceuticals of interest. Results showed that CG700 had a greater affinity for removing DCT (99%) and IBP (50%), while WS800 removed 72% of SPY and 68% of ACT after 24 h. Adsorption was influenced by the solution pH, surface area, net charge, and functional groups of the biochars. The mechanisms for removal included pore filling and diffusion, hydrophobic interactions, hydrogen bonding, and π-π electron donor acceptor interactions. To conduct predictive modeling of the column breakthrough curves, the Thomas, Adams-Bohart, and Yoon-Nelson models were applied to the experimental data. Results demonstrated that these models generally provided a poor fit for the description of asymmetrical breakthrough curves. Overall, the results demonstrate that biochars from cotton gin waste and walnut shells could be used as cost-effective, environmentally friendly alternatives to activated carbon for the removal of pharmaceuticals from aqueous solutions.

Mitigating risks and maximizing sustainability of treated wastewater reuse for irrigation.

Scarcity of freshwater for agriculture has led to increased utilization of treated wastewater (TWW), establishing it as a significant and reliable source of irrigation water. However, years of research indicate that if not managed adequately, TWW may deleteriously affect soil functioning and plant productivity, and pose a hazard to human and environmental health. This review leverages the experience of researchers, stakeholders, and policymakers from Israel, the United-States, and Europe to present a holistic, multidisciplinary perspective on maximizing the benefits from municipal TWW use for irrigation. We specifically draw on the extensive knowledge gained in Israel, a world leader in agricultural TWW implementation. The first two sections of the work set the foundation for understanding current challenges involved with the use of TWW, detailing known and emerging agronomic and environmental issues (such as salinity and phytotoxicity) and public health risks (such as contaminants of emerging concern and pathogens). The work then presents solutions to address these challenges, including technological and agronomic management-based solutions as well as source control policies. The concluding section presents suggestions for the path forward, emphasizing the importance of improving links between research and policy, and better outreach to the public and agricultural practitioners. We use this platform as a call for action, to form a global harmonized data system that will centralize scientific findings on agronomic, environmental and public health effects of TWW irrigation. Insights from such global collaboration will help to mitigate risks, and facilitate more sustainable use of TWW for food production in the future.

Occurrence of carbamazepine in soils under different land uses receiving wastewater.

Due to its resistance to many wastewater treatment processes, the antiepileptic drug carbamazepine (CBZ) is routinely found in wastewater effluent. Wastewater irrigation is an alternative to stream discharge of wastewater effluent, which utilizes the soil as a tertiary filter to remove excess nutrients and has the potential to remove pharmaceutical compounds. Previous data suggest that CBZ is strongly sorbed to soil; however, it is unknown what its fate is for long periods of irrigation and if land use affects its distribution. Therefore, the objectives of our research were to characterize CBZ concentrations in soils that have been receiving wastewater irrigation for >25 yr under three different land uses: cropped, grassed, and forested. Triplicate soil cores were collected at each of the land uses to a depth of 120 cm. Extractions for CBZ were performed using 5-g soil samples and 20 mL of acetonitrile. The extracted solutions were analyzed on a liquid chromatograph tandem mass spectrometer. The samples were also analyzed for supporting information such as organic carbon, pH, and electrical conductivity. Results suggest that there is accumulation of the CBZ in the surface soils, which have the highest organic carbon content. Average concentrations of CBZ in the surface soils were 4.92, 2.9, and 1.92 ng g, for the forested, grassed, and cropped land uses, respectively. The majority of the CBZ was found in the upper 30 cm of the profile. Our results suggest that the soils adsorb CBZ and slow its movement into groundwater, compared to the movement of nonadsorbed chemicals.

Assessing environmental impacts of treated wastewater through monitoring of fecal indicator bacteria and salinity in irrigated soils.

To assess the potential for treated wastewater irrigation to impact levels of fecal indicator bacteria (FIB) and salinity in irrigated soils, levels of Escherichia coli, Enterococcus, and environmental covariates were measured in a treated wastewater holding pond (irrigation source water), water leaving the irrigation system, and in irrigated soils over 2 years in a municipal parkland in Arizona. Higher E. coli levels were measured in the pond in winter (56 CFU 100 mL(-1)) than in summer (17 CFU 100 mL(-1)); however, in the irrigation system, levels of FIB decreased from summer (26 CFU 100 mL(-1)) to winter (4 CFU 100 mL(-1)), possibly related to low winter water use and corresponding death of residual bacteria within the system. For over 2 years, no increase in FIB was found in irrigated soils, though highest E. coli levels (700 CFU g(-1) soil) were measured in deeper (20-25 cm) soils during summer. Measurements of water inputs vs. potential evapotranspiration indicate that irrigation levels may have been sufficient to generate bacterial percolation to deeper soil layers during summer. No overall increase in soil salinity resulting from treated wastewater irrigation was detected, but distinct seasonal peaks as high as 4 ds m(-1) occurred during both summers. The peaks significantly declined in winter when surface ET abated and more favorable water balances could be maintained. Monitoring of seasonal shifts in irrigation water quality and/or factors correlated with increases and decreases in FIB will aid in identification of any public health or environmental risks that could arise from the use of treated wastewater for irrigation.

Sorption and desorption behavior of four antibiotics at concentrations simulating wastewater reuse in agricultural and forested soils.

Due to rises in antibiotic resistance, fate and transport of antibiotics in soil systems requires greater understanding to determine potential risks to human and animal health. Adsorption coefficients (Kd and Kf) are standard measures for determining sorption capacity and partitioning behavior of organic contaminants in solid matrices. Frequently, sorption studies use higher antibiotic concentrations (mg L-1) and larger spiked water volume to mass of soil (>5:1), which may not reflect sorption behaviors of antibiotics at low concentrations (ng L-1 - µg L-1) in natural soils. The aim of this study was to determine sorption and desorption behaviors of four antibiotics commonly found in soils due to wastewater reuse using parameters replicating typical soil conditions. Concentrations (µg L-1) of sulfamethoxazole (SMX), trimethoprim (TMP), lincomycin (LIN) and ofloxacin (OFL) were equilibrated with four soil types at a 2:1 ratio of spiked water volume to mass of soil, which better represents field conditions. Log Kf and log Kfoc value ranges in this study were 1.88-1.95 and 3.2-4.7 for TMP, 0.43-1.4 and 2.7-3.2 for SMX, and 0.65-1.4 and 2.0-4.1 for LIN, respectively. Ofloxacin adsorbed tightly to soil particles, and adsorption coefficients could not be calculated. Sorption values were higher than previous studies that used similar soil types but had higher ratios of spiking solution to mass of soil (>5:1). Overall, OFL and TMP are expected to strongly interact with soil particles and be less mobile, while SMX and LIN are expected to be more mobile due to weaker sorption interactions.

The dissemination of antibiotics and their corresponding resistance genes in treated effluent-soil-crops continuum, and the effect of barriers.

Irrigation with treated effluent is expanding as freshwater sources diminish, but hampered by growing concerns of pharmaceuticals contamination, specifically antibiotics and resistance determinants. To evaluate this concern, freshwater and effluent were applied to an open field that was treated with soil barriers including plastic mulch together with surface and subsurface drip irrigation, cultivating freshly eaten crops (cucumbers or melons) for two consecutive growing seasons. We hypothesized that the effluent carries antibiotics and resistance determinants to the drip-irrigated soil and crops regardless of the treatment. To test our hypothesis, we monitored for antibiotics abundance (erythromycin, sulfamethoxazole, tetracycline, chlortetracycline, oxytetracycline, amoxicillin, and ofloxacin) and their corresponding resistance genes (ermB, ermF, sul1, tetW, tetO, blaTEM and qnrB), together with class 1 integron (intl1), and bacterial 16S rRNA, in water, soil, and crop samples taken over two years of cultivation. The results showed that an array of antibiotics and their corresponding resistance genes were detected in the effluent but not the freshwater. Yet, there were no significant differences in the distribution or abundance of antibiotics and resistance genes, regardless of the irrigation water quality, or crop type (p > 0.05), but plastic-covered soil irrigated with effluent retained the antibiotics oxytetracycline and ofloxacin (p < 0.05). However, we could not detect significant correlations between the detected antibiotics and the corresponding resistance genes. Overall, our findings disproved our hypothesis suggesting that treated effluent may not carry antibiotics resistance genes to the irrigated soil and crops yet, plastic mulch covered soil retain some antibiotics that may inflict long term contamination.

Occurrence and distribution of antibiotics and corresponding antibiotic resistance genes in different soil types irrigated with treated wastewater.

Diminishing freshwater (FW) supplies necessitate the reuse of treated wastewater (TWW) for various purposes, like irrigation of agricultural lands. However, there is a growing concern that irrigation with TWW may transfer antibiotic resistance genes (ARGs) to the soil and crops. We hypothesized that TWW irrigation would increase the prevalence of antibiotic residues together with the corresponding ARGs in the irrigated soil. We further predicted that soil texture, especially pH, clay content, and organic matter variabilities, would change the antibiotic residues concentrations and thus ARGs dissemination. To test our predictions, three soils types (loamy-sand, loam, and clay) were irrigated with two water types (FW and TWW), over two consecutive seasons. We monitored physico-chemical parameters, the abundance of seven antibiotic residues, and their corresponding ARGs together with class 1 integron (intI1) in 54 water and soil samples collected at the end of the field experiments. The results revealed increase in antibiotics concentrations and ARGs relative abundance in TWW than FW. Yet, in the soil ARGs relative abundances were independent of the irrigation water quality, but dependent on the soil type, especially the clay content. Further, there were no clear associations between the targeted antibiotics or the presence of heavy metals and ARGs' relative abundance in the water or soil samples. Therefore, our results question the link between the discharge of antibiotics and heavy metals, and the dissemination of ARGs in soil environments.

Microplastics interaction with terrestrial plants and their impacts on agriculture.

Microplastics (MPs) are widespread in natural ecosystems and have attracted considerable attention from scientists all over the world because they are believed to threaten every life form. In addition to their potential physical and chemical effects on organisms, MPs may act as a carrier for many micropollutants, including antibiotics, heavy metals, and others. Over the last 10-15 yr, extensive research has been carried out on MPs in marine environments regarding their sources, fate, and toxicity. However, studies concerning their accumulation in the soil ecosystem, uptake, internalization, and impacts on photosynthetic components of the terrestrial ecosystem and risk assessments have been scanty. Thus, there is a large knowledge gap on the extent to which terrestrial environments, especially agroecosystems, are affected by MPs and their subsequent risks to human health. This review summarizes up-to-date findings about MPs on terrestrial environments and provides guidelines for future studies regarding the phytotoxic effects of MPs on plants; the mechanism of uptake and translocation in plant tissues; detection tools for MPs in plants; impacts on plant growth, plant development, and agricultural productivity; and, most important, the future prospects of MPs interaction and accumulation in plants.

The emergence, trajectory, and impacts of emerging contaminants publications in the Journal of Environmental Quality.

As analytical capabilities in the early 2000s began to enable the detection of chemicals in environmental media at increasingly small concentrations, chemicals with the potential to cause adverse human and ecosystem health effects began to be found nearly ubiquitously worldwide. The types of chemicals that were targeted for analysis included natural and synthetic hormones, human and veterinary pharmaceuticals, chemicals in personal care products, novel pesticides, nanoparticles, microplastics, and other chemicals of natural and synthetic origin. The impacts of these chemicals on environmental and human health in many cases remain unknown. Collectively, these chemicals became known as "emerging contaminants" or "contaminants of emerging concern." Much progress has been made toward understanding the sources of these contaminants in the environment, the processes that control their fate and transport once they are released into the environment, and the ability of technology and/or best management practices to mitigate their occurrence. As the Journal of Environmental Quality (JEQ) celebrates its 50th anniversary, we sought to understand how publications in the journal have made impactful contributions in the research area of emerging contaminants. Here, we present the trajectory of publications in JEQ that have shaped knowledge in this field, highlight the importance of these contributions, and conclude with opportunities for JEQ to continue attracting high-quality emerging contaminants research.

Modeling carbamazepine transport in wastewater-irrigated soil under different land uses.

The pharmaceutical compound carbamazepine (CBZ) is a contaminant of emerging concern. Wastewater irrigation can be a long-term, frequent source of CBZ; therefore, understanding the fate and transport of CBZ as a result of wastewater reuse practices has important environmental implications. The objective of this study was to estimate long-term soil transport of CBZ originating from treated wastewater irrigation on plots under different land uses. Field data from a previous study comparing CBZ concentrations in soil under different land uses were used in numerical modeling with HYDRUS-2D for the estimation of CBZ soil transport during 20 yr of irrigation with treated wastewater. This study showed high CBZ retention in soil under all investigated land uses. Adequate modeling results were obtained by using soil organic carbon-water partitioning coefficient (Koc ) for the CBZ linear sorption coefficient (Kd ) estimation, yet an underestimation of CBZ concentration in soil was still noted. Thus, results suggest that, although highly important, organic carbon content is probably not the only soil property governing CBZ sorption at this site, indicating the potential research perspective. Modeling results showed wastewater irrigation containing CBZ for 20 yr increased the CBZ concentration in the soil profile and its vertical movement, with the slowest vertical transport rate occurring on the forested plots. Overall results suggest that a beneficial management practice could be to increase soil organic carbon (e.g., compost addition) when using treated wastewater for irrigation in order to retain CBZ in the surface soil and thus limit its leaching through the soil profile.