Brief Summary of Minutes of Annual Meeting

Objective 1: Evaluate the short- and long-term chemistry and bioavailability of pharmaceuticals and personal care products, persistent organic contaminants, and pathogens in residuals, reclaimed water, and amended soils in order to assess the environmental and human health risk-based effects of their application at a watershed scale. Research for this objective was conducted by members from PA, WA, IN, MA, FL, VA, GA, MI, and KY.

Researchers from PA, VA, MI and FL performed studies addressing chemistry, bioavailability, fate, and transport of CECs/PPCPs. In PA, carbamazepine, estrogens, sulfamethoxazole, trimethoprim, and ofloxacin were quantified in soils, monitoring wells, and plants at a site receiving treated wastewater since 1983. An increase in antibiotic resistance occurred in soil microorganisms exposed long-term to wastewater antibiotics. Pharmaceuticals were detected in groundwater wells; however, concentrations were 100x lower than in the effluent, suggesting that the site soil acts as a biogeochemical filter. Risk calculations suggest effluent CEC levels pose moderate to high risk to aquatic organisms but minimal risk for humans drinking groundwater. In FL, data assessing retention-release of biosolids-borne ciprofloxacin and azithromycin demonstrated high sorption and limited desorption from a variety of biosolids. Biosolids characteristics associated with higher retention were identified. In VA, vertical and lateral soil transport of thiamethoxam, a neonicotinoid, under field conditions occurred within 23 and 36 days of planting, respectively. These results revealed that neonicotinoids can be transported from seed coatings both above and through the soil profile, which may enable migration into surrounding ecosystems. In MI, the fate, uptake, and distribution of pharmaceuticals in agricultural soils originating from irrigation with treated wastewater and land-applied biosolids were measured in soil pore water and plants. In one study, the distribution of pharmaceuticals between soil and pore water and their transformation governed the bioavailability of pharmaceuticals in soils to radish uptake. Fourteen of 15 pharmaceuticals entered radish tissue. Comparison of bioconcentration factors (BCFs) provided evidence that pharmaceuticals in soil pore water are the major bioavailable fractions to plant uptake. The pore water-based BCFs exhibited a positive linear relationship with log Dow for the pharmaceuticals with >90% as neutral species in soil pore water, while such relationship was not observed between bulk soil-based BCFs and log Dow due mainly to the sorption by soil. In addition to pharmaceutical hydrophobic nature, the dissociation of ionizable pharmaceuticals in the soil pore water and (or) root cells may lead to the "ion-trap" effects and thus influence the uptake and translocation process. Large molecular-size pharmaceuticals (e.g., tylosin) manifested a minimum uptake due plausibly to the limited permeability of cell membranes. In a hydroponic study, sorption by lettuce roots of 13 common pharmaceuticals was measured to evaluate transport from roots to shoots. Small-sized pharmaceuticals (e.g., caffeine and carbamazepine) with molecular weight (MW) <300 g mol⁻¹ and a low affinity to lettuce roots (sorption coefficient Kp < 0.05 L g⁻¹) manifested substantial transport to shoots. Small-sized molecules lamotrigine and trimethoprim had a relatively strong affinity to lettuce roots (Kp > 12.0 L g⁻¹) and demonstrated a reduced transport to shoots. Large-sized pharmaceuticals (e.g. MW >400 g mol⁻¹), including lincomycin, monensin sodium, and tylosin, were excluded from cell membranes, resulting in predominant accumulation in roots. Large-sized oxytetracycline existed as zwitterionic species that could slowly enter lettuce roots; however, the relatively strong interaction with lettuce roots limits its transport to shoots. Mass balance analysis revealed that acetaminophen, β-estradiol, carbadox, estrone and triclosan were readily metabolized in lettuce with >90% loss during 144-h exposure period. A scheme was proposed to describe pharmaceutical uptake and transport in plant, which could elucidate many literature-reported results. Molecular size, reactivity and ionic speciation of pharmaceuticals, as well as plant physiology, collectively determine their uptake, transport and accumulation in plants.

An organic CEC whose occurrence in water, soil, plants, and agricultural products is PFAS. PFAS exposure has been linked to increases in immunotoxicity, developmental toxicity, hormonal disruption, hepatoxicity, and certain cancers. In 2016, the Environmental Protection Agency (EPA) established a Lifetime Health Advisory (LHA) level of 70 ng/L for two of the most frequently detected compounds, perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA). Just this year (Feb 2020), the EPA proposed regulating PFOS and PFOA in drinking water and is seeking to engage the scientific community to discover and establish toxicity values for additional PFAS compounds. Researchers from numerous states (IN, FL, PA) performed laboratory and field studies quantifying the occurrence, persistence, fate and human health effects of PFAS. In PA, samples from the Penn State wastewater treatment plant and monitoring wells at the Penn State Living Filter were collected for analysis to understand the occurrence, persistence, fate, and potential human health impacts of PFAS in a beneficial reuse system. Crops are also being analyzed for PFAS uptake to assess potential risks for livestock consumption. In IN, researchers expanded their quantitation to over 40 biosolids-borne PFAS. They have revised and simplified PFAS biosolids extraction protocol to accommodate a suite of characteristics previously observed in biosolids from various types of treatment plants. Some biosolids show the presence of some side-chain polymer PFAS. Lastly, the researchers are evaluating ways to mitigate PFAS release from land-applied biosolids. The Purdue researchers received substantial funds through EPA to improve the understanding of how PFAS release may be mitigated and to evaluate PFAS contributions to groundwater in rural water supplies and agricultural operations. In FL, a project funded by the EPA to investigate the retention-release behavior of PFAS in biosolids and upon treatment with various sorbents is under way. Experiments are investigating the trophic transfer potential of PFAS in simulated terrestrial food chains. These experiments are also serving as a platform within which PFAS analytical capabilities are being developed at UF.

Modeling is essential to reduce the number of field experiments that must be performed to predict CEC/PPCP fate and transport to develop better regulations and practices. The transport of nonionic chemicals, such as carbamazepine (CBZ), is highly dependent upon interaction with soil organic carbon. The results of a CBZ modeling effort in PA found that land use impacted CBZ distribution in soil due to variations in organic carbon content. The model, using literature-based sorption parameters, gave a high r^2 range of 0.63 to 0.96. Simulated values underestimated total soil profile carbamazepine, indicating sorption processes are dependent upon parameters other than organic carbon.

Currently, no models with field-verified data that can aid land management decision-making exist for the wide range of CECs that are known to occur, persist, cause endocrine disruption in non-target species, and pose potential ecological and human health risks. Through combined field, lab, and modeling approach, Penn State researchers are seeking to advance the current state of knowledge on the occurrence and mechanisms controlling fate and transport of CECs. Existing field data will be used to expand the widely used Soil and Water Assessment Tool (SWAT) to simulate PFAS, pharmaceutical, and microplastics fate and transport. New modules have been developed for hormones and are currently being validated using existing data from the Penn State Agronomy Research Farm and from the Purdue Agronomy Center for Research and Education.

Additional CECs whose occurrence in land-applied wastes necessitate an understanding of their chemistry, transport, fate, and bioavailability are engineered nano-particles (ENP). Researchers in MA and GA have been studying ENP. In MA, ENPs are being released into soils, both intentionally and unintentionally, via land application of byproducts and irrigation with reclaimed wastewater. A survey of the scientific literature on four typical types of ENPs (i.e., TiO₂, Ag, CuO, graphene) revealed low concentrations in various environmental compartments (including soils). Environmental factors (e.g., hetero-aggregation and attenuation with soil clay particles and organic matter) could further reduce their availabilities. In general, the environmental risk of ENPs is currently of low concern currently due to low concentrations and reduced availability. In another review article, the UMass researchers reported that for many types of ENPs, various parameters of plant growth (e.g., biomass, photosynthesis) can be enhanced at relatively doses. Carbon nanotubes are a major type of carbon-based nanomaterials that have increased use and environmental releases. In GA, researchers studied the toxicities of multi-walled CNTs and three heavy metals, copper (Cu), cadmium (Cd) and zinc (Zn) to the microalgae Scenedesmus obliquus. Results showed that CNTs promoted algae growth and enhanced photosynthetic efficiency. CNTs appeared to alleviate the adverse effects of Cu, Cd or Zn on microalgae, but these effects differed depending on both the toxicity of each metal and the exposure period. During the next reporting year, UGA researchers will study the benefits of ENPs for crop growth and nutritional quality and on the attenuation of antibiotic resistance in soil and water using different materials.

CECs/PPCPs can affect soil microbial communities necessary for beneficial nutrient cycles and pathogens. Researchers from KY and VA are conducting research on microbial genomics that could elucidate effects of such constituents. Researchers in KY are developing state-of-the-art methods, a version of metatranscriptomics termed Reference Sequencing (RefSeq), which can quantify abundance of all genes expressed by all bacteria in the soil. The UKY researchers are using RefSeq to determine the effects of biosolids application on microbial community composition in soils that have been treated with and without biosolids. Using the RefSeq approach, UKY researchers discovered that application of biosolids did not affect the number of transcriptionally-active genera (average richness=3600 genera) but did cause a significant shift in genus composition (Multiple Response Permutation Procedure, p-value<0.05), including significant reductions in Shannon and Simpson Diversity (p<0.05), significant increases in several “potential” pathogens including Bacillus, Staphylococcus, Pseudomonas, Tissierella, and Clostridium at the expense of significantly more transcriptionally-active Luteitalea, Pedosphaera and Verrucomicrobia in unamended soil (log 2-fold changes>3, p<0.05).

Many of the changes in bacterial community composition in biosolids-amended soils also occurred in soils amended with plant litter, suggesting that changes were simply due to organic matter inputs, not pathogens in the biosolids. The UKY researcher’s goal for the next year is to focus more specifically on expression of virulence and antibiotic resistance genes in biosolids-amended soils. In VA, spectroscopic analyses, eDNA degradation and the associated alterations in DNA secondary structure were investigated by exposing DNase I to tested DNA in the presence of chlorpyrifos, a commonly used organophosphate pesticide. Molecular dynamics simulation was used to explore the weak interactions between the tested DNA and chlorpyrifos. Both spectroscopic and molecular simulation results indicated that chlorpyrifos significantly enhanced DNA degradation without affecting the enzyme activity of DNase I in an aqueous system. The findings provided novel insight into the genotoxicity and ecotoxicity of chlorpyrifos and chlorpyrifos-methyl, as well as their impacts on DNA persistence in aquatic environments. The Virginia Tech researchers employed an integrated, high-resolution examination of the effects of prior antibiotic use, composting, and a 120-day wait period on soil resistomes on manure-amended soil, demonstrating that all three management practices have measurable effects and should be taken into consideration in the development of policy and practice for mitigating the spread of antibiotic resistance.

In order to communicate the risk of CECs/PPCPs to regulators, government decision makers, and citizens, risk communication tools are necessary. Numerous studies on land application have demonstrated low human risk, yet public concerns persist. A communications tool was developed by WA researchers whereby they calculated the quantities of biosolids a person would need to consume, biosolids runoff water needed to drink, and food grown in biosolids-amended soils that must be eaten to receive the equivalent of a single day home exposure to such PPCPs, following the risk pathway approach used in the 503 regulations.

Practices for neutralizing and mitigating CEC/PPCP transport and effects have been studied by researchers in PA, VA, WA, and GA. UGA researchers developed a review of weak oxidation-induced spontaneous polymerization/coupling transformation of micropollutants, processes also referred to as humification, which plays a critical role in natural detoxification of aquatic micropollutants. The researchers summarized solution conditions and discussed toxicity evolution from the weak oxidation-induced coupling/polymerization of micropollutants. VA researchers studied the effects of temperature and initial pH shock on cephapirin and ARGs in dairy manure slurries using a microcosm. Results suggested that simple changes in temperature or initial pH adjustment during storage of dairy manure slurries could mitigate the spread of antibiotic resistance. Researchers from PA and VA compared the use of shallow disk injection to surface broadcasting of dairy manure in the field on hormones, veterinary antibiotic, and antibiotic-resistant fecal coliform bacteria (ARFCB) transport in surface water. Penn State researchers discovered that shallow disk injection reduced the mass of hormones transported during natural surface runoff by 400 times and veterinary antibiotics transported during surface runoff during rainfall simulation 4 times. In VA, liquid dairy manure spiked with 8 antibiotics from four classes (sulfonamides, tetracyclines, macrolides and lincosamides) at 500 μg/kg and applied to field plots at 56 Mg/ha were subjected to rainfall simulations 1 or 7 day(s) after manure application. Subsurface injection reduced (p<0.05) ARFCB in the surface runoff in the spring by 227-593x for day 1 rainfall and 9-30x for day 7 rainfall and 4-20x in fall. The ARFCB were detectable only in 0-5 cm depth of soil in the manure surface applied plots within the first 14 days after manure application but remained detectable in the injection slits of the subsurface injected plots for up to 45 days after manure application. Bioretention media to reduce CECs/PPCPs transport in urban areas were investigated in WA. University of Washington researchers evaluated composts, municipal biosolids, water treatment residuals (WTR), and sands for their ability to filter N, P, Zn, Cu, Pb, Cd and PAHs from stormwater collected from an urban highway. High Fe biosolids was most effective at removing metals and P, and a biosolids compost was more effective, with and without WTR, than a food-yard waste compost at removing PAHs from stormwater. Nitrogen release from the mixtures was mitigated by adding a high carbon material. These results showed that a wide range of mixtures are generally effective for use in bioretention soil media.

Soil arsenic (As) continues to pose a potential threat as a carcinogen, while ranking among the high priority pollutants in soil ecological risk assessment. The origin of soil As can be either geogenic with naturally high background levels or anthropogenic sources from industrial activity, transportation-related activity, or agricultural application of fertilizer and pesticides. Using soil properties to predict bioavailability and/or phytotoxicity of As for use in ecological risk assessment is highly desirable. In Oh, researchers demonstrated that As extracted from soil pore water and Bray-1 had strong relationships with plant tissue As concentration and could be used to predict the modifying effect of soil properties on phytoavailable As. Soil properties, such as clay, reactive Al and Fe, eCEC, pH and OC could directly or indirectly influence As adsorption or complexation on soil and consequently influence As bioavailability.

Objective 2: Evaluate the uses and associated environmental benefits for residuals and wastewaters in various ecosystems (e.g., agricultural, urban, recreational, forest, rangeland, mine-impacted, disturbed, degraded) with respect to changes in soil physical, chemical, biological, nutrient, and trace/heavy metals with respect to soil quality/soil health. Research on this topic was conducted by members from PA, HA, CO, OH, WA, FL, MN, VA, GA, NE and KS.

Researchers in FL, CO, and NE investigated beneficial effects of byproduct application on natural soil properties that promote vegetative growth with reduced environmental impact compared to fertilizers. In FL, a long-term, instrumented field study was established to evaluate agronomic and environmental impacts of biosolids and biochar applied to pastures. Results from field studies demonstrated that prudent nutrient management is possible even on biosolids-amended Spodosols with high water tables.  Inorganic fertilizer resulted in greater leachate N and P losses than biosolids. Approximately 1% of applied N was lost via leaching from biosolids treatments vs. 16% for inorganic fertilizer. Similarly, negligible (0.1 to 0.2% of applied P) P leaching occurred from biosolids-amended soils during a 3-yr field study. Negligible amounts (<1%) of N were lost as N2O from biosolids-amended soils. Efforts are also underway to attract research funds to support these research trials. CO researchers determined that agronomic rates of biosolids are equal to inorganic fertilizer for the production of dryland winter wheat and corn growth. Agronomic biosolids rates improved plant-available soil Zn, which is beneficial to crops grown on Colorado’s alkaline Zn-deficient soils. NE researchers are conducting or planning on-farm, field, and greenhouse experiments to elucidate management practices and soil conditions that result in the most beneficial use of the high amounts of animal manures generated by confined animal feeding operations. Soil productivity, soil health, water quality, and resource efficiency will be employed to assess manure management optimization.

Researchers from VA evaluated and developed protocols for mitigating the detrimental effects of mined and disturbed lands. Lime-stabilized biosolids were applied at high rates (> 35 Mg/ha) at Stafford County Airport in the early 2000s to remediate and revegetate acid sulfate soils. The effects of this treatment and two subsequent smaller applications have been studied for 20 years, following which occurred complete revegetation success and significant reductions in off-site water quality effects. Acid-forming materials remain below the treated surface and local acid seeps and “hot spots” are common, but cover <5% of the project area. In late 2020, the airport will move to a new runway extension that will disturb up to one million more cubic meters of potentially acid-forming materials. Testing those soil materials is resulting in the development of a further remediation plan. Similar levels of disturbance are currently occurring along I-95 road corridors in the region and are currently being minimally documented. The same VA researchers have studied long-term (>35 years) effects of biosolids applied to Appalachian mine soils (Wise County, VA) at rates of 22 to 224 Mg/ha. The original treatments are clearly expressed in much thicker ^A horizons, thicker and better structured subsoil (^Bw) horizons, and in much higher levels of total C and N and extractable P, Z and Cu. Native vegetation has invaded the biosolids plots to a greater extent than the non-treated plots. Soil pits were excavated in 2016, and lab analyses are being completed. Statistical comparisons of original 1982 vs. 2016 C, N and metal levels indicate that, while profound long-term signatures are still visible, much of the original C loadings are no longer detectable compared to background C sequestration. Working with the building and road construction industry in Richmond City and Botetourt County, VA scientists have developed and tested a new rapid approach for the determination of acid-forming materials in the field that will limit their exposure and quickly allow their isolation to minimize water quality impacts from acid drainage. All tests and decisions are formulated into a field flow chart for field personnel to follow sequentially. Field testing takes < 15 minutes per sample and is up to 90% reliable in placing a given soil, sediment or hard rock material into its appropriate category (e.g. 1 - non-acid forming, 2 -acidic – no lime needed; 3 - moderately acidic – site lime application needed; 4 -strongly acid forming – must be isolated away from site and local drainage. A similar approach is now being utilized to assist the “solar farm” industry in assessment of excavated/trenched materials in very large projects in the Mid-Atlantic Piedmont and Coastal Plain.

Biosolids organic matter mitigates/reduces heavy metal food chain, ecosystem, and phytotoxicity risk. A greenhouse study conducted in PA to compare the use of dairy manure (36 mg kg^-1 Cu) and high-Cu biosolids (~1100 mg kg^-1 Cu) on the growth and composition of perennial ryegrass (Lolium perenne) showed that ryegrass tissue Cu in the biosolids and manure treatments was statistically similar but well below phytotoxic levels reported in the literature. The lower ryegrass tissue Al and Fe concentrations in the manure and biosolids than in the control treatments were likely a result of manure- and biosolids-borne organic matter complexation and reduced uptake of the metals by plant roots and translocation to above-ground tissue. Scientists in CO quantified the effects of biosolids and other residuals on pollutant availability, assimilation, phytotoxicity, and remediation. GA scientists studied the ability of an agro-processing waste oil tea shell (OTS) to adsorb heavy metals in aqueous solution. Adsorbent dosage, pH, ion concentration, temperature, and contact time were investigated in batch experiments. GA scientists also evaluated the use of industrial microbial waste (IMW) from amylase production using Aspergillus niger as novel adsorbent to remove two model cationic dyes (crystal violet, CV; methylene blue, MB). IMW was composed of organic Aspergillus niger biomass and inorganic perlite and diatomite and regarded as a composite sorbent which was characterized using FTIR, SEM, and XPS. The sorptive properties of IMW were studied in batch experiments by varying initial dye concentration, contact time, temperature, sorbent dosage, and NaCl concentration. Most soil health assessments have been associated with crop productivity, but they can also be useful for other land management. OH scientists contributed to a chapter on Pb health and remediation issues. Soil assessment of Pb is currently conducted by evaluating exposure in human health risk assessment, but risk-based soil screening levels (SSL) are extremely conservative. This chapter provides a novel, risk-based soil health approach to management of soil Pb, including exposure pathways, risk assessment, and restoration strategies to improve soil health and reduce human health exposure and risk. A risk-based framework is applied to evaluate the use of soil amendments to remediate Pb-contaminated soils. KS researchers continue field to micro-scale investigations of biosolids amendments and Miscanthus for phytostabilization of lead-contaminated soils on a US Army reservation in Fort Riley, KS. Scientists have completed X-ray absorption spectroscopy analysis of soils from field and laboratory studies to understand the mechanisms of reducing Pb bioaccessibility and Pb uptake by Miscanthus. Results from three years show that one-time addition of biosolids at 45 Mg/ha to Pb-contaminated soil enabled establishment of Miscanthus, increasing biomass yield, and reducing phytoavailability and bioaccessibility of Pb. Plots amended with biosolids had significantly less total Pb uptake, plant tissue Pb concentration, and Pb bioaccessibility, and more soil enzyme activities, organic carbon, and microbial biomass.

Beneficial effects of residuals on soil carbon and greenhouse gas balance. Understanding the impact of biosolids end use on C emissions can help municipalities achieve C neutrality. Scientists in WA compared biosolids composting with land application to wheat. Urban compost use, including turfgrass, tree plantings, highway right-of-ways, and urban agriculture, was evaluated using results from scientific literature. The researchers found that compost used to amend subsoil or degraded soils provided greater C benefits than agronomic use. The WA scientists also compared biosolids to synthetic fertilizer for switchgrass-based ethanol production. Biosolids-amended soils generated lower N2O emissions than predicted. The CO2 generated for the production of switchgrass was lower for that fertilized with biosolids than with synthetic fertilizer. In VA, researchers determined that the addition of Fe to biosolids strengthens chemical binding, using synchrotron techniques, that increases the stability of land-applied biosolids C.

Thermal treatment of biosolids to create a partially (i.e., biochar) or fully (i.e., ash) combusted byproduct is becoming more common, but the properties and potential benefits of such residuals are not as well-understood as the uncombusted biosolids. W4170 members from HA, FL, CO, NE, and MN are investigating the properties and benefits of such byproducts. In HA, research is being conducted to specify characteristics of biochar that enable its recommendation for various uses. In FL, research on the co-application of biochar with organic residuals has provided evidence that that biochar may improve the efficiency of nutrients in biosolids. Results from laboratory and field, including rainfall simulation, trials suggested significantly lower risk of N and P losses via runoff and leaching than commercial inorganic fertilizer. In NE, researchers conducted field studies with biochar in collaboration with scientists from Germany. The data consistently showed an increase in soil organic carbon to a soil depth of 30 cm after 4-6 years of biochar application at rates exceeding 30 t ha^-1. The data also suggested that higher application rates and additional non-combusted organic amendments, such as compost, were required to improve pH, water holding capacity, cation exchange capacity, microbial biomass, and crop yield in the long-term. Additional studies by NE researchers resulted in two recently published articles evaluating laboratory and field experiments designed to evaluate the value of coal combustion residues (CCR) as soil amendments. The data suggested that optimum application rates of 70 t ha^-1 or higher of these CCRs reduce N volatilization loss and increase soil C with application rates. MN researchers conducted a 3-year field study to assess the value and safety of sewage sludge incinerator ash (SSA) as a phosphorus (P) source at the Rosemount Research and Outreach Center in Rosemount, MN. Corn and soybean grown with P applied in any form or amount had significantly higher yields than control plots.  DTPA-Zn and Cu increased with application rate; however, neither source nor rate affected available or total elemental soil concentrations.

Residuals sidestream and alternative products uses. Increasing numbers of municipalities are producing Class A biosolids that are not suitable for direct use by the public due to such properties as moisture content, appearance and odors. WA researchers investigated the production of suitable urban soil amendments manufactured from Class A biosolids and other residuals. Blending the biosolids with urban-derived wood waste produced a product that ranked high acceptability and high-quality petunias. KS researchers continued testing the utility of Ca-P recovered from simulated swine wastewater using a pilot-scale anaerobic membrane bioreactor (AnMBR). CO researchers demonstrated the capability of Al-based WTRs to sorb organic forms of P from swine effluent, removing almost 100% of organic P within 1 hour. A subsequent study showed that 17% (~ 3,000 mg P/kg Al-WTR) can be desorbed over time. The researchers showed that the organic P-Al-WTR composite material can be used to supply P to wheat grown in low-P containing soils. CO researchers also showed that oil and gas production waters used for irrigation negatively affect soil health, cause shifts in soil microbial communities that may impact soil biochemical cycling, and suppress plant immune responses.