Effect of liquid municipal biosolid application method on tile and ground water quality

The role of agricultural drainage, storm-events, and natural filtration on the biogeochemical cycling capacity of aquatic and sediment environments in Lake Erie's drainage basin

Lake Erie is the most at risk of the Great Lakes for degraded water quality due to non-point source pollution caused by agricultural activities in the lake's watershed. The extent and temporal patterns of nutrient loading from these agricultural activities is influenced by the timing of agronomic events, precipitation events, and water flow through areas of natural filtration within the watershed. Downstream impacts of these nutrient loading events may be moderated by the co-loading of functionally relevant biogeochemical cycling microbial communities from agricultural soils. This study quantified loading patterns of these communities from tile drain sources, assessed whether functional communities from agricultural sources influenced downstream microbial functionality, and investigated how distance from agricultural sources, storm events, and areas of natural filtration altered nutrient cycling and nutrient fluxes in aquatic and sediment environments. Water and sediment samples were collected in the Wigle Creek watershed in Ontario, from tile drains through to Lake Erie, from May to November 2021, and microbial nitrogen (N) and phosphorous (P) cycling capacity (quantitative PCR), and nutrient levels were evaluated. Results showed that N and P functional groups were co-loaded with nutrients, with increased loading occurring during storm events and during agricultural activities including fertilization and harvest. Overall functional capacity in the aquatic environment decreased with distance from the agricultural sources and as water transited through natural filtration areas. In contrast, the sediment environment was more resilient to both agricultural disturbances and abiotic factors. This study expands our understanding of when and where different stages of N and P cycling occurs in agriculturally impacted watersheds, and identifies both seasons and regions to target with nutrient mitigation strategies.

Important factors when simulating the water and nitrogen balance in a tile-drained agricultural field under long-term monitoring

Despite the effectiveness of tile drain systems as a water management practice in naturally poorly drained soils, they facilitate the transport of NO₃^--N to surface water bodies. In order to improve the risk assessment of this significant transport under increased applications of N fertilisers in agriculture, it is imperative to delineate the controlling factors and processes. The aim of this study was to acquire such knowledge using the 1D Daisy model to simulate water and N balance based on comprehensive data from a ten-year monitoring study of a tile-drained loamy field in Denmark under the actual crop rotation of winter wheat, sugar beet, spring barley, winter rape and maize. The model simulated the cumulative drainage and NO₃^--N leaching over the ten-year period satisfactorily with NSE of 1.00 and 0.87 respectively. While the annual N input to the model was 181 kg N ha^-1, an average of 139 kg N ha^-1 was harvested in the crop, 22 kg N ha^-1 was leached through deep percolation, 17 kg N ha^-1 was leached to the tile drains, and 14 kg N ha^-1 was lost due to denitrification. Although the model satisfactorily captured the monitored data, the results of this study highlight: (i) the requirement for improved parameterisation of winter crops, (ii) the need to give further consideration in the model to soil surface and macropore processes that govern water infiltration and (iii) that measured and simulated NO₃^--N concentrations in the drainage exceeded the limit defined by the European Drinking Water Directive and Nitrates Directive for drinking water and hence improved N management strategies are essential for tile-drained agricultural fields in temperate regions under conventional crop rotations.

Nitrogen release and leachable organic matter decomposition of anaerobically digested biosolids with variable pre-treatments

Thermal hydrolysis pretreatments (THP) coupled to anaerobic digestion (AD) are implemented to treat municipal solids, but limited study indicates whether THP-AD materials merit different land application rates than AD biosolids without THP. Three AD biosolids types with either no pretreatment, THP, or two-hour fermentation were evaluated for differences in leachable dissolved organic matter (DOM), DOM decomposition, and nitrogen (N) releases in biosolids incubated in sandy loam soil. DOM characterizations of size exclusion chromatography, FTIR, and fluorescence maxima > Ex: 400 nm indicated similarities in among AD-DOM that contrasted waste activated sludge Milorganite and Suwannee River Organic Matter (SRNOM). Fluorescence peak picking was a more adaptable analysis for shifted leachate spectra than fluorescence regional integration (FRI). Peak ratio analysis is recommended over FRI for biosolids-DOM. The 3-month net inorganic N produced in biosolids-soil incubations was 155 ± 12.1, 149 ± 18.2, 140 ± 17.4, and 354 ± 15.1 mg N/kg for AD biosolids with no pretreatment, fermentation-AD, THP-AD, and Milorganite respectively. Overall, there was limited evidence of differences in leachable organic matter quality or net mineral N release after 105 days for AD solids with or without THP. Red-shifted fluorescence of leachates decayed by day 45 in aerobic biosolids-soil incubations, suggesting that larger, complex carbon sources liberated during solids stabilization may decompose readily in soils. Overall, other variables (source material, AD operation) may have a greater influence on final nutrient releases and organic matter quality than full-scale pretreatments to AD alone. Critical and targeted application of DOM spectroscopy specific to biosolid-leachates will improve use in advanced stabilization studies.

Do reductions in agricultural field drainage during the growing season impact bacterial densities and loads in small tile-fed watersheds?

Predicting bacterial levels in watersheds in response to agricultural beneficial management practices (BMPs) requires understanding the germane processes at both the watershed and field scale. Controlling subsurface tile drainage (CTD) is a highly effective BMP at reducing nutrient losses from fields, and watersheds when employed en masse, but little work has been conducted on CTD effects on bacterial loads and densities in a watershed context. This study compared fecal indicator bacteria (FIB) [E. coli, Enterococcus, Fecal coliform, Total coliform, Clostridium perfringens] densities and unit area loads (UAL) from a pair of flat tile-drained watersheds (∼250-467 ha catchment areas) during the growing season over a 10-year monitoring period, using a before-after-control-impact (BACI) design (i.e., test CTD watershed vs. reference uncontrolled tile drainage (UCTD) watershed during a pre CTD intervention period and a CTD-intervention period where the test CTD watershed had CTD deployed on over 80% of the fields). With no tile drainage management, upstream tile drainage to ditches comprised ∼90% of total ditch discharge. We also examined FIB loads from a subset of tile drained fields to determine field load contributions to the watershed drainage ditches. Statistical evidence of a CTD effect on FIB UAL in the surface water systems was not strong; however, there was statistical evidence of increased FIB densities [pronounced when E. coli >200 most probable number (MPN) 100 mL^-1] in the test CTD watershed during the CTD-intervention period. This was likely a result of reduced dilution/flushing in the test CTD watershed ditch due to CTD significantly decreasing the amount of tile drainage water entering the surface water system. Tile E. coli load contributions to the ditches were low; for example, during the 6-yr CTD-intervention period they amounted to on average only ∼3 and ∼9% of the ditch loads for the test CTD and reference UCTD watersheds, respectively. This suggests in-stream, or off-field FIB reservoirs and bacteria mobilization drivers, dominated ditch E. coli loads in the watersheds during the growing season. Overall, this study suggested that decision making regarding deployment of CTD en masse in tile-fed watersheds should consider drainage practice effects on bacterial densities and loads, as well as CTD's documented capacity to boost crop yields and reduce seasonal nutrient pollution.

A review of selected microcontaminants and microorganisms in land runoff and tile drainage in treated sludge-amended soils

The objective of this study is to provide a snapshot of the quality of surface runoff and tile drainage in sludge-amended soil in terms of 57 microcontaminants, including pharmaceuticals, hormones and fragrances, and 5 different species of bacteria. It also discusses the main factors affecting their occurrence (soil characteristics, applied sludge load and rate, sludge application method, rain intensity and frequency). It is based on 38 investigations carried out by different research groups in Canada, Australia, the USA and Ireland. The most frequently investigated compounds were hormones, the antiseptics triclosan and triclocarban, the analgesics and anti-inflammatories acetaminophen, ibuprofen and naproxen, the antibiotic sulfamethoxazole, the lipid regulator gemfibrozil and the psychiatric drug carbamazepine. Of all the bacteria, E. coli was the most monitored species. It was found that concentrations of the studied pollutants in surface runoff and tile drainage may vary, depending on many factors. They are generally lower than those observed in the secondary municipal effluent and in surface water, but their contribution to the deterioration of surface water quality might be relevant, mainly in wide rural areas. In this context, the reported data or their ranges represent an attempt to provide reference thresholds and bands of observed concentrations for a rough estimation of the contribution made by the release of the selected pollutants into surface water bodies via surface runoff and tile drainage.

Perspectives of Microbial Inoculation for Sustainable Development and Environmental Management

How to sustainably feed a growing global population is a question still without an answer. Particularly farmers, to increase production, tend to apply more fertilizers and pesticides, a trend especially predominant in developing countries. Another challenge is that industrialization and other human activities produce pollutants, which accumulate in soils or aquatic environments, contaminating them. Not only is human well-being at risk, but also environmental health. Currently, recycling, land-filling, incineration and pyrolysis are being used to reduce the concentration of toxic pollutants from contaminated sites, but too have adverse effects on the environment, producing even more resistant and highly toxic intermediate compounds. Moreover, these methods are expensive, and are difficult to execute for soil, water, and air decontamination. Alternatively, green technologies are currently being developed to degrade toxic pollutants. This review provides an overview of current research on microbial inoculation as a way to either replace or reduce the use of agrochemicals and clean environments heavily affected by pollution. Microorganism-based inoculants that enhance nutrient uptake, promote crop growth, or protect plants from pests and diseases can replace agrochemicals in food production. Several examples of how biofertilizers and biopesticides enhance crop production are discussed. Plant roots can be colonized by a variety of favorable species and genera that promote plant growth. Microbial interventions can also be used to clean contaminated sites from accumulated pesticides, heavy metals, polyaromatic hydrocarbons, and other industrial effluents. The potential of and key processes used by microorganisms for sustainable development and environmental management are discussed in this review, followed by their future prospects.

Process performance assessment of advanced anaerobic digestion of sewage sludge including sequential ultrasound-thermal (55 °C) pre-treatment

The aim of this study was to evaluate the performance and digestate quality of advanced anaerobic digestion of sewage sludge including sequential ultrasound-thermal (55 °C) pre-treatment. Both stages of pre-treatment contributed to chemical oxygen demand (COD) solubilization, with an overall factor of 11.4 ± 2.2%. Pre-treatment led to 19.1, 24.0 and 29.9% increased methane yields at 30, 15 and 7.5 days solid retention times (SRT), respectively, without affecting process stability or accumulation of intermediates. Pre-treatment decreased up to 4.2% water recovery from the digestate, but SRT was a more relevant factor controlling dewatering. Advanced digestion showed 2.4-3.1 and 1.5 logarithmic removals of coliforms and coliphages, respectively, and up to a 58% increase in the concentration of inorganics in the digestate solids compared to conventional digestion. The COD balance of the process showed that the observed increase in methane production was proportional to the pre-treatment solubilization efficiency.

Quantitative real-time PCR-based assessment of tile drainage management influences on bacterial pathogens in tile drainage and groundwater

This study compared the impact of controlled tile drainage (CD) and freely draining (FD) systems on the prevalence and quantitative real-time PCR-based enumeration of four major pathogens including Arcobacter butzleri, Campylobacter jejuni, Campylobacter coli, and Helicobacter pylori in tile- and groundwater following a fall liquid swine manure (LSM) application on clay loam field plots. Although the prevalence of all target pathogens were detected in CD and FD systems, the loads of A. butzleri, C. jejuni, and C. coli were significantly lower in CD tile-water (p<0.05), in relation to FD tile-water. However, concentrations of A. butzleri were significantly greater in CD than FD tile-water (p<0.05). In shallow groundwater (1.2m depth), concentrations of A. butzleri, C. coli, and H. pylori showed no significant difference between CD and FD plots, while C. jejuni concentrations were significantly higher in FD plots (p<0.05). No impact of CD on the H. pylori was observed since quantitative detection in tile- and groundwater was scarce. Although speculative, H. pylori occurrence may have been related to the application of municipal biosolids four years prior to the LSM experiment. Overall, CD can be used to help minimize off-field export of pathogens into surface waters following manure applications to land, thereby reducing waterborne pathogen exposure risks to humans.

Evaluating the effects of triclosan on 3 field crops grown in 4 formulations of biosolids

A growing body of evidence suggests that amending soil with biosolids can be an integral component of sustainable agriculture. Despite strong evidence supporting its beneficial use in agriculture, there are concerns that chemicals, such as pharmaceuticals and personal care products, could present a risk to terrestrial ecosystems and human health. Triclosan is one of the most commonly detected compounds in biosolids. To date, laboratory studies indicate that triclosan likely poses a de minimis risk to field crops; however, these studies were either conducted under unrealistic exposure conditions or only assessed 1 or 2 formulations of biosolids. The purpose of the present study was to characterize the effects of triclosan on field crops in soils amended with 4 different formulations of biosolids (liquid, dewatered, compost, and alkaline-hydrolyzed), containing both background and spiked triclosan concentrations, following best management practices used in the province of Ontario. Three crop species (corn, soybean, and spring wheat) were evaluated using several plant growth endpoints (e.g., root wet mass, shoot length, shoot wet/dry mass) in 70-d to 90-d potted soil tests. The results indicated no adverse impact of triclosan on any crop-biosolids combination. Conversely, amending soil with biosolids either enhanced or had no negative effect, on the growth of plants. Results of the present study suggest little risk of triclosan to crops in agricultural fields amended with biosolids. Environ Toxicol Chem 2017;36:1896-1908. © 2016 SETAC.

Brominated flame retardants and perfluoroalkyl acids in groundwater, tile drainage, soil, and crop grain following a high application of municipal biosolids to a field

Dewatered municipal biosolids (DMB) were applied at a rate of 22Mgdwha^-1 to an agricultural field in fall 2008. Concentrations of polybrominated diphenyl ethers (PBDEs; BDE-47, -99, -100, -153, -154, -183, -197, -207, -209), other brominated flame retardants (BFRs; HBB, PBEB, DBDPE, BTBPE) and perfluoroalkyl acids (PFAAs; PFHxS, PFOS, PFDS, PFOSA, PFHpA, PFOA, PFNA, PFDA, PFUnA, PFDoA, PFTA) were monitored in tile drainage, groundwater (2m, 4m and 6m depth), soil cores (0-0.3m) pre- and post-application, DMB aggregates incorporated into the soil post-application, and in wheat (Triticum spp.) planted post-application. Several compounds were detected in soil and water pre-application and on a reference field plot. PBDEs, other BFRs and PFAAs were detected in tile drainage and 2m groundwater throughout the post-application study period; a few PBDEs were also detected sporadically at lower depths in groundwater. Some of these compounds had not been detected pre-application, while some exceeded reference field plot/pre-application levels (some significantly (p<0.05) in tile drainage); both cases indicating biosolid-based water contamination. In DMB aggregates, several PBDE congeners were found to have dissipated exponentially, with reductions >90% in many of them within 1year post-application. Exponential dissipation of other BFRs and PFAAs in DMB aggregates were not significant. No PBDEs, other BFRs, or PFAAs were detected in wheat grain.

Real scale environmental monitoring of zoonotic protozoa and helminth eggs in biosolid samples in Brazil

Biosolid is the product of the activated sludge treatment system and its final disposition is subject of ongoing discussion as this residue can therefore harbor a great number and variety of pathogens. This study was aimed to (1) monitor the presence of Giardia and Cryptosporidium in biosolid samples from a treatment plant in Campinas, SP, Brazil, (2) observe Giardia cyst wall morphological integrity in treated samples using scanning electron microscopy (SEM) and (3) verify the presence and viability of helminth eggs. Cysts were present in 33.3 % of the samples, whereas oocysts were detected in 8.3 %. Viable Ascaris sp. Toxocara sp. and similar to Trichuris sp. eggs were found through the use of Mexican Official Norm. Results demonstrate the difficulties inherent in working with biosolid as factors such as temperature, ionic strength and pH influenced the recovery of cysts and oocysts. Pores and ruptures were not observed in cyst wall visualized by SEM following 45 days of exposure to sunlight, only minimal morphological changes. These observations emphasize both the importance of adequate treatment of sewage sludge and the need to develop appropriate techniques for the detection of Giardia and Cryptosporidium in this type of sample. This is the first time that a study was done in a real scale for biosolid samples in determining the presence of pathogenic protozoa as Giardia and Cryptosporidium in Brazil, and also observed minimal cyst wall damage after sunlight treatment.

Quantitative Campylobacter spp., antibiotic resistance genes, and veterinary antibiotics in surface and ground water following manure application: Influence of tile drainage control

This work investigated chlortetracycline, tylosin, and tetracycline (plus transformation products), and DNA-based quantitative Campylobacter spp. and Campylobacter tetracycline antibiotic resistant genes (tet(O)) in tile drainage, groundwater, and soil before and following a liquid swine manure (LSM) application on clay loam plots under controlled (CD) and free (FD) tile drainage. Chlortetracycline/tetracycline was strongly bound to manure solids while tylosin dominated in the liquid portion of manure. The chlortetracycline transformation product isochlortetracycline was the most persistent analyte in water. Rhodamine WT (RWT) tracer was mixed with manure and monitored in tile and groundwater. RWT and veterinary antibiotic (VA) concentrations were strongly correlated in water which supported the use of RWT as a surrogate tracer. While CD reduced tile discharge and eliminated application-induced VA movement (via tile) to surface water, total VA mass loading to surface water was not affected by CD. At both CD and FD test plots, the biggest 'flush' of VA mass and highest VA concentrations occurred in response to precipitation received 2d after application, which strongly influenced the flow abatement capacity of CD on account of highly elevated water levels in field initiating overflow drainage for CD systems (when water level <0.3m below surface). VA concentrations in tile and groundwater became very low within 10d following application. Both Campylobacter spp. and Campylobacter tet(O) genes were present in groundwater and soil prior to application, and increased thereafter. Unlike the VA compounds, Campylobacter spp. and Campylobacter tet(O) gene loadings in tile drainage were reduced by CD, in relation to FD.

Long-Term Observations of Nitrogen and Phosphorus Export in Paired-Agricultural Watersheds under Controlled and Conventional Tile Drainage

Controlled tile drainage (CTD) regulates water and nutrient export from tile drainage systems. Observations of the effects of CTD imposed en masse at watershed scales are needed to determine the effect on downstream receptors. A paired-watershed approach was used to evaluate the effect of field-to-field CTD at the watershed scale on fluxes and flow-weighted mean concentrations (FWMCs) of N and P during multiple growing seasons. One watershed (467-ha catchment area) was under CTD management (treatment [CTD] watershed); the other (250-ha catchment area) had freely draining or uncontrolled tile drainage (UCTD) (reference [UCTD] watershed). The paired agricultural watersheds are located in eastern Ontario, Canada. Analysis of covariance and paired tests were used to assess daily fluxes and FWMCs during a calibration period when CTD intervention on the treatment watershed was minimal (2005-2006, when only 4-10% of the tile-drained area was under CTD) and a treatment period when the treatment (CTD) watershed had prolific CTD intervention (2007-2011 when 82% of tile drained fields were controlled, occupying >70% of catchment area). Significant linear regression slope changes assessed using ANCOVA ( ≤ 0.1) for daily fluxes from upstream and downstream monitoring sites pooled by calibration and treatment period were -0.06 and -0.20 (stream water) (negative values represent flux declines in CTD watershed), -0.59 and -0.77 (NH-N), -0.14 and -0.15 (NO-N), -1.77 and -2.10 (dissolved reactive P), and -0.28 and 0.45 (total P). Total P results for one site comparison contrasted with other findings likely due to unknown in-stream processes affecting total P loading, not efficacy of CTD. The FWMC results were mixed and inconclusive but suggest physical abatement by CTD is the means by which nutrient fluxes are predominantly reduced at these scales. Overall, our study results indicate that CTD is an effective practice for reducing watershed scale fluxes of stream water, N, and P during the growing season.

Using AnnAGNPS to Predict the Effects of Tile Drainage Control on Nutrient and Sediment Loads for a River Basin

Controlled tile drainage (CTD) can reduce pollutant loading. The Annualized Agricultural Nonpoint Source model (AnnAGNPS version 5.2) was used to examine changes in growing season discharge, sediment, nitrogen, and phosphorus loads due to CTD for a ∼3900-km agriculturally dominated river basin in Ontario, Canada. Two tile drain depth scenarios were examined in detail to mimic tile drainage control for flat cropland: 600 mm depth (CTD) and 200 mm (CTD) depth below surface. Summed for five growing seasons (CTD), direct runoff, total N, and dissolved N were reduced by 6.6, 3.5, and 13.7%, respectively. However, five seasons of summed total P, dissolved P, and total suspended solid loads increased as a result of CTD by 0.96, 1.6, and 0.23%. The AnnAGNPS results were compared with mass fluxes observed from paired experimental watersheds (250, 470 ha) in the river basin. The "test" experimental watershed was dominated by CTD and the "reference" watershed by free drainage. Notwithstanding environmental/land use differences between the watersheds and basin, comparisons of seasonal observed and predicted discharge reductions were comparable in 100% of respective cases. Nutrient load comparisons were more consistent for dissolved, relative to particulate water quality endpoints. For one season under corn crop production, AnnAGNPS predicted a 55% decrease (CTD) in dissolved N from the basin. AnnAGNPS v. 5.2 treats P transport from a surface pool perspective, which is appropriate for many systems. However, for assessment of tile drainage management practices for relatively flat tile-dominated systems, AnnAGNPS may benefit from consideration of P and particulate transport in the subsurface.

Decay of enteric microorganisms in biosolids-amended soil under wheat (Triticum aestivum) cultivation

There is a growing need for better assessment of health risks associated with land-applied biosolids. This study investigated in-situ decay of seeded human adenovirus (HAdV), Salmonella enterica, Escherichia coli, and bacteriophage (MS2) in biosolids-amended soil under wheat cultivation. The biosolids seeded with microorganisms were placed in decay chambers which were then placed in the topsoil (10 cm depth) at three different sites. Sites were selected in arid wheat-growing regions of Australia with loamy-sand soil type (Western Australia) and sandy soil (South Australia). Seeded E. coli and S. enterica had a relatively short decay time (T90 = 4-56 days) in biosolids-amended soil compared to un-amended soil (T90 = 8-83 days). The decreasing soil moisture over the wheat-growing season significantly (P < 0.05) influenced survival time of both bacteria and MS2 at Western Australia (Moora) and South Australia (Mt Compass) sites, particularly in the un-amended soils. Increasing soil temperature also significantly (P < 0.05) influenced the decay of MS2 at these sites. In this study, no notable decline in HAdV numbers (PCR detectable units) was observed in both biosolids-amended and the un-amended soils at all three sites. The HAdV decay time (T90 ≥ 180 days) in biosolids-amended and un-amended soils was significantly higher than MS2 (T90 = 22-108 days). The results of this study suggest that adenovirus could survive for a longer period of time (>180 days) during the winter in biosolids-amended soil. The stability of adenovirus suggests that consideration towards biosolids amendment frequency, time, rates and appropriate withholding periods are necessary for risk mitigation.

Long-term monitoring of waterborne pathogens and microbial source tracking markers in paired agricultural watersheds under controlled and conventional tile drainage management

Surface waters from paired agricultural watersheds under controlled tile drainage (CTD) and uncontrolled tile drainage (UCTD) were monitored over 7 years in order to determine if there was an effect of CTD (imposed during the growing season) on occurrences and loadings of bacterial and viral pathogens, coliphages, and microbial source tracking markers. There were significantly lower occurrences of human, ruminant, and livestock (ruminant plus pig) Bacteroidales markers in the CTD watershed in relation to the UCTD watershed. As for pathogens, there were significantly lower occurrences of Salmonella spp. and Arcobacter spp. in the CTD watershed. There were no instances where there were significantly higher quantitative loadings of any microbial target in the CTD watershed, except for F-specific DNA (F-DNA) and F-RNA coliphages, perhaps as a result of fecal inputs from a hobby farm independent of the drainage practice treatments. There was lower loading of the ruminant marker in the CTD watershed in relation to the UCTD system, and results were significant at the level P = 0.06. The odds of Salmonella spp. occurring increased when a ruminant marker was present relative to when the ruminant marker was absent, yet for Arcobacter spp., the odds of this pathogen occurring significantly decreased when a ruminant marker was present relative to when the ruminant marker was absent (but increased when a wildlife marker was present relative to when the wildlife marker was absent). Interestingly, the odds of norovirus GII (associated with human and swine) occurring in water increased significantly when a ruminant marker was present relative to when a ruminant marker was absent. Overall, this study suggests that fecal pollution from tile-drained fields to stream could be reduced by CTD utilization.

Comprehensive nitrogen budgets for controlled tile drainage fields in eastern ontario, Canada

Excessive N loading from subsurface tile drainage has been linked to water quality degradation. Controlled tile drainage (CTD) has the potential to reduce N losses via tile drainage and boost crop yields. While CTD can reduce N loss from tile drainage, it may increase losses through other pathways. A multiple-year field-scale accounting of major N inputs and outputs during the cropping season was conducted on freely drained and controlled tile drained agricultural fields under corn ( L.)-soybean [ (L.) Merr.] production systems in eastern Ontario, Canada. Greater predicted gaseous N emissions for corn and soybean and greater observed lateral seepage N losses were observed for corn and soybean fields under CTD relative to free-draining fields. However, observed N losses from tile were significantly lower for CTD fields, in relation to freely drained fields. Changes in residual soil N were essentially equivalent between drainage treatments, while mass balance residual terms were systematically negative (slightly more so for CTD). Increases in plant N uptake associated with CTD were observed, probably resulting in higher grain yields for corn and soybean. This study illustrates the benefits of CTD in decreasing subsurface tile drainage N losses and boosting crop yields, while demonstrating the potential for CTD to increase N losses via other pathways related to gaseous emissions and groundwater seepage.

Redistribution and persistence of microorganisms and steroid hormones after soil-injection of swine slurry

The redistribution and fate of contaminants in pig slurry after direct injection were investigated at two field sites, Silstrup (sandy clay loam) and Estrup (sandy loam), in Denmark. Intact soil samples were collected for up to seven weeks after slurry injection and concentrations of Salmonella Typhimurium Bacteriophage 28B (phage 28B), Escherichia coli, steroid hormones and other slurry components (water, volatile solids, chloride and mineral N) determined in and around the injection slit. The two experiments at Silstrup and Estrup differed with respect to slurry solid content (6.3 vs. 0.8%), as well as soil clay content (27 vs. 15%) and differed considerably with respect to the initial redistribution of slurry-borne contaminants in soil. The transport of microorganisms from the slurry injection slit to the surrounding soil was much lower than that of mineral N and chloride due to attachment and entrapment. The redistribution of E. coli was more affected by site-specific conditions compared to phage 28B, possibly due to the larger cell size of E. coli. The overall recovery of phage 28B was 0.8-4%, and of E. coli 0.0-1.3% in different samples, by the end of the study. Nine different steroid hormones were detected in the slurry slit, and a slow redistribution to the surrounding soil was observed. Overall recovery of estrogens was 0.0 to 6.6% in different samples. The study showed that the combination of soil and slurry properties determined the initial spreading of contaminants, and hence the potential for subsequent leaching.

Using Campylobacter spp. and Escherichia coli data and Bayesian microbial risk assessment to examine public health risks in agricultural watersheds under tile drainage management

Human campylobacteriosis is the leading bacterial gastrointestinal illness in Canada; environmental transmission has been implicated in addition to transmission via consumption of contaminated food. Information about Campylobacter spp. occurrence at the watershed scale will enhance our understanding of the associated public health risks and the efficacy of source water protection strategies. The overriding purpose of this study is to provide a quantitative framework to assess and compare the relative public health significance of watershed microbial water quality associated with agricultural BMPs. A microbial monitoring program was expanded from fecal indicator analyses and Campylobacter spp. presence/absence tests to the development of a novel, 11-tube most probable number (MPN) method that targeted Campylobacter jejuni, Campylobacter coli, and Campylobacter lari. These three types of data were used to make inferences about theoretical risks in a watershed in which controlled tile drainage is widely practiced, an adjacent watershed with conventional (uncontrolled) tile drainage, and reference sites elsewhere in the same river basin. E. coli concentrations (MPN and plate count) in the controlled tile drainage watershed were statistically higher (2008-11), relative to the uncontrolled tile drainage watershed, but yearly variation was high as well. Escherichia coli loading for years 2008-11 combined were statistically higher in the controlled watershed, relative to the uncontrolled tile drainage watershed, but Campylobacter spp. loads for 2010-11 were generally higher for the uncontrolled tile drainage watershed (but not statistically significant). Using MPN data and a Bayesian modelling approach, higher mean Campylobacter spp. concentrations were found in the controlled tile drainage watershed relative to the uncontrolled tile drainage watershed (2010, 2011). A second-order quantitative microbial risk assessment (QMRA) was used, in a relative way, to identify differences in mean Campylobacter spp. infection risks among monitoring sites for a hypothetical exposure scenario. Greater relative mean risks were obtained for sites in the controlled tile drainage watershed than in the uncontrolled tile drainage watershed in each year of monitoring with pair-wise posterior probabilities exceeding 0.699, and the lowest relative mean risks were found at a downstream drinking water intake reference site. The second-order modelling approach was used to partition sources of uncertainty, which revealed that an adequate representation of the temporal variation in Campylobacter spp. concentrations for risk assessment was achieved with as few as 10 MPN data per site. This study demonstrates for the first time how QMRA can be implemented to evaluate, in a relative sense, the public health implications of controlled tile drainage on watershed-scale water quality.

Tile Drainage Management Influences on Surface-Water and Groundwater Quality following Liquid Manure Application

This study investigated the potential for controlled tile drainage (CD) to reduce bacteria and nutrient loading to surface water and groundwater from fall-season liquid manure application (LMA) on four macroporous clay loam plots, of which two had CD and two had free-draining (FD) tiles. Rhodamine WT (RWT) was mixed into the manure and monitored in the tile water and groundwater following LMA. Tile water and groundwater quality were influenced by drainage management. Following LMA on the FD plots, RWT, nutrients, and bacteria moved rapidly via tiles to surface water; at the CD plots, tiles did not flow until the first post-LMA rainfall, so the immediate risk of LMA-induced contamination of surface water was abated. During the 36-d monitoring period, flow-weighted average specific conductance, redox potential, and turbidity, as well as total Kjeldahl N (TKN), total P (TP), NH-N, reactive P, and RWT concentrations, were higher in the CD tile effluent; however, because of lower tile discharge from the CD plots, there was no significant ( ≤ 0.05) difference in surface water nutrient and RWT loading between the CD and FD plots when all tiles were flowing. The TKN, TP, and RWT concentrations in groundwater also tended to be higher at the CD plots. Bacteria behaved differently than nutrients and RWT, with no significant difference in total coliform, , fecal coliform, fecal streptococcus, and concentrations between the CD and FD tile effluent; however, for all but , hourly loading was higher from the FD plots. Results indicate that CD has potential for mitigating bacteria movement to surface water.

A Review of the Use of Organic Amendments and the Risk to Human Health

Historically, organic amendments—organic wastes—have been the main source of plant nutrients, especially N. Their use allows better management of often-finite resources to counter changes in soils that result from essential practices for crop production. Organic amendments provide macro- and micronutrients, including carbon for the restoration of soil physical and chemical properties. Challenges from the use of organic amendments arise from the presence of heavy metals and the inability to control the transformations required to convert the organic forms of N and P into the minerals available to crops, and particularly to minimize the losses of these nutrients in forms that may present a threat to human health. Animal manure and sewage biosolids, the organic amendments in greatest abundance, contain components that can be hazardous to human health, other animals and plants. Pathogens pose an immediate threat. Antibiotics, other pharmaceuticals and naturally produced hormones may pose a threat if they increase the number of zoonotic disease organisms that are resistant to multiple antimicrobial drugs or interfere with reproductive processes. Some approaches aimed at limiting N losses (e.g. covered liquid or slurry storage, rapid incorporation into the soil, timing applications to minimize delay before plant uptake) also tend to favor survival of pathogens. Risks to human health, through the food chain and drinking water, from the pathogens, antibiotics and hormonal substances that may be present in organic amendments can be reduced by treatment before land application, such as in the case of sewage biosolids. Other sources, such as livestock and poultry manures, are largely managed by ensuring that they are applied at the rate, time and place most appropriate to the crops and soils. A more holistic approach to management is required as intensification of agriculture increases.

Accounting for the risks of phosphorus losses through tile drains in a phosphorus index

Tile drainage systems have been identified as a significant conduit for phosphorus (P) losses to surface water, but P indices do not currently account for this transport pathway in a meaningful way. Several P indices mention tile drains, but most account for either the reduction in surface runoff or the enhanced transport through tiles rather than both simultaneously. A summary of the current state of how tile drains are accounted for within P indices is provided, and the challenges in predicting the risk of P losses through tile drains that are relative to actual losses are discussed. A framework for a component P Index is described, along with a proposal to incorporate predictions of losses through tile drains as a component within this framework. Options for calibrating and testing this component are discussed.

Genetic evidence for the offsite transport of E. coli associated with land application of Class B biosolids on agricultural fields

The land-application of Class B biosolids is tightly regulated to allow for natural attenuation of co-applied pathogens. Since many agricultural fields that receive biosolids are artificially drained through subsurface tiles, it is possible that under scenarios of excessive drainage associated with heavy rainfall events, co-applied pathogens might be carried offsite to contaminate nearby surface waters. To address this concern, we used genetic as well as traditional methods to investigate the impact of rainfall on the offsite drainage of Escherichia coli from agricultural fields during biosolids application. Water samples from field drain tiles and a reference field (no biosolids applied) were collected pre-, during and post-biosolids application, while samples of applied biosolids were collected on site during application. The samples were analyzed for E. coli-density and community- and isolate-fingerprinting to assess the genetic link between E. coli in drainage water and those co-applied with biosolids. In contrast to E. coli densities present in the reference field drainage, our results revealed that post-application drainage water collected from biosolids treated fields contained significantly higher E. coli densities following heavy rainfall events, as compared to light rainfall events. Also, in contrast to the reference field, heavy rainfall correlated significantly with increased similarity of E. coli community fingerprints occurring in biosolids to those draining from treated field. Fingerprinting of individual E. coli revealed a high similarity (>94%) between some isolates collected from biosolids and post-application drainage water. Using a combination of enumeration and genetic typing methods, we show that heavy rainfall following biosolids application to agricultural fields induced the offsite transport of biosolids-associated E. coli, potentially compromising the quality of water draining through the watershed.

Bacterial contamination of tile drainage water and shallow groundwater under different application methods of liquid swine manure

A 2 year field experiment evaluated liquid manure application methods on the movement of manure-borne pathogens ( Salmonella sp.) and indicator bacteria ( Escherichia coli and Clostridium perfringens ) to subsurface water. A combination of application methods including surface application, pre-application tillage, and post-application incorporation were applied in a randomized complete block design on an instrumented field site in spring 2007 and 2008. Tile and shallow groundwater were sampled immediately after manure application and after rainfall events. Bacterial enumeration from water samples showed that the surface-applied manure resulted in the highest concentration of E. coli in tile drainage water. Pre-tillage significantly (p < 0.05) reduced the movement of manure-based E. coli and C. perfringens to tile water and to shallow groundwater within 3 days after manure application (DAM) in 2008 and within 10 DAM in 2007. Pre-tillage also decreased the occurrence of Salmonella sp. in tile water samples. Indicator bacteria and pathogens reached nondetectable levels within 50 DAM. The results suggest that tillage before application of liquid swine manure can minimize the movement of bacteria to tile and groundwater, but is effective only for the drainage events immediately after manure application or initial rainfall-associated drainage flows. Furthermore, the study highlights the strong association between bacterial concentrations in subsurface waters and rainfall timing and volume after manure application.

Associations among pathogenic bacteria, parasites, and environmental and land use factors in multiple mixed-use watersheds

Over a five year period (2004-08), 1171 surface water samples were collected from up to 24 sampling locations representing a wide range of stream orders, in a river basin in eastern Ontario, Canada. Water was analyzed for Cryptosporidium oocysts and Giardia cyst densities, the presence of Salmonella enterica subspecies enterica, Campylobacter spp., Listeria monocytogenes, and Escherichia coli O157:H7. The study objective was to explore associations among pathogen densities/occurrence and objectively defined land use, weather, hydrologic, and water quality variables using CART (Classification and Regression Tree) and binary logistical regression techniques. E. coli O157:H7 detections were infrequent, but detections were related to upstream livestock pasture density; 20% of the detections were located where cattle have access to the watercourses. The ratio of detections:non-detections for Campylobacter spp. was relatively higher (>1) when mean air temperatures were 6% below mean study period temperature values (relatively cooler periods). Cooler water temperatures, which can promote bacteria survival and represent times when land applications of manure typically occur (spring and fall), may have promoted increased frequency of Campylobacter spp. Fifty-nine percent of all Salmonella spp. detections occurred when river discharge on a branch of the river system of Shreve stream order = 9550 was >83 percentile. Hydrological events that promote off farm/off field/in stream transport must manifest themselves in order for detection of Salmonella spp. to occur in surface water in this region. Fifty seven percent of L. monocytogenes detections occurred in spring, relative to other seasons. It was speculated that a combination of winter livestock housing, silage feeding during winter, and spring application of manure that accrued during winter, contributed to elevated occurrences of this pathogen in spring. Cryptosporidium and Giardia oocyst and cyst densities were, overall, positively associated with surface water discharge, and negatively associated with air/water temperature during spring-summer-fall. Yet, some of the highest Cryptosporidium oocyst densities were associated with low discharge conditions on smaller order streams, suggesting wildlife as a contributing fecal source. Fifty six percent of all detections of ≥ 2 bacteria pathogens (including Campylobacter spp., Salmonella spp., and E. coli O157:H7) in water was associated with lower water temperatures (<∼ 14 °C; primarily spring and fall) and when total rainfall the week prior to sampling was >∼ 27 mm (62 percentile). During higher water temperatures (>∼ 14 °C), a higher amount of weekly rainfall was necessary to promote detection of ≥ 2 pathogens (primarily summer; weekly rainfall ∼>42 mm (>77 percentile); 15% of all ≥ 2 detections). Less rainfall may have been necessary to mobilize pathogens from adjacent land, and/or in stream sediments, during cooler water conditions; as these are times when manures are applied to fields in the area, and soil water contents and water table depths are relatively higher. Season, stream order, turbidity, mean daily temperature, surface water discharge, cropland coverage, and nearest upstream distance to a barn and pasture were variables that were relatively strong and recurrent with regard to discriminating pathogen presence and absence, and parasite densities in surface water in the region.

Microbial and chemical markers: runoff transfer in animal manure-amended soils

Fecal contamination of water resources is evaluated by the enumeration of the fecal coliforms and Enterococci. However, the enumeration of these indicators does not allow us to differentiate between the sources of fecal contamination. Therefore, it is important to use alternative indicators of fecal contamination to identify livestock contamination in surface waters. The concentration of fecal indicators (, enteroccoci, and F-specific bacteriophages), microbiological markers (Rum-2-bac, Pig-2-bac, and ), and chemical fingerprints (sterols and stanols and other chemical compounds analyzed by 3D-fluorescence excitation-matrix spectroscopy) were determined in runoff waters generated by an artificial rainfall simulator. Three replicate plot experiments were conducted with swine slurry and cattle manure at agronomic nitrogen application rates. Low amounts of bacterial indicators (1.9-4.7%) are released in runoff water from swine-slurry-amended soils, whereas greater amounts (1.1-28.3%) of these indicators are released in runoff water from cattle-manure-amended soils. Microbial and chemical markers from animal manure were transferred to runoff water, allowing discrimination between swine and cattle fecal contamination in the environment via runoff after manure spreading. Host-specific bacterial and chemical markers were quantified for the first time in runoff waters samples after the experimental spreading of swine slurry or cattle manure.

Dairy slurry application method impacts ammonia emission and nitrate in no-till corn silage

Reducing ammonia (NH3) emissions through slurry incorporation or other soil management techniques may increase nitrate (NO3) leaching, so quantifying potential losses from these alternative pathways is essential to improving slurry N management. Slurry N losses, as NH3 or NO3 were evaluated over 4 yr in south-central Wisconsin. Slurry (i.e., dairy cow [Bos taurus] manure from a storage pit) was applied each spring at a single rate (-75 m3 ha(-1)) in one of three ways: surface broadcast (SURF), surface broadcast followed by partial incorporation using an aerator implement (AER-INC), and injection (INJ). Ammonia emissions were measured during the 120 h following slurry application using chambers, and NO3 leaching was monitored in drainage lysimeters. Yield and N3 uptake of oat (Avena sativa L.), corn (Zea mays L.), and winter rye (Secale cereale L.) were measured each year, and at trial's end soils were sampled in 15- to 30-cm increments to 90-cm depth. There were significant tradeoffs in slurry N loss among pathways: annual mean NH3-N emission across all treatments was 5.3, 38.3, 12.4, and 21.8 kg ha(-1) and annual mean NO3-N leaching across all treatments was 24.1, 0.9, 16.9, and 7.3 kg ha' during Years 1, 2, 3, and 4, respectively. Slurry N loss amounted to 27.1% of applied N from the SURF treatment (20.5% as NH3-N and 6.6% as NO,-N), 23.3% from AER-INC (12.0% as NH3-N and 11.3% as NO3-N), and 9.19% from INJ (4.4% as NH3-N and 4.7% as NO3-N). Although slurry incorporation decreased slurry N loss, the conserved slurry N did not significantly impact crop yield, crop N uptake or soil properties at trial's end.

Frequency of virulence genes and antibiotic resistances inEnterococcusspp. isolates from wastewater and feces of domesticated mammals and birds, and wildlife

Enterococci are gastrointestinal tract residents and also an important cause of nosocomial infections. To understand which species, virulence determinants, and antibiotic resistances are prevalent in enterococci shed by various hosts groups, a total of 1460 strains isolated from 144 fecal samples obtained from wastewater, domesticated mammals and birds, and wildlife were characterized. Identification of isolates to the species level showed that Enterococcus faecalis was dominant in domesticated mammals and birds and wildlife feces, whereas Enterococcus faecium was dominant among wastewater isolates, and that no single Enterococcus species could be associated with a specific host group. The frequency of 12 virulence determinants was evaluated among isolates, but no single virulence determinant could be associated with a specific host group. Resistance to 12 antibiotics was evaluated among isolates, and it was shown that the highest frequency of resistance at breakpoint concentration was found in domesticated mammals and birds (P ≤ 0.05 for 4 antibiotics). Our results suggests that (1) species identification and virulence typing of Enterococcus spp. isolates are not useful for the identification of the host groups responsible for fecal contamination of water by microbial source tracking and that (2) antibiotic use for clinical, veterinary, or animal husbandry practices is promoting resistance.

Polybrominated diphenyl ethers, perfluorinated alkylated substances, and metals in tile drainage and groundwater following applications of municipal biosolids to agricultural fields

Polybrominated diphenyl ethers (PBDEs), perfluorinated alkylated substances (PFAS), and metals were monitored in tile drainage and groundwater following liquid (LMB) and dewatered municipal biosolid (DMB) applications to silty-clay loam agricultural field plots. LMB was applied (93,500 L ha(-1)) in late fall 2005 via surface spreading on un-tilled soil (SS(LMB)), and a one-pass aerator-based pre-tillage prior to surface spreading (AerWay SSD) (A). The DMB was applied (8 Mg d wha(-1)) in early summer 2006 on the same plots by injecting DMB beneath the soil surface (DI), and surface spreading on un-tilled soil (SS(DMB)). Key PBDE congeners (BDE-47, -99, -100, -153, -154, -183, -209) comprising 97% of total PBDE in LMB, had maximum tile effluent concentrations ranging from 6 to 320 ng L(-1) during application-induced tile flow. SS(LMB) application-induced tile mass loads for these PBDE congeners were significantly higher than those for control (C) plots (no LMB) (p<0.05), but not A plots (p>0.05). PBDE mass loss via tile (0-2h post-application) as a percent of mass applied was approximately 0.04-0.1% and approximately 0.8-1.7% for A and SS(LMB), respectively. Total PBDE loading to soil via LMB and DMB application was 0.0018 and 0.02 kg total PBDE ha(-1)yr(-1), respectively. Total PBDE concentration in soil (0-0.2m) after both applications was 115 ng g(-1)dw, (sampled 599 days and 340 days post LMB and DMB applications respectively). Of all the PFAS compounds, only PFOS (max concentration=17 ng L(-1)) and PFOA (12 ng L(-1)) were found above detectable limits in tile drainage from the application plots. Mass loads of metals in tile for the LMB application-induced tile hydrograph event, and post-application concentrations of metals in groundwater, showed significant (p<0.05) land application treatment effects (SS(LMB)>A>C for tile and SS(LMB) and A>C for groundwater for most results). Following DMB application, no significant differences in metal mass loads in tile were found between SS(DMB) and DI treatments (PBDE/PFAS were not measured). But for many metals (Cu, Se, Cd, Mo, Hg and Pb) both SS(DMB) and DI loads were significantly higher than those from C, but only during <100 days post DMB application. Clearly, pre-tilling the soil (e.g., A) prior to surface application of LMB will reduce application-based PBDE and metal contamination to tile drainage and shallow groundwater. Directly injecting DMB in soil does not significantly increase metal loading to tile drains relative to SS(DMB), thus, DI should be considered a DMB land application option.

Pharmaceutical and personal care products in tile drainage following surface spreading and injection of dewatered municipal biosolids to an agricultural field

Land application of municipal biosolids can be a source of environmental contamination by pharmaceutical and personal care products (PPCPs). This study examined PPCP concentrations/temporally discrete mass loads in agricultural tile drainage systems where two applications of biosolids had previously taken place. The field plots received liquid municipal biosolids (LMB) in the fall of 2005 at an application rate of approximately 93,500 L ha (-1), and a second land application was conducted using dewatered municipal biosolids (DMB) applied at a rate of approximately 8Mg dw ha (-1) in the summer of 2006 [corrected].The DMB land application treatments consisted of direct injection (DI) of the DMB beneath the soil surface at a nominal depth of approximately 0.11 m, and surface spreading (SS) plus subsequent tillage incorporation of DMB in the topsoil (approximately 0.10 m depth). The PPCPs examined included eight pharmaceuticals (acetaminophen, fluoxetine, ibuprofen, gemfibrozil, naproxen, carbamazepine, atenolol, sulfamethoxazole), the nicotine metabolite cotinine, and two antibacterial personal care products triclosan and triclocarban. Residues of naproxen, cotinine, atenolol and triclosan originating from the fall 2005 LMB application were detected in tile water nearly nine months after application (triclocarban was not measured in 2005). There were no significant differences (p>0.05) in PPCP mass loads among the two DMB land application treatments (i.e., SS vs. DI); although, average PPCP mass loads late in the study season (>100 days after application) were consistently higher for the DI treatment relative to the SS treatment. While the concentration of triclosan (approximately 14,000 ng g(-1) dw) in DMB was about twice that of triclocarban (approximately 8000 ng g(-1) dw), the average tile water concentrations for triclosan were much higher (43+/-5 ng L(-1)) than they were for triclocarban (0.73+/-0.14 ng L(-1)). Triclosan concentrations (maximum observed in 2006 approximately 235 ng L(-1)) in tile water resulting from land applications may warrant attention from a toxicological perspective.

Nitrogen, phosphorus, and bacteria tile and groundwater quality following direct injection of dewatered municipal biosolids into soil

Application of municipal biosolids (sewage) to agricultural land is a common practice to improve soil physical quality and fertility. The chosen method of land application can have a strong impact on the extent of adjacent water contamination by nutrients and bacteria. Dewatered municipal biosolids (DMB) were applied to silt-clay loam experimental field plots in Ontario, Canada using two application methods: (i) surface spreading followed by shallow incorporation (SS) and (ii) a newly developed implement that directly injects DMB into the topsoil (DI). The objective of this study was to compare N, P, and bacteria quality of tile drainage and shallow groundwater associated with each land application technique. There were no significant differences (P > 0.05) in N, P, and bacteria tile mass loads among the application treatments for time periods <100 d postapplication, when the greatest peak loads and peak tile water concentrations were observed. Both land application treatments caused groundwater Escherichia coli contamination to at least 1.2 m depth below surface after the first postapplication rainfall event, and NO(3)-N contamination to at least 2.0 m depth below surface. The DI treatment did, however, have significantly (P < 0.05) higher tile mass loads of total Kjeldahl N (TKN), total phosphorus (TP), E. coli, Enterococci, and Clostridium perfringens relative to the SS treatment for time periods >100 d postapplication. Nevertheless, relative to tile effluent data collected <100 d postapplication (no application treatment differences), peak loads, and concentrations during this time were, overall, considerably lower for both treatments. This finding, along with no significant differences in N, P, and bacteria groundwater concentrations among the application treatments, and that the direct injection technique could potentially reduce vector attraction problems and odor, suggests that the direct injection technique should be considered a dewatered municipal biosolid land application option.

Simulation of pharmaceutical and personal care product transport to tile drains after biosolids application

Pharmaceuticals and personal care products (PPCPs) carried in biosolids may reach surface waters or ground water when these materials are applied as fertilizer to agricultural land. During preferential flow conditions created by land application of liquid municipal biosolids (LMB), the residence time of solutes in the macropores may be too short for sorption equilibration. The physically based dual-permeability model MACRO is used in environmental risk assessments for pesticides and may have potential as an environmental risk assessment tool for PPCPs. The objective of this study was to evaluate MACRO and an updated version of MACRO that included non-equilibrium sorption in macropores using data from experiments conducted in eastern Ontario, Canada on the transport of three PPCPs (atenolol, carbamazepine, and triclosan), the nicotine metabolite cotinine, and the strongly sorbing dye rhodamine WT applied in LMB. Results showed that the MACRO model could not reproduce the measured rhodamine WT concentrations (Nash-Sutcliffe coefficient [NS] for the best simulation = -0.057) in drain discharge. The updated version resulted in better fits to measured data for PPCP (average NS = 0.97) and rhodamine WT (NS = 0.84) concentrations. However, it was not possible to simulate all compounds using the same set of hydraulic parameters, which indicates that the model does not fully account for all relevant processes. The results presented herein show that non-equilibrium sorption in macropores has a large impact on simulated solute transport for reactive compounds contained in LMB. This process should be considered in solute transport models that are used for environmental risk assessments for such compounds.

Pharmaceutical and personal care products in tile drainage following land application of municipal biosolids

Land application of municipal biosolids (sewage) is a common farming practice in many parts of the world. There is potential for transport of pharmaceuticals and personal care products (PPCPs) from agricultural fields to adjacent surface waters via tile drainage systems. In this study, liquid municipal biosolids (LMB) (total solids=11,933 mg L(-1)), supplemented with selected PPCPs and the fluorescent dye tracer rhodamine WT (RWT), were applied to tile drained fields using two land application approaches. Objectives included evaluating the relative benefits of land application practices with respect to reducing PPCP loadings to tile drains, evaluating PPCP persistence in tile water, and determining whether rhodamine WT can be used to estimate PPCP mass loads in tile. The PPCPs examined included an antibacterial agent used in personal care products (triclosan), a metabolite of nicotine (cotinine), and a variety of drugs including two sulfonamide antimicrobials (sulfapyridine, sulfamethoxazole), a beta-blocker (atenolol), an anti-epileptic (carbamazepine), an antidepressant (fluoxetine), analgesic/anti-inflammatories (acetaminophen, naproxen, ibuprofen), and a lipid-regulator (gemfibrozil). Maximum observed PPCP concentrations in the spiked LMB were about 10(3) ng g(-1) dry weight. PPCPs were shown to move rapidly via soil macropores to tile drains within minutes of the land application. Maximum observed PPCP concentrations in tile effluent associated with the LMB application-induced tile flow event were approximately 10(1) to 10(3) ng L(-1). PPCP mass loads, for the application-induced tile-hydrograph event, were significantly (p<0.1) higher for surface spreading over non-tilled soil (incorporation tillage occurring 20 h post-application), relative to aerating soil immediately prior to surface spreading using an AerWay slurry deposition system. PPCP concentrations that were detected above the limit of quantitation (LOQ) in tile water during several precipitation-induced tile flow events that occurred post-application, included: triclosan (max. approximately 1.5 x 10(2) ng L(-1)), carbamazepine (max. approximately 7 x 10(1) ng L(-1)), atenolol (max approximately 4 x 10(1) ng L(-1)), and cotinine (max approximately 2 x 10(1) ng L(-1)). In spite of their presence in biosolids, the other PPCPs were not observed above LOQ concentrations during these events. PPCP concentrations were predicted from RWT concentrations over a 40 day study period. Tile mass loads as a percent of PPCP mass applied to soil ranged from 4.2%+/-SD of 9.2% to 7.1%+/-10.9% for the AerWay system and surface spreading plus incorporation treatments, respectively.