139 6 Sorption and Degradation of Selected Pharmaceuticals in Soil and Manure Nadia Carmosini and Linda S. Lee 6.1 INTRODUCTION Overthepasttwodecades,thenumberoflivestockandpoultryfarmsintheUnited States has decreased by approximately half, while the number of animal units being raised has increased by about 10%. 1 Thisshifttowardfewerbutincreasinglylarger industrialized farms, termed “conned” or “concentrated animal feeding operations” (CAFOs), has resulted in concomitant increases in pharmaceutical use and manure generatedperunitlandarea.Duringtheirlifespan,roughly60to80%ofcommercial livestockaretreatedwithantibioticsastherapeutic,prophylactic,orgrowthpromot- ing agents, 2 andmuchoftheingesteddoseisexcretedunchangedorasactivemetab- olites. 3 Hormones are also used for growth promotion and reproductive control. In addition,hormonesandtheirmetabolitesareproducedandexcretednaturally,with more than 50 tons of reproductive hormones being released annually by farm ani- mals in the United States. 4 Asaresult,the130billionpoundsofmanureproduced everyyearrepresentanexpansivesourceofpharmaceuticalcontamination. CAFOstypicallystoreanimalwastesinanoutdoorlagoon,undergroundpit, or litter storage facility. For example, approximately 23% of swine operations in Contents 6.1 I ntroduction 139 6.2 Assessing Contaminant Fate and Transport in Soil Environments 140 6.3 Antibiotics 142 6.3.1 Sorption by Soil 142 6.3.2 Degradation in Manure and Soil 155 6.4 Hormones 157 6.4.1 Sorption by Soil and Sediment 157 6.4.2 Degradation in Manure and Soil 159 6.5 Conclusion 160 References 161 © 2008 by Taylor & Francis Group, LLC 140 Fate of Pharmaceuticals in the Environment and in Water Treatment Systems the United States use lagoons; 57% use below-ground pits; and the remaining 20% employotherstoragetechniques,suchasmanurepiles. 5 Lagoons and pits contain liquid, sludge, and solids that are periodically pumped out and injected or surface appliedtoagriculturallandasaneconomicaldisposalstrategythatcapitalizesonthe waste’sfertilizervalue.MostCAFOspumpdownordewaterlagoonsthreetofour timesannually(58%),whileothersdewaterlessthattwiceayear(16%)orneveratall (26%). 5 During these variable residence times, concentrations of excreted residues intheliquidphasemaydissipateasaresultofanaerobicdegradationandsorptionto particulates. After land application, aerobic degradation and sorption to soils further reducethepersistenceandmobilityofpharmaceuticalsintheenvironment.Inasim - il armanner,municipalwastewatertreatmentplantsgeneratepharmaceutical-laden biosolidsandwastewaterefuents,whicharedisposedbylandapplicationandused tomeetirrigationdemandsinaridregions.Recentsurveysoforganiccontaminants in wastewater efuents and biosolids have reported a suite of antibiotics and other pharmaceuticals, albeit at concentrations substantially lower than those in livestock andpoultrymanures(lessthanμg/kgvs.mg/kglevels). 6,7 Concern over potential negative impacts of biologically active pharmaceuticals on nontarget organisms and ecosystem health has prompted many laboratory-scale andafeweld-scaleassessmentsoftheirenvironmentalfate.Severalreviewsof thisinformationhavebeenpublishedinthepast5years,especiallyforveterinary pharmaceuticals.Mostrecently,Leeetal. 8 summarizedwhatisknownontheoccur- rence, environmental fate, ecological impacts, and analytical techniques associated with veterinary antibiotics and hormones. Khanal et al. 9 reviewed the removal rates andmechanismsfornaturalestrogensinwastewatertreatmentsystems.Sarmahet al. 10 compiled data on veterinary antibiotic use and sales trends for several countries, including the United States, the European Union, New Zealand, Kenya, Canada, Japan,China,andRussia.Kumaretal. 11 summarized veterinary antibiotic occur- rence, excretion rates, and subsequent environmental fate, including sorption, degra- dat ion, and transport. Preceding these reviews, Tolls 12 and Thiele-Bruhn 13 provided a review of the sorption and presence of veterinary antibiotics in soils, respectively. In this chapter we will emphasize the studies that have been particularly instrumen - ta lingleaninginformationontheprocessesthatdeterminethesorptionbehaviorof antibiotics, as well as present an overview of emerging research on the degradation of antibiotics and hormones in the environment. 6.2 ASSESSING CONTAMINANT FATE AND TRANSPORT IN SOIL ENVIRONMENTS Thepotentialforantibioticsandhormonestocontaminateandadverselyimpactthe environmentisdirectlyinuencedbytheirmobilityandpersistenceinanimalwastes andsoils.Asaresult,manystudieshaveexaminedthedissipationandpartitioningof these contaminants in environmental matrices, such as soil, manure, organic matter, clays, metal oxides, and oxyhydroxides. For the most part, either batch equilibrium or column displacement techniques have been used. The interpretation and applica - ti onofdatafromtheseexperimentsrequirescarefulconsiderationoftheexperimen- ta l design employed. In batch equilibrium experiments, multiple concentrations of a © 2008 by Taylor & Francis Group, LLC Sorption and Degradation of Selected Pharmaceuticals in Soil and Manure 141 sorbate are equilibrated with a constant amount of sorbent in an electrolyte solution (e.g., 5 mM CaCl 2 ). Ideally, experiments should be conducted using a sorbent mass to solution volume ratio and contaminant concentration range that ensure 50 ± 25% sorption of the applied compound when near-equilibrium conditions are attained. This degree of partitioning facilitates accurate quantication of sorbate concentra - t i onsinboththesolid(C s , mg/kg or mmol/kg) and aqueous (C w ,mg/Lormmol/L) phases. These concentrations are plotted against one another to construct a sorption isotherm, which can be described with one of three commonly used equilibrium based models: (1) Linear equation, K d = C s /C w ,whereK d (L/kg) is the linear distri- bution coefcient; (2) Freundlich equation, C s = K f C w N ,whereK f (mg 1-N L N kg –1 or mmol 1–N L N kg –1 )istheFreundlichsorptioncoefcientandN (unitless) is a measure of isotherm nonlinearity; and (3) Langmuir equation, C s = C s,max K L C w /(1+K L C w ), where K L (L/mgorL/mmol)istheLangmuirafnitycoefcientandC s,max is the maximum monolayer adsorption capacity (mg/kg or mmol/kg). Comparisons among sorbentscanbemadeindependentoflinearityusingnonlinearmodelcoefcientsby estimating a concentration-specic sorption coefcient ( K d * ) at an equilibrium con- centration (C w ) that falls within the experimental range: K d * = K f C w N–1 . Direct quantication of the contaminant in both phases is critical for assessing potentiallyreversiblesorptionandensuringthatthelossoftheparentcompound from solution is due only to sorption. If biotic and abiotic transformations, volatiliza - t i on,sorptiontolabware,andotherlossprocessesaresignicantandattributedto sorption, inated estimates of sorption will be obtained. Methods commonly used to inhibit biodegradation include sterilization of the sorbent by 60 Co irradiation, auto- claving,andltration,orincorporatingadiluteconcentrationofanantimicrobial, such as sodium azide (NaN 3 )ormercuricchloride(HgCl 2 ), in the batch reactor. 14,15 When these steps are not taken, batch experiments can be used to assess biotic transformations in conjunction with sorption as long as concentrations of the parent compound and metabolites in both sorbed and solution phases are determined. To a certainextent,biotictransformationsmayoccurevenaftersystemshavebeensteril - izedduetoextracellularenzymesthatremainactive. In column displacement studies, the movement of a contaminant front or pulse throughapackedorintactsoilcolumnisevaluatedovertime.Informationonthe chemical’spartitioningbetweenthesoilandaqueousphasesisderivedfromaplotof theoutowconcentrationvs.time,calledabreakthroughcurve,whichiscompared to the breakthrough curve for a nonsorbing, conservative tracer (e.g., Cl – ,Br – ). Com- pared to batch experiments, column studies may more closely mimic the spatial and temporal processes of a eld scenario, particularly when intact soil cores are used. Contaminants moving through a soil prole may not persist in space and time for a sufcientlylongperiodoftimetoreachequilibrium;thus,observationsunderow conditions can provide additional insights into the processes that affect a chemical’s persistenceandmobilityinsoils.However,mostcolumnstudiesareconductedunder saturatedsteady-stateowconditions,whicharefarnotrepresentativeofvertical transportthroughthevadosezonewhereunsaturatedtransientowisthenorm. Also,evencolumnstudiesperformedwithintactcoresoftencannotreecttheeffect of eld-scale heterogeneity on fate and transport phenomena or adequately represent the magnitude of macropore ow at the eld scale. 16 © 2008 by Taylor & Francis Group, LLC 142 Fate of Pharmaceuticals in the Environment and in Water Treatment Systems Oneofthemostchallengingaspectsofbatch,column,andeld-scaleexperi- ments is the accurate quantication of low analyte concentrations in complex sample matrices.Manyspectroscopictechniques,suchasultraviolet-visible(UV-VIS),uo- re scence, and mass spectrometry, are often plagued by positive or negative matrix effects, necessitating the use of internal standards or matrix-matched standards. Finally, the use of sorption data in environmental fate models will only accurately describe chemical partitioning in other systems with similar physicochemical prop - er ties (e.g., pH, electrolyte concentration and composition, solute concentration range,sorbentcomposition).Forexample,themagnitudeofsorptionexhibitedbya pureclaysorbentmaydifferfromthatoftheclaywithinasoilduetothepresence of other sorption domains and the interactions between those domains (e.g., organic matter coatings on clay surfaces). 6.3 ANTIBIOTICS 6.3.1 SORPTION BY SOIL Todate,researchonthefateofpharmaceuticalsisdominatedbyworkonveterinary antibioticsinresponsetoconcernsthattheirextensiveuseinlivestockproductionis contributing to bioactive residues in the environment. Although their physicochemi- cal properties are highly variable, most antibiotics are moderately water soluble and exhibit low octanol-water partition coefcients (K ow ) due to the presence of polar functional groups (e.g., -C=O, -OH, -COOH, -NO 2 ,-NH 2 , -CN). Some of these functionalities are ionizable, resulting in compounds that exist as either neutral or charged species (e.g., cations, anions, zwitterions) in proportions dependent on pH conditions.Whileneutralmoleculespartitiontosolidphasesviarelativelyweak van der Waals and electron donor-acceptor interactions, charged species can interact withchargedsorbents(e.g.,organicmatter,clays,metaloxides,andoxyhydroxides) through stronger electrostatic mechanisms, such as cation-exchange, cation-bridg - ing, and complexation. Table 6.1 summarizes t he structures, class assignments, molecular weights, acid dissociation constants (pK a ),andusageinformationforthe antibiotics discussed in this chapter. For antibiotics possessing a positive charge, cation exchange has emerged as an importantsorptionmechanism.Inworkconductedthreedecadesbeforethepresent surgeofinterestinantibiotics,Porubcanetal. 17 examined the sorption of clindamy- cinandtetracycline(TC)bymontmorilloniteclayoverabroadpHrange(1.5to11). X-ray diffraction analysis showed that the clay’s interlayer spacing increased under low pH conditions where the antibiotics’ cationic species predominated. In contrast, thespacingremainedunchangedathighpHwhereclindamycinisneutralandTC is predominantly anionic (+ or 0 ). Infrared radiation (IR) analyses also showed that clindamycin decreased the intensity of the water absorption band, which was attributed to the replacement of hydrated exchangeable cations in the clay’s inter - layerbyclindamycin.Underneutraltomoderatelyalkalineconditions,IRspectral shifts indicated that sorption of the TC zwitterions (+ 0 and + ) occurred by cation exchange as well as by the formation of a complex between the interlayer Ca 2+ cat- ions and the antibiotic’s carbonyl group. For the uncharged clindamycin molecule, © 2008 by Taylor & Francis Group, LLC Sorption and Degradation of Selected Pharmaceuticals in Soil and Manure 143 TABLE 6.1 Properties of Selected Antibiotics Antibiotic Class Molecular Weight (g mol –1 ) pKa Usage Clindamycin CH 3 O N H N Cl CH 3 H HO H 3 C HO OH S CH 3 O Lincosamide 424.98 7.6 a Human and veterinary therapeutic Tetracycline HO CH 3 CH 3 OH OOOOHOH OH NH 2 H 3 C N Tetracycline 444.44 3.3 b 7.68 b 9.3 b Human and veterinary therapeutic; Livestock growth promoter and prophylactic Oxytetracycline OH OH OH OH N H OH CH 3 HO CH 3 H 3 C OOO NH 2 H Tetracycline 460.44 3.27 b 7.32 b 9.11 b Human and veterinary therapeutic; Livestock growth promoter and prophylactic; Fruit production; Aquaculture (Continued) © 2008 by Taylor & Francis Group, LLC 144 Fate of Pharmaceuticals in the Environment and in Water Treatment Systems TABLE 6.1. (Continued) Antibiotic Class Molecular Weight (g mol –1 ) pKa Usage Chlortetracycline Cl HO CH 3 H 3 C CH 3 OH NH 2 OOHOH OH OO N Tetracycline 478.89 3.30 b 7.44 b 9.27 b Human and veterinary therapeutic; Livestock growth promoter and prophylactic Ciprooxacin HN F N N O OH O Fluoroquinolone 331.35 5.90 c 8.89 c Human therapeutic Enrooxacin H 3 C N NN O OH O F Fluoroquinolone 359.40 5.94 d 8.70 d Veterinary therapeutic © 2008 by Taylor & Francis Group, LLC Sorption and Degradation of Selected Pharmaceuticals in Soil and Manure 145 Flumequin F N CH 3 O OH O Fluoroquinolone 261.25 6.5 e Veterinary therapeutic Oxolinic Acid O OH O O O N H 3 C Quinolone 261.23 6.9 e Veterinary therapeutic; Aquaculture Saraoxacin O O N N F HN F OH Fluoroquinolone 385.37 4.1 e 6.8 e Veterinary therapeutic; Aquaculture (Continued) © 2008 by Taylor & Francis Group, LLC 146 Fate of Pharmaceuticals in the Environment and in Water Treatment Systems Monensin HO O O O O O O O H H H H H 3 C H 3 C CH 3 CH 3 CH 3 CH 3 CH 3 OH HO H HO H 3 C H 3 C Ionophore 670.88 4.2 f Livestock growth promoter and prophylactic Lasalocid H 3 C OH OH H OH O O O CH 3 CH 3 CH 3 CH 3 CH 3 CH 3 H 3 C OH H H H H H O Ionophore 590.80 2.6 f Livestock growth promoter and prophylactic TABLE 6.1. (Continued) Antibiotic Class Molecular Weight (g mol –1 ) pKa Usage © 2008 by Taylor & Francis Group, LLC Sorption and Degradation of Selected Pharmaceuticals in Soil and Manure 147 Salinomycin HO H 3 C O O CH 3 CH 3 CH 3 CH 3 CH 3 CH 3 OH H 3 C H 3 C CH 3 OH O O O O O OH Ionophore 751.01 4.45 g Livestock growth promoter and prophylactic Tylosin H 3 C CH 3 CH 3 H 3 C H 3 C H 3 C CH 3 CH 3 H 3 CCH 3 CH 3 O O O O O OH OH OO O O N OH HO O O O HO H 3 C Macrolid 916.11 7.7 h Veterinary therapeutic; Livestock growth promoter and prophylactic Erythromycin HO H 3 C CH 3 H 3 C CH 3 CH 3 CH 3 CH 3 CH 3 CH 3 H 3 C N CH 3 CH 3 OH OH OH HO O O O O O O O O H 3 C Macrolid 733.94 8.88 h Human and veterinary therapeutic; Livestock growth promoter and prophylactic (Continued) © 2008 by Taylor & Francis Group, LLC 148 Fate of Pharmaceuticals in the Environment and in Water Treatment Systems Roxithromycin H 3 C H 3 C CH 3 CH 3 H 3 C CH 3 CH 3 CH 3 CH 3 CH 3 CH 3 CH 3 H 3 C H 3 C O O O O HO O N OH OH O N O O OH O O OH Macrolid 837.05 9.28 g Human therapeutic Carbadox O – O – N + N O O CH 3 H N N + Quinoxaline 262.22 <0i9.61 i Livestock growth promoter and prophylactic Olaquindox O – CH 3 O – O OH N + H N N + Quinoxaline 263.25 None g Livestock growth promoter and prophylactic TABLE 6.1. (Continued) Antibiotic Class Molecular Weight (g mol –1 ) pKa Usage © 2008 by Taylor & Francis Group, LLC [...]... Addition of NaN3 (50 g/L), intended to eliminate biodegradation, increased these times to 90 h and 500 h, respectively In contrast, aerating the systems in either the presence or absence of NaN3 reduced the 90% disappearance times for the open and covered lagoons to 12 h and ≤32 h, © 2008 by Taylor & Francis Group, LLC 1 56 Fate of Pharmaceuticals in the Environment and in Water Treatment Systems respectively,... Analysis and occurrence of estrogenic hormones and their glucuronides is surface water and waste water in the Netherlands, Sci Total Environ., 225, 101, 1999 64 Ying, G.-G., Kookana, R.S., and Ru, Y.-J., Occurrence and fate of hormone steroids in the environment, Environ Int., 28, 545, 2002 65 Lewis, K.M and Archer, R.D pKa values of estrone, 17 -estradiol, and 2methoxyestrone, Steroids, 34, 485, 1979 66 ... antibiotic in soils systems, Toxicol Lett., 131, 19, 2002 © 2008 by Taylor & Francis Group, LLC 162 Fate of Pharmaceuticals in the Environment and in Water Treatment Systems 15 Sassman, S.A., Sarmah, A.K., and Lee, L.S., Sorption of tylosin A, tylosin D and tylosin A-aldol in soils, Environ Toxicol Chem., Accepted, 26, 2007 16 Haws, N.W., Integrated flow and transport processes in subsurface-drained agricultural... oxidatively transform fluoroquinolones, albeit at rates approximately three orders of magnitude lower than MnO2, reflecting the lower redox potential (0 .63 V) of the mineral .60 6. 4 HORMONES 6. 4.1 SORPTION BY SOIL AND SEDIMENT The occurrence of natural and synthetic estrogens and androgens in surface waters has sparked interest by the research community and the general public because of their potential to elicit... measured at the soils’ natural pH, which ranged from 3 .6 to 7.5, and not the operational CEC values at the buffered isotherm pH of 5.5 CEC values can differ substantially over the pH © 2008 by Taylor & Francis Group, LLC 152 Fate of Pharmaceuticals in the Environment and in Water Treatment Systems range of interest for soils containing significant amounts of sorbents with variable or pH-dependent charge... fluoroquinolone antibiotics, which consist of a bicyclic aromatic ring © 2008 by Taylor & Francis Group, LLC Sorption and Degradation of Selected Pharmaceuticals in Soil and Manure 153 skeleton with a carboxylic acid at position 3, keto group at position 4, and a basic N-moiety at position 7. 36 38 Gu and Karthikeyan39 examined the binding of ciprofloxacin (CIP) (pKa1 = 6. 16, pKa2 = 8 .62 ) to Al- and Fe-hydrous... domain There is also evidence that processes other than hydrophobic partitioning to OC contribute to sorption of steroid hormones Several researchers have reported slight© 2008 by Taylor & Francis Group, LLC 158 Fate of Pharmaceuticals in the Environment and in Water Treatment Systems to-moderate nonlinear sorption isotherms (N . in the environment. 6. 2 ASSESSING CONTAMINANT FATE AND TRANSPORT IN SOIL ENVIRONMENTS Thepotentialforantibioticsandhormonestocontaminateandadverselyimpactthe environmentisdirectlyinuencedbytheirmobilityandpersistenceinanimalwastes andsoils.Asaresult,manystudieshaveexaminedthedissipationandpartitioningof these. 153 skeletonwithacarboxylicacidatposition3,ketogroupatposition4,andabasic N-moiety at position 7. 36 38 Gu and Karthikeyan 39 examined the binding of cipro- oxacin (CIP) (pK a1 =6. 16, pK a2 =8 .62 )toAl-andFe-hydrousoxides.CIPisan important third-generation. their release into the environment. Over a 180-d anaerobic incubation in liquid swine manure, rst-order half-lives were estimated for erythro - mycin,roxithromycin,andsalinomycinof41d,130d ,and6 d,respectively,whereas nodegradationoftiamulinwasobserved. 51 The