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

Abstract

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 β-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 ~ 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. ~ 1.5 × 10 2 ng L − 1 ), carbamazepine (max. ~ 7 × 10 1 ng L − 1 ), atenolol (max ~ 4 × 10 1 ng L − 1 ), and cotinine (max ~ 2 × 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.