Potential implications of amending agricultural soils with biosolids

Evelyn Walters, Rolf Halden

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Municipal biosolids recycled on agricultural land are known to contain contaminants such as pharmaceutical and personal care products (PPCPs) at parts-per-million levels. A literature review was conducted to extract from peer-reviewed sources half-life data for 16 PPCPs often detected in biosolids. These data were then used in modeling simulations to determine the accumulation potential of various compounds (t1/2 = 40, 130, 360 d) when applied to land in the form of biosolids. Finally, threshold half-life values were calculated at which compounds are expected to accumulate in soil when applied tri-annually as well as once, twice or three times annually. The literature review revealed notable data gaps with respect to the availability of half-life information relevant to field situations. In addition, half-lives determined in field studies were found to be longer than those obtained in laboratory studies and from quantitative structure activity relationships (QSAR) that predict the fate of a single chemical spiked into agricultural soil. If these more rapid, but inappropriate, half-life values are used in chemical safety decisions or risk assessments, the result will be an underestimation of the actual concentrations and risks posed by biosolids-borne chemicals. The modeling exercise indicated that even a compound with a short half-life (e.g., 40 d) can accumulate when applied three times annually. Contaminants with a moderate half-life (e.g., 130 d) are predicted to show a multi-year net accumulation when applied only once annually. For compounds with a long half-life (e.g., 360 d), accumulation was forecasted to occur even at an application frequency of once every three years. Predicted threshold half-lives for accumulation of biosolids-borne compounds such as PPCPs varied between 12 d for 3 applications per year (assuming no losses due to runoff and wind erosion) and 331 d for a single application every three years, when assuming additional annual losses of 10% in mass from chemical leaching and wind erosion. It is concluded that for risk and safety assessments of chemicals contained in recycled biosolids, it is essential to consider the effect of chemical accumulation over time due to slow degradation under field conditions and repeated application of biosolids.

Original languageEnglish (US)
Title of host publicationContaminants of Emerging Concern in the Environment
Subtitle of host publicationEcological and Human Health Considerations
PublisherAmerican Chemical Society
Number of pages18
ISBN (Print)9780841224964
StatePublished - Nov 2 2010

Publication series

NameACS Symposium Series
ISSN (Print)0097-6156
ISSN (Electronic)1947-5918

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)


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