Metal and nanoparticle occurrence in biosolid-amended soils

Abstract

• Biosolid land application increased the unregulated metal contents in surface soil.• Metals (e.g., Ag) associated with ENMs show accumulation and low mobility in soils.• Titanium-containing nanoparticle (50 nm in diameter) was identified in the soils. Metals can accumulate in soils amended with biosolids in which metals have been concentrated during wastewater treatment. The goal of this study is to inspect agricultural sites with long-term biosolid application for a suite of regulated and unregulated metals, including some potentially present as commonly used engineered nanomaterials (ENMs). Sampling occurred in fields at a municipal and a privately operated biosolid recycling facilities in Texas. Depth profiles of various metals were developed for control soils without biosolid amendment and soils with different rates of biosolid application (6.6 to 74 dry tons per hectare per year) over 5 to 25 years. Regulated metals of known toxicity, including chromium, copper, cadmium, lead, and zinc, had higher concentrations in the upper layer of biosolid-amended soils (top 0-30 cm or 0-15 cm) than in control soils. The depth profiles of unregulated metals (antimony, hafnium, molybdenum, niobium, gold, silver, tantalum, tin, tungsten, and zirconium) indicate higher concentrations in the 0-30 cm soil increment than in the 70-100 cm soil increment, indicating low vertical mobility after entering the soils. Titanium-containing particles between 50 nm and 250 nm in diameter were identified in soil by transmission electron microscopy (TEM) coupled with energy dispersive x-ray spectroscopy (EDX) analysis. In conjunction with other studies, this research shows the potential for nanomaterials used in society that enter the sewer system to be removed at municipal biological wastewater treatment plants and accumulate in agricultural fields. The metal concentrations observed herein could be used as representative exposure levels for eco-toxicological studies in these soils. a b s t r a c t a r t i c l e i n f o

Monte Carlo simulations of the transformation and removal of Ag, TiO2, and ZnO nanoparticles in wastewater treatment and land application of biosolids

“…In sum, this study Table 6 Predicted exposure concentrations in effluent and biosolids for the ENMs of interest using global input numbers according to Keller et al (2013). of NP transport in LAUs suggests limited mobility of metal NP species in the soil matrix, which agrees with recent field investigation results (Yang et al, 2014). Overall, the maximum estimates of ZnO NPs in LAU soils at steady state were predicted to be orders of magnitude less than the background level concentrations for Zn.…”

“…This concentration is a few orders of magnitude less than the average background concentration of Zn metal in soils (~150 mg kg −1 ), however accumulation over time could be an issue (Kearney, 1996). For example, a recent study that investigated the concentrations of metals in agricultural fields with biosolid amendments suggests that accumulation of NP-related, regulated metals (including Zn, Ti, and Ag) is occurring as a result of biosolid utilization (Yang et al, 2014). Further work to understand the environmental impacts of this accumulation of nano-species is necessary.…”

Probabilistic modelling of engineered nanomaterial emissions to the environment: a spatio-temporal approach

“…As mentioned above, after passing through wastewater transfer and treatment, most of the nano-Ag is transformed to Ag sulfides. Most of the CNT and fullerenes end up either in landfill or recycling, and this can be explained 15 ) and quantile 85IJQ 85 ) values are also given in the right text field. A compartment code is used to identify each compartment and these are shown at the corner of each compartment box.…”

Modulation of CuO nanoparticles toxicity to green pea (Pisum sativum Fabaceae) by the phytohormone indole-3-acetic acid

“…A recent study has shown that agricultural fields, amended with biosolids from wastewater treatment plants, contain nanomaterials used in consumer products (Yang et al, 2014). Green pea (Pisum sativum L.), a legume rich in protein, aminoacids, vitamins, and minerals (Iqbal et al, 2006) could, thus, be unintentionally exposed to NPs when grown in biosolid amended soils.…”