The aim of this exploratory study is to examine the extent and mineral speciation, nanomaterial characterization, and aggregation/dissolution kinetics of copper-based particles in Nordox 75 WP (wettable granule) fungicide/bactericide product which is available in the world markets. As per the manufacturer, the product contains 839 g of cuprous oxide [Cu2O] kg-1 as an active ingredient and 161 g of inert ingredients kg-1. The metallic copper equivalent of this product is 750 g kg-1, in accordance with the manufacturer’s reporting. The total extractable metal concentrations of this product in triplicates were analyzed using an inductively coupled plasma atomic emission spectrophotometer (ICP-AES, Thermos Scientific iCAP 6000 Series) after acid digestion following EPA method 3051 to confirm the presence of 750 g of metallic copper equivalent kg-1 and assess other trace metals. The identification and morphology (i.e., size and shape) of the particles in this product was determined using TEM (JEOL-1200 EX operating at 120 kV) equipped with energy dispersive X-ray (EDX) to confirm whether the identified particles are Cu-based. The mineral species of Cu in this product were determined using XRD (Phillips X’Pert operating at 45 kV and 40 mA) technique. The XRD data were processed using X’Pert HighScore Plus. The hydrodynamic diameter (HDD) and surface zeta potential (ζ potential) of the particles of this product were determined in Mill-Q water, Suwannee River Humic Acid (SRHA) (5 and 15 mg L-1) and Sigma Aldrich humic acid (SAHA) (5 and 15 mg L-1) solutions, respectively in triplicates using particle sizer-and-zeta potential analyzer (NanoBrook Omni, Brookheaven Instruments Corporation). The impact of changes in environmental conditions (i.e., pH, ionic strength, monovalent/divalent background electrolytes) on the stability and dissolution of the particles was investigated in a span of two months’ period in Milli-Q water and SAHA (5 and 15 mg L-1) suspensions. The experimental results from the dissolution experiment were compared with the theoretical values obtained from MINEQL+5 software analysis. The study findings are of critical importance for estimating the fate and transport of copper particles in different environmental scenarios as well as enabling a more accurate assessment of their risk that is largely impacted by chemical speciation and size.

Potential environmental implications of select copper-based fungicide/bactericide employed in world markets

254th National Meeting (2017)

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