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Phthalates are the most prevalent plasticizers in poly(vinyl chloride) (PVC), the most commonly used polymer for drinking water distribution pipes. Though typically considered inert to the free chlorine necessary for drinking water disinfection, we found that certain commercially relevant phthalates leach from PVC and transform in the presence of free chlorine. The extent of aqueous phthalate leaching was alkyl chain length-dependent; the greatest leaching was observed for the most soluble 1-carbon chain phthalate, which was unaffected by free chlorine. In contrast, 2- and 4-carbon chain phthalates leached significantly less, and their concentrations decreased further in the presence of free chlorine. These observations were rationalized by experiments showing increased chlorine consumption with increasing phthalate alkyl chain length, indicative of structure-dependent chemical transformations of the parent phthalate with free chlorine. Using gas and liquid chromatography, high-resolution mass spectrometry, and nuclear magnetic resonance spectroscopy, we identified 13 disinfection byproducts of diisobutyl phthalate, 2 of which were confirmed using reference materials. The presence of both chlorinated and hydroxylated transformation products suggests reactions with both free chlorine and chlorine-derived reactive intermediates. This study underscores the need for consideration of chemical structure in predicting phthalate reactivity and highlights potential exposure risks in drinking water infrastructure. 

While biopolymers have the potential to enhance agrochemical delivery and mitigate environmental impacts such as runoff, previous plant studies have often been limited to examining single biopolymers in isolation. This approach has hindered effective comparisons of plant outcomes due to variations in plant type, growth duration, and soil characteristics. The current study addresses this gap by incorporating six separate milled biopolymers: pectin, starch, chitosan, polycaprolactone (PCL), polylactic acid (PLA), or polyhydroxybutyrate (PHB) into soil and directly comparing their impacts on tomato (Solanum lycopersicum) plants cultivated under identical environmental parameters. Plant outcomes were also studied when biopolymers were modified via the inclusion of two phosphorus (P) salts, forming two types of Polymer-P-containing salt composites with amorphous CaPO4 (CaP) and CaHPO4 (DCP). Our results revealed that chitosan-based treatments significantly improved tomato root and shoot biomass, with increases of 200–300% compared to the control plants. Chitosan-CaP and Chitosan-DCP also enhanced P uptake, though the effect was significantly more pronounced in the former, suggesting a synergy between chitosan and CaP. Neither Chitosan-P-containing salt treatment, however, mitigated P leaching from soil when compared to CaP or DCP applied in isolation. The two most hydrophilic biopolymers, pectin and starch, as well as their P-salt-containing counterparts, showed the most substantial reductions in biomass (∼80%) with respect to control plants, while similarly lowering P uptake and P retention in soil compared to CaP- and DCP-only plants. PCL- and PHB-based treatments also adversely influenced biomass and plant P, though these effects were not as drastic as those observed with pectin and starch. PLA-based soil amendments had no effect on any plant performance metric, though PLA-CaP, specifically, was the only treatment to appreciably mitigate P leaching (−63%). Based on these findings, subsequent tomato growth experiments were conducted over a longer 8-week period with CaP, DCP, Chitosan, Chitosan-CaP, and Chitosan-DCP. While all chitosan-treated plants showed similar enhancements in biomass, plants treated with Chitosan-CaP and Chitosan-DCP were the only ones to fruit, demonstrating the benefit of using chitosan in conjunction with a P source as compared to either treatment in isolation. These findings contribute to an expanding body of evidence that biopolymer carriers can offer a more sustainable approach to improving the precision of nutrient delivery, while also highlighting the pivotal role of biopolymer and nutrient type in the development of these carriers. 

The challenges inherent to the extraction of micro- and nanoplastics (MNPs) from the environment and the limited range of commercially available MNPs have prompted an increasing number of researchers to generate in-house reference and test MNPs. 

A suite of acyl chloride structural isomers (C6H11OCl) was used to effect gas-phase esterification of starch-based phytoglycogen nanoparticles (PhG NPs). The surface degree of substitution (DS) was quantified using X-ray photoelectron spectroscopy, while the overall DS was quantified using 1H NMR spectroscopy. Gas-phase modification initiates at the NP surface, with the extent of surface and overall esterification determined by both the reaction time and the steric footprint of the acyl chloride reagent. The less sterically hindered acyl chlorides diffuse fully into the NP interior, while the branched isomers are restricted to the near-surface region and form self-limiting hydrophobic shells, with shell thicknesses decreasing with increasing steric footprint. These differences in substitution were also reflected in the solubility of the NPs, with water solubility systematically decreasing with increasing DS. The ability to separately control both the surface and overall degree of functionalization and thereby form thin hydrophobic shells has significant implications for the development of polysaccharide-based biopolymers as nanocarrier delivery systems. 

Abstract Microplastics and nanoplastics (collectively, MNPs) are increasingly entering soils, with potential adverse impacts to agriculture and groundwater. Environmental detection, characterization, and quantification of MNPs is difficult and subject to artifacts, often requiring labor-intensive separation from environmental matrices. These analytical challenges make it difficult to conduct experiments investigating specific MNP characteristics influencing their transport and fate, particularly when examining multiple plastic types at low concentrations. By synthesizing a suite of metal-tagged polymers, which are cryomilled to create polydisperse fragmented particle suspensions, single particle ICP-MS (spICP-MS) can be used to quantify MNP particle size and concentration in controlled fate and transport studies. Use of unique metal-polymer pairs enables accurate, simultaneous analysis of multiple MNP types which can be used to track total particle transport and retention within a variety of environmental matrices. This was demonstrated using saturated sand column transport experiments to quantify the movement of two plastics having different properties: tin-tagged polystyrene (Sn-PS) and tantalum-tagged polyvinylpyrrolidone (Ta-PVP). The behavior of these polydisperse, fragmented MNPs was compared to that of fluorescent, carboxylated monodisperse PS spherical microspheres (Fl-PS). Mobility of all MNP types increased with decreasing particle size, and hydrophilic Ta-PVP particles migrated more effectively than the hydrophobic Sn-PS particles. Furthermore, the addition of humic acid (HA) to the carrier solution increased the colloidal stability of both metal-tagged MNP suspensions, resulting in much greater elution from the column than in HA-free deionized water or moderately- hard water (ionic strength = 5mM). This combination of particle synthesis and spICP-MS analysis provides insights into the transport of MNP having physical properties that are representative of environmental MNPs and opens up a broad range of applications for study of MNP environmental fate and transport. 

Top-down fabrication method to prepare metal-tagged nanoplastics with irregular shapes and diverse sizes for lab-based studies using spICP-MS.