We can't find the internet
Attempting to reconnect
Something went wrong!
Hang in there while we get back on track
Biodegradable microplastics adsorb more Cd than conventional microplastic and biofilms enhance their adsorption
Summary
Researchers compared how biodegradable polylactic acid and conventional polyethylene microplastics adsorb the heavy metal cadmium, with and without biofilm development from outdoor weathering. They found that pristine PLA adsorbed significantly more cadmium than pristine PE, and that biofilms forming on weathered plastics were responsible for most of the increased cadmium uptake. The study suggests that biodegradable microplastics in agricultural soils may pose a greater risk for heavy metal transport than conventional plastics.
Biodegradable polylactic acid (PLA) mulch has been developed to replace conventional polyethylene (PE) mulch in agriculture to reduce plastic pollution and the accumulation of microplastics (MPs) in soil. Cadmium (Cd) is a significant soil contaminant, and can be adsorbed by MPs. It is increasingly recognised that in the natural environment biofilms can develop on MPs and that this can affect their adsorption properties. We exposed PLA and PE mulches outdoors for 16 months. MPs were then generated from pristine and weathered mulches. Biofilms developed on the weathered plastics. Oxygen-containing functional groups were detected on the weathered, but not the pristine PE, abundance of these groups increased for the weathered PLA. After removal of the biofilm the observed increases in oxygen-containing functional groups relative to the pristine plastics remained. In adsorption experiments pristine PLA MPs had a greater maximum adsorption capacity than pristine PE MPs (106-126 vs 23.2 mg/kg) despite having a lower specific surface area (0.325 m/g vs 1.82 m/g) suggesting that the greater levels of adsorption were due to MP chemistry. The weathered plastics adsorbed more Cd than the pristine plastics (e.g. maximum adsorption capacities of 153-185 and 152 mg/kg for the weathered PLA and PE respectively). However, after removal of the biofilm, adsorption of Cd to the weathered MPs was no greater than for the pristine plastics. This suggests that the increased adsorption of Cd due to weathering was caused primarily by adsorption onto the biofilm.
Sign in to start a discussion.
More Papers Like This
Insights into interactions of biodegradable and non-biodegradable microplastics with heavy metals
Researchers found that biodegradable polylactic acid microplastics can adsorb heavy metals like cadmium, copper, and chromium at rates comparable to or exceeding conventional non-biodegradable plastics, suggesting biodegradable microplastics may also serve as carriers of toxic metals in the environment.
Insights into effects of drying–wetting cycles on dissolved organic matter and Cd bioavailability in riparian sediments amended with microplastics
This study examined how microplastics interact with cadmium, a toxic heavy metal, in riverside sediments during wet and dry cycles that mimic natural flooding conditions. Biodegradable polylactic acid microplastics increased cadmium availability more than conventional plastics, likely because they release chemical additives as they break down. The results suggest that even biodegradable plastics in soil and sediment can make heavy metal contamination worse, raising concerns about their impact on water quality and food safety.
Microplastics and metals: Microplastics generated from biodegradable polylactic acid mulch reduce bioaccumulation of cadmium in earthworms compared to those generated from polyethylene
Researchers compared how microplastics from biodegradable (PLA) and conventional (polyethylene) plastic mulch interact with cadmium, a toxic heavy metal, in soil with earthworms. PLA microplastics absorbed much more cadmium than polyethylene, reducing the amount of this toxic metal available to earthworms. While this suggests biodegradable plastics may offer some protection against heavy metal exposure in contaminated soils, both types still contribute to microplastic pollution.
Adsorption Behaviors of Cadmium Regulated by Microplastics Properties in a Forest Soil
Microplastics and cadmium (a toxic heavy metal) frequently pollute forest soils together, and this study examined how different types, sizes, and concentrations of microplastics affect cadmium's behavior in soil. Biodegradable plastics like PBS and PBA adsorbed and released more cadmium than conventional polyethylene, and microplastics altered the soil's organic matter in ways that influenced how cadmium moved and became available to organisms. These findings matter because co-contamination by microplastics and heavy metals in soils may compound environmental and food-chain risks beyond what either pollutant causes alone.
Insight into the interactions between microplastics and heavy metals in agricultural soil solution: adsorption performance influenced by microplastic types
Environmental-simulating microplastics (aged under environmental conditions) showed higher cadmium and chromium adsorption capacity than commercial microplastics in agricultural soil solutions, with surface oxidation increasing adsorption—suggesting that aged microplastics are more effective co-transporters of heavy metals in contaminated agricultural soils.