Numeric uptake drives nanoplastic toxicity: Size-effects uncovered by toxicokinetic-toxicodynamic (TKTD) modeling.

Predicting nanoplastic bioaccumulation and toxicity using process-based models is challenging due to the difficulties in tracing them at low concentrations. This study investigates the size-dependent effects of nanoplastic exposure on Daphnia magna using a toxicokinetic-toxicodynamic (TKTD) model. Palladium-doped fluorescent nanoplastics in three sizes (30-nm, 66-nm, 170-nm) were tested at two numeric exposure concentrations.

Sediment Ballet: Unveiling the Dynamics of Metal Bioavailability in Sediments Following Resuspension and Reequilibration.

Assessing the risk of metal-contaminated sediments under disturbed conditions is challenging due to the lack of methods that capture instant changes in metal bioavailability. Existing approaches provide inadequate understandings of the processes regulating metal bioavailability under nonequilibrium conditions. Experiments were conducted to improve our understanding of the metal bioavailability dynamics induced by sediment resuspension and subsequent redeposition (reequilibration).

Toxicokinetics and Mussel Watch: Addressing Interspecies Differences for Coastal Cadmium Contamination Assessment.

Bivalves are often employed for biomonitoring contaminants in marine environments; however, in these large-scale programs, unavoidably, using multiple species presents a significant challenge. Interspecies differences in contaminant bioaccumulation can complicate data interpretation, and direct comparisons among species may result in misleading conclusions. Here, we propose a robust framework based on toxicokinetic measurements that accounts for interspecies differences in bioaccumulation.

Metabolome analysis revealed the critical role of betaine for arsenobetaine biosynthesis in the marine medaka (Oryzias melastigma).

Arsenobetaine (AsB), a non-toxic arsenic (As) compound found in marine fish, structurally resembles betaine (GB), a common methyl donor in organisms. This study investigates the potential role of GB in AsB synthesis in marine medaka (Oryzias melastigma) using metabolomic analysis. Dietary exposure to arsenate (As(V)) and varying GB concentrations (0.

Turbid Waters and Clearer Standards: Refining Water Quality Criteria for Coastal Environments by Encompassing Metal Bioavailability from Suspended Particles.

Suspended particulate matter (SPM) carries a major fraction of metals in turbid coastal waters, markedly influencing metal bioaccumulation and posing risks to marine life. However, its effects are often overlooked in current water quality criteria for metals, primarily due to challenges in quantifying SPM's contribution. This contribution depends on the SPM concentration, metal distribution coefficients (), and the bioavailability of SPM-bound metals (assimilation efficiency, AE), which can collectively be integrated as a modifying factor (MF).

Cell-excreted proteins mediate the interactions of differently sized silica nanoparticles during cellular uptake.

Exposure to different types of nanoparticles (NPs) results in their deposition in human bodies. While most studies have examined the cellular uptake of only one type of NP at a time, how the dynamics of NP uptake may change in the presence of other types of NPs remains unclear. We therefore investigated the interplay of two differently sized SiO NPs during their uptake by A549 human lung carcinoma cells.

Prioritizing ecological restoration in hydrologically sensitive areas to improve groundwater quality.

Greening is the optimal way to mitigate climate change and water quality degradation caused by agricultural expansion and rapid urbanization. However, the ideal sites to plant trees or grass to achieve a win-win solution between the environment and the economy remain unknown. Here, we performed a nationwide survey on groundwater nutrients (nitrate nitrogen, ammonia nitrogen, dissolved reactive phosphorus) and heavy metals (vanadium, chromium, manganese, iron, cobalt, nickel, copper, arsenic, strontium, molybdenum, cadmium, and lead) in China, and combined it with the global/national soil property database and machine learning (random forest) methods to explore the linkages between land use within hydrologically sensitive areas (HSAs) and groundwater quality from the perspective of hydrological connectivity.

Stimulated Raman Scattering Microscopy Reveals Bioaccumulation of Small Microplastics in Protozoa from Natural Waters.

Microplastics (MPs) are pollutants of global concern, and bioaccumulation determines their biological effects. Although microorganisms form a large fraction of our ecosystem's biomass and are important in biogeochemical cycling, their accumulation of MPs has never been confirmed in natural waters because current tools for field biological samples can detect only MPs > 10 μm. Here, we show that stimulated Raman scattering microscopy (SRS) can image and quantify the bioaccumulation of small MPs (<10 μm) in protozoa.

Silica nanoparticles inhibit cadmium uptake by the protozoan Tetrahymena thermophila without the need for adsorption.

The simultaneous presence of nanoparticles (NPs) and heavy metals in the environment may affect their mutual biological uptake. Although previous studies showed that NPs could alter the cellular uptake of heavy metals by their adsorption of heavy metals, whether they could affect metal uptake without the need for adsorption is unknown. This study examined the effects of silica (SiO) NPs on the uptake of Cd ion by the protozoan Tetrahymena thermophila.

Silica Nanoparticle Size Determines the Mechanisms Underlying the Inhibition of Iron Oxide Nanoparticle Uptake by .

Aquatic environments are complicated systems that contain different types of nanoparticles (NPs). Nevertheless, recent studies of NP toxicity, and especially those that have focused on bioaccumulation have mostly investigated only a single type of NPs. Assessments of the environmental risks of NPs that do not consider co-exposure regimes may lead to inaccurate conclusions and ineffective environmental regulation.

Enhancing Sediment Bioaccumulation Predictions: Isotopically Modified Bioassay and Biodynamic Modeling for Nickel Assessment.

Quantifying metal bioaccumulation in a sedimentary environment is a valuable line of evidence when evaluating the ecological risks associated with metal-contaminated sediments. However, the precision of bioaccumulation predictions has been hindered by the challenges in accurately modeling metal influx processes. This study focuses on nickel bioaccumulation from sediment and introduces an innovative approach using the isotopically modified bioassay to directly measure nickel assimilation rates in sediment.

Toward Citizen Science-Based Ocean Acidification Observations Using Smartphone Devices.

pH is a key parameter in many chemical, biological, and biogeochemical processes, making it a fundamental aspect of environmental monitoring. Rapid and accurate seawater pH measurements are essential for effective ocean observation and acidification investigations, resulting in the need for novel solutions that allow robust, precise, and affordable pH monitoring. In this study, a versatile smartphone-based environmental analyzer (vSEA) was used for the rapid measurement of seawater pH in a field study.

Interspecies calibration for biomonitoring metal contamination in coastal waters using oysters and mussels.

Differences in metal bioaccumulation among species make it difficult to compare biomonitoring results obtained using different marine bivalve species. To address this challenge and improve the interpretation of biomonitoring data, we studied the toxicokinetic mechanisms underlying these differences and developed a method to estimate seawater metal concentrations based on metal concentrations in the organisms. We transplanted six common species of oysters and mussels found in Chinese coastal waters into the Jiulong River estuary and monitored metal concentrations in the organisms, water, and suspended particles every three days over a six-week period.

Higher Risks of Copper Toxicity in Turbid Waters: Quantifying the Bioavailability of Particle-Bound Metals to Set Site-Specific Water Quality Criteria.

In coastal waters, particulate metals constitute a substantial fraction of the total metals; however, the prevalent water quality criteria are primarily based on dissolved metals, seemingly neglecting the contribution of particulate metals. Here we developed a method to quantify the toxicity risk of particulate metals, and proposed a way to calculate modifying factors (MFs) for setting site-specific criteria in turbid waters. Specifically, we used a side-by-side experimental design to study copper (Cu) bioaccumulation and toxicity in an estuarine clam, , under the exposure to "dissolved only" and "dissolved + particulate" Cu.

Label-Free Imaging of Humic Substance Bioaccumulation by Pump-Probe Microscopy.

Humic substances (HS) are the most abundant forms of natural organic matter on the earth surface. Comprised of decomposed plant and animal materials rich in carbon, oxygen, hydrogen, nitrogen, and sulfur complexes, HS facilitate global carbon and nitrogen cycling and the transport of anthropogenic contaminants. While it is known that HS also interact with organisms at different trophic levels to produce beneficial and harmful effects whether HS exert these biological effects through accumulation remains unknown.

[Toxicity Testing Organisms for Marine Ecotoxicological Research in China].

Since the late 1970s, marine ecotoxicology began to sprout and develop in China. Based on the principles of dose-response relationships, some marine organisms are used in toxicity tests to evaluate the impact of marine pollutants on marine organisms and marine ecosystems. At the early stage, marine ecotoxicological research mainly focused on the bioaccumulation, biomagnification, and biodegradation of traditional pollutants such as heavy metals, radioactive elements, organotin, petroleum hydrocarbons, and pesticides, as well as their toxic effects on survival, growth, and other physiological indicators.

Isotopically Modified Bioassay Bridges the Bioavailability and Toxicity Risk Assessment of Metals in Bedded Sediments.

The application of bioavailability-based risk assessment for the management of contaminated sediments requires new techniques to rapidly and accurately determine metal bioavailability. Here, we designed a multimetal isotopically modified bioassay to directly measure the bioavailability of different metals by tracing the change in their isotopic composition within organisms following sediment exposure. With a 24 h sediment exposure, the bioassay sensed significant bioavailability of nickel and lead within the sediment and determined that cadmium and copper exhibited low bioavailable concentrations and risk profiles.

Phycosphere pH of unicellular nano- and micro- phytoplankton cells and consequences for iron speciation.

Surface ocean pH is declining due to anthropogenic atmospheric CO uptake with a global decline of ~0.3 possible by 2100. Extracellular pH influences a range of biological processes, including nutrient uptake, calcification and silicification.

Development of a versatile smartphone-based environmental analyzer (vSEA) and its application in on-site nutrient detection.

The citizen-science-based environmental survey can benefit from the smartphone technology used in chemical and biological sensing of a wide range of analytes. Quantification by smartphone-based colorimetric assays is being increasingly reported, however, most of the quantification uses empirical formula or complex exhaustive methods. In this study, a versatile and robust algorithm is proposed to overcome these limitations.

Intestinal uptake and low transformation increase the bioaccumulation of inorganic arsenic in freshwater zebrafish.

Arsenate [As(V)] is the main form of arsenic (As) present in freshwater taken up by freshwater fish. Data on the main uptake tissue, biotransformation, and bioaccumulation in freshwater fish exposed to As(V) were limited, and the reasons for its bioaccumulation in the muscle tissue of freshwater fish remain undetermined. Accordingly, we simulated bioaccumulation and depuration in zebrafish (Danio rerio) exposed to waterborne As(V) by employing a six-compartment physiologically based pharmacokinetic model and As speciation analysis.

Physiologically based pharmacokinetic model revealed the distinct bio-transportation and turnover of arsenobetaine and arsenate in marine fish.

Arsenobetaine (AsB) is the major form of arsenic in marine fish; however, its biodynamics within the fish tissues is not well understood. This study simulated the biodynamics and biotransportation (absorption, distribution, and elimination) of dietary AsB and arsenate [As(V)] in the marine grouper Epinephelus fuscoguttatus, by constructing a physiologically based pharmacokinetic (PBPK) model. The transfer rates between different compartments (gill, intestine, liver, heart, kidney, and muscle) and blood were modeled during exposure (14 d) and depuration (20 d).

Application of a Multi-Metal Stable-Isotope-Enriched Bioassay to Assess Changes to Metal Bioavailability in Suspended Sediments.

The direct measurement of particulate contaminant bioavailability is a challenging aspect for the environmental risk assessment of contaminated sites. Here, we demonstrated a multi-metal stable-isotope-enriched bioassay to simultaneously measure the bioavailability of Cd, Cu, and Zn in naturally contaminated sediments following differing periods of resuspension treatment. Freshwater filter-feeding clams were pre-labeled with the isotopes Cd, Cu, and Zn to elevate isotope abundances in their tissues and then exposed to metal-contaminated suspended sediments.

Field to laboratory comparison of metal accumulation on aged microplastics in coastal waters.

The ubiquity of microplastics in the environment has attracted much attention on their risks. Though newly produced plastics were considered inert to aqueous metals, a few studies suggest aged microplastics can accumulate metals. Still, knowledge gap exists on the comparability of metal accumulation in field condition and that acquired in controlled laboratory settings.

Algal Organic Matter Drives Methanogen-Mediated Methylmercury Production in Water from Eutrophic Shallow Lakes.

Algal blooms bring massive amounts of algal organic matter (AOM) into eutrophic lakes, which influences microbial methylmercury (MeHg) production. However, because of the complexity of AOM and its dynamic changes during algal decomposition, the relationship between AOM and microbial Hg methylators remains poorly understood, which hinders predicting MeHg production and its bioaccumulation in eutrophic shallow lakes. To address that, we explored the impacts of AOM on microbial Hg methylators and MeHg production by characterizing dissolved organic matter with Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) and three-dimensional excitation-emission matrix (3D-EEM) fluorescence spectroscopy and quantifying the microbial Hg methylation gene .