Repeated release of cerium oxide nanoparticles altered algal responses: Growth, photosynthesis, and photosynthetic gene expression.

The expanding production of engineered nanomaterials (ENMs) can eventually cause their increased release into and presence in aquatic ecosystems, potentially threatening the health of aquatic organisms and the stability of the ecological environment. Generally, ENMs are repeatedly released into real-world aquatic environments in relatively low concentrations, potentially affecting photosynthesis in primary producers such as algae. However, knowledge regarding the effects of repeated exposure to ENMs on algal photosynthesis is still lacking. Herein, the physiological responses of the freshwater algae Chlorella vulgaris following single and repeated exposures to cerium oxide nanoparticles (CeO2 NPs) were investigated at 10 mg/L, with a focus on photosynthesis. The results showed that repeated exposures triggered increased photosynthetic pigment contents, oxidative stress levels, decreased photosynthetic performance, and lower biomass in C. vulgaris compared to a single exposure. Photosynthesis-related genes (i.e., petA, petB, psaA, atpB, and rbcL) were found to be upregulated following repeated exposures. Particularly for petB, repeated rather than single exposure treatment significantly upregulated its expression levels by 2.92-10.24-fold compared to unexposed controls. Furthermore, increased exposure times could aggravate the interaction between CeO2 NPs and algae, elevating 8.13%, 12.13%, and 20.51% Ce distribution on the algal cell surface or intracellularly, compared to a single exposure. This study is the first to investigate the effects of ENM exposure times on algal photosynthesis, providing new insights into the assessment of the risks these materials pose to real-world aquatic environments.

Source identification of microplastics in highly urbanized river environments and its implications for watershed management.

The extensive use of plastic products has resulted in a significant influx of microplastics into aquatic ecosystems, particularly in highly urbanized areas and their associated river environments. However, the specific pathways and quantities through which these microplastics enter the river environment are still unclear, which poses a challenge in developing effective measures to mitigate their sources. In this paper, the spatiotemporal variations of microplastics from different sources in highly urbanized rivers within the Shenzhen Bay watershed were investigated through field sampling, experimental and statistical analysis, and the measures of microplastic reduction were discussed. The observation results exhibited a negative logarithmic correlation between the abundance of microplastics in river water and monthly rainfall (R = 0.994, MSE = 0.051, p < 0.05). When the monthly rainfall was <6 mm, the abundance of microplastics was absolutely dependent on point sources. While the rainfall exceeded 470 mm, the abundance was absolutely predominantly influenced by nonpoint source microplastics. The annual load of microplastics from the watershed was 5.39 × 1012 items, of which 61.6 % originated from point sources. Among the microplastics from point sources, 92.1 % were derived from fibers generated by textile washing. Fragmented microplastics (41.9 %) were the most common type of microplastics from nonpoint sources, primarily originating from the disintegration and weathering of disposable plastics. In the future, there is an expectation to reduce the microplastic load in the watershed to 15.9 % of the total by improving sewage treatment processes and infrastructure. This study can provide scientific guidance for environmental planning and serve as a warning regarding the impact of microplastics on ecosystems in urbanized areas.

Location-dependent occurrence and distribution of metal-based nanoparticles in bay environments.

Metal-based nanoparticles (MNPs) are increasingly being released into the marine environment, posing potential environmental risks. However, factors governing the environmental occurrence and distribution of MNPs in bays still lack a comprehensive understanding. Herein, we collected seawater and sediment samples from two adjacent bays (Daya Bay and Honghai Bay, which have similar water qualities), and determined the particle concentrations and sizes of multi-element MNPs (Ti-, Cu-, Zn-, Ag-, Mn-, Pb- and Cr-based NPs) via single particle inductively coupled plasma-mass spectrometry (spICP-MS). The internal circulation in Daya Bay has resulted in an even distribution of MNPs' particle concentrations and sizes in both seawater and sediments, while the terrestrial discharge in Honghai Bay has led to a gradient-decreasing trend in MNPs' concentrations from nearshore to offshore. Moreover, the relatively high abundance of MNPs in Honghai Bay has contributed to 2.35-fold higher environmental risks than Daya Bay. Overall, this study has provided solid evidence on the critical but overlooked factors that have shaped the occurrence and distribution of MNPs, providing new insights for risk management and emission regulation.

[Spatio-temporal Evolution and Coordinated Development of Compactness with Carbon Emission Intensity in the Chengdu-Chongqing Urban Agglomeration].

Studies on the spatio-temporal variation and coordinated development level of compactness with carbon emission intensity in the Chengdu-Chongqing urban agglomeration is of great significance to achieve green, low-carbon, and high-quality development of society. The spatial-temporal differentiation, coupling coordination, and driving factors of the compactness and carbon emission intensity of the Chengdu-Chongqing urban agglomeration from 2010 to 2020 were analyzed by using the methods of comprehensive evaluation, carbon emission identical equality, coupling coordination, and the Geo-detector model. The results showed that:① The compactness of the Chengdu-Chongqing urban agglomeration continued to rise from 0.18 in 2010 to 0.22 in 2020, with an overall increase of 22.22 %, in which the contribution rate of economic compactness to urban compactness increased yearly. There were significant regional differences in the compactness of cities. The high-value areas were concentrated in Chengdu, Deyang, and Mianyang in the northwest and Zigong, Neijiang, and Luzhou in the southwest, whereas the low-value areas were distributed in the middle. Ya'an was always the area with the lowest compactness of urban agglomeration. ② The carbon emission intensity of the Chengdu-Chongqing urban agglomeration was decreasing yearly, with a decrease rate of 39.57 % during the study period. The carbon emission intensity in the southern part of the urban agglomeration was higher than that in other regions as a whole, whereas Chengdu and Chongqing were low-value areas all the year round, and the regional differences of carbon emission intensity were gradually narrowing. ③ The coupling degree between urban compactness and carbon emission intensity changed from the antagonistic stage to the running-in stage; the coupling coordination degree increased notably, from 0.21 in 2010 to 0.69 in 2020; and the two systems gradually moved towards benign and coordinated development. The coupling coordination between the northwest of the urban agglomeration (Chengdu, Deyang, and Mianyang) and the south of Sichuan (Zigong and Luzhou) was generally high. Industrial structure, scientific and technological innovation, urbanization level, government intervention, and environmental livability all had significant effects on the coupling and coordination of the two systems. ④ Optimizing industrial structure, strengthening scientific and technological support, improving the quality of urbanization development, implementing active policy guidance, and building green barriers were effective ways to promote the coordinated development of compactness and low carbon in the Chengdu-Chongqing urban agglomeration.

Transcriptomic Responses and Larval-Stage Growth of Protandrous Yellowfin Seabream (Acanthopagrus Latus) to Different Polyethylene Microplastics Exposure.

Polyethylene microplastics (PE-MPs) were widespread in the marine environment; thus, their influences on marine hermaphroditic fish cannot be ignored. This study intends to evaluate the adverse biological effects of two different sources of PE, identified by Raman spectroscopy, on protandrous yellowfin seabream (Acanthopagrus latus) larvae. Growth retardation, brain lesions, head/body length ratio increase, and neuroendocrine system disorders were found, and growth and neuroendocrine regulation-related genes such as sstr2, ghrb, irs1, UGT2B15, UGT2C1, drd4a, esr2b, hsd3b7, and hsd17b2 were identified. PE microbeads (100 µm) showed more severe tissue damage on fish, while environmental PE fibers (500-2500 µm) showed more imperceptible adverse effects. There were 218 DEGs up-regulated and 147 DEGs down-regulated in the environmental PE group, while 1284 (up) and 1267 (down) DEGs were identified in the virgin PE group. PE-MP stress influenced physiological processes like growth and neuroendocrine regulation and cholesterol-steroid metabolism, and caused tissue damage in the fish larvae. The study highlights the effects of environmental PE exposure on hermaphroditic protandrous fish.

Niche overlap between native Cirrhinus molitorella and potential invasive competitors.

Biological invasion is one of the important reasons for the decline of freshwater biodiversity in China and even in the world. The Pearl river basin is one of the most threatened areas in China by biological invasion. Over the past four decades, mrigal carp Cirrhinus mrigala and rohu Labeo rohita have invaded the Pearl river. They potentially pose a huge threat to a well-known economic species, native mud carp Cirrhinus molitorella. However, little is known about the likely habitat distributions of these two invasive species, which limits our management of them. In this study, we detected the stable isotope ratios of nitrogen and carbon for fish and quantified their niche overlap with nicheROVER in R. The result showed that the individuals of two invasive species had a higher probability to be found in niche region of native C. molitorella (i.e., 65 % for C. mrigala and 74 % for L. rohita). Moreover, to increase understanding of their habitat distributions and potential range of spread, the existing habitats data of these three fish species obtained from previous literatures and the high-resolution bioclimatic parameters from WorldClim were analyzed via Maxent model. The results stressed that niche overlap was high among species, which could have an impact on local biodiversity in future. Furthermore, the visualization of habitat distributions could help show the dynamic habitat changes of invasive and native species over time, while also provide new insights into the subsequent prevention and control for invasive species in other river regions around the world.

Environmental Concentrations of Herbicide Prometryn Render Stress-Tolerant Corals Susceptible to Ocean Warming.

Global warming has caused the degradation of coral reefs around the world. While stress-tolerant corals have demonstrated the ability to acclimatize to ocean warming, it remains unclear whether they can sustain their thermal resilience when superimposed with other coastal environmental stressors. We report the combined impacts of a photosystem II (PSII) herbicide, prometryn, and ocean warming on the stress-tolerant coral Galaxea fascicularis through physiological and omics analyses. The results demonstrate that the heat-stress-induced inhibition of photosynthetic efficiency in G. fascicularis is exacerbated in the presence of prometryn. Transcriptomics and metabolomics analyses indicate that the prometryn exposure may overwhelm the photosystem repair mechanism in stress-tolerant corals, thereby compromising their capacity for thermal acclimation. Moreover, prometryn might amplify the adverse effects of heat stress on key energy and nutrient metabolism pathways and induce a stronger response to oxidative stress in stress-tolerant corals. The findings indicate that the presence of prometryn at environmentally relevant concentrations would render corals more susceptible to heat stress and exacerbate the breakdown of coral Symbiodiniaceae symbiosis. The present study provides valuable insights into the necessity of prioritizing PSII herbicide pollution reduction in coral reef protection efforts while mitigating the effects of climate change.

Hepatotoxic of polystyrene microplastics in aged mice: Focus on the role of gastrointestinal transformation and AMPK/FoxO pathway.

Microplastic (MP) toxicity has attracted widespread attention, whereas before triggering hepatotoxicity, ingested MPs first undergo transportation and digestion processes in the gastrointestinal tract, possibly interacting with the gastrointestinal contents (GIC). More alarming is the need for more understanding of how this process may impact the liver health of aged animals. This study selected old mice. Firstly, we incubated polystyrene microplastics (PS-MPs, 1 µm) with GIC extract. The results of SEM/EDS indicated a structural alteration in PS-MPs. Additionally, impurities resembling corona, rich in heteroatoms (O, N, and S), were observed. This resulted in an enhanced aggregating phenomenon of MPs. We conducted a 10-day experiment exposing aged mice to four concentrations of PS-MPs, ranging from 1 × 103 to 1 × 1012 particles/L. Subsequent measurements of tissue pathology and body and organ weights were conducted, revealing alterations in liver structure. In the liver, 12 crucial metabolites were found by LC-MS technology, including purines, lipids, and amino acids. The AMPK/FoxO pathway was enriched, activated, and validated in western blotting results. We also comprehensively examined the innate immune system, inflammatory factors, and oxidative stress indicators. The results indicated decreased C3 levels, stable C4 levels, inflammatory factors (IL-6 and IL-8), and antioxidant enzymes were increased to varying degrees. PS-MPs also caused DNA oxidative damage. These toxic effects exhibited a specific dose dependence. Overall, after the formation of the gastrointestinal corona, PS-MPs subsequently impact various cellular processes, such as cycle arrest (p21), leading to hepatic and health crises in the elderly. The presence of gastrointestinal coronas also underscores the MPs' morphology and characteristics, which should be distinguished after ingestion.

Alkaline surface treatment and time-resolved reading of mn-doped nanocrystal signal transducer for enhanced bioassay sensitivity.

Recently, Mn-doped semiconductor nanocrystals (NCs) with high brightness, long lifetimes, and low-energy excitation are emerging for time-resolved luminescence biosensing/imaging. Following our previous work on Mn-doped NCs, in this work we developed poly(styrene-co-maleic anhydride) (PSMA)-encapsulated Mn-doped AgZnInS/ZnS NCs as signal transducers for immunoassay of capsular polysaccharide (CPS), a surface antigen and also a biomarker of Burkholderia pseudomallei which causes a fatal disease called melioidosis. To enhance the assay sensitivity, a surface treatment for PSMA-encapsulated NCs (NC-probes) was performed to promote the presence of carboxyl groups that help conjugate more anti-CPS antibodies to the surface of NC-probes and thus enhance bioassay signals. Meanwhile, time-resolved reading on the luminescence of NC-probes was adopted to minimize the assay background autofluorescence. Both strategies essentially enhance the assay signal-to-background ratio (or equivalently the assay sensitivity) by increasing the signal and decreasing the background, respectively. Through performing and comparing immunoassays with different NC-probes (with and without surface treatment) and different signal reading methods (time-resolved reading and non-time-resolved reading), it was proven that the immunoassay adopting surface-treated NC-probes and time-resolved reading achieved a lower limit-of-detection (LOD) than the ones adopting non-surface-treated NC-probes or non-time-resolved reading. Moreover, the achieved LOD is comparable to the LOD of immunoassay using enzyme horseradish peroxidase as a signal transducer.

Neglected negative effect of carbon quantum dots (CQDs) entering the ocean on marine organisms living in different water layers.

Carbon quantum dots (CQDs) are well dispersed in water, but their potential risks in the marine environment have not been described. This study characterized CQDs and investigated their biological effects (including growth, photosynthesis and behavioural changes) in three marine organisms living in different water layers (the surface phytoplankton Phaeodactylum tricornutum and zooplankton Artemia salina and the benthic coral Zoanthus sp. at the bottom). The results showed that over 78 % of CQDs were suspended in seawater after 96 h. The biomass and photosynthesis of P. tricornutum were significantly affected, with a maximum reduction of 89.49 % in algal cells. CQDs accumulated in the intestinal tract of A. salina, reducing grazing and filtration rates by up to 71.88 % and 89.46 %, respectively. In contrast, CQD exposure had irreversible effects on the tentacle expansion behaviour of Zoanthus sp. This study helps clarify the environmental effects and ecological risks associated with the release of CQDs into the ocean.

Editorial for the Special Issue "Nanomaterials Ecotoxicity Evaluation".

Nanotechnology has made enormous progress over the last few decades, and the current use of nanomaterials is rapidly increasing [...].

Are Physical Sunscreens Safe for Marine Life? A Study on a Coral-Zooxanthellae Symbiotic System.

Limited toxic and ecological studies were focused on physical sunscreen that is considered to have "safer performance", in which nanosize zinc oxide (nZnO) and nanosize titanium dioxide (nTiO2) generally are added as ultraviolet filters. Herein, the common button coral Zoanthus sp. was newly used to assess the toxic effects and underlying mechanisms of physical sunscreen. Results showed that physical sunscreen induced severe growth inhibition effects and largely compelled the symbiotic zooxanthellae, indicating that their symbiotic systems were threatened and, also, that neural and photosynthesis functions were influenced. Zn2+ toxicity and bioaccumulation were identified as the main toxic mechanisms, and nTiO2 particles released from physical sunscreen also displayed limited bioattachment and toxicity. Oxidative stress, determined by increased reactive oxygen species, superoxide dismutase, and malondialdehyde content, was indicated as another important toxic mechanism. Furthermore, when Zoanthus sp. was restored, the inhibited individual coral could be largely recovered after a short (3 d) exposure time; however, a longer exposure time damaged the coral irretrievably, which revealed the latent environmental risks of physical sunscreen. This study investigated the toxic effect of physical sunscreen on Zoanthus sp. in a relatively comprehensive manner, thus providing new insights into the toxic response of sunscreen on marine organisms.

Effective Energy Transfer Boosts Emission of Rare-Earth Double Perovskites: The Bridge Role of Sb(III) Doping.

Halide perovskites have attracted considerable interest due to their excellent photoelectric properties. In this study, we synthesized Sb3+-doped Cs2NaTbCl6 using a solvothermal method to investigate its tunable photoelectric properties and low toxicity. Upon Sb3+ ion doping, the photoluminescence yield (PLQY) of Cs2NaTbCl6 significantly increased from ∼1.7 to ∼47%. The introduced Sb3+ ions with ns2 electronic configuration expanded the rare-earth element's absorption cross section, broke intrinsic forbidden transitions, and suppressed nonradiative recombination. Additionally, the codoping of Sb3+ and Mn2+ facilitated efficient energy transfer, resulting in highly efficient photoluminescence. The PLQY of 1%Sb3+,3%Mn2+:Cs2NaTbCl6 reached a remarkable 85.8%, marking the highest reported value for rare-earth double perovskites in the visible light region. This study highlights the vital role of Sb(III) doping as a bridging agent to enhance the emission in rare-earth double perovskites.

Environmental occurrence and ecotoxicity of aquaculture-derived plastic leachates.

Plastic products such as fishing nets and foam buoys have been widely used in aquaculture. To enhance the desirable characteristics of the final equipment, plastic gear for aquaculture is mixed with a wide range of additives. Recent studies have shown that additives could be leached out to the environment with a long-term use of aquaculture plastics, forming aquaculture-derived plastic leachates. It should be emphasized that some leachates such as phthalic acid esters (PAEs) and organophosphate esters (OPEs) are endocrine disruptors, which could increase the exposure risk of aquatic products and subsequently display potential threats to human health via food chain. However, systematic studies on the release, occurrence, bioaccumulation, and toxic effects of aquaculture-derived plastic leachates are missing, overlooking their potential sources and ecotoxicological risks in aquatic environments. We have reviewed and compared the concentrations of major plastic leachates in the water environment and organisms of global aquaculture and non-farmed areas, confirming that aquaculture leachate is an important source of contaminants in the environment. Moreover, the toxic effects of aquaculture-derived plastic additives and the related mechanisms are summarized with fish as a representative, revealing their potential health risk. In addition, we proposed current challenges and future research needs, which provides scientific guidance for the use and management of plastic products in aquaculture industries.

Metal leaching from plastics in the marine environment: An ignored role of biofilm.

A large quantity of metal compounds in plastics are released into the marine environment every year. However, our understanding of the extent and mechanism by which polymer-bound metals leach into seawater is still limited. In this study, a comprehensive survey was conducted to measure the metal concentrations in commonly used plastics and evaluate the effects of environmental factors (temperature, radiation, and salinity) and the physiochemical properties (surface roughness, specific surface area, hydrophobicity, and crystallinity) of the plastics on their metal leaching into seawater. In particular, we observed the metal loss from six plastics submerged in coastal seawater for eight months and studied the role of biofilm in controlling the leaching of Sb, Sn, Pb, Ba, and Cr. Our results indicate that increased temperature enhanced the release of these metals, while exposure to ultraviolet radiation significantly increased the leaching of Sn from polylactide (PLA). High salinity facilitated the leaching of Sn from PLA and Pb from polyvinylchloride ball, however inhibited the leaching of Ba from PE wrap. The leaching rate was primarily determined by the inherent property of crystallinity. Metal loss from the plastics in the field was apparent during the first three weeks, but then was hindered by the development of biofilm. Our study provides the mechanisms underlying metal leaching from physical, chemical, and biological perspectives, which is useful for understanding the environmental risk of the plastic-containing metals.

Enrichment of antibiotic resistant genes and pathogens in face masks from coastal environments.

Face masks (FMs) are essential to limit the spread of the coronavirus during pandemic, a considerable of which are accumulated on the coast. However, limited is known about the microbial profile in the biofilm of the face masks (so-called plastisphere) and the impacts of face masks on the surrounding environments. We herein performed face mask exposures to coastal sediments and characterized the microbial community and the antibiotic resistome. We detected 64 antibiotic-resistance genes (ARGs) and 12 mobile gene elements (MGEs) in the plastisphere. Significant enrichments were found in the relative abundance of total ARGs in the plastisphere compared to the sediments. In detail, the relative abundance of tetracycline, multidrug, macrolide-lincosamide-streptogramin B (MLSB), and phenicol-resistant genes had increased by 5-10 times. Moreover, the relative abundance of specific hydrocarbonoclastic bacteria (e.g., Polycyclovorans sp.), pathogens (e.g., Pseudomonas oleovorans), and total MGEs significantly increased in the sediments after face mask exposure, which was congruent with the alteration of pH value and metal concentrations in the microcosms. Our study demonstrated the negative impacts of FMs on coastal environments regardless of the profiles of ARGs or pathogens. These findings improved the understanding of the ecological risks of face masks and underlined the importance of beach cleaning.

Silicon Limitation Impairs the Tolerance of Marine Diatoms to Pristine Microplastics.

Marine diatoms are currently facing increasing threats from microplastic (MP) pollution that is intertwined with the disturbed nutrient stoichiometry in seawater. The effects of nutrient imbalances such as silicon (Si) limitation on the interactions between diatoms and MPs remain poorly understood. In contrast to previous studies which mainly focused on MP toxicity, this study emphasizes how Si availability affects nano-scale interactions between pristine polystyrene MPs and diatom surfaces. Results showed that Si-starved cells were less tolerant to MP toxicity than the Si-enriched counterparts. Si limitation significantly changed the configuration and chemical composition of the perforated frustules, forming less negatively charged, more adhesive, and mechanically weaker cells. All of these changes facilitated the adsorption and hetero-aggregation between the diatom cells and MPs and compromised the diatoms' resistance to MP attack. Our study provides novel insights into the effects of pristine MPs in the marine environment under the context of dynamic nutrient conditions.

The occurrence, speciation, and ecological effect of plastic pollution in the bay ecosystems.

Bay is a unique part of the ecosystem, acting as the intersection for marine and terrestrial systems and hosting diverse biological organisms. The ubiquitous application of plastics has resulted in a massive amount of plastic waste released and accumulated in the bay ecosystem, posing significant ecological effects. Thus, thoroughly understanding plastic pollution's occurrence, speciation, and ecological effect in the bay ecosystems is of vital importance. We conducted a comprehensive review on the sources and distribution of plastics in the bay ecosystem, and the associate ecological effects, from individual toxicity to trophic transfer in ecosystems. Among bay areas around the world, the concentrations of microplastics vary from 0.01 to 3.62 × 105 item/m3 in seawater and 0 to 6.75 × 105 item/kg in sediment. Small-sized plastic particles (mostly <2 mm) were widely reported in bay organisms with the concentration range of 0 to 22.5 item/ind. Besides, the toxicity of plastics on marine organisms has been documented in terms of mortality, growth, development, reproduction, enzyme activity and transcription. Since abundance of small plastic particles (e.g., micro- and nano-scale) is far greater than large plastic debris in the bay ecosystems, in-depth risk assessment of small-sized plastics needs to be conducted under environmentally realistic conditions. Our review could provide a better understanding on the occurrence, speciation, and ecological effect of plastic pollution in the bay ecosystems.

Competing Energy Transfer-Modulated Dual Emission in Mn2+-Doped Cs2NaTbCl6 Rare-Earth Double Perovskites.

A2BIBIIIX6 double perovskites are promising materials due to their outstanding photoelectronic properties and excellent stability in the environment. Herein, we synthesized Mn2+:Cs2NaTbCl6 with dual emission through a solvothermal method for the first time. Mn2+:Cs2NaTbCl6 double perovskites exhibit excellent environmental stability and high photoluminescence quantum yields (PLQYs). The Cs2NaTbCl6 was successfully doped with Mn2+ in two modes: at Mn-feeding concentrations below 1%, Mn2+ first tend to insert into the interstitial void, but if the Mn-feeding concentration exceeds 1%, Mn2+ will further substitute Na+ site of the Cs2NaTbCl6 lattice and thus both two doping modes coexist. After Mn2+ doping, efficient energy transfer from the 5D4 level of Tb3+ ions to the 4T1 level of Mn2+ ions occurs, resulting in tunable dual emission from the Tb3+5D4 → 7FJ=6,5,4,3 transition and Mn2+4T1 → 6A1 transition. Further, LED based on the Mn2+:Cs2NaTbCl6 double perovskites exhibits excellent performance and stability. This work demonstrates a strategy to achieve novel lanthanide-based double perovskites with potential applications in photonics.