Anammox and denitrification are key processes for nitrogen removal in lake sediments.However,how environmental changes mediate the community structure and functional genes of nitrogen removal bacteria in lakes remain ...Anammox and denitrification are key processes for nitrogen removal in lake sediments.However,how environmental changes mediate the community structure and functional genes of nitrogen removal bacteria in lakes remain unclear.Using metagenome and amplicon sequencing,we investigated the anammox and denitrifying bacteria and their nitrogen remov-ing potentials in lakes experiencing significant spatiotemporal and environmental variations.The community structure of anammox and denitrifying bacteria exhibited stronger lake-wide spatial variations than that of seasonality,while only the denitrification-related functional genes showed substantial variations in both lakes.Anammox genes(e.g.,hzsA/B/C and hdh)showed no significant spatial variations.However,the abundances of anammox and denitrifying genes were significantly higher in winter than in summer.The mesotrophic Lake Weishan demonstrated a greater capacity for complete denitrification in winter,while the eutrophic Lake Donghu exhibited a higher potential of anammox in summer.Differences in functional gene abundances between lakes were more pronounced than variations in phylogenetic diversity,indicating clear functional adaptations to local environments.The coupled nitrogen removal potentials also reflected ecological interactions among anammox and denitrifying genes.Importantly,anammox and denitrifying bacterial communities and their functional genes were primarily driven by dissolved organic carbon,total phosphorous and zinc(Zn).The dissimilarities of anammox and denitrifying bacterial communities increased with geographic distance,indicating a clear distance-decay effect.This study highlights the anammox and denitrifying bacteria and their nitrogen removal potentials in lake sediments that are mediated by both spatial and seasonal environmental changes.展开更多
Light intensity directly affects phytoplankton and can alter the toxicity of phytotoxic pollutants present in natural water bodies.Light fluctuation in aquatic ecosystems often occurs as a function of water turbidity,...Light intensity directly affects phytoplankton and can alter the toxicity of phytotoxic pollutants present in natural water bodies.Light fluctuation in aquatic ecosystems often occurs as a function of water turbidity,water movement,cloud cover,and seasonality.Atrazine and simazine are commonly used herbicides that inhibit photosynthesis,posing significant risks to aquatic primary producers,and may be found simultaneously in aquatic ecosystems.The interactions between light and herbicide mixtures on phytoplankton growth and physiological state are poorly understood.Therefore,we addressed the toxicity of the herbicides,atrazine and simazine(individually and mixed),on the growth and photosynthetic activity of three freshwater phytoplankton under three light intensities.We found that the toxic effects of single and mixed herbicides are species-specific and significantly modulated by light intensity,with synergistic effects observed for herbicide mixtures under high light conditions.Atrazine and simazine(individually and mixed)toxicities on photosynthesis were greater for the three species grown under low light than under very low light.However,high-light adapted strains of M.aeruginosa were less sensitive to single and mixed herbicides than those adapted to low-and very low-light conditions.Under low-and high-light conditions,the photoprotective ability was extremely sensitive to the inhibitory effects of atrazine and simazine,individually and when mixed.Understanding these interactions is important because microalgae form the base of aquatic food webs and their impairment can have cascading effects on ecosystems.These findings underscore the importance of considering multiple environmental stressors in assessing the ecological risks of herbicides,highlighting potential impacts on aquatic primary productivity.展开更多
The extensive use of cobalt nanoparticles(CoNPs)in industrial and biomedical applications has raised envi-ronmental concerns,necessitating effective mitigation strategies.This study examines the phytotoxicity and phyt...The extensive use of cobalt nanoparticles(CoNPs)in industrial and biomedical applications has raised envi-ronmental concerns,necessitating effective mitigation strategies.This study examines the phytotoxicity and phytoremediation potential of CoNPs using Lemna minor L.,a recognized Co-hyperaccumulator.CoNPs exhibited significant sublethal toxicity at concentrations≥1000μg Co^(2+)/L,leading to oxidative stress and impaired growth,photosynthesis,and respiration.Despite these challenges,L.minor effectively removed over 99%of CoNPs from the medium,even at high concentrations(up to 20.000μg Co^(2+)/L),with gravimetric cobalt con-centrations reaching 1771μg Co^(2+)/g dry weight in plant tissues.Physiological responses to CoNPs were similar to those induced by equivalent concentrations of CoCl_(2),suggesting that CoNPs dissolve into Co^(2+)ions upon interaction with plants.However,ultrastructural analysis revealed distinct intracellular cobalt localization with CoNPs causing more severe chloroplast damage than ionic Co^(2+).These findings suggest two toxicity mechanisms:ionic effects from dissolved Co^(2+)and direct physical damage from intact nanoparticles.The resilience and hyperaccumulation capacity of L.minor makes it a promising candidate for the phytoremediation of cobalt-contaminated waters.The study underscores the importance of further research to elucidate CoNP environ-mental behavior and optimize phytoremediation approaches.展开更多
基金supported by the National Natural Sci-ence Foundation of China(32030015,W2433059,42377111)the Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(SML2024SP002,SML2024SP022).
文摘Anammox and denitrification are key processes for nitrogen removal in lake sediments.However,how environmental changes mediate the community structure and functional genes of nitrogen removal bacteria in lakes remain unclear.Using metagenome and amplicon sequencing,we investigated the anammox and denitrifying bacteria and their nitrogen remov-ing potentials in lakes experiencing significant spatiotemporal and environmental variations.The community structure of anammox and denitrifying bacteria exhibited stronger lake-wide spatial variations than that of seasonality,while only the denitrification-related functional genes showed substantial variations in both lakes.Anammox genes(e.g.,hzsA/B/C and hdh)showed no significant spatial variations.However,the abundances of anammox and denitrifying genes were significantly higher in winter than in summer.The mesotrophic Lake Weishan demonstrated a greater capacity for complete denitrification in winter,while the eutrophic Lake Donghu exhibited a higher potential of anammox in summer.Differences in functional gene abundances between lakes were more pronounced than variations in phylogenetic diversity,indicating clear functional adaptations to local environments.The coupled nitrogen removal potentials also reflected ecological interactions among anammox and denitrifying genes.Importantly,anammox and denitrifying bacterial communities and their functional genes were primarily driven by dissolved organic carbon,total phosphorous and zinc(Zn).The dissimilarities of anammox and denitrifying bacterial communities increased with geographic distance,indicating a clear distance-decay effect.This study highlights the anammox and denitrifying bacteria and their nitrogen removal potentials in lake sediments that are mediated by both spatial and seasonal environmental changes.
基金supported by a Fisheries and Oceans Canada(DFO)grant(MECTS-#3789712)obtained by Philippe Juneau,Johann Lavaud and Beatrix Beisnerthe Natural Science and Engineering Research Council of Canada(NSERC)(RGPIN-2017-06210)awarded to Philippe Juneau。
文摘Light intensity directly affects phytoplankton and can alter the toxicity of phytotoxic pollutants present in natural water bodies.Light fluctuation in aquatic ecosystems often occurs as a function of water turbidity,water movement,cloud cover,and seasonality.Atrazine and simazine are commonly used herbicides that inhibit photosynthesis,posing significant risks to aquatic primary producers,and may be found simultaneously in aquatic ecosystems.The interactions between light and herbicide mixtures on phytoplankton growth and physiological state are poorly understood.Therefore,we addressed the toxicity of the herbicides,atrazine and simazine(individually and mixed),on the growth and photosynthetic activity of three freshwater phytoplankton under three light intensities.We found that the toxic effects of single and mixed herbicides are species-specific and significantly modulated by light intensity,with synergistic effects observed for herbicide mixtures under high light conditions.Atrazine and simazine(individually and mixed)toxicities on photosynthesis were greater for the three species grown under low light than under very low light.However,high-light adapted strains of M.aeruginosa were less sensitive to single and mixed herbicides than those adapted to low-and very low-light conditions.Under low-and high-light conditions,the photoprotective ability was extremely sensitive to the inhibitory effects of atrazine and simazine,individually and when mixed.Understanding these interactions is important because microalgae form the base of aquatic food webs and their impairment can have cascading effects on ecosystems.These findings underscore the importance of considering multiple environmental stressors in assessing the ecological risks of herbicides,highlighting potential impacts on aquatic primary productivity.
基金financial support from several institutions,and we express our gratitude for their contributionsWe acknowledge the Coordenaçao de Aperfeiçoamento de Pessoal de Nível Superior of Brazil(CAPES,Finance Code 001)+1 种基金the Fundaçao Araucaria de Apoio ao Desenvolvimento Científico e Tecnologico do Parana,mainly through the Programa Paranaense de Pesquisas em Saneamento Ambiental(PPPSA/Sanepar,Finance Code SAN2021251000002)the Natural Science and Engineering Research Council of Canada(NSERC)(Finance Code RGPIN-2023-05681).
文摘The extensive use of cobalt nanoparticles(CoNPs)in industrial and biomedical applications has raised envi-ronmental concerns,necessitating effective mitigation strategies.This study examines the phytotoxicity and phytoremediation potential of CoNPs using Lemna minor L.,a recognized Co-hyperaccumulator.CoNPs exhibited significant sublethal toxicity at concentrations≥1000μg Co^(2+)/L,leading to oxidative stress and impaired growth,photosynthesis,and respiration.Despite these challenges,L.minor effectively removed over 99%of CoNPs from the medium,even at high concentrations(up to 20.000μg Co^(2+)/L),with gravimetric cobalt con-centrations reaching 1771μg Co^(2+)/g dry weight in plant tissues.Physiological responses to CoNPs were similar to those induced by equivalent concentrations of CoCl_(2),suggesting that CoNPs dissolve into Co^(2+)ions upon interaction with plants.However,ultrastructural analysis revealed distinct intracellular cobalt localization with CoNPs causing more severe chloroplast damage than ionic Co^(2+).These findings suggest two toxicity mechanisms:ionic effects from dissolved Co^(2+)and direct physical damage from intact nanoparticles.The resilience and hyperaccumulation capacity of L.minor makes it a promising candidate for the phytoremediation of cobalt-contaminated waters.The study underscores the importance of further research to elucidate CoNP environ-mental behavior and optimize phytoremediation approaches.
