土壤微孔对有机物吸附/解吸的影响及其表征

土壤吸附是影响环境中有机化合物迁移、降解及生物有效性的重要过程,而微孔的存在是影响有机化合物慢吸附过程的重要因素之一,土壤孔隙结构(pore structure)及土壤微孔的研究对于理解发生在土壤中的吸附/解吸过程十分必要。综述了近年来土壤微孔对有机化合物吸附解吸行为影响的研究态势,包括土壤的孔隙结构及微孔的存在形式、微孔吸附有机化合物的吸附动力学和可能机理、土壤中微孔表征的技术方法、孔隙大小分布的计算以及对未来的研究展望,以期对土壤有机污染生物修复的深入研究提供理论依据。

盐渍化土壤中土著菌的石油烃降解潜力研究

自盐渍化地区(黄河三角洲)采集4种不同石油污染程度的土壤样品,从中筛选出高效降解石油烃的4个菌系和8个单菌株。分别以原油、柴油、烷烃和多环芳烃(PAHs)为底物进行培养,测定降解菌的生物量和降解率,研究其对不同底物的耐受浓度和降解潜力。结果表明,获得的石油烃降解菌为轻度嗜盐菌;不同菌株对不同底物的耐受浓度不同,混合菌系对不同底物的降解能力强于单菌株,对单一组分底物的降解优于复杂组分的底物;单菌株I-2、3、5、7能较好地降解PAHs并且对原油的降解能力高于柴油,单菌株I-1、4、6、8能够利用烷烃且对柴油的降解能力要比原油高;降解菌对柴油和原油的最高降解率分别可达78.4%和70.7%,对正十六烷和菲的生物降解率分别高达87.7%和88.1%,表现出较强的降解能力。研究结果表明黄河三角洲盐渍化土壤中土著菌对石油烃污染土壤具有较强的生物修复潜力。

土壤和沉积物中凝聚态有机质的表征

在375℃条件下用三氟醋酸(TFA)、通氧燃烧的方法,从珠江三角洲被污染的3个土壤和6个沉积物样品中提取非水解有机碳(NHC)和碳黑(BC),并进行了元素分析、傅里叶变换红外光谱(FTIR)、固态13C核磁共振(13CNMR)、放射性碳加速质谱等一系列定性、定量的研究。结果表明:用三氟醋酸(TFA)可以成功地提取凝聚态的非水解碳,消除了碳水化合物等可水解有机质对凝聚态有机质研究的干扰。样品中非水解碳和碳黑碳分别占总有机碳含量的25.6%～70.5%和4.14%～17.3%,其平均值分别为44.2%和11.2%。非水解碳和碳黑两者的O/C和H/C比值都比较低;13C核磁共振显示NHC中主要含有脂肪碳和芳香碳峰,其中含氧官能团几乎可以忽略。研究表明,非水解碳主要由不同成熟度的沥青或干酪根、古老的陆源有机质、碳黑、煤、木质素等组成。实验结果表明:用水解的方法可以从土壤和沉积物中分离出凝聚态的碳。

黄河三角洲原油污染土壤的微生物固定化修复技术

研究从原油污染土壤中驯化分离出高效石油烃降解菌系,以海藻酸钠和硅藻土复合载体将其制备成固定化菌,比较了固定化降解菌与游离菌对土壤中原油的降解率以及它们在土壤中活性与数量的变化。结果表明,土著降解菌经驯化后显示了较高的耐受性和环境适应能力,固定化降解菌产生了较同等菌量的游离菌明显高的降解优势,特别是在实验初期(20天时),低(IL)、中(IM)、高(IH)三个固定化菌接种处理比同等接种量的游离菌分别高出12.4%、10.1%和6.4%,并且低接种量的固定化菌表现了比高接种量的游离菌更强的降解优势;30天后,各实验组降解菌的数量和微生物活性趋于稳定,相应的原油降解率也趋于缓慢。另外,所用载体均不会破坏土壤结构,适用于长期大面积石油污染土壤的现场修复。

有机质官能团及微孔特性对疏水性有机污染物吸附的影响机制

作为重要的地质吸附剂,土壤/沉积物中的有机质是环境中疏水性有机污染物主要的汇.由于有机质的结构异质性,疏水性有机污染物一旦进入其中,会被吸附在不同的位点上,反应活性和生态风险进而会发生变化.对疏水性有机污染物在有机质上的吸附进行研究有助于了解其在环境中的分布,传输及生物有效性.本文就疏水性有机污染物在土壤/沉积物中的有机质上吸附的国内外研究进展进行了综述,讨论了重要有机质组分(腐殖质和碳黑)的结构和吸附作用差异性,重点分析了有机质的微孔特性和官能团对吸附的影响机制.

水生植物提取液对噬菌体的化感作用

为比较不同水生植物的提取液对噬菌体的抑制作用,采用双层琼脂平板计数法研究了水蓼、红蓼、芦苇、芦竹和香蒲等5种水生植物不同部位的提取液对噬菌体T4和f2的化感作用。当提取液浓度为0.5g/L时,水蓼叶对噬菌体T4、f2的抑制率分别达到91%、93%;水蓼茎对T4、f2的抑制率分别为65%、61%;水蓼根对T4、f2的抑制率分别为66%、100%。水蓼根对噬菌体的化感抑制作用最强,对噬菌体T4的半效应浓度(EC50)为0.6mg/L,对噬菌体f2的EC50为7.6mg/L;芦竹茎对噬菌体T4和f2的EC50均为16mg/L,香蒲叶对T4和f2的EC50分别为16mg/L和20mg/L。可见,水蓼具有强抑制噬菌体的能力。

Steam disinfection enhances bioaccessibility of metallic nanoparticles in nano-enabled silicone-rubber baby bottle teats,pacifiers,and teethers

Nano-enabled silicone-rubber articles for feeding or chewing could be a source of metallic nanoparticles(NPs)directly exposed to infants and young children.However,the impact of steam disinfection on release of NPs and the related potential risks to children's health are unknown.Here,we investigated contents and form of Ag and Zn in 57 nano-enabled silicone-rubber baby bottle teats,pacifiers,and teethers of seven countries and examined the impacts of steam disinfection on in vitro bioaccessibility(IVBA)of Ag and Zn in the articles.Nearly 89%articles had a mixture of Ag-and Zn-containing NPs and the teethers had relatively high Ag and Zn contents(up to 501 and 254μg/g,respectively).Steam disinfection caused rubber decomposition into micro(nano)plastics(0.54-15.7μm)and NP release from the interior of bulk rubber and micro-sized plastics,thus enhancing the IVBA of Ag and Zn by up to 5.5 times.The findings provide insights into mechanisms for NP release by steam disinfection.Though oral exposure risk assessment suggested low health concerns on individual metal release,our study points out the need to assess the potential health risks of child co-exposure to metallic NPs and micro(nano)plastics.

Accelerated aging: The hidden harm of microplastic exposure

The widespread contamination of plastic materials has become a significant ecological concern, hindering progress toward sustainable development [1,2]. Plastic waste is widespread across various natural habitats, including terrestrial and marine ecosystems[3,4]. Microplastics (MPs) primarily originate from the fragmentation of larger plastic pieces. Due to their small size, MPs are easily ingested by organisms and subsequently transferred through food webs, posing risks to human health [5,6].

Emerging contaminants:A One Health perspective

Environmental pollution is escalating due to rapid global development that often prioritizes human needs over planetary health.Despite global efforts to mitigate legacy pollutants,the continuous introduction of new substances remains a major threat to both people and the planet.In response,global initiatives are focusing on risk assessment and regulation of emerging contaminants,as demonstrated by the ongoing efforts to establish the UN’s Intergovernmental Science-Policy Panel on Chemicals,Waste,and Pollution Prevention.This review identifies the sources and impacts of emerging contaminants on planetary health,emphasizing the importance of adopting a One Health approach.Strategies for monitoring and addressing these pollutants are discussed,underscoring the need for robust and socially equitable environmental policies at both regional and international levels.Urgent actions are needed to transition toward sustainable pollution management practices to safeguard our planet for future generations.

Biochar application in remediating salt-affected soil to achieve carbon neutrality and abate climate change

Salt-affected soils urgently need to be remediated to achieve the goals of carbon neutrality and food security.Limited reviews are available on biochar performance in remediating salt-affected soils in the context of carbon neutrality and climate change mitigation.This work summarized the two pathways to achieve carbon neutrality during remediating salt-affected soils using biochars,i.e.,biochar production from sustainable feedstock using thermal technologies,application for promoting plant productivity and mitigating greenhouse gas(GHG)emission.Converting biomass wastes into biochars can reduce GHG emission and promote carbon dioxide removal(CDR),and collection of halophyte biomass as biochar feedstocks,development of biochar poly-generation production systems with carbon neutrality or negativity could be promising strategies.Biochar can effectively improve plant growth in salt-affected soils,showing that the grand mean of plant productivity response was 29.3%,via improving physicochemical characteristics,shifting microbial communities,and enhancing plant halotolerance.Moreover,biochar can mitigate GHG emission via inducing negative priming effect,improving soil properties,changing microbial communities associated with carbon and nitrogen cycle,direct adsorption of GHG.However,biochar also may pose negative effects on plant growth because of stress of toxic compounds and free radicals,and deterioration of soil properties.The promoted GHG emission is mainly ascribed to positive priming effect,and provision of labile carbon and inorganic nitrogen fractions as microbial substrates.Finally,this review pointed out the gaps in the current studies and the future perspectives.Particularly,the development of“carbon neutral”or“carbon negative”biochar production system,balancing the relationship of biochar effectiveness and functionality with its environmental risks and costs,and designing biochar-based GHG adsorbents would be important directions for remediating salt-affected soils to achieve carbon neutrality and abate climate change.

Mutual influence of copper and paraquat on their adsorption in soil

Paraquat and copper (Cu) are commonly used and detected in soil.Therefore,it is important to understand their mobility in the environment.In this study,the competitive effects of paraquat and Cu on their adsorption in five representative Chinese soils were investigated using batch adsorption equilibrium experiments and spectroscopic analysis.The results showed that the adsorption of paraquat in soil varied with soil type and was positively correlated with both soil cation exchange capacity and organic matter content.Paraquat exerted a more remarkable suppression effect on the adsorption of Cu than Cu on the adsorption of paraquat.In the presence of 0.12 and 0.19 mmol L-1paraquat,Cu adsorption decreased by 16%and 22%in Heilongjiang soil and by 24%and37%in Jiangxi soil,respectively.In the presence of 0.1 and 0.2 mmol L-1Cu,paraquat adsorption decreased by 4%and 8%in Heilongjiang soil and by15%and 19%in Jiangxi soil,respectively.Exchange selectivity involving symmetric cation (paraquat2+and Cu2+) exchange is the probable basis for the suppression effect.The ultraviolet-visible absorption experiments suggested that the formation of Cu-paraquat complexes was unlikely to happen in a solution or at the soil surface.Copper K-edge X-ray absorption spectroscopy indicated that Cu in soil may have some water as hydration layers as the nearest neighbors,and each Cu atom was coordinated with five oxygen atoms.These findings greatly improve our knowledge of the molecular-scale adsorption mechanisms of paraquat and Cu in soil and can be used to predict the behavior,transport,and fate of paraquat and Cu in agricultural soils.

The frontier of microplastics and nanoplastics: Soil health and carbon neutrality

Microplastics and nanoplastics(MNPs)in soil have drawn increasing concerns about their potential threats to soil ecosystems due to their ubiquitous occurrence and persistence.The interactions of MNPs with soil components,microbial community,plants,and fauna determine their impacts on soil biogeochemical processes and food security.However,they are not largely explored.Further research is also needed to develop reliable and standardized techniques and methods to characterize the relevant MNPs interacting with different types of soil ecosystems and to deeply examine their impacts on soil health,food security,and climate changes.In addition,mitigation protocols and regulation guidelines need to be developed.New findings will provide scientific and technological support for the understanding and management of soil health and carbon neutrality as influenced by MNPs.

Insights into the enzymatic degradation of DNA expedited by typical perfluoroalkyl acids

Perfluoroalkyl acids(PFAAs)are considered forever chemicals,gaining increasing attention for their hazardous impacts.However,the ecological effects of PFAAs remain unclear.Environmental DNA(eDNA),as the environmental gene pool,is often collected for evaluating the ecotoxicological effects of pollutants.In this study,we found that all PFAAs investigated,including perfluorohexanoic acid,perfluorooctanoic acid,perfluorononanoic acid,and perfluorooctane sulfonate,even at low concentrations(0.02 and 0.05 mg/L),expedited the enzymatic degradation of DNA in a nonlinear dose–effect relationship,with DNA degradation fragment sizes being lower than 1,000 bp and 200 bp after 15 and 30 min of degradation,respectively.This phenomenon was attributed to the binding interaction between PFAAs and AT bases in DNA via groove binding.van der Waals force(especially dispersion force)and hydrogen bonding are the main binding forces.DNA binding with PFAAs led to decreased base stacking and right-handed helicity,resulting in loose DNA structure exposing more digestion sites for degrading enzymes,and accelerating the enzymatic degradation of DNA.The global ecological risk evaluation results indicated that PFAA contamination could cause medium and high molecular ecological risk in 497 samples from 11 contamination-hot countries(such as the USA,Canada,and China).The findings of this study show new insights into the influence of PFAAs on the environmental fates of biomacromolecules and reveal the hidden molecular ecological effects of PFAAs in the environment.

Fluorescence regional integration and differential fluorescence spectroscopy for analysis of structural characteristics and proton binding properties of fulvic acid sub-fractions

Structural characteristics and proton binding properties of sub-fractions（FA3–FA13） of fulvic acid（FA）, eluted stepwise by pyrophosphate buffer were examined by use of fluorescence titration combined with fluorescence regional integration（FRI） and differential fluorescence spectroscopy（DFS）. Humic-like（H-L） and fulvic-like（F-L） materials, which accounted for more than 80% of fluorescence response, were dominant in five sub-fractions of FA. Based on FRI analysis, except the response of F-L materials in FA9 and FA13, maximum changes in percent fluorescence response were less than 10% as pH was increased from 2.5 to 11.5.Contents of carboxylic and phenolic groups were compared for fluorescence peaks of FA sub-fractions based on pH-dependent fluorescence derived from DFS. Static quenching was the dominant mechanism for binding of protons by FA sub-fractions. Dissociation constants（p Ka） were calculated by use of results of DFS and the modified Stern-Volmer relationship. The p Kaof H-L, F-L, tryptophan-like and tyrosine-like materials of FA subfractions exhibited ranges of 3.17–4.06, 3.12–3.97, 4.14–4.45 and 4.25–4.76, respectively, for acidic pHs. At basic pHs, values of p Ka for corresponding materials were in ranges of 9.71–10.24, 9.62–10.99, 9.67–10.31 and 9.33–10.28, respectively. At acidic pH, protein-like（P-L）materials had greater affinities for protons than did either H-L or F-L materials. The dicarboxylic and phenolic groups were likely predominant sites of protonation for both H-L and F-L materials at both acidic and basic pHs. Amino acid groups were significant factors during proton binding to protein-like materials of FA sub-fractions at basic pH.

Uptake of graphene enhanced the photophosphorylation performed by chloroplasts in rice plants

New and enhanced functions were potentially imparted to the plant organelles after interaction with nanoparticles.In this study,we found that∼44%and∼29%of the accumulated graphene in the rice leaves passively transported to the chloroplasts and thylakoid,respectively,significantly enhanced the fluorescence intensity of chloroplasts,and promoted about 2.4 times higher adenosine triphosphate production than that of controls.The enhancement of graphene on the photophosphorylation was ascribed to two reasons:One is that graphene facilitates the electron transfer process of photosystem II in thylakoid,and the other is that graphene protects the photosystem II against photo-bleaching by acting as a scavenger of reactive oxygen species.Overall,our work here confirmed that graphene translocating in the thylakoid promoted the photosynthetic activity of chloroplast in vivo and in vitro,providing new opportunities for designing biomimetic materials to enhance the solar energy conversion systems,especially for repairing or increasing the photosynthesis activity of the plants grown under stress environment.

Adsorptive removal of hydrophobic organic compounds by carbonaceous adsorbents:A comparative study of waste-polymer-based,coal-based activated carbon,and carbon nanotubes

Adsorption of the hydrophobic organic compounds （HOCs） trichloroethylene （TCE）, 1,3-dichlorobenzene （DCB）, 1,3-dirdtrobenzene （DNB） and y-hexachlorocyclohexane （HCH） on five different carbonaceous materials was compared. The adsorbents included three polymer-based activated carbons, one coal-based activated carbon （F400） and multiwalled carbon nanotubes （MWNT）. The polymer- based activated carbons were prepared using KOH activation from waste polymers： polyvinyl chloride （PVC）, polyethyleneterephthalate （PET） and tire rubber （TR）. Compared with F400 and MWNT, activated carbons derived from PVC and PET exhibited fast adsorption kinetics and high adsorption capacity toward the HOCs, attributed to their extremely large hydrophobic surface area （2700 m2/g） and highly mesoporous structures. Adsorption of small-sized TCE was stronger on the tire-rubber-based carbon and F400 resulting from the pore-filling effect. In contrast, due to the molecular sieving effect, their adsorption on HCH was lower. MWNT exhibited the lowest adsorption capacity toward HOCs because of its low surface area and characteristic of aggregating in aqueous solution.