荒漠草地中氮添加与多环芳烃降解的关系

多环芳烃作为环境污染物中一类极为重要的物质,探索它的去除方法吸引了全球环境学者及政府的高度重视。大气氮沉降在过去几十年不断增加,已影响到陆地生态系统氮循环过程。但目前,氮沉降与多环芳烃降解之间的关系尚不明确。通过在新疆克拉玛依市石油化工厂附近的荒漠草地上,模拟氮沉降实验,通过在4氮添加梯度(CK=0;N1=10;N2=30;N3=90 kg N hm-2 a-1)上调查土壤中16种优先控制多环芳烃的含量和总量(∑PAHs),以及它们与生物非生物环境因子(土壤环境因子、土壤酶活性和土壤微生物功能多样性)之间的关系,旨在揭示氮沉降对多环芳烃降解的影响。结果表明:除苊烯(Acenaphthylene)和苊(Acenaphthene)两种多环芳烃在4个N添加梯度上未检测到含量外,∑PAHs和其他14种优先控制多环芳烃在土壤中的含量均随氮添加量增加显著减小(N2≤N3<N1<CK)(P<0.01);对照样地(CK)在施氮前后,低高分子多环芳烃含量的比值>1.00,且0.40<荧蒽(Fluoranthene)/[(荧蒽(Fluoranthene)+芘(Pyrene)]<0.50,石油污染物是当地土壤中多环芳烃的主要来源;9月份克拉玛依市荒漠草地土壤中∑PAHs约(28.91±2.32) mg/kg,属于多环芳烃重污染土壤;广义线性混合效应模型结果显示,在大多数情况下,∑PAHs和14种多环芳烃的含量与土壤有机质、铵态氮、硝态氮、总氮、有效磷和脲酶活性显著相关(P<0.05),但其与生物非生物环境因子之间的回归关系在不同种类多环芳烃之间差异较大。综上可知,土壤中多环芳烃的降解是一个非常复杂的过程,它是自身属性、植物根系和土壤微生物等多重因子相互共同作用的结果。在干旱区荒漠草地中,氮添加能提升土壤中营养物质的可利用性、植物根系和土壤微生物的活性,有利于降解土壤多环芳烃。

全氟和多氟烷基化合物的分析检测

全氟和多氟烷基化合物(Perfluorinated and Polyfluoroalkyl Substances,PFAS)已成为引人关注的新型污染物,其检测难点包括微量或痕量分析、复杂PFAS组分的定量分析等。对PFAS的分析和检测,除了传统的高效液相色谱-质谱(HPLC-MS)法之外,新的分析测试技术也不断涌现,一方面有效补充了传统的实验室方法,另一方面也使得现场检测成为可能,特别是那些能够快速得到半定量结果的预筛选检测技术。本文试图对这些新报道的PFAS的测试技术进行评述,包括电化学检测、光学检测,以及基于智能手机应用程序的检测,并对未来的研究方向进行了展望。

A review of electrokinetically enhanced bioremediation technologies for PHs

Since the early 1980’s there have been several different strategies designed and applied to the remediation of subsurface environment including physical, chemical and biological approaches.They have had varying degrees of success in remediating contaminants from subsurface soils and groundwater.The objective of this review is to examine the range of technologies for the remediation of contaminants, particularly petroleum hydrocarbons, in subsurfaces with a specific focus on bioremediation and electrokinetic remediation.Further, this review examines the efficiency of remediation carried out by combining bioremediation and electrokinetic remediation.Surfactants, which are slowly becoming the selected chemicals for mobilizing contaminants, are also considered in this review.The current knowledge gaps of these technologies and techniques identified which could lead to development of more efficient ways of utilizing these technologies or development of a completely new technology.

Current advancements on charge selective contact interfacial layers and electrodes in flexible hybrid perovskite photovoltaics

Perovskite-based photovoltaic materials have been attracting attention for their strikingly improved performance at converting sunlight into electricity.The beneficial and unique optoelectronic characteristics of perovskite structures enable researchers to achieve an incredibly remarkable power conversion efficiency.Flexible hybrid perovskite photovoltaics promise emerging applications in a myriad of optoelectronic and wearable/portable device applications owing to their inherent intriguing physicochemical and photophysical properties which enabled researchers to take forward advanced research in this growing field.Flexible perovskite photovoltaics have attracted significant attention owing to their fascinating material properties with combined merits of high efficiency,light-weight,flexibility,semitransparency,compatibility towards roll-to-roll printing,and large-area mass-scale production.Flexible perovskite-based solar cells comprise of 4 key components that include a flexible substrate,semi-transparent bottom contact electrode,perovskite(light absorber layer)and charge transport(electron/hole)layers and top(usually metal)electrode.Among these components,interfacial layers and contact electrodes play a pivotal role in influencing the overall photovoltaic performance.In this comprehensive review article,we focus on the current developments and latest progress achieved in perovskite photovoltaics concerning the charge selective transport layers/electrodes toward the fabrication of highly stable,efficient flexible devices.As a concluding remark,we briefly summarize the highlights of the review article and make recommendations for future outlook and investigation with perspectives on the perovskite-based optoelectronic functional devices that can be potentially utilized in smart wearable and portable devices.

Amelioration of Salinity Stress in Maize Seed Germination and Seedling Growth Attributes through Seed Priming

Germination of seeds and growth of seedling respond to seed priming as priming can guard the damage of salinity stress. A study conducted in the net house of the Department of Agronomy, BAU, Mymensingh during the period from November 2012 to April 2013 investigated the ameliorative effect of seed priming on seed germination and seedling attributes of maize under various salinity stress conditions. The experiment consisted of five seed priming and four salinity levels (NaCl) and laid out in a Completely Randomized Design (CRD) with three replications. Seed germination and seedling attributes of maize varied due to salinity stress and priming. The highest seed germination (95.7%) was recorded when no stress was imposed under hydropriming (48 hours). The germination of seeds performed even well (92.3%) when treated with hydropriming (48 hours) and NaCl@0.25 dS&#183m-1 which was followed by hydropriming (24 hours) under no salinity imposed and NaCl@0.25 dS&#183m-1 salinity. Hydropriming for 48 hours without salt stress performed the best on number of leaves seedling-1 (8), shoot length (28.2 cm), root length (14.5 cm), fresh weight (100.8 g) and dry weight of seedling (50.3 g). The germination and seedling growth parameters were reduced with the increase in salinity levels irrespective of priming while all seed priming treatments showed ameliorative effects. However, reduction in seed germination and seedling attributes were minimal with hydropriming for 48 hours. The results revealed that priming of maize seeds could be used for amelioration of salinity stress and hydropriming for 48 hours appeared as the best seed priming treatment.

The interaction mechanisms of co-existing polybrominated diphenyl ethers and engineered nanoparticles in environmental waters: A critical review

This review focuses on the occurrence and interactions of engineered nanoparticles(ENPs)and brominated flame retardants(BFRs)such as polybrominated diphenyl ethers(PBDEs)in water systems and the generation of highly complex compounds in the environment.The release of ENPs and BFRs(e.g.PBDEs)to aquatic environments during their usage and disposal are summarised together with their key interaction mechanisms.The major interaction mechanisms including electrostatic,van derWaals,hydrophobic,molecular bridging and steric,hydrogen andπ-bonding,cation bridging and ligand exchange were identified.The presence of ENPs could influence the fate and behaviour of PBDEs through the interactions as well as induced reactions under certain conditions which increases the formation of complex compounds.The interaction leads to alteration of behaviour for PBDEs and their toxic effects to ecological receptors.The intermingled compound(ENPs-BFRs)would show different behaviour from the parental ENPs or BFRs,which are currently lack of investigation.This review provided insights on the interactions of ENPs and BFRs in artificial,environmental water systems and wastewater treatment plants(WWTPs),which are important for a comprehensive risk assessment.

Chromium adsorption on surface activated biochar made from tannery liming sludge:A waste-to-wealth approach

In a beamhouse,liming plays a key role in the removal of hair/wool and epidermis,but problems are created when waste liming sludge is discharged to the environment.The treatment of tannery wastewater is another major challenge to the industry.In this study,thermally-activated biochars derived from liming sludge were studied for their effective adsorption of chromium(Cr)from the tannery wastewater.The thermally activated biochars(B500,B550,B600,and B650)were prepared at different temperatures from the liming sludge.Their characteristics before and after the treatment were investigated using Fourier transform infrared spectroscopy,energy dispersive X-ray spectroscopy,Bru-nauer-Emmett-Teller,and scanning electron microscopy analyses.The related functional groups(C-H,O-H,C-N,and=C-O)and chromium adsorption capacity were determined according to the surface morphology,element contents(C,O,Ca,Na,Al,Mg,and Si),surface area(5.8-9.2 m^(2)/g),pore size(5.22-5.53 nm),and particle size(652-1034 nm)of the experimental biochars.The biochar originated at 600°C from the tannery liming sludge(B600)had a greater surface area with a chromium adsorption capacity of 99.8%in comparison to B500,B550,and B650 biochars.This study developed an innovative way of utilizing liming sludge waste to minimize the pollution load and wastewater treatment cost in the tannery industry.

Groundwater arsenic poisoning in a primary educational institution:health risks to school-going children

This study aimed to estimate arsenic(As)and iron(Fe)content in tubewell water(n=58)in primary educational institutions and subsequently assess the health risks to school-going children.Results described that the As concentration ranged between 0.002 and 0.994 mg L^(-1)with an average value of 0.044 mg L^(-1);which exceeded the World Health Organization(WHO)provisional guideline value of 0.01 mg L^(-1).Similarly,the Fe content varied from 0.05 to 10 mg L^(-1)averaging to 2.84 mg L^(-1).Samples of 55.17%contained a greater As concentration than0.01 mg L^(-1)and 18.97%greater than Bangladesh drinking water quality(BDWQ)standard of 0.05 mg L^(-1),respectively.Meanwhile,75.86%of samples contained a higher Fe concentration than the maximum Bangladesh permissible limit of 1 mg L^(-1).Health risk assessment indicated that girls are more vulnerable than boys are.The average hazard quotients(HQs)for As intake through drinking water were 6.01±17.85 and 7.41±22.03 for boys and girls,respectively,implying non-carcinogenic health risks to both genders.The HQs for Fe intake were less than threshold value of 1 indicating no health issues may arise from Fe intake alone.However,consumption of As and Fe may trigger health risks to students as indicated by the hazard index(HI),which was higher than 1.The average cancer risk(CR)values for both boys(0.0027±0.008)and girls(0.0033±0.0099)exceeded the threshold limit of 10-6-10-4,suggesting a possibility of lifetime cancer risks to the school-going children.Consequently,school authorities should find alternative ways to ensure safe drinking water for school-going children to avoid possible cancer and non-cancer health risks through consumption of As-poisoning water.

Investigating Microplastics and Nanoplastics Released from a Rubber Band Used for Orthodontic Treatment with Improved Raman Imaging Algorithms

Most teenagers experience orthodontic treatment,but we do not know the possible adverse effect of the released microplastics and nanoplastics that are recently categorized as emerging contaminants.Herein,we test the rubber band that has been employed to improve the biting of teeth during the orthodontic process to confirm the release of microplastics and nanoplastics.We improve the characterization of microplastics and nanoplastics by(i)Raman imaging,to extract and map the signal from the scanning spectrum matrix or the hyperspectral matrix and to enhance the signal-to-noise ratio statistically.To effectively extract the signal,(ii)chemometrics such as principal component analysis(PCA)are explored to convert the hyperspectral matrix to an image with an increased certainty.The nonsupervised PCA is intentionally corrected,via(iii)the algebra-based algorithm,to further increase the certainty to image the microplastics and nanoplastics.Once the signal is weak,(iv)an additional algorithm of image reconstruction via deconvolution is developed to average the background noise and smooth the image.By doing so,we estimate that millions of microplastics and nanoplastics are released daily in potential from a rubber band applied in a teenager's mouth,which might be a big concern.Overall,our approach provides a suitable option to characterize the microplastics and nanoplastics from a complex background.

Mercury remediation potential of a mercury resistant strain Sphingopyxis sp.SE2 isolated from contaminated soil

A mercury resistant bacterial strain SE2 was isolated from contaminated soil.The 16 s rRNA gene sequencing confirms the strain as Sphingopyxis belongs to the Sphingomonadaceae family of the α-Proteobacteria group.The isolate showed high resistance to mercury with estimated concentrations of Hg that caused 50%reduction in growth（EC_（50）） of 5.97 and 6.22 mg/L and minimum inhibitory concentrations（MICs） of 32.19 and 34.95 mg/L in minimal and rich media,respectively.The qualitative detection of volatilized mercury and the presence of mercuric reductase enzyme proved that the strain SE2 can potentially remediate mercury.ICP-QQQ-MS analysis of the remaining mercury in experimental broths indicated that a maximum of 44%mercury was volatilized within 6 hr by live SE2 culture.Furthermore a small quantity（23%） of mercury was accumulated in live cell pellets.While no volatilization was caused by dead cells,sorption of mercury was confirmed.The mercuric reductase gene merA was amplified and sequenced.Homology was observed among the amino acid sequences of mercuric reductase enzyme of different organisms from a-Proteobacteria and ascomycota groups,

Influence of soil physicochemical properties,particle size fractions and mineralogy on the leaching potentials of arsenic and antimony in abandoned mine soils

At abandoned mine sites,arsenic(As)-and antimony(Sb)-enriched soils are often disposed of through onsite burial or capping.In highly weathered mine sites,the mobility of As and Sb is typically controlled by iron(Fe)(III)/Fe(II)phases;thus,the suitability of such disposal methods and appropriate testing techniques are questionable.In the present study,leaching potentials of As and Sb were examined using the toxicity characteristic leaching procedure(TCLP),waste extraction test(WET),and WET-extended procedure(WET-EXT)at three abandoned mine site soils in Australia.The leached concentration of As regularly exceeded USEPA criteria(5 mg L^(-1)).The highest leached concentrations of As and Sb were observed in the finest particle size fraction(<0.053 mm)by WET-EXT(1040 mg L^(-1)for As and 21.10 mg L^(-1)for Sb)followed by WET(800 mg L^(-1)for As and 20.90 mg L^(-1)for Sb).The TCLP method resulted in the lowest concentrations of leached As(0.0009 mg L^(-1))and Sb(0.0003 mg L^(-1)).Crystalline and amorphous As-bearing Fe oxides were the main phases in the soils studied.However,the best correlations of leached As determined by TCLP(0.832),WET(0.944),and WET-EXT(0.961)were found with the non-specifically sorbed(NS1)As fraction.The mineralogical and sequential extraction data clearly indicate the dominant role of Fe geochemistry in controlling leachability of As and Sb.The TCLP method was unlikely to be suitable for assessing leachability,as it exhibited no relationship with leachable Fe and substantially lower leached As and Sb than the other two methods.Given the high to extremely high leachable As and Sb concentrations,most of the soil samples would not be recommended for placement in capping works,old shafts,or reduction systems(e.g.,collection in drainage basins).

Bioavailability of Arsenic and Antimony in Terrestrial Ecosystems:A Review

Arsenic (As) and antimony (Sb) are metalloids that belong to group 15 of the periodic table and exhibit toxic properties in the environment. They mostly occur naturally at low concentrations in soil, although these can be significantly elevated in both aquatic and terrestrial food chains as a result of dispersion from anthropogenic sources, e.g ., mining activities. The bioavailability, i.e., the proportion of the contaminant in soil and dust that is available for uptake by plants and other living organisms, presents the greatest risk to terrestrial ecosystems. Various in vivo and in vitro methods have been used to measure As and Sb bioaccessibility in soil and dust. In vivo measurement of bioavailability can be time consuming, expensive, and unethical;thus, in vitro methods are commonly preferred. However, there is considerable uncertainty around the efficacy of in vitro tools used to measure the bioavailable fractions of As and Sb. The results of these methods are dependent on many variables, e.g., soil characteristics, contaminant sources, and chemical composition of in vitro methods. Therefore, substantial variations are observed between in vitro and in vivo results obtained from different test animals and endpoints. In this paper, we review the literature on As and Sb bioavailability in terrestrial ecosystems and current in vivo and in vitro techniques used for assessing bioavailability and bioaccessibility of metalloids. This would reveal research gaps and allow scientists and environmental policy makers to gain a deeper understanding of the potential risks associated with these metalloids in the environment.

Response of microbial communities to biochar-amended soils:a critical review

Application of biochar to soils changes soil physicochemical properties and stimulates the activities of soil microorganisms that influence soil quality and plant performance.Studying the response of soil microbial communities to biochar amendments is important for better understanding interactions of biochar with soil,as well as plants.However,the effect of biochar on soil microorganisms has received less attention than its influences on soil physicochemical properties.In this review,the following key questions are discussed:(i)how does biochar affect soil microbial activities,in particular soil carbon(C)mineralization,nutrient cycling,and enzyme activities?(ii)how do microorganisms respond to biochar amendment in contaminated soils?and(iii)what is the role of biochar as a growth promoter for soil microorganisms?Many studies have demonstrated that biochar-soil application enhances the soil microbial biomass with substantial changes in microbial community composition.Biochar amendment changes microbial habitats,directly or indirectly affects microbial metabolic activities,and modifies the soil microbial community in terms of their diversity and abundance.However,chemical properties of biochar,(especially pH and nutrient content),and physical properties such as pore size,pore volume,and specific surface area play significant roles in determining the efficacy of biochar on microbial performance as biochar provides suitable habitats for microorgan-isms.The mode of action of biochar leading to stimulation of microbial activities is complex and is influenced by the nature of biochar as well as soil conditions.

Biochar and its importance on nutrient dynamics in soil and plant

Biochar,an environmentally friendly soil conditioner,is produced using several thermochemical processes.It has unique characteristics like high surface area,porosity,and surface charges.This paper reviews the fertilizer value of biochar,and its effects on soil properties,and nutrient use efficiency of crops.Biochar serves as an important source of plant nutrients,especially nitrogen in biochar produced from manures and wastes at low temperature(≤400℃).The phosphorus,potassium,and other nutrient contents are higher in manure/waste biochars than those in crop residues and woody biochars.The nutrient contents and pH of biochar are positively correlated with pyrolysis temperature,except for nitrogen content.Biochar improves the nutrient retention capacity of soil,which depends on porosity and surface charge of biochar.Biochar increases nitrogen retention in soil by reducing leaching and gaseous loss,and also increases phosphorus availability by decreasing the leaching process in soil.However,for potassium and other nutrients,biochar shows inconsistent(positive and negative)impacts on soil.After addition of biochar,porosity,aggregate stability,and amount of water held in soil increase and bulk density decreases.Mostly,biochar increases soil pH and,thus,influences nutrient availability for plants.Biochar also alters soil biological properties by increasing microbial populations,enzyme activity,soil respiration,and microbial biomass.Finally,nutrient use efficiency and nutrient uptake improve with the application of biochar to soil.Thus,biochar can be a potential nutrient reservoir for plants and a good amendment to improve soil properties.

Visualizing the emerging trends of biochar research and applications in 2019:a scientometric analysis and review

Biochar,derived from thermal pyrolysis of biomass,has been regarded as a low-cost,sustainable and beneficial material and widely applied in agriculture,environment and energy during the last two decades.To elucidate the research status timely and future trends in biochar field,CiteSpace is used to systematically analyze the related literature retrieved from the Web of Science core collection in 2019.Based on the keywords clustering analysis,it was found that“biochar production”,“organic pollutants removal”,“heavy metals immobilization”,“bioremediation”were the main hotspots in research covering biochar.“Bioremediation”is an emerging topic and deserves extensive attention due to its highly effective and environmentally friendly treatment of pollutants.Improving the phytoremediation effect,immobilizing functional microorganisms on biochar,and using microorganisms as raw materials to produce biochar were the common methods of biochar-assisted bioremediation.While studies focused on“soil quality and plant growth”and“biochar and global climate change”decreased,investigations concentrated in the toxicity of biochar to soil biota and ruminants are sustainably growing.Research on direct and catalytic thermal pyrolysis of green waste(mainly microalgae)for biofuels(bio-oil,biodiesel,syngas,etc.)and biochar production is increasing.Converting municipal wastes(e.g.,sewage sludge,fallen leaves)into biochar through pyrolysis was a suitable treatment for municipal waste and became a popular topic in recent time.Moreover,the biochar produced from these municipal wastes exhibited excellent performance in the removal of pollutants from wastewater and soil.This review may help to identify future directions in biochar research and applications.

In situ stabilization of arsenic in soil with organoclay,organozeolite,birnessite,goethite and lanthanum-doped magnetic biochar

Arsenic(As)is a known carcinogen and naturally occurring semi-metal in soils and in the Earth's crust.Contamination of soils and water with As poses a serious threat to millions of people worldwide due to its health hazards and toxicological properties.Hence,devising novel and efficient methods for remediation of contaminated areas has attracted a great deal of interest across the globe.In this study,we investigated the usefulness of synthetic birnessite,goethite,hexadecylpyridinium chloride-modified montmorillonite(HDPC-M),hexadecylpyridinium bromide-modified zeolite(HDPB-Z),and lanthanum(La)-doped magnetic biochar produced from eucalyptus bark(La-Euchar)as adsorbents at 10%dosage for As stabilization in a soil spiked with 1000 mg kg^(-1)As.The effectiveness of the above adsorbents in As immobilization in soil was assessed using single-step extractions with 2 mol L^(-1)HNO_(3)and deionized water,the simplified bioaccessibility extraction test(SBET)method,and sequential extraction with the modified Community Bureau of Reference(BCR)method.Application of the adsorbents shifted the exchangeable fraction of As to more recalcitrant fractions and dramatically reduced the exchangeable fraction by 6%-99%and the extractable amounts with HNO_(3),deionized water,and SBET method by 30%-92%,17%-95%,and 12%-90%,respectively,compared to the unamended control.The immobilizing effects of adsorbents on As decreased in the sequence of birnessite>La-Euchar>goethite>HDPB-Z>HDPC-M.Birnessite exhibited great affinity for As and drastically reduced As extractability by more than 90%in all single extractions.The results revealed that HDPC-M,HDPB-Z,La-Euchar,birnessite,and goethite are promising immobilizing agents for in situ stabilization of As in terrestrial environments.

Visualizing the development trend and research frontiers of biochar in 2020:a scientometric perspective

This study presents a scientometric analysis on biochar research to investigate the research status and developments as well as future trends in this field in 2020.A total of 3671 publications were retrieved from the Web of Science core collection database in 2020,which were analyzed for categories,countries,authors,and keywords.China and USA played a leading role in the research of biochar.Yong Sik Ok and Daniel C.W.Tsang were the most prolific authors in the application of biochar in agriculture,environment,and energy.Based on the keywords clustering analysis,biochar applications in“bioenergy produc-tion”,“global climate change mitigation”,“salinity and drought stress amelioration”,“organic pollutants degradation”,“heavy metals immobilization”,and“bioremediation”were the main hotspots.Biochar for salinity and drought stress amelioration became the focus in biochar area in 2020 as biochar amendment had great potential in alleviating salt-and drought-affected soils.Organic pollutants’degradation via advanced oxidation process(AOPs)represents a sustainable growing topic.Radical and non-radical pathways were summarized for AOPs.Bioremediation using functional bacteria(e.g.,heavy metal-resistant bacteria and organic pollutant-degraders)immobilized on biochar was still a research hotspot.Immobilized cells showed excellent performance in removing various contaminants by combining the advantages of highly efficient physiochemical sorption of biochar and microbial metabolisms.The review improves our understanding on scientific advances and potential future research directions in biochar research.