土壤样品中微塑料的分析方法研究进展

微塑料作为一种新型污染物,因其粒径小、难以降解、本身含有多种污染物、且易吸附疏水性有机污染物和重金属等产生复合污染,已成为国内外学者研究的热点问题。微塑料广泛存在于土壤环境中,进入土壤中的微塑料会影响土壤理化性质,同时影响土壤动物生长、植物生长和微生物活动等,并且,微塑料会在土壤中发生迁移或沿食物链传递从而对人类健康构成潜在风险。高效、统一、准确的微塑料分析方法是研究微塑料在土壤中分布、迁移、归趋和生态风险的基础。本文对近年来土壤中微塑料的采集、分离提取、鉴定量化和分析方法的质量保证等方面的研究进展进行了评述,比较了各个方法的优缺点及应用范围。最后,结合国内外微塑料污染最新研究进展,针对目前土壤微塑料分析方法存在的问题,对今后土壤微塑料分析技术的发展趋势进行了展望。     

浅谈重金属元素在土壤中的迁移及黏土矿物对其修复作用

重金属元素在土壤中的存在形式有多种,且迁移能力各不相同,而影响重金属元素形态的因素是土壤p H、土壤植物根际环境,重金属元素迁移的过程还受到土壤类型、含水量以及土壤中有机和无机配体的影响。黏土矿物具有良好的吸附作用,它主要是通过离子交换、配合反应和共沉淀反应来修复土壤中的重金属污染。     

有机酸对土壤中镉形态及其生物有效性影响的研究进展

根系分泌的低相对分子质量有机酸与土壤中镉之间相互作用影响着土壤中镉的吸附、解吸，使镉在土壤-水-植物系统中的迁移、转化规律发生重大改变，从而影响到镉在土壤中的形态及其生物有效性。对近二十年来有关有机酸与重金属镉交互作用的研究进展、有机酸对土壤中镉的有效性、毒性的影响以及作用机制进行了综述，并对现在研究存在的问题以及今后的研究趋势做了初步展望。     

土壤微塑料污染及生态环境效应研究进展

微塑料作为一种新的污染物,具有粒径小、疏水性强、性质稳定、可以吸附多种污染物等特点,近年来受到了广泛的关注.目前关于微塑料的研究主要集中在水环境中,土壤环境中的微塑料研究相对滞后.土壤与人类生活息息相关,但土壤微塑料污染的现状却不容乐观,土壤微塑料的环境效应需要重视.本文综述了土壤微塑料的来源、分离和鉴定方法、微塑料在...     

重金属有效态与土壤环境质量标准制订

制订合适的土壤环境质量标准是评价土壤健康质量及食品安全的核心问题,而土壤重金属有效态对制定土壤环境质量标准具有重要意义。土壤重金属有效态主要指植物有效态,它与重金属形态关系密切。影响土壤重金属有效态的因素很多,主要包括:土壤pH值、氧化还原电位、CEC、有机质含量、粒径组成(黏粒含量)、铁铝锰氧化物含量、植物种类、土壤微生物、土壤温度的高低、重金属来源等。化学试剂浸提法是测量重金属生物有效性的常用方法,所用化学试剂主要有三类:弱(稀)酸、络合剂和中性盐,中性盐由于对土壤pH值影响小而受到重视。我国现行土壤质量标准采用土壤重金属总量和pH两个因素为依据,但是不少学者认为,该标准仅适用于重金属有效态较高的土壤,而不能反映重金属有效态含量较低土壤的实际状况。     

土壤中微塑料检测技术及生态效应研究进展

微塑料(MPs)指长度或宽度小于5 mm的塑料颗粒.作为一种新兴污染物,其因粒径小、性质稳定、难降解,已成为地球系统功能的重大威胁之一.目前,水体环境中微塑料污染已得到广泛研究,而土壤中微塑料污染研究刚刚起步.本文对国内外土壤中微塑料污染现状、分离检测方法及生态风险进行综述,对未来土壤中微塑料研究提出展望.土壤中微塑料分离方法主要包括筛分法、密度分离法、泡沫浮选法等.微塑料的鉴别及表征方法包括显微镜观察法、傅里叶红外光谱法、拉曼光谱法等.这些方法存在耗时长、破坏微塑料结构等问题,将各方法适当结合或改进有望弥补不足.土壤微塑料的生态影响主要体现在动物的生长、发育、繁殖,植物的光合作用、氧化应激、生长存活以及微生物多样性等方面.今后研究重点为:(1)规范微塑料分离鉴别方法;(2)明确微塑料污染的剂量-效应关系;(3)土壤微塑料降解及其与其他污染物协同作用造成的土壤生态影响.     

石墨炉原子吸收光谱法测定土壤中重金属铅、镉的方法改进

土壤重金属污染是生态环境污染中最为常见也是最严重的一种污染,土壤中的重金属具有难降解、易积累和毒性大等特点,它在土壤中不断积累,进而通过食物链被植物和其他生物体吸收、富集,直接影响植物、动物甚至人类的健康[1-4]。     

不同基团修饰聚苯乙烯微塑料对大型溞的影响及其在肠道中的积累

选择3种结构不同的绿色荧光聚苯乙烯微塑料(聚苯乙烯微球(PS)、表面键合羧基聚苯乙烯微球(PS-COOH)和表面键合氨基聚苯乙烯微球(PS-NH₂))为研究目标,探讨其对淡水模式生物大型溞的影响及其在肠道中的积累情况。急性毒性实验结果表明,PS,PS-COOH和PS-NH2的72 h半数致死浓度(LC50)分别为12.29,41.36和24.89 mg/L。显微荧光成像结果表明,3种微塑料主要在大型溞的肠道积累,其中低浓度暴露组(50μg/L)在72 h微塑料生物积累达到最大,高浓度组(500μg/L)在24～48 h微塑料生物积累达到最大。将暴露的大型溞转移至不含微塑料的纯培养液中,1 h即可观察到微塑料通过肠道开始排出体外,低浓度组的微塑料在12 h后基本排出,高浓度组的微塑料在36 h基本排出。     

环境样品中微塑料分析技术研究进展

微塑料一般是指直径小于5 mm的塑料纤维、碎片或颗粒。环境中的微塑料来源广泛,性质稳定,是疏水性有机污染物和重金属的理想载体。微塑料易被浮游生物、鱼类及低等生物误食,并在食物网各营养级之间发生转移和富集,对食品安全存在潜在风险。开展微塑料分析技术研究是研究微塑料在环境中的分布、迁移、转化、归趋和生态毒理效应的基础。该文综述了国内外环境样品中微塑料的采集、分离提取、定性鉴别技术的研究进展,并探讨了各方法的优缺点。最后针对现阶段微塑料分析方法存在的问题和不足,展望了环境中微塑料分析技术的发展趋势。     

利用植物生物技术和农艺措施控制镉在食物链中的迁移

由于人类的工农业活动，Cd成为了自然环境和农业环境中主要散布的重金屑。Cd对各种生物有机体具有潜在的毒性，能引起人类诸多的疾病。由于具有高的移动性和低的中毒浓度，Cd是环境中最危险的重金属之一。而土壤—作物系统是农业生态系统的核心，它是农用化学物质施用及污水灌溉等的主要场所，是Cd向人类食物链迁移积累、直接或间接地危害人体健康的关键环节。利用植物生物技术选育低积累镉的植物基因型、采取相应的农艺措施、控制Cd在食物链中的迁移是农产品安全生产的有效途径。     

Influence of Different Microplastic Forms on pH and Mobility of Cu2+ and Pb2+ in Soil

Microplastics, due to their surface properties, porosity and electrostatic interactions have a high affinity for cations sorption from the aqueous phase. As soil is a complex matrix, interactions between microplastics, soil constituents and heavy metals (HM) may modify the soil microenvironment for heavy metal mobilization/immobilization processes. In order to better understand the problem, three commonly found forms of microplastics in soil (fibers, fragments and microbeads) were mixed with Cu²⁺- or Pb²⁺-contaminated soil and incubated at 22 °C for 180 days. In soil samples pH and the content of water and acid exchangeable species of metals were analyzed. The results of this study showed that the presence of microplastics in HM-contaminated soil affected metal speciation, increasing the amount of easily exchangeable and potentially bioavailable forms of Cu²⁺ or Pb²⁺ in the tested soil. Soil pH also increased, confirming that microplastic particles affect soil properties relevant to the sorption/desorption process of metal cations. Overall, the smallest microplastic particles (≤1 mm), such as fibers or glitter microbeads, had a greater impact on the change in the sorption and desorption conditions of metals in tested soil than larger particles. The findings of our study show that microplastic form, shape and size should be considered as important factors that influence the soil properties and mobility of heavy metals in soil.     

How well-protected are protected areas from anthropogenic microplastic contamination? Review of analytical methods,current trends,and prospects

Microplastics have sparked global concern due to their negative effects on organisms' health and the environment. Microplastics research in protected areas (marine and freshwater) has recently gained prominence and is expected to grow in the coming years. This review of 36 published studies examines current progress and identifies future research challenges. It begins with an overview of microplastic evaluation methodologies, followed by a discussion of recent advances in the abundance of microplastics in water, sediment, biota, wet and dry deposition, and particulate matter. Current quality assurance and control measures are also summarized. The majority of studies (44 %) examined sediment samples. In biota, the gastrointestinal system was the most evaluated for microplastics. Digestion (using H₂O₂ and KOH) and density separation (using NaCl) are the most common microplastic extraction methods. We found that microplastic contamination is pervasive in all the surveyed protected areas, with varying levels of abundance geographically, and over 50 % of the biota ingest microplastics. The methodological discrepancies amongst the investigations, from sampling to microplastics characterization, make it difficult to compare the results and generate baseline data on microplastic contamination levels. Close monitoring and a standardized approach are thus required to determine the extent to which microplastics might enter and persist in protected area environments, as well as to devise effective mitigating strategies.     

Current trends and analytical methods for evaluation of microplastics in stormwater

Stormwater runoff is an important source of microplastics (plastic particles <5 mm) into the aquatic environment and studies documenting the microplastics abundance and their characteristics are constantly expanding. The lack of standardized methods as well as the development of many analytical techniques to evaluate microplastics greatly influence reported results and calls for a better understanding of approaches adopted by microplastic studies in stormwater. Hence, this paper aims to systematically review currently employed methods for sampling, isolating and identifying microplastics and to summarize the data on the abundance of microplastics in the samples of water, sediment and biota collected from stormwater, stormwater catchment areas and stormwater discharging sites. There were significant methodological variations between the studies throughout the experimental procedures and different techniques including, sieving, digestion (chemical and enzyme), density separation and filtration were reported for microplastics extraction from sample matrix. A combination of visual sorting and spectroscopic approaches such as infrared and Raman was adopted to identify and study microplastic characteristics such as shape, size, color and polymer. The microplastic abundance in each sample matrix was different with relatively high concentrations of smaller size particles (10−500 μm), majorly fibrous shaped (51 %) and polymers of polypropylene (27 %) and polyethylene (26 %). Finally, we conclude by identifying analytical challenges and suggesting appropriate methods that can be implemented to enable effective monitoring and comparison of microplastic contamination in stormwater.     

Metal-Organic Framework-based Wood Aerogel for Effective Removal of Micro/Nano Plastics

The large amount of microplastic pollution in the aquatic environment has been regarded as a major challenge facing the world. Although some traditional water treatment processes can effectively remove microplastics in the millimeter range, research is still needed to solve the problem of removing smaller microplastics. Here, we made a durable zinc metal-organic framework-based composite material ZIF-8@Aerogel by in situ growing ZIF-8 on wood aerogel fibers, which can successfully remove microplastics in simulated water and seawater. The removal efficiencies on micro/nano plastics including poly(1,1-difluoroethylene)(60-110 nm) and polystyrene(90-140 nm) reached 91.4% and 85.8%, respectively. This work is expected to provide a new and efficient way to remove small-sized microplastic particles in the environment.     

Organic pollutants adsorbed on microplastics: Analytical methodologies and occurrence in oceans

The massive use of plastics in several products has generated microplastic debris worldwide. Besides their negative effect on marine organisms by ingestion, microplastics are a contamination vector due to their capacity to transport organic pollutants around our planet. To evaluate the magnitude of this issue, it is necessary to know what kinds of contaminants are adsorbed on microplastics, as well as their concentrations. In order to assess the adsorption and desorption of pollutants from microplastics, effective and reliable extraction procedures are required. In this overview, literature reports, in which extraction, separation and determination methods have been applied to analyse the organic pollutants adsorbed on microplastics, are revised and discussed. Furthermore, the worldwide occurrence of organic compounds found on microplastics in oceans is reviewed and the results obtained from different geographical areas and their global distribution trends are compared. Priority organic pollutants, such as polycyclic aromatic hydrocarbons, hexachlorocyclohexanes, polychlorinated benzenes, perfluoroalkyl substances or bisphenol analogues, have been widely found on microplastic samples. Future research that focuses on different kinds of emerging pollutants is required.     

Quality assessment for methodological aspects of microplastics analysis in soil

Over the last several years, a number of studies have concentrated on the occurrence, potential sources, and ecological implications of soil systems. However, the studies’ methodological aspects have received little attention. Thus, this study performed a quality assessment for the methodological aspects of soil microplastics studies by adopting the Criteria for Reporting and Evaluating Ecotoxicity Data (CRED) evaluation method. A total of 35 soil microplastic studies have been evaluated in terms of methodological aspects using 13 criteria, namely, sampling methods and strategy, sample processing and storage, sample size, laboratory preparation, clean air conditions, chemical purity, negative control, positive control, sample pre-treatment, microplastics particle data, particle size, particle shape and polymer type identification. The quality assessment findings indicated that no study scored a maximum of two in all criteria, reiterating the urgent need for enhanced quality assurance for future soil microplastics studies. The average quality assessment scores in soil microplastics studies also indicated that the conditions requiring the most improvement involve both the criteria of positive controls and the criteria of clean air conditions. With a value of zero in 13 assessed criterion, the relevance of the study’s findings in environmental risk assessment was restricted, suggesting that future studies should consider strengthening the implementation and reporting of QA/QC protocol. Adoption of proper quality assurance and contamination control measures will guarantee high data quality and establish confidence in the study’s findings, which allow for reproducibility and comparability as well as acceptability to be utilized in risk assessments.     

Thermodynamic Characteristics and Mechanisms of Heavy Metals Adsorbed onto Urban Soil

The thermodynamic characteristics of heavy metals adsorbed onto urban soil and the relative adsorption mechanisms were studied by the batch experiment. The results show that there existed dynamic adsorption-desorption equilibrium processes of cationic and anionic ions of heavy metals onto urban soil, which may have an impact on the pH of the adsorption system. The amounts of heavy metals adsorbed onto urban soil increased with the increase of the equilibrium concentration, but their adsorption amounts were not the maximum adsorption amounts. The higher the pH was, the greater the adsorption capacity of the urban soil at the same equilibrium concentration was, and the adsorption amounts of heavy metals onto urban soil followed the order of Pb>Cu>Cd>Zn>Ni. There were coordination reaction, hydrolysis reaction, exchange reaction in the adsorption processes of heavy metals onto urban soil. With the increase of pH, the influencing degree of pH on the different reactions of heavy metals in the soil increased, meanwhile the effects of other physicochemical properties of soil on the adsorption of heavy metals were weakened.     

水环境中微塑料的样品采集与分析进展

微塑料在环境中难以降解,可在水体、沉积物等环境介质中长期存在,并在水生生物体内积累,成为人们高度关注的环境问题之一。有关水环境中微塑料的污染研究尚处于起步阶段,快速、高效、准确的检测技术是水环境中微塑料研究的重要环节,对于优化研究路线、分析研究结果、总结微塑料污染规律至关重要。本文结合国内外微塑料污染研究进展,介绍了微塑料污染现状,并通过对环境样品中微塑料的采样、预处理以及定性定量分析方法的系统比较,总结了现行各种检测方法的优缺点及各自应用范围,最后指出了进一步研究的方向。