PAEs胁迫对高/低累积品种水稻根系形态及根系分泌低分子有机酸的影响

以前期筛选获得的邻苯二甲酸酯(PAEs)高/低累积基因型水稻(Oryza sativa L.)品种(培杂泰丰/丰优丝苗)进行水培试验,分别于分蘖期和拔节期采集样品,采用根系扫描仪分析根系形态学特性、高效液相色谱法测定根系分泌物中低分子有机酸成分,以及采用气相色谱-质谱仪(GC-MS)测定水稻根、茎、叶中PAEs质量分数。对比研究两种基因型水稻的根系形态特征和根系分泌物(低分子有机酸)的差异,初步探讨两种基因型水稻吸收累积PAEs差异原因,为保障农产品质量安全提供科学依据。结果表明,随着培养液中PAEs质量浓度增加,两种基因型水稻总根长、根表面积和根体积先增大后减小;相同PAEs质量浓度下,高累积型品种培杂泰丰根系形态指标大多高于丰优丝苗。两种水稻体内的PAEs质量分数均随污染物浓度增大而升高,高PAEs水平(80 mg·L-1)处理是低PAEs水平(20 mg·L-1)处理的3.8~7.3倍(邻苯二甲酸二丁酯(DBP))和2.7~20.4倍(邻苯二甲酸二(2-乙基己基)酯(DEHP)),培杂泰丰高于丰优丝苗。植物体内DBP和DEHP质量分数呈现根叶≥茎。分蘖期两种水稻体内DBP和DEHP质量分数高于拔节期,且与营养液中PAEs的质量浓度呈显著相关,但拔节期的相关程度减弱。拔节期两种水稻根系分泌物中低分子有机酸质量浓度随培养液中PAEs质量浓度升高呈现不同的变化规律,但二者草酸质量浓度均增加(在1.11~8.13 mg·L-1之间),并与根系中DBP和DEHP的质量分数呈显著正相关。说明PAEs胁迫会影响水稻根系形态和低分子有机酸分泌,进而影响水稻对PAEs的吸收累积。     

江苏省不同地区设施菜地土壤-蔬菜中邻苯二甲酸酯分布特征

在江苏省设施菜地共采集50个表层土壤样品和50个蔬菜样品,采用加速溶剂萃取-气质联用仪技术,对土壤-蔬菜中邻苯二甲酸酯(PAEs)含量进行分析,并对其污染分布和污染程度进行评价。结果显示:江苏省设施菜地土壤样品中6种w(PAEs)范围为42.46~276.76μg·kg~(-1),平均值为116.7μg·kg~(-1),检出率为100%,以邻苯二甲酸二正丁酯(DBP)和邻苯二甲酸(2-乙基己基)酯(DEHP)为主,分别占w(PAEs)的64.49%和23.92%;4个产区土壤中w(PAEs)平均值从大到小依次为苏州、淮安、盐城和宿迁,与美国土壤6种优控的PAEs控制标准相比,w(DBP)超过控制标准,超标率为24%。蔬菜样品中w(PAEs)范围为38.31~241.87μg·kg~(-1),平均含量为104.25μg·kg~(-1),检出率为100%,以DEHP和邻苯二甲酸二正辛酯(Dn OP)为主,分别占w(PAEs)的25.34%和24.59%,不同产区蔬菜中w(PAEs)平均值从大到小依次为苏州、盐城、淮安和宿迁,蔬菜中PAEs含量及各组分含量均低于美国和欧洲的建议摄入标准。土壤-蔬菜中w(PAEs)、w(DBP)和w(DEHP)存在显著正相关,不同蔬菜对土壤中6种PAEs化合物的富集能力存在明显差异,对PAEs的富集系数约为1。因此,在设施菜地土壤质量评价过程中,应重视蔬菜自身特性对PAEs吸收和富集的影响。     

接种邻苯二甲酸酯(PAEs)降解菌缓解PAEs对玉米胁迫效应和机制研究

邻苯二甲酸酯(PAEs)是一类典型的环境内分泌干扰物,国内农业土壤普遍受PAEs的污染。土壤中的PAEs可被农作物吸收累积,影响植物的生理生化特性和农产品的质量安全。探索PAEs污染土壤的生物修复技术以及高效降解菌缓解PAEs污染胁迫和降低农作物吸收累积PAEs迫在眉睫。以在土壤中的质量分数和检出频率均较高的邻苯二甲酸二(2-乙基己基)酯(DEHP)为目标化合物,采用DEHP污染土壤(18 mg·kg~(-1)和75 mg·kg~(-1))进行盆栽玉米(Zea mays)试验,研究接种PAEs高效降解菌(嗜吡啶红球菌Rhodococcus pyridinivorans XB)缓解DEHP胁迫对玉米生长、吸收积累DEHP的影响及其抗氧化酶系统的响应。结果显示,经DEHP处理的玉米丙二醛质量摩尔浓度显著增加(P0.05),尤其是高浓度处理的玉米根系丙二醛质量摩尔浓度增加464%;且高浓度处理的玉米根系过氧化氢酶和多酚氧化酶活性显著增加(P0.05),生物量显著下降(P0.05),说明DEHP严重影响玉米的生长。与不接种微生物处理相比,玉米接种菌株XB能显著提高玉米体内超氧化物歧化酶(10%~154%)、过氧化氢酶(11%~34%)及多酚氧化酶(48%~288%)活性,显著降低丙二醛质量摩尔浓度(30%~60%),提高玉米生物量(5%~85%),减少玉米对DEHP的吸收积累(4%~60%)。结果说明菌株XB能缓解土壤DEHP对玉米生长的胁迫,降低玉米吸收积累DEHP,有利于保障农产品质量安全。     

典型废旧塑料处置地土壤中邻苯二甲酸酯污染特征及健康风险

对河北某典型废旧塑料处置地土壤中邻苯二甲酸酯污染水平及分布特征进行了研究.结果表明,废旧塑料处置地土壤中∑_(16)PAEs含量0.517—30.1μg·g~(-1),平均为6.98μg·g~(-1),与电子垃圾处理地土壤PAEs含量处于同一个数量级,高出一般土壤1—2个数量级.邻苯二甲酸二(2-乙基)己酯(DEHP),邻苯二甲酸二异丁酯(DIBP)和邻苯二甲酸二丁酯(DBP)为PAEs污染的主要同系物,其中DEHP对总量贡献率最大,平均为68.8%.废旧塑料回收利用过程中的污染排放是该研究区土壤中PAEs的主要来源.对美国EPA和欧盟优先控制的6种PAEs(邻苯二甲酸二甲酯、邻苯二甲酸二乙酯、邻苯二甲酸二丁酯、邻苯二甲酸丁基苄基酯、邻苯二甲酸二(2-乙基)己酯、邻苯二甲酸二正辛酯)同系物进行了风险评价,结果表明成人和儿童对DEHP暴露的致癌风险超出了可接受水平.废旧塑料处置地土壤的PAEs污染应引起高度重视.     

土壤中酞酸酯类化合物测定的精密度控制指标

酞酸酯类化合物(PAEs)包括邻苯二甲酸二甲酯(DMP)、邻苯二甲酸二乙酯(DEP)、邻苯二甲酸二丁酯(DBP)、邻苯二甲酸二辛酯(DOP)、邻苯二甲酸二丁基苄基酯(BBP)和邻苯二甲酸二(2-乙基已基)酯(DEHP).PAEs随着工业生产的发展及塑料制品的大量使用,PAEs已成为全球性最普遍的污染物,造成对空气、水和土壤的污染.我国土壤中PAEs的测     

一株同时降解3种邻苯二甲酸酯降解菌的筛选鉴定及降解特性

选择邻苯二甲酸二甲酯(DMP)、邻苯二甲酸二丁酯(DnBP)和邻苯二甲酸二(2-乙基己基)酯(DEHP)作为目标污染物,采用富集驯化法从设施菜地土壤中筛选出1株可同时降解DMP、DnBP和DEHP的细菌MB1.经形态、生理生化特征及16S rDNA序列分析,初步鉴定为微杆菌属(Microbacterium sp.).通过正交试验研究了该菌株的最优降解条件以及最优条件下该菌株的生长曲线和降解曲线,最后在培养条件下研究了该菌株对人工污染土壤中邻苯二甲酸酯的降解特性.结果表明,菌株MB1的最优降解条件为:pH值为8,温度为25℃,接菌量为5%,每种邻苯二甲酸酯浓度为300 mg·L~(-1).在此最优条件下该菌株呈S型曲线增长,7 d后无机盐培养液中DMP、DnBP和DEHP的降解率分别为99.62%%、99.65%和55.26%.人工污染土壤中空白试验和投加菌株试验结果为:在不添加菌液的处理中,灭菌土壤21 d时DMP、DnBP和DEHP的降解率分别为3.86%、4.19%和2.01%;未灭菌土壤21 d时对DMP、DnBP和DEHP的降解率分别为4.82%、5.99%和3.44%.在添加菌液的处理中,21 d时土壤灭菌处理中DMP、DnBP和DEHP的降解率分别达94.45%、95.65%和39.21%;而土壤未灭菌处理中DMP、DnBP和DEHP的降解率分别达94.93%、95.99%和41.16%.该结果表明:土壤中土著微生物仅能降解微量PAEs,菌株MB1对土壤中DMP、DnBP和DEHP等3种PAEs污染物具有较为高效的降解能力,未灭菌土壤中邻苯二甲酸酯的降解效果略高于灭菌土壤.     

中国中西部地区土壤和农产品中邻苯二甲酸酯污染特征及评价

为评估不同地区农田土壤和农产品中邻苯二甲酸酯（phthalic acid esters,PAEs）风险,在江苏、陕西、河南、河北开展土壤-农产品（蔬菜和小麦）协同采样,共采集106对土壤-农产品样品,分析了土壤-农产品中PAEs化合物含量,并对其污染分布、污染程度进行了评价.结果显示,调查区土壤样品中6种PAEs化合物总浓度（∑PAEs）范围为33.70—895.53μg·kg^-1,平均值为152.22μg·kg^-1,检出率为100%.土样中邻苯二甲酸二乙酯（diethyl phthalate, DEP）、邻苯二甲酸二正丁酯（di-n-butyl phthalate, DBP）、邻苯二甲酸丁基苄（benzyl butyl phthalate, BBP）、邻苯二甲酸（2-乙基已基）酯(di（2-ethylhexyl）phthalate, DEHP)和邻苯二甲酸二正辛酯（di-n-octyl phthalate, DnOP）的检出率为100%,其中DBP、 DEHP和BBP是调查区土壤中PAEs的主要组成部分,分别占∑PAEs总量的51.51%、...     

长江干流、嘉陵江和乌江重庆段邻苯二甲酸酯污染特征及生态风险评估

以重庆境内长江干流及其主要支流嘉陵江和乌江,作为研究对象,系统分析了沿江不同监测位点水体和沉积物中16种邻苯二甲酸酯(phthalic acid esters,PAEs)的含量、组成和分布;同时开展了水体和沉积物中PAEs的生态风险评估。水体中共检出7种PAEs,总浓度范围为6.18～81.8μg·L-1,主要污染物为邻苯二甲酸二丁酯(dibutyl phthalate,DBP)、邻苯二甲酸丁基苄基酯(butyl benzyl phthalate,BBP)和邻苯二甲酸二甲酯(dimethyl phthalate,DMP)。长江干流中游水体中PAEs的浓度明显高于上游和下游,在乌江汇入长江干流的监测位点水体中也检出了较高浓度的PAEs,主要原因可能与其受周围工业园区所排放废水的影响有关。沉积物中共检出8种PAEs,浓度范围为2.24～12.26μg·g-1,污染物以邻苯二甲酸二(2-乙基己基)酯(bis(2-ethylhexyl) phthalate,DEHP)、BBP和DBP为主;沉积物中PAEs的沿江分布均未发现明显规律,其受工业废水排放的影响相对较小。生态风险评估结果表明,水体中DBP在大部分位点,以及邻苯二甲酸二异丁酯(DIBP)和DEHP在少数位点,均存在一定程度的潜在生态风险,而DMP、邻苯二甲酸二乙酯(DEP)、BBP和邻苯二甲酸二正辛酯(DOP)的生态风险均处于可接受范围;沉积物中DEHP对生物体存在一定的潜在影响,而DBP的潜在风险相对较小。     

汾河流域邻苯二甲酸酯的分布特征及生态风险评价

本文以汾河流域作为研究对象,系统研究了水相及沉积物中6种邻苯二甲酸酯(PAEs)的含量、组成和空间分布,同时对汾河流域水体和沉积物中PAEs进行生态风险评价.研究表明,汾河流域丰水期水相中PAEs总量为2.79—206.33μg·L~(-1),平均浓度按DEHP(邻苯二甲酸(2-乙基己基)酯)DBP(邻苯二甲酸二丁酯)BBP(邻苯二甲酸丁基节基酯)DEP(邻苯二甲酸二乙酯)DMP(邻苯二甲酸二甲酯)DNOP(邻苯二甲酸二正辛酯)的顺序递减.其空间分布结果表现为,干流PAEs浓度低于支流,从上游到下游干流PAEs浓度呈现先升后降的趋势.依据国家地表水环境质量标准(GB3838—2002)对DBP、DEHP标准限值的规定,丰水期有60%的站点超过3μg·L~(-1)和8μg·L~(-1)的限值.丰水期沉积物中PAEs浓度范围为0.064—3.551μg·L~(-1),平均浓度按DEHPDBPDMPDEPBBP的顺序递减,干流PAEs高于支流,中下游PAEs含量高于上游,其中中游的太原段沉积相中PAEs污染相对严重.生态风险评价结果表明,汾河流域水相中PAEs的生态风险大小排序依次为DBPDEHPDEPDMP,DBP和DEHP在大部分采样点存在一定的潜在生态风险,DMP和DEP的生态风险在可接受范围;沉积物PAEs中所有种类的平均含量未超过风险评价的低值(ERL),对生物的潜在危害较小.     

1月天津市大气PM_(2.5)中邻苯二甲酸酯污染特征及暴露分析

本文研究了2014年1月天津市大气PM2.5中邻苯二甲酸酯(PAEs)的污染状况.结果表明,天津市大气PM2.5中PAEs污染以邻苯二甲酸二丁酯(DBP)和邻苯二甲酸二异辛酯(DEHP)为主;PM2.5上载带的∑6PAEs浓度与PM2.5浓度存在相关关系;文教区PAEs浓度低于工业及居住区浓度;大气PM2.5中PAEs经呼吸的日均暴露量邻苯二甲酸二甲酯(DMP)和邻苯二甲酸二丁酯(DBP)较高,且男性高于女性.     

Distribution and sources of phthalate esters in the topsoils of Beijing,China

Phthalate esters in the topsoil samples collected from Beijing were determined by derivatization and gas chromatography–mass spectrometry techniques. The results showed that diethyl phthalate (DEP), diisobutyl phthalate ester (DIBP), dibutyl phthalate ester (DBP), dibutyl (2-ethyl hexyl) phthalate (DEHP), and dimethyl phthalate (DMP) were found in the topsoils. The total concentrations of the five phthalate esters varied from 2.30 to 24.71 μg g^?1. According to phthalate esters (PAEs) control standards in soil of the USA, the standard exceeding rates of DMP, DBP, and DEHP were 100 %, 100 %, and 4.84 % in soils of Beijing, respectively. The rate of DBP exceeding soil remediation standard was 12.9 %. Overall, concentrations of PAEs in Beijing were at a high level in China. The concentrations of DBP, DEHP, and DIBP were high, and the total concentrations of all the phthalate esters were higher in the areas with intensive human activities than in the other areas, which may be related to the use of phthalate compounds (such as the use of plastic products). The total and individual concentrations of phthalate compounds were relatively low in the areas that used plastic films compared with other samples due to the diffusion of atmospheric motion, categories, and amounts of plastic products and other factors. The greatest contributor may be the usage amount of plastic products in people’s daily lives.     

Phytotoxicity in seven higher plant species exposed to di-<Emphasis Type="Italic">n</Emphasis>-butyl phthalate or bis (2-ethylhexyl) phthalate

We investigated phytotoxicity in seven plant species exposed to a range of concentrations (0–500 mg·kg^?1 soil) of di-n-butyl phthalate (DnBP) or bis (2-ethylhexyl) phthalate (DEHP), two representative phthalate esters (PAEs) nominated by USEPA as priority pollutants and known environmental estrogens. We studied seed germination, root elongation, seedling growth, biomass (fresh weight, FW) and malondialdehyde (MDA) content of shoots and roots of wheat (Triticum aestivum L.), alfalfa (Medicago sativa L.), perennial ryegrass (Lolium perenne), radish (Raphanus sativus L.), cucumber (Cucumis sativus L.), oat (Avena sativa) and onion (Allium cepa L.), together with monitoring of plant pigment content (chlorophyll a, b and carotinoids) in alfalfa, radish and onion shoots. Root elongation, seedling growth and biomass of the test species were generally inhibited by DnBP but not by DEHP, indicating a lower level of phytotoxicity of DEHP than of DnBP. MDA contents of four species were promoted by PAE exposure, but not in alfalfa, ryegrass or onion shoots, indicating lower sensitivity of these three species to PAE pollutants. Plant pigment contents were clearly affected under the stress of both pollutants, implying the potential damage to the photosynthetic system of test plants, mainly by decreasing the content of chlorophyll a and b. Results of DnBP and DEHP phytotoxicity to the primary growth of test plants has provided information for the assessment of their environmental risk in the soil and also forms a basis for the further analysis of their toxic effects over the whole growth period of different plant species.     

Phytotoxicity in seven higher plant species exposed to di-n-butyl phthalate or bis (2-ethylhexyl) phthalate

We investigated phytotoxicity in seven plant species exposed to a range of concentrations (0– 500 mg·kg⁻¹ soil) of di-n-butyl phthalate (DnBP) or bis (2-ethylhexyl) phthalate (DEHP), two representative phthalate esters (PAEs) nominated by USEPA as priority pollutants and known environmental estrogens. We studied seed germination, root elongation, seedling growth, biomass (fresh weight, FW) and malondialdehyde (MDA) content of shoots and roots of wheat (Triticum aestivum L.), alfalfa (Medicago sativa L.), perennial ryegrass (Lolium perenne), radish (Raphanus sativus L.), cucumber (Cucumis sativus L.), oat (Avena sativa) and onion (Allium cepa L.), together with monitoring of plant pigment content (chlorophyll a, b and carotinoids) in alfalfa, radish and onion shoots. Root elongation, seedling growth and biomass of the test species were generally inhibited by DnBP but not by DEHP, indicating a lower level of phytotoxicity of DEHP than of DnBP. MDA contents of four species were promoted by PAE exposure, but not in alfalfa, ryegrass or onion shoots, indicating lower sensitivity of these three species to PAE pollutants. Plant pigment contents were clearly affected under the stress of both pollutants, implying the potential damage to the photosynthetic system of test plants, mainly by decreasing the content of chlorophyll a and b. Results of DnBP and DEHP phytotoxicity to the primary growth of test plants has provided information for the assessment of their environmental risk in the soil and also forms a basis for the further analysis of their toxic effects over the whole growth period of different plant species.     

玉米修复芘污染土壤的初步研究

采用60d室内盆栽试验,研究了玉米CT38(ZEAMAYSL.)对多环芳烃芘污染土壤的修复作用.结果表明,无论种植玉米土P系列、无植物对照土M系列(无植物且添加叠氮化钠的灭菌土)和对照土W系列(无植物未灭菌土)中芘的可提取浓度都随着时间的推移逐渐减少,种植玉米加快了土壤中可提取态芘浓度的下降.在芘处理浓度为10—100mg.kg-1的污染土壤中,种植玉米CT38的土壤中芘的去除率达81.9%—89.3%,分别比无植物对照土M系列和对照W系列中芘的去除率高67.5%—70.9%和26.2%—47.0%.玉米也可积累少量芘,但积累量所占芘去除量的比例不足0.3%,植物吸收不是芘去除的主要机理.种植玉米增强了土壤中脱氢酶和脲酶等酶活性,从而促进了植物-根圈微生物体系对芘的生物降解.     

最大累积率识别中国地表水中邻苯二甲酸酯类关键污染物和复合污染生态风险

邻苯二甲酸酯类物质(phthalic acid esters,PAEs)环境存在量大,研究表明其能对水生生物造成寿命减少、发育不良、细胞受损等负效应.因此,为保护水生生物,我国地表水中PAEs的生态风险需要科学评估.本文利用了风险商法(risk quotient,RQ)、最大累积率法(maximum cumulative ratio,MCR)、联合概率曲线法(joint probability curve,JPC)结合毒性当量的概念构建了三层级生态风险评价体系,借此评估了我国地表水中PAEs的分布情况与生态风险.结果显示,我国地表水中共检出19种PAEs,浓度范围为ND—5616.80μg·L^-1.邻苯二甲酸二(2-乙基)己酯(di(2-ethylhexyl)phthalate,DEHP)和邻苯二甲酸二丁酯(dibutyl phthalate,DBP)环境存在量最高,且DEHP为PAEs风险的主要贡献者.以DEHP为参照物,JPC的结果显示我国PAEs对5%生物造成急性影响的概率为6.25%—24.02%,造成慢性影响的概率为8.05%—27.79%.PAEs对我国水生生态系统,尤其是西北、东北、中部及华东地区存在较高的生态风险.     

Investigating into composition,distribution, sources and health risk of phthalic acid esters in street dust of Xi’an City,Northwest China

Phthalic acid esters (PAEs) are widely used as plasticizers and in consumer products, which may enter the environment and present risks to human health. U.S. EPA classifies six PAEs as priority pollutants, which could be accumulated in street dust at the interface of atmosphere, biosphere and geosphere. This study collected a total of 58 street dust samples from Xi’an City in Northwest China and analyzed for concentrations of the priority PAEs. Composition, distribution, sources and health risk of the PAEs were further examined. All the priority PAEs were detected in the street dust. The concentrations of individual PAEs varied between not detected and 183.19 mg/kg. The sum of the 6 priority PAEs (∑6PAEs) ranged from 0.87 to 250.30 mg/kg with a mean of 40.48 mg/kg. The most abundant PAEs in the street dust were di-n-butyl phthalate and di (2-ethylhexyl) phthalate (DEHP). Higher concentrations of ∑6PAEs in the street dust were found in the south and west parts of Xi’an City as well as its urban center, which were possibly attributed to the prevailing northerly Asian winter monsoon. The PAEs in the street dust originated mainly from wide application of plasticizers as well as cosmetics and personal care products. The main pathways of human exposure to PAEs in the street dust were ingestion and dermal adsorption of dust particles. The non-cancer risk of human exposure to PAEs in the street dust was relatively low, while the risk to children was higher than that to adults. The cancer risk of human exposure to DEHP in the street dust was lower than the standard limit value of 10^?6.     

日常衣物中的邻苯二甲酸酯污染及其人体暴露风险

邻苯二甲酸酯(PAEs)作为一类内分泌干扰物,被广泛应用于工业生产。为了查明日常衣物中PAEs的污染状况,并评估其通过衣物的皮肤接触可能造成的人体暴露风险,本研究检测了日常生活中的新、旧衣服中7种典型PAEs的浓度,并通过实验模拟研究了衣料中PAEs向汗液的析出行为。结果表明,邻苯二甲酸二丁酯(DBP)和邻苯二甲酸二异辛酯(DEHP)分别是旧衣服和新衣服中的代表性PAE。旧衣服中DEHP的浓度显著高于新衣服;婴儿衣服中DEHP的浓度高于成人衣服。穿着和清洗过程中的二次污染可能对衣服中的PAEs有显著影响,衣服材质可能是影响旧衣服中PAEs浓度的重要因素。汗液会导致衣物中的PAEs析出,从而明显增加PAEs的人体暴露风险。     

行道树悬铃木叶片中邻苯二甲酸酯的研究

采集上海市杨浦区部分交通道路两侧行道树悬铃木叶片样品,对邻苯二甲酸酯(PAEs)的分布特征进行分析.结果表明,叶片组织和表面附着物中均含有邻苯二甲酸二丁酯(DBP)和邻苯二甲酸二(2-乙基)己酯(DEHP);叶片组织易于吸收主要以气相存在于大气中的DBP,质量面积比范围高于表面附着物8倍以上;而主要存在于大气悬浮颗粒中的DEHP在叶片表面附着物中的质量面积比高于DBP.行道树悬铃木叶片中的PAEs质量面积比与机动车流量有一定的相关性.     

Occurrence and migration of microplastics and plasticizers in different wastewater and sludge treatment units in municipal wastewater treatment plant

● Reduce the quantifying MPs time by using Nile red staining. ● The removal rate of MPs and PAEs in wastewater and sludge were investigated. ● MPs and PAEs were firstly analyzed during thermal hydrolysis treatment. ● The removal of PAEs from wastewater and sludge was mainly biodegradation. Microplastics (MPs) and plasticizers, such as phthalate esters (PAEs), were frequently detected in municipal wastewater treatment plants (MWTP). Previous research mainly studied the removal of MPs and PAEs in wastewater. However, the occurrence of MPs and PAEs in the sludge was generally ignored. To comprehensively investigate the occurrence and the migration behaviors of MPs and PAEs in MWTP, a series of representative parameters including the number, size, color, shape of MPs, and the concentrations of PAEs in wastewater and sludge were systematically investigated. In this study, the concentrations of MPs in the influent and effluent were 15.46±0.37 and 0.30±0.14 particles/L. The MP removal efficiency of 98.1% was achieved and about 73.8% of MPs were accumulated in the sludge in the MWTP. The numbers of MPs in the sludge before and after digestion were 4.40±0.14 and 0.31±0.01 particles/g (dry sludge), respectively. Fourier Transform Infrared Spectroscopy (ATR FT-IR) analysis showed that the main types of MPs were polyethylene terephthalate (PET), polypropylene (PP), polyethylene (PE), and polystyrene (PS). Six PAEs, including phthalate (DMP), diethyl phthalate (DEP), diisobutyl phthalate (DIBP), ortho dibutyl phthalate (DBP), butyl benzyl phthalate (BBP), and bis(2-ethyl) hexyl phthalate (DEHP), were detected in the MWTP. The concentrations of total PAEs (ΣPAEs) in the influent and effluent were 76.66 and 6.28 µg/L, respectively. The concentrations of ΣPAEs in the sludge before and after digestion were 152.64 and 31.70 µg/g, respectively. In the process of thermal hydrolysis, the number and size of MPs decreased accompanied by the increase of the plasticizer concentration.     

A simple approach to modeling microbial biomass in the rhizosphere

Microorganisms make an important contribution to the degradation of contaminants in bioremediation as well as in phytoremediation. An accurate estimation of microbial concentrations in the soil would be valuable in predicting contaminant dissipation during various bioremediation processes. A simple modeling approach to quantify the microbial biomass in the rhizosphere was developed in this study. Experiments were conducted using field column lysimeters planted with Eastern gamagrass. The microbial biomass concentrations from the rhizosphere soil, bulk soil, and unplanted soil were monitored for six months using an incubation–fumigation method. The proposed model was applied to the field microbial biomass data and good correlation between simulated and experimental data was achieved. The results indicate that plants increase microbial concentrations in the soil by providing root exudates as growth substrates for microorganisms. Since plant roots are initially small and do not produce large quantities of exudates when first seeded, the addition of exogenous substrates may be needed to increase initial microbial concentrations at the start of phytoremediation projects.