The Preliminary Study on Screening and Application of Phthalic Acid-Degrading Bacteria

Phthalic acid is a main pollutant, which is also an important reason for the continuous cropping effect of tobacco. In order to degrade the phthalic acid accumulated in the environment and relieve the obstacle effect of tobacco continuous cropping caused by the accumulation of phthalic acid in the soil. In this study, phthalate degrading bacteria B3 is screened from continuous cropping tobacco soil. The results of biochemical identification and 16sDNA comparison show that the homology between degrading bacterium B3 and Enterobacter sp. is 99%. At the same time, the growth of Enterobacter hormaechei subsp. B3 and the degradation of phthalic acid under different environmental conditions are studied. The results show that the environment with a temperature of 30˚C, PH of 7, and inoculation amount of not less than 1.2%, which is the optimal growth conditions for Enterobacter sp. B3. In an environment with a concentration of phthalic acid not exceeding 500 mg/L, Enterobacter sp. B3 has a better effect on phthalic acid degradation, and the degradation rate can reach 77% in 7 d. The results of indoor potting experiments on tobacco show that the degradation rate of phthalic acid by Enterobacter B3 in the soil is about 45%, which can reduce the inhibitory effect of phthalic acid on the growth of tobacco seedlings. This study enriches the microbial resources for degrading phthalic acid and provides a theoretical basis for alleviating tobacco continuous cropping obstacles.

Adsorption of Phthalic Acid Esters by Humic Acid and Its Research Progress

Humic acid is rich in highly electronegative oxygen-containing organic functional groups,so it has high reactivity and can adsorb phthalic acid ester(PAEs)in the environment to reduce the risk of environmental pollution from PAEs.In this paper,the extraction,characterization and adsorption models of humic acid were reviewed,and the research status of adsorption of PAEs by humic acid was further summarized.Based on these,the feasibility and observable application prospect of humic acid as a cheap adsorbent were analyzed.

Abiotic degradation of four phthalic acid esters in aqueous phase under natural sunlight irradiation

Abiotic degradability of four phthalic acid esters （PAEs） in the aquatic phase was evaluated over a wide pH range 5-9. The PAE solutions in glass test tubes were placed either in the dark and under the natural sunlight irradiation for evaluating the degradation rate via hydrolysis or photolysis plus hydrolysis, respectively, at ambient temperature for 140 d from autumn to winter in Osaka, Japan. The efficiency of abiotic degradation of the PAEs with relatively short alkyl chains, such as butylbenzyl phthalate （BBP） and di-nbutyl phthalate （DBP）, at neutral pH was significantly lower than that in the acidic or alkaline condition. Photolysis was considered to contribute mainly to the total abiotic degradation at all pH. Neither hydrolysis nor photolysis of di-ethylhexyl phthalate （DEHP） proceeded significantly at any pH, especially hydrolysis at neutral pH was negligible. On the other hand, the degradation rate of di- isononyl phthalate （DINP） catalyzed mainly by photolysis was much higher than those of the other PAEs, and was almost completely removed during the experimental period at pH 5 and 9. As a whole, according to the half-life （t1/2） obtained in the experiments, the abiotic degradability of the PAEs was in the sequence： DINP （32-140 d） 〉 DBP （50-360 d）, BBP （58-480 d） 〉 DEHP （390-1600 d） under sunlight irradiation （via photolysis plus hydrolysis）. Although the abiotic degradation rates for BBP, DBP, and DEHP are much lower than the biodegradation rates reported, the photolysis rate for DINP is comparable to its biodegradation rate in the acidic or alkaline condition.

Biodegradability of four phthalic acid esters under anaerobic condition assessed using natural sediment

Biodegradability of di-n-butyl phthalate （DBP）, butylbenzyl phthalate （BBP）, di-ethylhexyl phthalate （DEHP）, and di-isononyl phthalate （DINP） under an anaerobic condition was evaluated using three natural sediment microcosms obtained from ponds in Osaka, which had not been significantly polluted by the chemicals. The degradabilities of the four phthalic acid esters（PAEs） were analyzed by a first-order kinetic model with a lag phase and ranked as DBP〉BBP〉〉DEHP〉DINP. The PAEs with shorter alkyl-chains, DBP and BBP, were degraded with quite short lag phases near to zero and short half-lives of a few days. The PAEs with longer alkyl-chains, DEHP and DINP, were degraded with lag phases of 5-30 d and the quite long half-lives of a couple of hundred days. Although no data was available on the anaerobic biodegradability of D1NP before this study, it was clarified that DINP can be degraded with slow degradation rates. The fact that all the three intact sediments were capable of biodegradation of the PAEs suggests that potential of anaerobic biodegradation of PAEs is widespread in the aquatic environment.

Zirconium-mediated Synthesis and Crystal Structure of 3,6-Diiodo-4,5-dialkyl-phthalic Acid Dimethyl Ester

A novel series of para-diiodobenzene derivatives, 3,6-diiodo-4,5-dialkyl-phthalic acid dimethyl esters, were prepared via cycloaddition of two TMS-substituted alkynes and dimethyl acetylenedicarboxylate, which was mediated by zirconocene. After iodination, three new compounds of 3,6-diiodo-4,5-dimethyl（dipropyl, dibutyl）-phthalic acid dimethyl esters （3a, 3b, 3c） were synthesized in high region-selectivity and yields, and characterized by NMR. The crystal structures were determined by single-crystal X-ray diffraction. The crystal of 3a （C12H121204, Mr = 474.02） belongs to the triclinic system, space group Pi with a = 7.6238（10）, b = 9.4571（12）, c = 10.8221（14） A, a = 66.611（10）, fl = 88.511（12）, 7 ： 77.604（11）% V= 697.93（16） A3, Z= 2, F（000） = 444, Dc = 2.256 mg/m3, g = 4.509 mm-1, T=133（2） K, S = 1.014, R = 0.0229 and wR = 0.0547 for 2644 observed reflections with I 〉 20（/）; the crystal of 3b （C16H201204, Mr - 530.12） is of triclinic system, space group Pi with a = 9.4122（19）, b = 10.626（2）, c = 11.353（2） A, a = 97.90（3）, fl = 113.83（3）, y = 110.22（3）°, V= 922.6（3） A3, Z- 2, F（000） = 508, Dc - 1.908 mg/m3, g = 3.422 mm-1, T = 113（2） K, S = 1.115, R = 0.0428 and wR = 0.1072 for 3971 observed reflections with I〉 20（/）; the crystal of 3c （ClsH241204, Mr = 558.17） belongs to the monoclinic system, space group P21/c with a = 26.396（2）, b = 8.7560（8）, c = 25.7970（18） A, fl = 91.721（4）o, V= 5959.6（8） A3, Z = 12, F（000） = 3240, Dc = 1.866 mg/m3,/z = 3.184 mm-l, T= 113（2） K, S = 1.154, R = 0.0424 and wR = 0.0766 for 13056 observed reflections with I 〉 20（/）.

Syntheses, Structures, and Properties of Five Coordination Polymers Involving Phthalic Acid

Five new coordination polymers Cu（phen）（H2O）（phth）·CH3OH（1）, [Cu（2,2′-bipy）（H2O）]（phth）·3.5H2O（2）, Zn（phen）（phth）（H2O）·1.125H2O（3） and [M（4,4′-bipy）（H2O）2]（phth）·2H2O[M=Zn（4）, Mn（5）]（H2phth=phthalic acid, bipy=bipyridine, phen=1,10-phenanthroline） have been synthesized from the amino acid derivatives（phthalyl-l- valine, H2L） and structurally characterized. H2L was hydrolyzed into phth2- group during the reaction, but the strucure feature was different from that of the complex directly synthesized from H2phth in the reported literature, revealing that H2L played an important role in composing the novel compounds. Compounds 1, 2 and 3 are all 1D chains, but the differences are that compound 1 is further hydrogen-bonded into 2D networks, and compound 2 is further extended into 3D supramolecular network through π-π stacking and hydrogen-bonding interactions. However, compound 3 is a 1D helix chain structure and further links into 2D networks through π-π stacking. Compounds 4 and 5 are isostructural and exhibit the same 2D layers, which are further connected by hydrogen-bonding interactions to form 3D supramolecular network. Antiferromagnetic superexchange was observed for compounds 1, 2 and 5.

QSPR Analysis of the Physicochemical Properties for Phthalic Acid Esters

Based on quantitative structure-property relationship （QSPR） of organic compounds, the molecular connectivity indices of 21 phthalic acid ester compounds were extracted. Relationship between the physicochemical properties （n-octanol/air partition coefficient, vapor pressure, water solubility） and the molecular connectivity indices of phthalic acid ester compounds have been established by multiple linear regression （MLR） method. The results showed that the zero-order valence connectivity index （0Xu） is the topology parameter which affects octanol/water partition coefficient and water solubility, and the topology parameter which affects vapor pressure is the first-order connectivity index （1X）. This indicated to a certain extent_that the molecular connectivity indices can be well used to express the quantitative relationship between the physicochemical properties and structure descriptions of phthalic acid ester compounds. The models constructed have good robustness and highly predictive capability.

Synthesis, Crystal Structure and Properties of a New Coordination Polymer Constructed with 3-(4-hydroxypyridinium-1-yl)phthalic Acid

A new nickel coordination polymer {[Ni（dpa）（bpe）（H2O）]2}n（1） has been hydro-thermally synthesized, and structurally characterized by UV spectroscopy, elemental analyses and single-crystal X-ray diffraction（H2dpa=3-（4-hydroxypyridinium-1-yl） phthalic acid, bpe=μ-1,2-di（4-pyridyl） ethylene）. It crystallizes in the triclinic system, space group P1 with a=8.779（2）, b=10.909（3）, c=12.739（3）, α=72.45（2）, β=75.13（2）, γ=86.47（2）°, V=1124.1（5） 3, Z=2, Mr=516.14, Dc=1.525 g/cm3, μ=0.912 mm-1, Rint=0.0532, F（000）=532, the final R=0.0523 and wR=0.1089 for 3949 observed reflections（I〉2σ（I））. The coordination around the Ni center is a distorted octahedron coordination geometry involving two protonated H2dpa ligands, two bpe ligands, and one coordinated H2O molecule. The dpa2- anion, as a bridging ligand, connects two Ni centers to form binuclear units, which are linked together by the bpe ligands to form two-dimensional layers, and the interlayer hydrogen bonding further extends the 2D sheet into a 3D supramolecular framework.

Transformation of phthalic acid diesters in an anaerobic/anoxic/oxic leachate treatment process

Transformations of di-n-butyl phthalate(DBP) and di(2-ethylhexyl) phthalate(DEHP) have been investigated in anaerobic/anoxic/oxic(A/A/O) leachate treatment processes. Although the DBP removal processes are different when the DBP initial concentration is different, the overall system DBP removal efficiencies are high(N 94%).DEHP is much more difficult to remove than DBP. The removal efficiency of DEHP is approximately 75%–78%.The results of mass balance calculations indicate that approximately 33.7%–50.7% of the DBP is degraded by the activated sludge, 48.9%–64.9% accumulates in the system, and 0.4%–1.4% is contained in the final effluent. Approximately 15.0%–19.0% of the DEHP is degraded by activated microcosms, 75.8%–79.0% accumulates in the system, and 5.2%–6.0% is contained in the final effluent. Biodegradation and adsorption to the activated sludge are the main mechanisms for DBP removal and adsorption to the activated sludge is the main mechanism for DEHP removal. The different removal mechanisms of the two PAEs may be related to their different molecular structures. However, PAEs are not really removed when they adsorb onto the sludge. Therefore, methods for decreasing PAEs adsorption and increasing the biodegradation efficiencies of the leachate treatment processes should be further investigated.

Screening and Application of Phthalic Acid Degrading Bacteria

O-phthalic acid is a kind of important pollutant, which accumulates in the environment with the extensive use of plastics and other products. Meanwhile, phthalic acid is one of the high content of allelopathic autotoxic substances secreted by tobacco. The accumulation of phthalic acid in soil is an important cause of tobacco continuous cropping effect. In order to degrade phthalic acid accumulated in environment, the barrier effect of tobacco continuous cropping caused by phthalic acid accumulation in soil can be removed. A strain capable of degrading phthalic acid was isolated from sludge of sewage treatment plant and compared with 16 s DNA. The homology between this strain and Enterobacter sp. is 99%. The optimum growth conditions are as follows: pH7 at 30°C, 500 mg/L of o-phthalic acid, inoculation concentration ≥ 1.2% and its highest degradation rate of o-phthalic acid is 74%. The results of pot experiment showed that the degradation efficiency of o-phthalic acid in soil was about 40%, which alleviated the inhibitory effect of o-phthalic acid accumulation on tobacco growth.

Unveiling the Nexus the link between water quality index and phthalic acid ester concentrations in Tigris River

Monitoring water quality in an aquatic system is a crucial objective in pursuing sustainable development,despite the challenges posed by water scarcity and the impact of climate change.The objective of the present study was to examine the water quality of the Tigris River along its course from the point of entry into Baghdad city to its exit,particularly in the presence of Phthalic Acid Esters(PAEs).In both dry and wet seasons and from five sites of the river,nine environmental factors(Turbidity,Total dissolved solids,pH,dissolved oxygen,Chloride,nitrate,phosphate,sulfate,and Biological oxygen demand)and three PAEs(di-n-butyl phthalate(DBP),di-isononyl phthalate(DiNP),and di-2-ethyl hexyl phthalate(DEHP))were investigated.Results revealed that the river has high levels of turbidity and Total dissolved solids,slightly alkaline,and well-aerated(dissolved oxygen>7 mg/L).Chloride,nitrate,phosphate,and sulfate values varied between seasons,as high values were recorded in the wet season.Biochemical oxygen demand levels were higher during the dry season.The highest value of total PAEs(2.20μg/L)was observed during the dry season,and the lowest value was in the wet season(1.16μg/L).The HQ results revealed that the river was ranked as a moderate risk area.However the water quality index and environmental risk index classified the water quality as a poor category,with a high-risk score in the study sites within Baghdad city.Therefore,despite the acceptable limit of PAEs in the river's water(<3μg/L),its presence is an early alarm to withdraw attention to its environmental risk.These findings highlight the need for appropriate measures to control and remove pollutants to ensure a safe and healthy water supply in the Tigris River.

Concentration and source identification of polycyclic aromatic hydrocarbons and phthalic acid esters in the surface water of the Yangtze River Delta,China

The pollution from polycyclic aromatic hydrocarbons（PAHs） and phthalic acid esters（PAEs） in the surface water of the rapidly urbanized Yangtze River Delta region was investigated.Fourteen surface water samples were collected in June 2010.Water samples were liquid-liquid extracted using methylene chloride and analyzed by gas chromatography-mass spectrometry.Concentrations of PAHs and PAEs ranged 12.9-638.1 ng/L and 61-28550 ng/L,respectively.Fluoranthene,naphthalene,pyrene,phenanthrene,di-2ethylhexyl phthalate,and di-n-butyl phthalate were the most abundant compounds in the samples.The water samples were moderately polluted with benzo[a]pyrene according to China＇s environmental quality standard for surface water.The two highest concentrations of PAHs and PAEs occurred in samples from Taihu Lake,Wuxi City and the western section of Yangchenghu Lake.Potential sources of pollution at S7 were petroleum combustion and the plastics industry,and at Yangchenghu Lake were petroleum combustion and domestic waste.Pollution in samples from the Beijing-Hangzhou Grand Canal originated from diesel engines.There were no obvious sources of pollution for the other water samples.These results can be used as reference levels for future monitoring programs of pollution from PAHs and PAEs.

Distribution and sources of polycyclic aromatic hydrocarbons and phthalic acid esters in water and surface sediment from the Three Gorges Reservoir

After the impoundment of the Three Gorges Reservoir（TGR）, the hydrological situation of the reservoir has changed greatly. The concentration and distribution of typical persistent organic pollutants in water and sediment have also changed accordingly. In this study, the concentration, distribution and potential sources of 16 polycyclic aromatic hydrocarbons（PAHs） and 6 phthalic acid esters（PAEs） during the water drawdown and impoundment periods were investigated in water and sediment from the TGR. According to our results, PAHs and PAEs showed temporal and spatial variations. The mean ΣPAH and ΣPAE concentrations in water and sediment were both higher during the water impoundment period than during the water drawdown period. The water samples from the main stream showed larger ΣPAH concentration fluctuations than those from tributaries. Both the PAH and PAE concentrations meet the Chinese national water environmental quality standard（GB 3838-2002）. PAH monomers with 2–3 rings and 4 rings were dominant in water, and 4-ring and 5–6-ring PAHs were dominant in sediment. Di-n-butyl phthalate（DBP） and di-2-ethylhexyl phthalate（DEHP）were the dominant PAE pollutants in the TGR. DBP and DEHP had the highest concentrations in water and sediment, respectively. The main source of PAHs in water from the TGR was petroleum and emissions from coal and biomass combustion, whereas the main sources of PAHs in sediments included coal and biomass combustion, petroleum, and petroleum combustion. The main source of PAEs in water was domestic waste, and the plastics and heavy chemical industries were the main sources of PAEs in sediment.

Abiotic association of phthalic acid esters with humic acid of a sludge landfill

The abiotic association between phthalic acid esters （PAEs） and humic substances （HS） in sludge landfill plays an important role in the fate and stability of PAEs. An equilibrium dialysis combined with 14C-labeling was used to study the abiotic association of two abundant PAEs （diethyl phthalate and di-n-butyl phthalate） with humic acid （HA） isolated from a sludge landfill with different stabilization times and different molecular weights. Ele- mental analysis and Fourier Transform Infrared Spectro- photometer （FTIR） suggested that high KA value of HA was related to the high aromatic content and large molecular weight of HA. The results indicated that the association strength of PAEs with HA depended on both the properties of the PAEs and the characteristics of HA. The KA values of the association were strongly dependent on solution pH, and decreased dramatically as the pH was increased from 3.0 to 9.0. The results suggested that non- specific hydrophobic interaction between PAEs and HA was the main contributor to the association of the PAEs with HA. The interactive hydrogen-bonds between the HA and the PAEs molecules may also be involved in the association.

Synthesis and Insecticidal Activities of Novel Phthalic Acid Diamides

In order to discover novel insecticides with the new action mode on ryanodine receptor （RyR）, a series of novel phthalic acid diamide derivatives were designed and synthesized. All compounds were characterized by 1H NMR spectra and HRMS. The preliminary results of biological activity assessment indicated that some title compounds exhibited excellent insecticidal activities against Mythimna separata, Spodoptera exigua, and Plutella xylostella. The title compound 3-nitro-N-cyclopropyl-N＇-[2-methyl-4-（perfluoropropan-2-yl）phenyl]phthalamidte （4a） was more efficient against diamondback moths than the control （chlorantraniliprole）. The effects of some title compounds on intracellular calcium of neurons from the Spodoptera exigua proved that the title compounds were RyR activators.

邻苯二甲酸酯降解功能内生菌群的筛选及定殖效能

为降低邻苯二甲酸酯(PAEs)污染作物对人体健康的威胁,从PAEs污染蔬菜中富集驯化具有PAEs降解高效性和广谱性的功能内生菌群,解析菌群群落组成并优化其降解条件,借助水培体系研究了功能内生菌群在作物体内的定殖效能.高通量测序结果表明,从门的分类水平看,菌群主要由变形菌门(Proteobacteria,76.57%)、拟杆菌门(Bacteroidetes,21.04%)和放线菌门(Actinobacteria,2.37%)组成;从属的分类水平看,菌群主要由鞘氨醇杆菌属(Sphingobacterium,33.03%)、代尔夫特菌属(Delftia,40.61%)、假单胞菌属(Pseudomonas,11.70%)、无色杆菌属(Achromobacter,3.04%)和根瘤菌属(Rhizobium,6.90%)组成.在无机盐纯培养体系中,该菌群在7d内对5mg/L的邻苯二甲酸二甲酯(DMP)、邻苯二甲酸二乙酯(DEP)、邻苯二甲酸二丁酯(DBP)和邻苯二甲酸丁基苄基酯(BBP)降解率分别为97.08%、94.47%、98.02%和44.82%.单因素试验结果表明,菌群降解PAEs的最佳条件为:pH值7、25℃、盐度1%、底物浓度5mg/L.水稻水培试验表明,菌群可以定殖到水稻体内并有效促进PAEs的去除,与对照组相比,处理15d后水稻体内DMP、DEP、DBP和∑PAEs含量分别降低了41.09%、45.33%、63.06%和32.3%.菌群的定殖还能够提高水稻根长、株高和生物量,促进水稻的生长.该菌群在降低作物PAEs积累、保障PAEs污染地区农产品质量安全方面具有良好的应用前景,能有效降低作物PAEs污染对人体健康的威胁.

葡萄叶片对空气中邻苯二甲酸酯的吸收累积特征

【目的】为探索葡萄叶片及其内部组成物质对空气中PAEs的吸收累积特征,阐明葡萄叶片从空气中吸收累积DBP、DEHP、DIBP的能力及规律。【方法】试验采用盆栽葡萄覆盖玻璃罩的方式,在玻璃罩内放置盛有DBP、DEHP、DIBP混合物的甲醇溶液培养皿,让PAEs自然挥发被植株吸收累积,研究叶片及其内部组成物质脂肪、糖、蛋白质对PAEs的吸收累积特征。【结果】3个品种葡萄叶片对DBP、DEHP和DIBP的累积量随着PAEs处理浓度的增高而增大,且不同污染水平各单体含量及总含量差异显著(P<0.05)。葡萄叶片对DEHP的累积量最高,在高污染处理中其累积量占比在92.90%~93.86%,其次为DBP和DIBP。叶片脂肪、糖、蛋白质中均检出DBP、DEHP和DIBP,各污染处理3种化合物的含量与空白差异显著(P<0.05),三者在脂肪中的累积量最多,最高可达87.06 mg/kg,在糖中最高仅为5.818 mg/kg,在蛋白质中最高仅为3.793 mg/kg。通过对葡萄叶片累积PAEs能力与组成物质的相关性进行分析,葡萄叶片PAEs累积量与脂肪中PAEs含量呈显著正相关相关,与糖和蛋白无显著相关性。【结论】葡萄叶片可从空气中吸收累积PAEs,其累积PAEs能力与脂肪密切相关。

再生水受纳湖泊中邻苯二甲酸酯的生态风险时空分布及管控建议

本研究以再生水受纳湖泊J湖为研究对象,基于多介质归趋模型对湖泊水相和沉积相中邻苯二甲酸酯(phthalic acid esters,PAEs)进行不同时空生态风险评估。结果显示,水相和沉积相中邻苯二甲酸二甲酯(dimethyl phthalate,DMP)和邻苯二甲酸二乙酯(diethyl phthalate,DEP)的危险商(hazard quotient,HQ)均小于0.1,对湖泊水生生物的风险水平为无风险;湖泊中的邻苯二甲酸二丁酯(dibutyl phthalate,DBP)和邻苯二甲酸二(2-乙基己)酯(di-(2-ethylhexyl)phthalate,DEHP)生态风险表现出显著的空间异质性,水相中,DBP低风险区占42.7%,DEHP中风险、低风险区分别占93.5%、5.6%;在沉积相中,DBP中风险、低风险区分别占0.5%、69.2%,DEHP中风险、低风险区分别占0.9%、68.3%。不同季节中,湖泊水相DEP、DBP和DEHP的生态风险差异较大,沉积物中PAEs的生态风险随季节变化与水相相似。最后,建议降低再生水中DBP和DEHP的浓度并从源头管控降低DEHP的生产和使用,可以有效降低受纳湖泊中DBP和DEHP的风险水平。

肉桂酸和邻苯二甲酸对沙芥属植物幼苗光合特性的影响

【目的】探讨酚酸类自毒物质对沙芥属植物生长及光合特性的影响,为沙芥属植物的野生资源保护和开发利用提供理论依据。【方法】以沙芥和斧翅沙芥幼苗为试验材料,选择肉桂酸和邻苯二甲酸2种自毒物质,采用盆栽试验,设置0,0.01,0.1,1,10 mmol/L浓度梯度处理,考察幼苗生长、叶绿素含量、叶绿素荧光参数和气体交换参数的变化特征。【结果】(1)肉桂酸、邻苯二甲酸对沙芥幼苗生长均表现为低浓度促进高浓度抑制,而对斧翅沙芥生长则表现为抑制作用,且均在浓度为10 mmol/L时对生长抑制作用最显著。(2)在不同浓度肉桂酸和邻苯二甲酸处理后,沙芥和斧翅沙芥幼苗叶片的叶绿素a、叶绿素b、叶绿素总量均出现不同程度下降。(3)沙芥和斧翅沙芥叶片净光合速率、蒸腾速率、气孔导度在肉桂酸和邻苯二甲酸浓度为10 mmol/L显著低于对照,胞间CO_(2)浓度此时无显著变化,其光合速率降低主要由非气孔因素所致。(4)沙芥和斧翅沙芥的最大光化学效率(F_(v)/F_(m))、实际光化学效率(Ф_(PSⅡ))和光化学淬灭系数(qP)均在肉桂酸和邻苯二甲酸浓度为10 mmol/L显著低于对照,而此时非光化学淬灭系数(NPQ)则显著高于对照。【结论】高浓度邻苯二甲酸和肉桂酸抑制沙芥和斧翅沙芥幼苗的光合作用,降低其光合速率,导致它们叶片的PSⅡ反应中心活性和开放程度受损,进而影响其正常生长;肉桂酸和邻苯二甲酸对沙芥属植物光合特性的影响存在差异,斧翅沙芥幼苗受到影响更大。

酞酸酯在农田土壤中的迁移转化行为和毒性效应

酞酸酯又称邻苯二甲酸酯(phthalic acid esters,PAEs),是环境激素类有机污染物,作为添加剂被广泛应用于各种塑料、橡胶和树脂制品中。随着生产和使用量的大幅增加,PAEs已成为我国农田土壤中残留最多且关注度最高的有机污染物,对农业生态环境和人类健康构成潜在威胁。根据现有研究,在系统梳理我国农田土壤中PAEs的主要来源与分布情况的基础上,综述了PAEs在农田土壤中的吸附、生物降解、迁移和挥发等环境行为的研究进展,并分别评述了PAEs对土壤生物(包括微生物、动物和农作物)和人体的毒性效应。农膜覆盖及其残留物是引起我国农田土壤PAEs污染的最主要原因。其中,约58.5%的PAEs主要分布在农田土壤表层0~20 cm处,并且具有显著的地域性差异。正辛醇-水分配系数对数值(lg K_(ow))大、脂溶性强的PAEs主要吸附在土壤表层,而lg K_(ow)小、水溶性高的PAEs具有极高的迁移潜力;有机质是阻滞PAEs向下迁移的主要原因;微生物降解是去除农田土壤中PAEs的主要途径,受化合物结构和土壤特性的影响。高浓度PAEs的短期暴露会对土壤生物产生不同程度的生理生化毒性乃至遗传毒性影响,最终可通过饮食摄入危害人体(特别是儿童)健康。目前有关农田土壤PAEs的研究仍局限于土壤污染分布和赋存特征的调查性研究,今后可在真实土壤环境中PAEs迁移转化过程、联合毒性效应以及代谢产物的行为和毒性等方面加强研究,以期为农田土壤环境中PAEs控制标准制定和生态风险评估提供理论依据。