镉和微塑料及二者复合对秋茄生长及光合特征的影响

doi:10.7525/j.issn.1673-5102.2025.04.012

摘要/Abstract

摘要：

城市红树林面临重金属和微塑料（MPs）复合污染的环境问题。其中，镉（Cd）具有较高的生态风险，聚乙烯（PE）和聚氯乙烯（PVC）是红树林中常见的微塑料污染物。该研究以红树植物秋茄（Kandelia obovata）为研究对象，开展重金属Cd（0、5、50 mg·kg^-1）和微塑料（小粒径PE（13 μm）、大粒径PE（830 μm）；小粒径PVC（13 μm）、大粒径PVC（830 μm））复合胁迫试验，探究Cd和MPs及二者复合对秋茄生长和光合特征的影响。结果表明：（1）PE对秋茄生长的影响不显著；在高Cd胁迫（50 mg·kg^-1）下，大粒径PVC显著抑制根和叶的生长（P<0.05）。（2）叶中营养元素Na、K、Ca、Mg含量受Cd胁迫程度、MPs类型和粒径的影响。（3）MPs与Cd对叶绿素含量的抑制具有协同作用，其中，低Cd（5 mg·kg^-1）与小粒径PVC复合胁迫下叶片中叶绿素a和类胡萝卜素含量最低，高Cd与小粒径PVC复合胁迫下叶片中叶绿素b含量最低；在高Cd胁迫下，小粒径PVC处理使叶净光合速率（P_n）、气孔导度（G_s）和蒸腾速率（T_r）及叶片实际光化学量子产量（Y（Ⅱ））、电子传递速率（ETR）、光化学淬灭系数（q_P）和光化学耗散的相对份额（P）显著提高（P<0.05），说明小粒径PVC处理可以缓解Cd胁迫对秋茄光合作用的毒害作用；与单独Cd胁迫相比，Cd与PE复合胁迫对秋茄叶绿素荧光参数无显著影响。综上，PE及其与Cd复合胁迫对秋茄生长及光合作用影响不显著；PVC对Cd胁迫具有较强的协同作用，小粒径PVC缓解Cd对秋茄光合作用的负面影响，而大粒径PVC的毒害作用更强。

关键词: 秋茄, 重金属, 微塑料, 植物生长

Abstract:

Urban mangroves are faced with the environmental problem of combined pollution of heavy metals and microplastics（MPs）. Cadmium（Cd） has a relatively high ecological risk， with polyethylene（PE） and polyvinyl chloride（PVC） to be common microplastic pollutants in mangroves. A combined stress experiment of Cd（0， 5， 50 mg·kg^-1） and microplastics （small particle size PE-S（13 μm）， large particle size PE-L（830 μm）， small particle size PVC-S（13 μm）， large particle size PVC-L（830 μm）） was carried out for mangrove plant Kandelia obovata. The aims were to explore the influence of Cd， MPs， and their combination on the growth and photosynthetic characteristics of K. obovata. The results showed that （1）the impact of PE-MPs on the growth of K. obovata was not significant. Under high Cd stress（50 mg·kg^-1）， PVC-L significantly restricted the growth of roots and leaves（P<0.05）. （2）The contents of nutrient elements Na，K，Ca，and Mg in leaves were affected by Cd stress， the types and sizes of MPs. （3）MPs and Cd had synergistic effect on the inhibition of chlorophyll content. The contents of chlorophyll a and carotenoids were the lowest under Cd5PVC-S stress， with the lowest content of chlorophyll b under Cd50PVC-S stress. Under Cd50 stress， PVC-S significantly improved net photosynthetic rate P_n， stomatal conductance G_s， transpiration rate T_r， actual photochemical quantum yield（Y（Ⅱ））， electron transfer rate（E_TR）， photochemical quenching coefficient（q_P） and the proportion used for photochemical dissipation（P） of K. obovata leaves（P<0.05）， indicating that PVC-S can alleviate the toxic effects of Cd stress on the photosynthesis of K. obovata. Compared to Cd stress alone， the combined stress of Cd and PE showed no significant effects on chlorophyll fluorescence parameters of K. obovata. Overall， PE and its combined stress with Cd showed no significant effects on the growth and photosynthesis of K. obovata； PVC had a stronger synergistic effect on Cd stress， with PVC-S alleviating the negative effects of Cd on the photosynthesis， and PVC-L having stronger toxic effect.

Key words: Kandelia obovata, heavy metal, microplastics, plant growth

中图分类号:

Q949.761.7

柴民伟, 吴一凡, 李瑞利, 周琳, 沈小雪. 镉和微塑料及二者复合对秋茄生长及光合特征的影响[J]. 植物研究, 2025, 45(4): 603-613.

Minwei CHAI, Yifan WU, Ruili LI, Lin ZHOU, Xiaoxue SHEN. The Influence of Cadmium, Microplastics, and Their Combination on the Growth and Photosynthetic Characteristics of Kandelia obovata[J]. Bulletin of Botanical Research, 2025, 45(4): 603-613.

图/表 7

表1

图1

图2

表2

表3

图3

表4

Cd和MPs复合胁迫下秋茄叶片叶绿素荧光参数特征

组别 Group	最大光化学量子产量F_v/F_m	实际光化学量子产量Y（Ⅱ）	电子传递速率E_TR	光化学淬灭系数q_P	非光化学淬灭系数N_PQ	PSⅡ调节性能量耗散的量子产量 Y（N_PQ）	PSⅡ非调节性能量耗散的量子产量Y（N_PQ）	光化学耗散的相对份额P	非光化学耗散的相对份额E_x	天线热耗散份额D
Cd0N-MPs	0.813±0.037^a	0.67±0.02^a	38.75±1.20^a	0.911±0.029^a	0.20±0.04^a	0.06±0.01^a	0.27±0.01^a	0.67±0.02^a	0.066±0.021^c	0.260±0.008^b
Cd0PE-L	0.811±0.011^a	0.64±0.03^ab	36.66±1.42^ab	0.880±0.035^ab	0.26±0.13^a	0.07±0.03^a	0.29±0.01^a	0.64±0.03^ab	0.087±0.025^bc	0.276±0.001^ab
Cd0PE-S	0.813±0.009^a	0.60±0.02^bc	34.74±0.95^bc	0.854±0.008^bc	0.37±0.10^a	0.11±0.03^a	0.29±0.01^a	0.60±0.02^bc	0.103±0.009^ab	0.293±0.025^a
Cd0PVC-L	—	—	—	—	—	—	—	—	—	—
Cd0PVC-S	0.811±0.002^a	0.59±0.02^c	33.63±1.25^c	0.816±0.028^c	0.30±0.05^a	0.10±0.01^a	0.32±0.02^a	0.59±0.02^c	0.132±0.020^a	0.283±0.004^ab
Cd5N-MPs	0.807±0.006^ab	0.56±0.02^a	31.99±1.15^a	0.814±0.024^a	0.42±0.04^a	0.13±0.01^a	0.31±0.02^a	0.56±0.02^a	0.127±0.016^a	0.317±0.005^a
Cd5PE-L	0.799±0.006^b	0.57±0.01^a	32.80±0.58^a	0.838±0.011^a	0.42±0.04^a	0.13±0.01^a	0.30±0.01^a	0.57±0.01^a	0.110±0.007^a	0.320±0.003^a
Cd5PE-S	0.809±0.003^a	0.62±0.04^a	35.44±2.29^a	0.855±0.044^a	0.27±0.09^a	0.08±0.03^a	0.30±0.01^a	0.62±0.04^a	0.104±0.031^a	0.280±0.018^b
Cd5PVC-L	—	—	—	—	—	—	—	—	—	—
Cd5PVC-S	0.804±0.009^ab	0.58±0.02^a	33.02±0.90^a	0.836±0.017^a	0.39±0.07^a	0.12±0.02^a	0.31±0.02^a	0.57±0.02^a	0.113±0.009^a	0.310±0.021^a
Cd50N-MPs	0.782±0.005^ab	0.44±0.02^c	25.40±1.31^c	0.763±0.029^ab	1.08±0.13^a	0.29±0.01^a	0.27±0.02^a	0.44±0.02^c	0.137±0.016^bc	0.422±0.012^a
Cd50PE-L	0.795±0.003^ab	0.48±0.01^b	27.34±0.53^b	0.768±0.004^b	0.80±0.07^a	0.23±0.01^b	0.29±0.01^a	0.48±0.01^b	0.143±0.004^ab	0.381±0.012^b
Cd50PE-S	0.777±0.019^b	0.47±0.01^b	27.13±0.67^b	0.755±0.009^b	0.67±0.29^ab	0.21±0.06^bc	0.32±0.06^a	0.47±0.01^b	0.153±0.006^a	0.376±0.012^b
Cd50PVC-L	—	—	—	—	—	—	—	—	—	—
Cd50PVC-S	0.804±0.003^a	0.56±0.02^a	31.92±1.24^a	0.825±0.009^a	0.47±0.05^b	0.14±0.01^c	0.30±0.02^a	0.56±0.02^a	0.118±0.003^c	0.327±0.020^c

表4

参考文献 43

[1]	SHI C， YU L Y， CHAI M W，et al.The distribution and risk of mercury in Shenzhen mangroves，representative urban mangroves affected by human activities in China［J］.Marine Pollution Bulletin，2020，151：110866.
[2]	RAHMAN S U， HAN J C， ZHOU Y，et al.Adaptation and remediation strategies of mangroves against heavy metal contamination in global coastal ecosystems：a review［J］.Journal of Cleaner Production，2024，441：140868.
[3]	CHEN Z L， LEE S Y.Contribution of microplastics to carbon storage in coastal wetland sediments［J］.Environmental Science & Technology Letters，2021，8（12）：1045-1050.
[4]	RICO A， REDONDO-HASSELERHARM P E， SCHELL T，et al.Microplastic burial potential and ecological risks in mangrove forests of the Amazon River delta［J］.Science of the Total Environment，2024，957：177666.
[5]	GUO J J， HUANG X P， XIANG L，et al.Source，migration and toxicology of microplastics in soil［J］.Environment International，2020，137：105263.
[6]	刘加强，崔陆，周子振，等.土壤中微塑料：类型、载体效应、迁移行为和潜在风险综述［J］.生态学报，2024，44（9）：3586-3599.
	LIU J Q， CUI L， ZHOU Z Z，et al.Microplastics in soils：a review of types，carrier effects，migration behavior，and potential risks［J］.Acta Ecologica Sinica，2024，44（9）：3586-3599.
[7]	MAI L， HE H， BAO L J，et al.Plastics are an insignificant carrier of riverine organic pollutants to the coastal oceans［J］.Environmental Science & Technology，2020，54（24）：15852-15860.
[8]	DENG J， GUO P Y， ZHANG X Y，et al.Microplastics and accumulated heavy metals in restored mangrove wetland surface sediments at Jinjiang Estuary（Fujian，China）［J］.Marine Pollution Bulletin，2020，159：111482.
[9]	刘倡君，罗专溪，闫钰，等.九龙江口红树林湿地表层沉积物中微塑料赋存特征与重金属的关系［J］.环境科学，2022，43（1）：239-246.
	LIU C J， LUO Z X， YAN Y，et al.Occurrence characteristics of microplastics in mangrove sediments in the Jiulong River estuary and the association with heavy metals［J］.Environmental Science，2022，43（1）：239-246.
[10]	吴萍，张杏锋，高波，等.微塑料对超富集植物少花龙葵Cd累积的影响［J］.环境科学与技术，2022，45（1）：174-181.
	WU P， ZHANG X F， GAO B，et al.Effects of polyethylene on Cd accumulation of hyperaccumulator Solanum photeinocarpum ［J］.Environmental Science & Technology，2022，45（1）：174-181.
[11]	WANG F Y， ZHANG X Q， ZHANG S Q，et al.Effects of co-contamination of microplastics and Cd on plant growth and Cd accumulation［J］.Toxics，2020，8（2）：36.
[12]	ZHANG Z Q， LI Y， QIU T Y，et al.Microplastics addition reduced the toxicity and uptake of cadmium to Brassica chinensis L［J］.Science of the Total Environment，2022，852：158353.
[13]	王泽正，杨亮，李婕，等.微塑料和镉及其复合对水稻种子萌发的影响［J］.农业环境科学学报，2021，40（1）：44-53.
	WANG Z Z， YANG L， LI J，et al.Single and combined effects of microplastics and cadmium on the germination characteristics of rice seeds［J］.Journal of Agro-Environment Science，2021，40（1）：44-53.
[14]	刘沙沙，杨越，吴静华.微（纳）米塑料介导下多环芳烃的毒性效应研究进展［J］.肇庆学院学报，2022，43（2）：61-65.
	LIU S S， YANG Y， WU J H.Toxic effects of polycyclic aromatic hydrocarbons mediated by micro （nano） plastics［J］.Journal of Zhaoqing University，2022，43（2）：61-65.
[15]	WANG B B， WANG P H， ZHAO S B，et al.Combined effects of microplastics and cadmium on the soil-plant system：phytotoxicity，Cd accumulation and microbial activity［J］.Environmental Pollution，2023，333：121960.
[16]	CAO Y X， ZHAO M J， Ma X Y，et al.A critical review on the interactions of microplastics with heavy metals：mechanism and their combined effect on organisms and humans［J］.Science of the Total Environment，2021，788：147620.
[17]	HUANG F Y， CHEN L， YANG X，et al.Unveiling the impacts of microplastics on cadmium transfer in the soil-plant-human system：a review［J］.Journal of Hazardous Materials，2024，477：135221.
[18]	李荣玉，邱国玉，沈小雪，等.镉胁迫下铵态氮对红树植物秋茄（Kandelia obovata）生理生态特征的影响［J］.植物研究，2018，38（5）：653-660.
	LI R Y， QIU G Y， SHEN X X，et al.Effects of ammonium nitrogen on physiological and ecological characteristics of Kandelia obovata under cadmium stress［J］.Bulletin of Botanical Research，2018，38（5）：653-660.
[19]	CHAI M W， LI R L， LI B，et al.Responses of mangrove （Kandelia obovata） growth，photosynthesis，and rhizosphere soil properties to microplastic pollution［J］.Marine Pollution Bulletin，2023，189：114827.
[20]	NACARIO P B，ALFAFARA P A M， CENIZA N A M，et al.Uptake，growth，and oxidative stress responses of Rhizophora mucronata （Poir.in Lam.） propagules exposed to high-density polyethylene microplastics［J］.Marine Pollution Bulletin，2025，212：117569.
[21]	DAI M Y， LU H L， LIU W W，et al.Phosphorus mediation of cadmium stress in two mangrove seedlings Avicennia marina and Kandelia obovata differing in cadmium accumulation［J］.Ecotoxicology and Environmental Safety，2017，139：272-279.
[22]	CHAI M W， LI R L， DING H，et al.Occurrence and contamination of heavy metals in urban mangroves：a case study in Shenzhen，China［J］.Chemosphere，2019，219：165-173.
[23]	FULLER S， GAUTAM A.A procedure for measuring microplastics using pressurized fluid extraction［J］.Environmental Science & Technology，2016，50（11）：5774-5780.
[24]	FEI Y F， HUANG S Y， ZHANG H B，et al.Response of soil enzyme activities and bacterial communities to the accumulation of microplastics in an acid cropped soil［J］.Science of the Total Environment，2020，707：135634.
[25]	郝再彬，苍晶，徐仲.植物生理实验［M］.哈尔滨：哈尔滨工业大学出版社，2004.
	HAO Z B， CANG J， XU Z.Plant physiological experiment［M］.Harbin：Harbin Industrial University Press，2004.
[26]	GENTY B， BRIANTAIS J M， BAKER N R.The relationship between the quantum yield of photosynthetic electron transport and quenching of chlorophyll fluorescence［J］.Biochimica et Biophysica Acta（BBA）-General Subjects，1989，990（1）：87-92.
[27]	张守仁.叶绿素荧光动力学参数的意义及讨论［J］.植物学通报，1999，16（4）：444-448.
	ZHANG S R.A discussion on chlorophyll fluorescence kinetics parameters and their significance［J］.Chinese Bulletin of Botany，1999，16（4）：444-448
[28]	KLUGHAMMER C， SCHREIBER U.Saturation pulse method for assessment of energy conversion in PSⅠ［J］.PAM Application Notes，2008，1：11-14.
[29]	DEMMIG-ADAMS B， ADAMS W W， BARKER D H，et al.Using chlorophyll fluorescence to assess the fraction of absorbed light allocated to thermal dissipation of excess excitation［J］.Physiologia Plantarum，1996，98（2）：253-264.
[30]	杨杰，李连祯，周倩，等.土壤环境中微塑料污染：来源、过程及风险［J］.土壤学报，2021，58（2）：281-298.
	YANG J， LI L Z， ZHOU Q，et al.Microplastics contamination of soil environment：sources，processes and risks［J］.Acta Pedologica Sinica，2021，58（2）：281-298.
[31]	WANG F Y， ZHANG X Q， ZHANG S Q，et al.Interactions of microplastics and cadmium on plant growth and arbuscular mycorrhizal fungal communities in an agricultural soil［J］.Chemosphere，2020，254：126791.
[32]	陈欣，郭薇，李济之，等.土壤微塑料影响植物生长的因素与机制研究进展［J］.农业环境科学学报，2024，43（3）：488-495.
	CHEN X， GUO W， LI J Z，et al.Research progress on the influencing factors and mechanisms of soil microplastics on plant growth［J］.Journal of Agro-Environment Science，2024，43（3）：488-495.
[33]	URBINA M A， CORREA F， ABURTO F，et al.Adsorption of polyethylene microbeads and physiological effects on hydroponic maize［J］.Science of the Total Environment，2020，741：140216.
[34]	QI Y L， YANG X M， PELAEZ A M，et al.Macro- and micro- plastics in soil-plant system：effects of plastic mulch film residues on wheat （Triticum aestivum） growth［J］.Science of the Total Environment，2018，645：1048-1056.
[35]	JIANG X F， CHEN H， LIAO Y C，et al.Ecotoxicity and genotoxicity of polystyrene microplastics on higher plant Vicia faba ［J］.Environmental Pollution，2019，250：831-838.
[36]	DE SOUZA MACHADO A A， LAU C W， KLOAS W，et al.Microplastics can change soil properties and affect plant performance［J］.Environmental Science & Technology，2019，53（10）：6044-6052.
[37]	JAMES R A， MUNNS R， VON CAEMMERER S，et al.Photosynthetic capacity is related to the cellular and subcellular partitioning of Na⁺，K⁺ and Cl^- in salt-affected barley and durum wheat［J］.Plant，Cell & Environment，2006，29（12）：2185-2197.
[38]	GOGORCENA Y， LARBI A， ANDALUZ S，et al.Effects of cadmium on cork oak（Quercus suber L.） plants grown in hydroponics［J］.Tree Physiology，2011，31（12）：1401-1412.
[39]	李贞霞，李庆飞，李瑞静，等.黄瓜幼苗对微塑料和镉污染的生理响应［J］.农业环境科学学报，2020，39（5）：973-981.
	LI Z X， LI Q F， LI R J，et al.Physiological response of cucumber seedlings to microplastics and cadmium［J］.Journal of Agro-Environment Science，2020，39（5）：973-981.
[40]	WANG J L， LIU W T， WANG X，et al.Assessing stress responses in potherb mustard （Brassica juncea var. multiceps） exposed to a synergy of microplastics and cadmium：insights from physiology，oxidative damage，and metabolomics［J］.Science of the Total Environment，2024，907：167920.
[41]	ZOUARI M， AHMED C BEN， ZORRIG W，et al.Exogenous proline mediates alleviation of cadmium stress by promoting photosynthetic activity，water status and antioxidative enzymes activities of young date palm （Phoenix dactylifera L.）［J］.Ecotoxicology and Environmental Safety，2016，128：100-108.
[42]	YAN Z Z， TAM N F Y.Effects of lead stress on anti-oxidative enzymes and stress-related hormones in seedlings of Excoecaria agallocha Linn［J］.Plant and Soil，2013，367（1/2）：327-338.
[43]	BENAVIDES M P， GALLEGO S M， TOMARO M L.Cadmium toxicity in plants［J］.Brazilian Journal of Plant Physiology，2005，17（1）：21-34.

指标 Indicators	变异来源 Sources
指标 Indicators	PE	Cd	PE×Cd	PVC	Cd	PVC×Cd
根生物量 Root biomass	0.75	1.52	1.17	17.02^**	1.22	1.32
茎生物量 Stem biomass	3.10	2.07	0.02	1.34	16.55^***	0.11
叶生物量 Leaf biomass	0.26	6.72^*	0.27	—	—	—
总生物量 Total biomass	0.72	2.22	0.59	22.62^***	2.75	2.88
根冠比 Root-shoot ratio	0.30	2.27	0.77	2.72	8.68^**	4.47^*
叶Na含量 Leaf Na content	22.77^**	17.60^**	0.40	—	—	—
叶K含量 Leaf K content	3.12	1.23	3.36	—	—	—
叶Ca含量 Leaf Ca content	0.10	13.16^**	1.56	—	—	—
叶Mg含量 Leaf Mg content	0.05	19.05^**	7.28^*	—	—	—
叶叶绿素a含量 Leaf chlorophyll a content	1.21	5.43^*	4.15^*	—	—	—
叶叶绿素b含量 Leaf chlorophyll b content	1.65	4.56^*	3.21	—	—	—
叶类胡萝卜素含量 Leaf carotenoids content	0.30	8.33^**	2.22	—	—	—
叶总叶绿素含量 Leaf total chlorophyll content	1.48	4.99^*	3.94^*	—	—	—
叶净光合速率 Leaf P_n	8.23^**	64.70^***	0.55	—	—	—
叶气孔导度 Leaf G_s	12.43^***	23.57^***	41.79^***	—	—	—
叶蒸腾速率 Leaf T_r	0.34	34.97^***	44.10^***	—	—	—
叶水分利用效率 Leaf E_WU	0.56	132.51^***	103.47^***	—	—	—
叶最大光化学量子产量 Leaf F_v/F_m	0.18	10.65^**	3.11	—	—	—
叶实际光化学量子产量 Leaf Y（Ⅱ）	0.08	79.17^***	5.18^*	—	—	—
叶电子传递速率 Leaf E_TR	0.08	79.17^***	5.18^*	—	—	—
叶光化学淬灭系数 Leaf q_P	0.43	33.04^***	1.25	—	—	—
叶非光化学淬灭系数 Leaf N_PQ	0.62	15.15^***	1.51	—	—	—
叶PSⅡ调节性能量耗散的量子产量 Leaf Y（N_PQ）	0.73	29.24^***	2.46	—	—	—
叶PSⅡ非调节性能量耗散的量子产量 Leaf Y（N_O）	0.72	0.92	0.81	—	—	—
光化学耗散的相对份额 Leaf P	0.08	79.17^***	5.18^*	—	—	—
非光化学耗散的相对份额 Leaf E_x	0.68	15.75^***	0.64	—	—	—
天线热耗散份额Leaf D	2.01	73.90^***	6.02^*	—	—	—

组别 Group	元素质量分数 Element mass fraction/（mg·g^-1）				Na∶K
组别 Group	Na	K	Ca	Mg	Na∶K
Cd0N-MPs	10.60±2.46^a	24.30±1.01^a	11.24±1.45^a	7.63±0.73^a	0.44±0.12^a
Cd0PE-L	6.01±0.90^a	17.99±2.14^b	12.05±1.63^a	7.04±0.82^a	0.34±0.07^a
Cd0PE-S	7.82±1.53^a	12.05±1.17^c	9.27±0.36^a	5.87±0.45^a	0.61±0.09^a
Cd0PVC-L	—	—	—	—	—
Cd0PVC-S	7.00±1.87^a	13.57±2.71^c	9.43±0.41^a	6.18±1.11^a	0.51±0.07^a
Cd5N-MPs	11.08±3.76^a	16.82±1.03^b	9.54±2.04^a	6.41±1.39^a	0.66±0.21^a
Cd5PE-L	11.72±1.51^a	22.23±1.54^a	10.79±3.17^a	6.94±1.29^a	0.53±0.05^a
Cd5PE-S	7.23±2.19^a	22.35±4.20^ab	11.90±0.52^a	8.10±0.35^a	0.34±0.16^a
Cd5PVC-L	—	—	—	—	—
Cd5PVC-S	7.84±0.30^a	19.25±±1.07^ab	9.18±1.53^a	6.45±0.49^a	0.41±0.02^a
Cd50N-MPs	8.58±1.93^b	23.28±1.34^a	10.28±0.98^a	6.56±0.66^a	0.37±0.08^a
Cd50PE-L	14.69±1.55^a	23.57±1.70^a	7.94±2.62^ab	6.28±0.27^a	0.63±0.09^a
Cd50PE-S	11.24±1.10^ab	16.90±5.20^b	6.05±0.45^b	5.31±0.28^b	0.70±0.19^a
Cd50PVC-L	—	—	—	—	—
Cd50PVC-S	8.63±2.51^b	11.96±1.14^b	10.21±1.40^a	7.14±0.50^a	0.70±0.25^a