不同裂解温度稻壳生物炭对阿特拉津的吸附行为及机制

为探究不同裂解温度下稻壳生物炭的结构和性质差异及其对阿特拉津（AT）的吸附作用机制和构-效关系,以稻壳为原料在300、500和700℃下制备稻壳生物炭（分别记为RH300、RH500、RH700）,通过电镜扫描、元素分析仪、比表面积分析仪和傅里叶变换红外光谱分析仪等对3种稻壳生物炭进行结构表征分析,并采用批量等温吸附法研究稻壳生物炭对AT的吸附特性.结果表明:裂解温度由300℃升至700℃时,稻壳生物炭中w（C）由48.81%升至64.67%,w（H）、w（N）和w（O）则由3.22%、1.45%和34.66%分别降至0.89%、0.92%和16.29%,原子比H/C、O/C和（O+N）/C值均降低.可见,随着裂解温度升高,稻壳生物炭的芳香性增强,亲水性和极性降低,且比表面积和孔体积增大,平均孔径减小.3种稻壳生物炭对AT的吸附均可用Freundlich和Langmuir两种等温吸附模型进行较好地拟合（R≥0.948,P < 0.01）,吸附作用及非线性程度与生物炭的比表面积（SSA）、芳香性（H/C）、亲水性（O/C）和极性〔（O+N）/C〕呈良好的指数关系,大小表现为RH700 > RH500 > RH300.稻壳生物炭对AT的吸附机制主要包括分配作用和表面吸附,分配作用强度与生物炭的极性和炭化程度有关;而表面吸附作用与AT的分子大小有关,3种稻壳生物炭对AT的表面吸附除表面覆盖外,还存在多层平铺、毛细管现象和孔隙填充等.研究显示,裂解温度是影响生物炭吸附有机污染物的重要因素,在综合考虑成本和制备工艺的同时,适当提高裂解温度可增强生物炭对有机污染物的吸附作用.      

水稻秸秆生物碳对重金属Pb2+的吸附作用及影响因素

以农业废弃物水稻秸秆为原料,采用限氧裂解法制备了不同温度(350、500和700℃)下的秸秆生物碳(RC350、RC500和RC700),研究了生物碳对Pb2+的吸附性能、作用机制及影响因素,为准确预测生物碳还田固碳对土壤中重金属迁移行为的影响提供理论参考.结果表明,生物碳对Pb2+的吸附行为符合准一级动力学方程,Pb2+在RC350、RC500、RC700上的吸附速率分别为0.167h-1、0.154h-1、0.388h-1;其等温吸附曲线符合Langmuir方程,最大吸附量分别为65.3、85.7和76.3mg·g-1,是原秸秆生物质RC100的5～6倍、活性炭AC的2～3倍.生物碳单位面积上的有效吸附点位比AC高约10倍.经酸化去除表面矿物成分后,RC350和RC700对Pb2+的吸附能力急剧下降,其最大吸附量、吸附亲和力与AC相近;红外光谱分析表明,去灰分后生物碳上有机碳官能团并无明显减少,而无机矿物(如SiO2)含量显著降低.生物碳中的有机碳组分和无机矿物组分对其吸附Pb2+均有重要贡献,其中无机矿物组分的吸附量及亲和力均大于有机碳组分.     

秸秆生物碳的结构特征及其对17β-雌二醇的吸附性能

以小麦和水稻秸秆为原料,采用限氧裂解法在400 ℃下制备秸秆生物碳,利用热重分析、元素分析、FTIR(红外光谱分析)和BET-N₂比表面及孔径分布等手段表征生物碳的结构与组成,探讨其对天然类固醇雌激素E2(17β-雌二醇)的吸附特性. 结果表明:小麦和水稻秸秆在40~70、300~350 ℃有2个失重峰,分别为失水和纤维素热解所致;小麦秸秆生物碳中w(C)、w(H)、w(O)、w(N)分别为59.45%、2.81%、20.17%、1.20%,水稻秸秆生物碳中分别为51.14%、2.44%、17.02%、1.04%,2种秸秆生物碳均含有丰富的芳香性官能团及无机矿物组分;小麦和水稻秸秆生物碳比表面积分别为51.32和28.63 m2/g. E2在2种秸秆生物碳中的吸附动力学曲线均符合Elovich方程,吸附热力学曲线符合Freundlich方程,其中,非线性指数(n)分别为0.46和0.42,Freundlich系数K_f为2 526.15和4 368.23. 吸附过程可以被双模型方程很好地拟合,其中表面吸附的饱和吸附量(Q₀)与20 nm以下的总孔体积呈良好正相关,分配作用则因原料不同而呈很大差异,影响因素尚需进一步研究.      

芦苇秸秆生物炭对水中菲和1,1-二氯乙烯的吸附特性

在500℃热解温度下自制芦苇秸秆生物炭吸附剂,研究生物炭对水中两种典型有机污染物菲(PHE)和1,1-二氯乙烯(1,1-DCE)的吸附特性,探讨其吸附机制,并考察溶液p H和生物炭投加量对吸附效果的影响.结果表明,生物炭对PHE和1,1-DCE的吸附分别在60 min和480 min时达到平衡,最大去除率分别为81.87%和90.18%,两者的吸附动力学规律均符合准二级动力学方程,其中PHE的二级动力学吸附速率大于1,1-DCE,两者的吸附过程均由膜扩散和颗粒内扩散共同控制,且后者是主要限速步骤;两种有机污染物的等温吸附曲线均可用Freundlich方程描述,且生物炭对1,1-DCE的吸附亲和力强于PHE;PHE和1,1-DCE在生物炭上的吸附机制包括表面吸附作用和分配作用,且以表面吸附作用为主,其中1,1-DCE的表面吸附作用大于PHE,而其分配作用小于PHE,说明污染物性质中分子体积和相对极性是影响总体吸附的主要因素;红外图谱显示,含氧、含氢官能团及π—π相互作用对生物炭吸附两种有机污染物有重要贡献;溶液p H对生物炭吸附PHE和1,1-DCE的影响较小,而生物炭投加量从5增至50 mg时,PHE和1,1-DCE的平衡吸附量分别减少6.78倍和2.18倍,去除率分别提高20.21%和15.78%.     

不同热解温度制备的玉米芯生物炭对对硝基苯酚的吸附作用

以玉米芯为原料,采用限氧热解法制备了不同温度(200~600℃)的玉米芯生物炭,研究玉米芯生物炭对水中对硝基苯酚(PNP)的吸附行为,并对其吸附机制进行了探讨.结果表明,热解温度对生物炭的物理化学性质影响较大,随着热解温度的升高,含氢、氧官能团逐渐消失,生物炭的极性降低,芳香性增强.等温吸附曲线可以被Freundlich模型很好地描述,生物炭的性质对其吸附PNP有着重要影响,Freundlich模型回归参数(n和KF)与玉米芯生物炭的芳香性、亲水性和极性指数[H/C、O/C、(O+N)/C]呈良好的线性关系.定量描述了表面吸附和分配作用的相对贡献,PNP在低温(200℃)制备生物炭上的吸附主要为分配作用,而高温(300~600℃)制备的生物炭对PNP的吸附为π—π电子受体-供体作用和孔填充效应为主的表面吸附机制.     

秸秆生物炭对有机染料的吸附作用及机制

研究了裂解温度分别为500℃和700℃的两种水稻秸秆生物炭(分别标记为W500、W700)对有机染料日落黄和亚甲基蓝的吸附作用及机制.同时,针对实际印染废水的特点,考察了反应温度、p H和硫酸盐对吸附去除效率的影响.结果显示,生物炭对两种染料的吸附均符合准二级动力学方程,等温吸附曲线均可用Freundlich模型较好地描述,但其对两种染料的吸附机制显著不同.生物炭对阳离子染料亚甲基蓝的吸附主要通过离子交换作用,随着生物炭裂解温度升高,其极性基团减少,离子交换作用减弱.生物炭对阴离子染料日落黄的吸附则主要通过生物炭芳香结构与日落黄分子芳环之间的π-π相互作用,随裂解温度升高,生物炭芳香化程度增大,π-π作用随之增大;生物炭对两种染料的吸附去除效率均随反应温度的升高(5~45℃)而增大,且在3p H11、硫酸盐浓度25~2500 mg·L~(-1)的变化范围内,吸附去除效率均保持稳定.     

水稻秸秆主要组分的提取及其对芘的吸附作用

从水稻秸秆中提取主要组分--木质素、纤维素、半纤维素,利用元素分析和红外光谱对其性质进行了表征,并研究了芘在秸秆及其3种组分上的吸附行为.结果表明,各组分性质差异很大,木质素具有较高的芳香性和较低的极性,而纤维素和半纤维素具有较高的极性和脂肪性.不同组分对芘的吸附等温线均符合Freundlich方程,但吸附能力因其结构的差异而不同,木质素对芘的吸附能力最强, 吸附容量KF为5.04×104,比纤维素高100倍左右,而芘在半纤维素上的吸附能力略低于纤维素.低浓度(水相平衡浓度ce=0.01 Sw)下,秸秆对芘的吸附主要受木质素的控制,而且分配系数Kd略低于按照木质素质量分数计算的预测值,可能是由于木质素的烷基和芳香结构被周围的极性结构所覆盖.但在高浓度(ce = 0.5 Sw)时,秸秆对芘的吸附高于各组分的加和,芘向秸秆其他组分的分配作用不能忽略.芘在木质素上的吸附表现为非线性(非线性指数,n = 0.89),而其它3种吸附剂对芘的吸附更趋向于线性(n > 0.96).n值与芳香性呈负相关关系,而与极性呈正相关关系,表明芳香性导致的特殊作用力是造成吸附非线性的主要原因.有机碳标化分配系数Koc随吸附剂芳香性的增强而增大,但随极性的增强而减小.     

不同烧制温度下玉米秸秆生物炭的性质及对萘的吸附性能

以玉米秸秆为原料,在300、500和700℃这3个温度下烧制生物炭,使用元素分析仪测定其元素组成,扫描电镜观测其表面特性,并采用批量吸附实验研究了生物炭对萘的吸附特性.结果表明,随烧制温度升高,玉米秸秆生物炭的碳元素含量从66.79%上升到76.30%,氢和氧元素从4.92%和19.25%下降到3.18%和9.53%;H/C、O/C和(O+N)/C值降低,芳香性和疏水性增强,极性降低.扫描电镜结果显示玉米秸秆生物炭主要是片状颗粒,孔隙少,生物炭表面粗糙程度随温度升高增加.对萘的动力学吸附曲线符合Lagergren准二级模型,初始吸附速率与平衡吸附量随烧制温度上升而上升;等温吸附曲线可用Freundlich模型进行描述,生物炭的吸附能力随烧制温度升高而增强,非线性先下降后上升.玉米秸秆生物炭表面形态上具有显著特点,且不同烧制温度对其元素组成、表面特征和对萘的吸附行为有显著影响.     

老化的生物质炭性质变化及对菲吸持的影响

将稻壳分别在350℃和550℃热解温度下制备成生物质炭,避光条件下恒温培养300 d,通过傅里叶变换红外光谱、扫描电镜和核磁共振等技术手段及平衡吸附实验,探究生物质炭老化前后的动态结构变化及对菲吸持作用的影响.结果表明,生物质炭老化过程中氧含量增加,含氧基团增多,对菲的非线性吸附行为显著增强.热解温度的不同决定了生物质炭老化过程中性质变化的差异,350℃热解的生物质炭,老化后极性增强,芳香性减弱,而550℃热解的生物质炭,老化后脂肪族碳类物质增加,羧基减少,芳香性增强,Langmiur预测的菲在350℃热解的生物质炭上老化前后的最大吸附量分别为3.57 mg·g-1、2.35mg·g-1,主要是老化后性质变化抑制了表面吸附作用,而550℃热解的生物质炭上老化前后的最大吸附量分别为0.42mg·g-1、4.17 mg·g-1,老化后吸附量的显著增加主要是生物质炭性质变化促进了对菲的分配作用与表面吸附作用.研究生物质炭在自然环境中的老化行为对环境污染物固定的稳定性有着重要意义.     

不同裂解温度对水稻秸秆制备生物炭及其特性的影响

以农业废弃物水稻秸秆为原料,采用限氧裂解法不同温度(300℃、400℃、500℃、600℃、700℃)下制备生物炭,利用SEM电镜扫描、比表面测定、傅里叶红外光谱、元素分析等现代分析手段对生物炭的结构、形貌、比表面积、孔径、表面官能团和元素含量等理化特性指标进行分析表征.结果表明:随着热解温度的升高,产率和挥发分比例下降,灰分含量升高,p H值增大,含碳量上升,N、H、O含量下降,H/C、O/C、(O+N)/C下降,这表明生物炭芳香性增强,亲水性和极性减弱.生物炭具有丰富的孔隙结构,随着温度升高,孔隙数量增加,孔结构发育更加完全.稻秆生物炭孔结构主要为中孔,且随着热解温度的升高,平均孔径变小,比表面积有所增大,在600℃达到最大.红外光谱结果显示,随着裂解温度升高,水稻秸秆中烷烃基缺失,甲基(—CH3)和亚甲基(—CH2)逐渐消失,而芳香族化合物增加,芳香化程度增强.     

Evaluation of phytoextracting cadmium and lead by sunflower, ricinus, alfalfa and mustard in hydroponic culture

Soil contaminated with heavy metals cadmium(Cd)and lead(Pb)is hard to be remediated.Phytoremediation may be a feasible method to remove toxic metals from soil,but there are few suitable plants which can hyperaccumulate metals.In this study,Cd and Pb accumulation by four plants including sunflower(Helianthus annuus L.),mustard(Brassica juncea L.),alfalfa(Medicago sativa L.), ricinus(Ricinus communis L.)in hydroponic cultures was compared.Results showed that these plants could phytocxtract heavy metals, the ability of accumulation differed with species,concentrations and categories of heavy metals.Values of BCF(bioconcentration factor)and TF(translocation factor)indicated that four species had dissimilar abilities of phytoextraction and transportation of heavy metals.Changes on the biomass of plants,pH and Eh at different treatments revealed that these four plants had distinct responses to Cd and Pb in cultures.Measurements should be taken to improve the phytoremediation of sites contaminated with heavy metals,such as pH and Eh regulations,and so forth.     

Oxidation of As(Ⅲ) by potassium permanganate

The oxidation of As(Ⅲ) with potassium permanganate was studied under conditions including pH, initial As(Ⅲ) concentration and dosage of Mn(Ⅶ). The results have shown that potassium permanganate was an effective agent for oxidizing of As(Ⅲ) in a wide pH range. The pH value of tested water was not a significant factor affecting the oxidation of As(Ⅲ) by Mn(Ⅶ). Although theoretical redox analyses suggest that Mn(Ⅶ) should have better performance in oxidization of As(Ⅲ) within lower pH ranges, the experimental results show that the oxidation efficiencies of As(Ⅲ) under basic and acidic conditions were similar, which may be due to the adsorption of As(Ⅲ) on the Mn(OH)2 and MnO2 resulting from the oxidation of As(Ⅲ).     

Chlorobenzenes in waterweeds from the Xijiang River （Guangdong section） of the Pearl River

The Xijiang River is the major source of water for about 4.5 millions of urban population and 28.7 millions of rural population. The water quality is very important for the health of the rural population. The concentration and distribution of chlorobenzenes (CBs) in both water and waterweeds collected from 4 stations in the Xijiang River (Gangdong section) of the Pearl River in April and November were determined. The result showed that nearly every congener of CBs was detected. The total contents of CBs (∑CBs) in the river water ranged from 111.1 to 360.0 ng/L in April and from 151.9 to 481.7 ng/L in November, respectively. The pollution level of CBs in the water in April was higher than that in November. The contents of ∑ CBs in waterweeds ranged from 13.53×102 μg/g to 38.27×102μg/g dry weight (dw). There was no significant difference between April and November in waterweeds. The distribution of CBs in roots, caulis, and leaves of Vallisneria spiralis L. showed different patterns. The leaves mainly contained low-molecular-weight CBs(DCBs), whereas the roots accumulated more PCBs and HCBs. The average lgBCFlip (bioconcentration factor) of CBs ranged from 0.64 to 3.57 in the waterweeds. The spatial distribution character of CBs in the Xijiang River was: Fengkai County ＜ Yunan County ＜Yun'an County ＜ Gaoyao County according to the ∑CBs, and the pollution deteriorated from the upstream to the downstream of the Xijiang River. Further analysis demonstrated that the discharge of waste containing CBs may be the main source of CBs pollution in the Xijiang River.     

Degradation of 2,4-dichlorophenol with a novel TiO2/Ti-Fe-graphite felt photoelectrocatalytic oxidation process

Degradation of 2,4-dichlorophenol(2,4-DCP)was studied in a novel three-electrode photoelectrocatalytic(PEC)integrative oxidation process,and the factors influencing the degradation rate,such as applied current,flow speed of O_2,pH,adscititious voltage and initial 2,4-DCP concentration were investigated and optimized.H_2O_2 was produced nearby cathode and Fe~(2 )continuously generated from Fe anode in solution when current and O_2 were applied,so,main reactions,H_2O_2-assisted TiO_2 PEC oxidation and E-Fenton reaction,occurred during degradation of 2,4-DCP in this integrative system.The degradation ratio of 2,4-DCP was 93% in this integrative oxidation process,while it was only 31% in E-Fenton process and 46% in H_2O_2-assisted TiO_2 PEC process.So,it revealed that the degradation of 2,4-DCP was improved greatly by photoelectrical cooperation effect.By the investigation of pH,it showed that this integrative process could work well in a wide pH range from pH 3 to pH 9.     

Effect of copper on the degradation of pesticides cypermethrin and cyhalothrin

The influence of coexisting copper (Cu) ion on the degradation of pesticides pyrethroid cypermethrin and cyhalothrin in soil and photodegradation in water system were studied.Serial concentrations of the pesticides with the addition of copper ion were spiked in the soil and incubated for a regular period of time,the analysis of the extracts from the soil was carried out using gas chromatography (GC).The photodegradation of pyrethroids in water system was conducted under UV irradiation.The effect of Cu~(2 ) on the pesticides degradation was measured with half life (t_(0.5)) of degradation.It was found that a negative correlation between the degradation of the pyrethroid pesticides in soil and Cu addition was observed.But Cu~(2 ) could accelerate photodegradation of the pyrethroids in water.The t_(0.5) for cyhalothrin extended from 6.7 to 6.8 d while for cypermethrin extended from 8.1 to 10.9 d with the presence of copper ion in soil.As for photodegradation,t_(0.5) for cyhalothrin reduced from 173.3 to 115.5 rain and for cypermethrin from 115.5 to 99.0 min.The results suggested that copper influenced the degradation of the pesticides in soil by affecting the activity of microorganisms.However, it had catalyst tendency for photodegradation in water system.The difference for the degradation efficiency of pyrethroid isomers in soil was also observed.Copper could obviously accelerate the degradation of some special isomers.     

Effects of arsenic on seed germination and physiological activities in wheat seedlings

The effects of arsenic(As)were investigated on seed germination,root and shoot length and their biomass and some other factors to elucidate the toxicity of As.The results showed low concentrations of As(O-1 mg/kg)stimulated seed germination and the growth of root and shoot,however,these factors all decreased gradually at high concentrations of As(5-20 mg/kg).The contents Of O2-,MDA,soluble protein and peroxidase(POD)activity all increased with increasing As concentrations.Soluble sugar content,ascorbate peroxidase(APX),and superoxide dismutase(SOD)activities decreased at low concentrations of As,and increased at high concentrations of As.While acetylsalicylic acid(ASA)and chlorophyll contents,catalase(CAT)activity displayed increasing trend when the concentrations of As was lower than 1 mg/kg,and then decreasing trend.By polyacrylamide gel electrophoresis(PAGE).As induced the expression of POD isozymes of wheat seedlings.As induced the expression of CAT isozymes but inhibited the expression of SOD isozymes of wheat seedlings at concentrations lower than 1 mg/kg.However,As inhibited the expression of CAT isozymes but induced the expression of SOD isozymes at concentrations higher than 5 mg/kg.The results indicated As could exert harmfulness in the early development stage of wheat at inappropriate concentrations.     

Sustainability： A view from the wind-eroded field

This article explores the assessment of sustainability in fields subject to wind erosion. In the first part, simple sustainability audits are examined, as of soil depth and nutrients. Direct measurement of these characteristics has many problems, largely because of huge variability in space and time at all scales. Modelling still has its problems, but it may be possible to overcome many of them soon. It is true that wind erosion preferentially removes soil nutrients, but there are imponderables even here. The nutrient balance in many of these soils includes considerable input from dust. In West Africa, it has been shown that the amounts of calcium and potassium that are added in dust are sufficient to fertilize dispersed crops. In mildly acidic sandy soils, such as those found on the widespread palaeo- aeolian deposits, much of the phosphorus is fixed and unavailable to plants by the time it is removed by wind erosion, so that erosion has no added downside. Most of the nutrients carried by dust have been shown to travel close to the ground （even when they are attached to dust-sized particles）, and so are trapped in nearby fallow strips, and are thus not lost to the farming system. Second, the sustalnabillty of a whole semi-arid farming system is explored. Wind erosion in semi-arid areas （like China, the Sahel and Norflawestern Europe） generally takes place on aeolian deposits of the recent geological past. Most of these soils are deep enough to withstand centuries of wind erosion before they are totally lost to production, and some of these soils have greater fertility at greater depth （so that wind erosion may even improve the soil）. Finally some remarks are made about environmental change in relation to sustainability.     

Bioconcentration kinetics of PCBs in various parts of the lifecycle of the tadpoles Xenopus laevis

Polychlorinated biphenyls （PCBs） in Xenopus laevis have been reported only for a few congeners. Additionally, there is very little information on the ability of Xenopus laevis to bioconcentrate PCBs. To address these issues, the tadpole Xenopus laevis was exposed to Aroclor 1254 mixtures in water at room temperature for 110 d followed by an additional 110 d of nonspiked PCBs in the water for the control group. During the whole process, bioconcentration factors （BCFs） of PCBs ranged from 1180 to 15670. For most PCB congeners, the highest and lowest bioconcentrations of the kinetic curves were found to be remarkably simultaneous, respectively. All 141 PCB congeners under the same experimental conditions had no linear correlation on the lgBCF versus lgKow relationship. The relationship between lgBCFs and lgKow followed a parabolic pattern indicative of selective bioconcentration, suggesting that the kinetic curves of the PCB congeners observed in the lifecycle of the tadpoles may be concentrated due to the amphibian special species and internal metabolism. In contrast, lgBCFs for PCBs were inversely related to lgKow, suggesting that a metabolism of the higher Kow PCB congeners occurred. These results support the author＇s conclusion that the tadpole Xenopus laevis plays major roles in the bioconcentration of PCB congeners, and demonstrated that the exposure kinetic curves of PCB congeners are complex. Besides the amphibian metamorphous development, the lifecycle of the tadpole Xenopus laevis also may be of importance in determining the bioconcentration of PCB congeners.     

Amplification of plasmid DNA bound on soil colloidal particles and clay minerals by the polymerase chain reaction

Polymerase chain reaction(PCR)was used to amplify a 600-base pair(bp)sequence of plasmid pGEX-2T DNA bound on soil colloidal particles from Brown soil(Alfisol)and Red soil(Ultisol),and three different minerals(goethite,kaolinite,montmorillonite). DNA bound on soil colloids,kaolinite,and montmorillonite was not amplified when the complexes were used directly but amplification occurred when the soil colloid or kaolinite-DNA complex was diluted,10- and 20-fold.The montmorillonite-DNA complex required at least 100-fold dilution before amplification could be detected.DNA bound on goethile was amplified irrespective of whether the complex was used directly,or diluted 10- and 20-fold.The amplification of mineral-bound plasmid DNA by PCR is,therefore,markedly influenced by the type and concentration of minerals used.This information is of fundamental importance to soil molecular microbial ecology with particular reference to monitoring the fate of genetically engineered microorganisms and their recombinant DNA in soil environments.     

Arsenic uptake and transport of Pteris vittata L. as influenced by phosphate and inorganic arsenic species under sand cu｜ture

In order to understand the similarity or difference of inorganic As species uptake and transport related to phosphorus in As-hyperaccumulator, uptake and transport of arsenate (As(Ⅴ)) and arsenite (As(Ⅲ)) were studied using Pteris vittata L. under sand culture. Higher concentrations of phosphate were found to inhibit accumulation of arsenate and arsenite in the fronds of P. vittata. The reduction in As accumulation was greater in old fronds than in young fronds, and relatively weak in root and rhizome. Moderate increases, from 0.05 to 0.3 mmol/L, in phosphate reduced uptake of As(Ⅲ) more than As(Ⅴ), while the reverse was observed at high concentrations of phosphate (≥ 1.0 mmol/L). Phosphate apparently reduced As transport and the proportion of As accumulated in fronds of P. vittata when As was supplied as As(Ⅴ). It may in part be due to competition between phosphorus and As(Ⅴ) during transport. In contrast, phosphate had a much smaller effect on As transport when the As was supplied as As(Ⅲ). Therefore, the results from present experiments indicates that a higher concentration of phosphate suppressed As accumulation and transport in P. vittata, especially in the fronds, when exposure to As(Ⅴ); but the suppression of phosphate to As transport in the root or rhizome may be insignificant when P. vittata when exposure to As(Ⅲ) under sand culture conditions. The finding will help to understand the interaction of P and As during their uptake process in P. vittata.