Based on field investigation of wave, sediment suspension and the changes in nutrient concentration of the water column in Lake Taihu, China, we proposed two release models to quantify nutrient release under static and dynamic conditions, respectively. Under static conditions, nutrient release from sediments to the overlying water mainly depends on chemical diffusion induced by concentration gradient, in which the nutrient release is controlled by the temperature, dissolved oxygen concentration in the sediment-water interface, oxidation-reduction potential and the concentration difference between porewater and overlying water. Under dynamic condition (or disturbed condition), both dissolved and particulate nutrients in sediments are released into the water column because of wind-induced sediment suspension. The amount of nutrient release under dynamic conditions is larger than that under the static condition. The release of dissolved nutrients, however, does not increase because the wind induced turbulence made oxidation of metallic elements such as Fe (ferric iron), Mn which are capable of precipitating soluble reactive phosphate (SRP). Under dynamic conditions, therefore, the release of total phosphorus (TP) increases dramatically but the release of SRP is close to those under static conditions. In sediments of Lake Taihu, high Fe content leads to a high ratio of Fe to P contents in sediments (Fe:P ratio). Under dynamic conditions, therefore, nutrient release is controlled by the intensity of disturbance, sediment consolidation and nutrient content in sediments. As for dissolved nutrients, especially SRP, the release is also controlled by the intensity of dynamic re-oxidation, Fe content in sediments and nutrient concentration gradient between porewater and overlying water. Based on these two release modes, the release flux in Lake Taihu has been estimated. In the static condition (i.e. laboratory experimental condition), total release of NH4 +-N for whole lake is ca. 10,000 ton/a, and PO4 3−-P is ca. 900 ton/a. In the dynamic condition, nutrient release following sediment suspension was estimated according to three different intensities of wind forcing which were defined as “calm” (wind speed is less than 2 m/s), “gentle” (wind speed is greater than 2 m/s and less than 6 m/s) and “gust” (wind speed is greater than 6 m/s). The release rate in the condition of “calm” was estimated in terms of the nutrient release in the laboratory experimental static condition; whereas the release rate in conditions of “gentle” and “gust” was estimated in terms of measurement during sediment resuspension conducted in flume experiments. With the observation of wind velocity and frequency in 2001, each type of wind forcing took the frequency of 12%, 82% and 6% for “calm”, “gentle” and “gust”, respectively. The yearly release of nitrogen was 81,000 ton and phosphorus was 21,000 ton, which is about 2–6 folds of annual external loading, respectively.
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1.
本文以组织培养技术培养的菹草无菌苗为实验材料,研究了不同浓度(0、0.05、0.10、0.15、0.20 mmol/L)Ni2+胁迫对菹草过氧化氢(H2O2)、超氧阴离子(O2.-)和丙二醛(MDA)的含量、抗氧化系统、脯氨酸代谢途径的影响.结果显示:(1)Ni2+胁迫影响了活性氧水平,主要表现为H2O2和O2.-的大量积累;MDA含量也随着Ni2+浓度的升高呈上升趋势;(2)随着Ni2+浓度的升高,超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性及还原型谷胱甘肽(GSH)、非蛋白巯基(NP-SH)含量均表现为先升后降趋势;抗坏血酸(AsA)含量变化不明显;植物络合素(PCs)则表现为上升趋势;(3)脯氨酸代谢关键酶在Ni2+胁迫下表现为:鸟氨酸转氨酶(OAT)活性在0～0.10 mmol/L Ni2+胁迫下高于对照组;吡咯啉-5-羧酸合成酶(P5CS)活性在Ni2+大于0.10 mmol/L时,显著增加;脯氨酸脱氢酶(ProDH)活性无显著变化;脯氨酸(Pro)含量则均显著高于对照组.以上结果表明,Ni2+胁迫提高了活性氧的水平,加重了膜脂过氧化的程度,干扰了抗氧化系统的内在平衡;此外,低浓度Ni2+胁迫下菹草脯氨酸积量主要依赖于鸟氨酸途径,而高浓度下则主要依靠谷氨酸途径. 相似文献
2.
以菹草(Potamogeton crispus L.)无菌苗为实验材料,研究其在不同浓度汞(Hg2+)的胁迫下,光合色素含量、叶绿体自发荧光强度、ATP酶活性及相关矿质营养元素(Ca、Mg、Na、K、Fe)的含量变化以及可溶性蛋白含量的变化,以探讨Hg2+胁迫对菹草无菌苗光合系统及相关生理指标变化的影响.研究表明:随着Hg2+浓度的增加,各种光合色素的含量均呈现下降的趋势,叶绿体自发荧光强度逐渐减弱;Na/K逐渐增大,Na+ K+-ATP酶活性逐渐降低,Ca2+ Mg2+-ATP酶活性呈先升后降趋势;可溶性蛋白含量先升后降.结果表明,菹草无菌苗在Hg2+胁迫下,光合及其它正常的生理过程遭到破坏,功能紊乱. 相似文献
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以组织培养的菹草无菌苗为实验材料,研究了外源Ca(NO3)2的添加对汞(Hg)胁迫下菹草体内Hg积累、矿质元素、光合色素、活性氧、丙二醛(MDA)、维生素C(VC)、维生素E(VE)、谷胱甘肽(GSH)以及多胺(PAs)代谢产生的影响效应机制.结果表明:(1)Hg胁迫下,菹草体内Hg大量积累,达165.79μg/g(FW),并伴随矿质元素P、K、Fe、Mg和Na含量的明显降低.外源Ca(NO3)2的添加很大程度上可抑制菹草体内Hg积累,使其降至110.15μg/g(FW),并减轻Hg胁迫所造成的元素失衡;(2)Hg胁迫使菹草体内光合色素含量及叶绿素a/b值大幅降低,并诱导积累大量超氧阴离子、过氧化氢及MDA,同时VC、VE和GSH含量显著提升.外源Ca(NO3)2的添加则减缓了菹草体内光合色素的分解,降低活性氧水平,减轻了膜脂过氧化程度,更使VC、VE及GSH含量在一定程度上恢复到正常水平;(3)Hg胁迫下,伴随着多胺氧化酶、二胺氧化酶和精氨酸脱羧酶活性的显著提升以及鸟氨酸脱羧酶活性的降低,导致菹草体内腐胺(Put)、精胺(Spm)含量明显降低,亚精胺(Spd)含量及游离态(Spd+Spm)/Put比值轻微增加.而外源Ca(NO3)2添加后,菹草通过调节体内PAs代谢酶活性,改变了Hg胁迫下PAs含量变化,主要表现为Put、Spm含量回升显著,游离态(Spd+Spm)/Put比值进一步升高.综上所述,外源Ca的添加可抑制Hg的吸收并参与调节多胺代谢,通过内源多胺含量的改变抑制了植物体内活性氧的积累、膜脂过氧化、光合色素及抗氧化物质的分解,增强菹草无菌苗对重金属Hg的耐受力,对减轻植物Hg胁迫有重要作用. 相似文献
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以植物组织培养技术培养的水花生愈伤组织为实验材料,研究了过量Zn2+(0、0.2、0.4、0.8、1.6 mmol/L)对水花生愈伤组织的氧化损伤及多胺代谢的影响.结果表明,随着Zn2+浓度增加:(1)水花生愈伤组织的超氧阴离子产生速率和硫代巴比妥酸反应物水平显著提升,超氧化物歧化酶活性明显抑制,叶绿素a含量显著降低;(2)精氨酸脱羧酶和鸟氨酸脱羧酶活性均升高,多胺氧化酶和二胺氧化酶活性在低Zn2+浓度处升高、高Zn2+浓度处降低;(3)总腐胺和总精胺含量在低Zn2+浓度处降低、高Zn2+浓度处增加,总亚精胺含量仅在Zn2+浓度为1.6 mmol/L时有显著增加;(4)游离态腐胺含量变化与总腐胺含量相似,游离态亚精胺含量在高Zn2+浓度时下降,游离态精胺含量仅在Zn2+浓度为0.2 mmol/L时略有下降;(5)结合态腐胺和精胺在Zn2+浓度为0.2 mmol/L时下降而在其余处理组中上升,结合态亚精胺含量各处理组中均增加;(6)束缚态腐胺和亚精胺含量均下降.可见,过量Zn2+胁迫导致水花生愈伤组织氧化性损伤,并扰乱其多胺代谢平衡;束缚态多胺向结合态多胺的转化是过量Zn2+胁迫下水花生愈伤组织多胺代谢变化的一个显著特征;以结合态为代表的内源性多胺积累对水花生愈伤组织抵抗过量Zn2+胁迫具有重要意义. 相似文献
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风浪扰动对太湖水体悬浮物重金属含量的影响 总被引：10，自引：2，他引：8
通过离心浓缩的方法,获取太湖梅梁湾口东岸处(即梅梁湾与贡湖湾的交界处)不同风浪条件下的悬浮颗粒物．冷冻干燥,微波消解,ICP-AES的方法测定了其中Co、Cr、Cu、Ni、Pb、Zn等重金属元素及Al、Ca、Fe、Mn等相关金属元素的含量．结果发现,小风浪(2 m/s)、中风浪(7 m/s)和大风浪(11 m/s)下：①水体总悬浮颗粒态金属的量依次大幅度增加;②单位悬浮颗粒物中各金属元素的含量在不同风浪下变化不同．Ca在小、中、大风浪下含量依次增大;Zn在小、中、大风浪下含量依次减少;Mn和Cu的含量变化趋势相同：与小风浪相比,中风浪下Mn、Cu的含量显著增大;与中风浪相比,大风浪下含量显著减少;其它元素Al、Fe、Ni、Pb、Co、Cr等在单位悬浮物中,中风浪与小风浪相比含量减少,大风浪与中风浪相比含量略微增加．研究表明：①金属元素在水体总悬浮物中的含量主要受风浪影响,但风浪对单位悬浮物中金属含量的影响则因元素而异;②除Cu、Mn、Zn外,悬浮物中重金属含量随粒径增大含量减少． 相似文献
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云南属都湖沉积物金属元素地球化学 总被引：2，自引：0，他引：2
通过对属都湖短岩芯Esdrl重金属元素的分析,结合沉积物粒度、流域降水和人类活动资料,讨论属都湖沉积物金属元素地球化学变化特征.结果表明.沉积物中AI、Mg、Co、Zn、Cr、Ti、V、Cu、Ni等元素含量变化与粘土含量、夏季降水量显著相关,降水导致的流域侵蚀强弱变化是影响元素含量变化的主要因素.元素Pb含量从岩芯底部到顶部总体呈上升趋势,25-17.5cm沉积物中Pb含量较稳定主要为自然侵蚀过程控制;17.5-10.5cm沉积物中Pb含量迅速增加后逐渐降低推测为20世纪50年代湖区附近矿山开采产生的粉尘沉降的影响;10.5-Ocm Pb含量逐渐增加,80年代以后大气中Pb含量上升.Pb在漉域的干湿沉降应是岩芯上部Pb含量升高的原因.在氧化还原作用下沉积物中Fe、Mn易在沉积物一水界面发生再迁移.25-7.5cm沉积物中的Fe、Mn含量变化特征为沉积后再迁移作用的结果;7.5-0cm Fe和bin含量明显上升,夏季降水量增加导致流域侵蚀增强和土壤的潜育化可能是岩芯上部Fe、Mn含量显著上升的原因. 相似文献
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由于新生代巨量陆源物质的堆积,发育完好的多金属结核在南海北部罕见.对南海西北陆缘大型多金属结核进行了矿相显微镜观察,电子探针、X射线粉晶衍射(XRD)、等离子质谱(ICP-MS)等方面的分析和铍同位素测年.结核壳层显微结构类型丰富,呈现柱状、纹层状、叠层状、花瓣状、斑杂状等类型;主要矿物为δMnO2.与东太平洋海盆结核相比,南海样品Fe,Si,Al和REE(稀土元素)含量高,Mn,Cu,Co和Ni含量低,Mn/Fe低;REE平均含量达1370.4ppm,存在较强的Ce正异常;铍同位素测年显示结核的初始生长时间约为3.29～1.83Ma,形成结核的内致密层,纹层状和叠层状构造发育,陆源属性的Fe,Si,REE和Al等含量较低,反映底流活动和氧化条件较弱的古海洋环境.1.83～0.73Ma,结核生长速率提高了约3%,显微结构为叠层状和柱状构造,Si和Al等组分含量升高近10%,指示南海北部陆源物质向海输入的增加;但Ce含量下降约16%,代表海底氧化程度明显降低.0.73～0.69Ma,结核生长速率急剧升高,达平均生长速率的8.27倍,壳层中Fe,Al和REE等含量也迅速上升,形成以鲕状、颗粒状、斑杂状、花瓣状为特征的疏松层,指示南海北部出现沉积速率升高、陆源物质供应充分的古海洋环境;0.69～0.22Ma,结核生长速率骤然减慢,形成外致密层,壳层中Fe,Si,REE,Al及Mn,Cu,Co和Ni等元素含量均明显降低,壳层以纹层状和裂隙充填构造为特征,反映底流活动平稳、环境氧化强度减弱等不利于结核生长的古海洋环境.结核S04-1DG-1的生长历史,对新生代末期南海北部古海洋环境的变化产生了灵敏的响应. 相似文献
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对Cr6+胁迫条件下不同pH处理对菹草无菌苗元素、光合色素、活性氧、丙二醛、抗氧化酶、脯氨酸(Pro)及多胺(PAs)含量的影响进行研究,以探讨不同pH处理影响水生植物Cr6+毒害效应的机制.结果表明:(1)偏酸性pH处理加剧菹草对铬的蓄积,而pH为7.0时Cr6+胁迫所造成的矿质元素失衡有所减弱;(2)Cr6+胁迫下pH为6.0~8.0的处理延缓了菹草的失绿症状,促进了光合色素的合成;(3)Cr6+胁迫下菹草超氧化物歧化酶、过氧化氢酶的活性在pH为6.0和7.0的处理组诱导程度最小;(4)Cr6+胁迫下pH为6.0和7.0处理的菹草Pro含量显著提高;(5)pH为4.0和5.0的处理使腐胺(Put)含量显著提高,而pH为6.0和7.0的处理则促进亚精胺(Spd)含量及游离态(Spd+Spm)/Put比值上升,精胺(Spm)含量总体趋势为随pH值升高而逐步上升,仅在pH为4.0和5.0的处理组中低于Cr6+胁迫对照组.因此,pH条件可影响菹草对铬及营养元素的积累,抗氧化酶、Pro、PAs代谢等生理生化过程,导致铬毒性效应差异.在pH为6.0~7.0的范围内,菹草能调节抗氧化酶系统,较有效地清除体内活性氧,提高机体中Pro、PAs含量及游离态(Spd+Spm)/Put比值,减轻膜系统脂质过氧化,维持机体内矿质元素平衡,致使毒性效应达到最小程度. 相似文献
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本文研究了不同浓度Cu2+(0、1、2、4、8、12μmol/L)对菹草无菌苗多胺(PAs)及活性氧代谢的影响.结果表明,随着Cu2+处理浓度的升高:(1)菹草无菌苗植株的超氧化物歧化酶(SOD)活性逐渐上升,过氧化物酶(POD)和过氧化氢酶(CAT)活性则表现为先升后降;(2)超氧阴离子(O2.-)产生速率逐渐增大,过氧化氢(H2O2)和丙二醛(MDA)有所积累,可溶性蛋白含量降低;(3)游离态多胺含量与多胺总含量的变化一致,均表现为腐胺(Put)含量先升后降,亚精胺(Spd)含量逐渐降低,精胺(Spm)含量逐渐上升;游离态多胺(Spd+Spm)/Put的比值在高浓度Cu2+胁迫时迅速上升;结合态Put和Spm的含量变化与游离态的变化一致,而结合态Spd的含量与对照相比均略有上升;束缚态Put和Spd含量先升后降,而Spm含量则逐渐降低;(4)精氨酸脱羧酶(ADC)、多胺氧化酶(PAO)和二胺氧化酶(DAO)活性均表现为先升后降,而鸟氨酸脱羧酶(ODC)活性变化不明显.可见,Cu2+对菹草无菌苗造成了明显的氧化胁迫,抗氧化酶活性的升高,Spm含量的升高,Put向Spd和Spm的转化以及不同状态多胺之间的转化,在菹草无菌苗抵抗Cu2+胁迫过程中发挥着重要的作用. 相似文献
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Hg2+对水鳖(Hydrocharis dubia)叶片生理生化及超微结构的毒害效应 总被引：6，自引：0，他引：6
研究了不同浓度Hg^2 对水鳖叶片光合放氧速率,呼吸速率、细胞膜透性、硝酸还原酶活性以及超微结构的毒害影响,结果表明,随着Hg^2 浓度的增加,水鳖叶片的光合放氧速率逐渐下降,呼吸速率、硝酸还原酶活性先升后降,而细胞膜透性则逐渐上升,电镜观察发现,水鳖叶细胞受Hg^2 毒初期,染色质凝集,叶绿体中类囊体片层以及线粒体嵴突膨胀,随着叶细胞遭受毒害程度的加深,核膜破裂,染色质与核质消失,叶绿体膨胀解体,线粒体空泡化。 相似文献
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《Marine pollution bulletin》2012,64(5-12):334-338
The increasing use of nanotechnology highlights the need to understand and clarify the environmental impacts of nanomaterials. In this study, the acute toxicity and oxidative stress of titanium dioxide nanoparticles (nTiO2) in mature marine abalone (Haliotis diversicolor supertexta) were assessed. No acute effect was found in any of the treatment groups with nTiO2 concentration gradients ranging from 0.1 to 10 mg/L. However, the activity of an antioxidant enzyme superoxide dismutase (SOD) significantly increased in the group that was exposed to 1.0 mg/L nTiO2. The content of a non-enzymatic antioxidant, glutathione (GSH), significantly decreased in the groups with an nTiO2 concentration ⩾1.0 mg/L. The level of lipid peroxidation (LPO) was found to increase as the nTiO2 dose increased. Furthermore, NO was produced in excess in abalone. These results demonstrated that, although nTiO2 is not acutely toxic to abalone, it does exert oxidative stress on abalone. 相似文献
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伴随结冰过程的盐分排出是驱动冰封浅湖营养盐动态变化的关键过程,影响湖泊水质、环境与生态演变.为探究湖冰冻融过程如何改变寒区浅湖营养盐条件,采用自制定向冻结装置开展了无机氮磷营养盐溶液(NH3-N、NO-2-N、NO-3-N、PO3-4-P)的室内冻结试验,结合现场采样分析评估了冻结排出效应对典型浅湖氮磷营养盐的影响.结果表明:营养盐浓度、盐度(以NaCl表征)是影响冻结排出效率的关键因素;随营养盐浓度的升高,冰内营养盐浓度升高,但冻结分离系数减小;若盐度升高,冰内营养盐浓度和分离系数均增大,主要与未冻卤水泡的形成有关;3种形态的无机氮、磷酸根的分离系数均存在明显差异.将试验结果应用于内蒙古乌梁素海结冰期氮磷营养分析,计算表明湖冰冻结排盐过程不仅造成湖水各类营养盐浓度升高,同时改变无机氮素构成、氮磷比等营养结构状态;特别是若湖泊盐度发生变化,氮磷营养盐的冻结排出效率及其差异性均会显著改变,增加冰封期湖泊营养条件的时空变异性.本文结果可广泛应用于定量评价冰层冻融过程对冬季湖泊营养条件的影响,有助于理解冰封期浮游植物群落演变的内在驱动力. 相似文献
16.
Sukran Akkus Tulin Bal Nagihan M. Karaaslan Emre Yaman Ersin Kilinc Mehmet Yaman 《洁净——土壤、空气、水》2013,41(12):1229-1234
Five‐step sequential extractions were employed to fractionation of Ni, Cr and Cu in soil polluted by anthropogenic activities and determine the mobility of the metals. Twelve samples were collected on an agricultural area that was located near an airport and intercity roads in Elazig‐Turkey. Exchangeable, organically bounded, carbonate bounded, adsorbed species on Fe and Mn oxides and residual species (except silicates) of Ni, Cr and Cu were extracted into solution by using CaCl2, Na4P2O7, Na2EDTA, NH2OH–HCl and HNO3–H2O2, respectively. Mobile metal concentrations in fractions and total recoverable in soils were determined by using inductively coupled plasma‐optical emission spectrometry (ICP‐OES). Total recoverable Ni, Cr and Cu concentrations were in the range of 40–119, 45–126 and 23–72 mg kg?1, respectively. It was observed that total concentrations of metals in some of the samples were higher than the permitted values. The sum of the mobile percentages of metals was found to be lower than 50%. The Ni, Cr and Cu percentages for exchangeable species are in the ranges of 0.18–1.64, 0.03–0.59 and 0.42–2.53%, respectively. 相似文献
17.
In this study,accumulation and distribution of Pb,Cu,Zn,Co,Ni,Mn and Fe in water,bottom sediments and four plant species (Myriophyllum verticillatum,Hydrocharis morsus-ranae,Nymphaea alba and Typha latifolia) were investigated in (C)ernek Lake of Kizihrmak Delta.The Kizdirmak Delta is one of the largest natural wetlands of Turkey and it is protected by the Ramsar convention since 1993.Selected physico-chemical parameters such as pH,conductivity and dissolved oxygen and also trace metal concentrations were monitored in water.All the parameters obtained were found higher than that of the national standards for the protected lakes and reserves.The accumulated amounts of various trace metals in bottom sediments and wetland plants were found in the following order of Fe ＞ Mn ＞ Zn ＞ Ni ＞ Co ＞ Cu ＞ Pb and Fe ＞ Mn ＞ Zn ＞ Ni ＞ Co respectively.The historical trace metal intake of Myriophyllum verticillatum,Hydrocharis morsus-ranae,Typha latifolia and Nymphaea alba were obtained higher than that of the toxic metal levels and these plants may be accepted as accumulators for the detected trace metals and also bioindicators in the historically polluted natural areas. 相似文献
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对于不同生长期、不同湿度条件下芦苇(Phragmites australis)茎、叶中多种类型植硅体含量变化的探讨,能够为植硅体形成机理研究和探讨植硅体对气候变化的响应提供理论依据.选取长春市南湖为实验样点,于5—10月在3种不同生境(旱生、季节性水生和水生生境)采集芦苇样品,并分别统计芦苇茎、叶植硅体形态和数量.实验结果显示:首先,茎、叶植硅体组合特征存在明显差异,茎中帽型及个体较大的尖型等植硅体多于叶中,而叶中硅化气孔含量明显高于茎中.其次,随着植株的生长,芦苇茎中硅化气孔含量先增加后减少,鞍型植硅体含量变化较小而帽型植硅体含量先减少后增加,棒型植硅体含量逐渐增加、尖型植硅体含量先增加后减少;芦苇叶中硅化气孔含量持续增加,鞍型、帽型等短细胞植硅体含量下降,尖型、扇型等个体较大的植硅体含量逐渐增加.最后,不同植硅体类型的含量在3种生境中的变化情况较为复杂,茎中植硅体的数量变化没有明显规律,而芦苇叶中硅化气孔含量由旱生生境向水生生境逐渐增加,可见叶中硅化气孔含量的增加可以指示相对湿润的生境条件.总之,芦苇茎、叶内不同类型植硅体的数量对植株生长及不同湿度环境有不同程度的响应,对芦苇植硅体的研究也有助于理解湿生植物植硅体与环境因子的关系,进而为探讨植硅体对古环境、古气候的响应提供理论基础. 相似文献
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