沉水植物生长对沉积物间隙水中的氮磷分布及界面释放的影响

采集未破坏沉积物结构的柱状沉积物样品,通过室内41 d的培养实验,研究了沉水植物生长过程对间隙水中NH_4~ -N和PO_4~(3-)-P的浓度的动态影响,分析了沉水植物生物量与沉积物中氮磷释放通量的对应关系．结果表明：随沉水植物生长和生物量增加,上部0-5 cm沉积物垂向各层间隙水中NH_4~ -N含量呈逐步降低,表现出沉积物-水界面氮的释放通量与沉水植物生物量存在负相关性;而间隙水PO_4~(3 )-P含量则随沉水植物生长呈单峰型变化,磷释放通量与生物量相关性不明显．初步反映沉水植物在沉积物的生长过程中对氮磷吸收的生物地球化学机制是不同的．     

不同环境下镉对小球藻吸收磷速率的影响

在人工配制的污水中进行静态模拟实验,研究了不同光照强度及不同pH值下,镉对小球藻(Chlorella vulgaris)在悬浮和固定状态下对污水中正磷酸盐的吸收速率的影响。结果表明,镉存在的情况下,在实验所设的各光照强度内,悬浮态小球藻对磷的吸收速率为4~10μg/(h.个),固定化小球藻为12~16μg/(h.个);而相同的镉浓度下,在不同的pH范围中,悬浮态小球藻对磷的吸收速率为1.9~9.4μg/(h.个),固定化小球藻为5.7~12μg/(h.个)。在不同光照强度下,镉总体上降低了小球藻对磷的吸收速率,其中使悬浮藻普遍下降40%~60%,而固定处理使藻受镉的影响较少,至多下降10%~20%,但在个别光照强度下镉反而促进了小球藻对磷的吸收速率。不同pH值时,无论悬浮态还是固定态,镉在大多pH下使小球藻的磷吸收速率下降20%~30%,固定处理并没有减少镉的影响,同样在个别pH下镉促进了对磷的吸收。     

祁连山中部祁连圆柏生长与更新方式的树轮记录

选择祁连山中部50m×15m的祁连圆柏样方进行树轮生态学取样与分析。分析结果表明,样方内大部分祁连圆柏的树龄小于250年,最近几年有大量幼苗萌生。祁连圆柏的径生长方式各有异同,大部分祁连圆柏在生长过程中出现1次以上生长释放事件,1970¹980年间出现生长释放的频率最高,占总释放次数的35%,轮宽年表也显示祁连圆柏的轮宽指数自1970s以来持续上升。另外,相关分析结果表明,温度是影响采样点区域祁连圆柏径向生长的主要环境因子,较高的温度有利于树木生长,6、7月份的降水也与树木径向生长呈显著正相关。在全球变暖的背景下,如果能积极开展植树造林,并有效控制人类活动的干扰,该区域祁连圆柏林更新状况将会显著改观。     

沉水植物黑藻对上覆水中各形态磷浓度的影响

室内模拟研究了沉水植物黑藻对上覆水中不同形态磷浓度的影响及其季节性变化,并从沉水植物生长、间隙水和碱性磷酸酶活性(APA)三方面进行了讨论,进一步揭示磷在浅水湖泊水-沉积物界面的交换机理。结果表明,在本研究条件下,上覆水中各形态磷以溶解性总磷(DTP)为主,其他形态磷浓度变异较大,黑藻降低了上覆水中总磷(TP)、溶解性活性磷(SRP)和DTP浓度,也降低了DTP和SRP占总磷的比例,从而使颗粒态总磷(PP)和溶解性有机磷(DOP)占总磷比例升高。黑藻主要通过吸收上覆水中的磷和抑止沉积物、上覆水中APA使上覆水中各形态磷浓度保持较低水平,其中对SRP和DTP浓度的影响更明显。上覆水中各形态磷浓度呈现明显的季节性变化。在7～8月,TP、SRP和DTP浓度呈下降趋势,并在8月达到最低值;9～10月间有所升高,但仍然维持在较低水平,不同采样时间存在波动。     

波浪作用下沉积物中氮、磷释放速率的试验研究

湖泊或海湾中的沉积物吸附氮(N)、磷(P)等元素所形成的沉积层成为水体富营养化的內源。在波浪作用下,尤其是强浪作用下,沉积物中的N、P会通过内源释放作用大量进入水体中。本文在自制的U型水槽中开展实验,采用不同水头差来模拟波浪的循环荷载作用,研究了沉积层中的N、P在静置固结状态(Ⅰ)、加波未液化状态(Ⅱ)、加波液化状态(Ⅲ)下的释放规律,并给出该试验条件下的沉积物释放速率的拟合方程。试验结果表明:沉积物中总氮(TN)和溶解性总氮(TDN)的释放速率会随着水动力作用的增强而增加;总磷(TP)、溶解性总磷(TDP)和活性磷酸盐(SRP)的释放速率也随着水动力作用增强而增加,但水体中悬浮物(SS)含量过高会限制其释放速率。     

Annual Variation of Benthic Nutrient Fluxes in Shallow Coastal Waters (Gulf of Trieste, Northern Adriatic Sea)

Abstract. Benthic fluxes of dissolved N. Si and P nutrients, alkalinity, dissolved inorganic C (DIC), and O₂ from sediments in the Gulf of Trieste (northern Adriatic, Italy) were measured monthly for 16 months, using laboratory incubated flux chambers at in siru temperatures in the dark. The annual average fluxes were: 02 = -19.3 ± 8.2, DIC = 13.7 ± 9.6, NO3 = -0.04 ± 0.16, NH4 = 0.3 ± 0.4. PO₄= 4.001 ± 0.01, Si = 0.9 ± 0.1 mmol m-² d^-1, with strong temporal fluctuations. The highest effluxes of all nutrients and DIC were observed in the summer. Small effluxes of DIC and NH4 and influxes of Si and PO4 were observed in late winter. Only NH₄ (ca. 50%) and Si (ca. 70%) fluxes were significantly correlated with temperature. This correlation suggests that the rate of downward input and the quality of sedimented organic matter (autochthonous and allochthonous) were superimposed on the temperature fluctuations. High DIC, NH₄ and Si effluxes observed in May 1993 during low temperature were due to the degradation of sedimentary organic matter produced by an early spring bloom of benthic microalgae which occurred about 6 weeks earlies while the autumn phytoplankton bloom was simultaneously reflected in enhanced benthic fluxes due to higher temperature. The role of benthic biological advection in this transport across the sediment-water interface, evaluated by comparison between measured benthic and calculated diffusive fluxes from nutrient pore water concentrations, was of minor importance. This is probably due to low infaunal activity throughout the year it was localized mostly in the narrow surficial layer. The annual average diffusive fluxes of NH4 and PO4 were higher than those measured, probably due to the presence of nitrificationdenitrifi-cation processes and redox-dependent chemical reactions at the oxic sediment-water interface, respectively. Only during bottom-water hypoxia in September 1993 did strong PO₄ effluxes prevail. Calculations based on the Redfield stoichiometry of oxic decomposition of organic N to NH4 and NO3, and differences between diffusive and measured NH₄ fluxes showed that denitrifkation averaged 0.8 mmol m^-2 d^-1. Significant correlations between NH₄ and PO₄ DIC and Si, and NH4 and Si fluxes suggested their parallel regeneration and utilization at the sediment-water interface. The nutrient fluxes observed were not significantly linked to O₂ consumption, suggesting also that anaerobic oxidation processes were important at the sediment-water interface in the gulf. The N, P and Si nutriqnts released from sediment pore waters are probably utilized in benthic microalgal and bottorn-hater primary production. This indicates that pelagic and benthic communities in the central part of the Gulf of Trieste function relatively independently of each other.     

珠江口海域无机氮和活性磷酸盐含量的时空变化特征

主要利用1998年在珠江口海域连续同步观测资料，研究该海域无机氮、活性磷酸盐含量和富营养化状况。结果表明，无机氮主要来自四个口门的径流，但深圳湾附近的陆源亦有一定贡献；无机氮的形态主要以硝酸氮为主，而在深圳湾附近海域则以氨氮为主；无机氮含量普遍超过0．30mg/dm^3的我国海水水质标准二类标准值，大部分海域已超过0．50mg/dm^3的四类水质标准值，径流对活性磷酸盐含量的贡献不显著，而深圳湾附近的陆源则有明显的贡献，从珠江口附近由沿岸流和涨潮流带来的活性磷酸盐亦有明显的影响；除深圳湾附近海域活性磷酸盐含量超过0．030mg/dm^3的二类海水水质标准值外，其他海域基本符合0.015mg/dm^3的一类海水水质标准值要求。该海域的N／P值普遍较高，而且北部海域的高于南部海域；最高值超过300，最小值也大小30；该水域的营养盐主要为磷限制。     

臭氧及臭氧类高级氧化技术降解甲基对硫磷的效能

文章研究了臭氧及臭氧类高级氧化技术(AOPs-O3)在不同pH条件下降解甲基对硫磷(MP)的效能。结果表明,在pH 3~10的条件下(反应过程控制pH),单独臭氧化5min即可完全降解MP,但不同pH下化学耗氧量(COD)和有机磷的释放率差异明显。在pH为3.3,7.5和9.4的条件下单独臭氧30min后COD的去除率分别为55.17%,89.64%和93.10%,有机磷的释放率分别为16.33%,95.00%和99.99%。考虑酸性条件下可以规避碳酸盐的负面影响(特别是高浓度废水),利用O3/H2O2/Ti(IV)在pH 3.3条件下处理MP溶液,COD去除率和有机磷释放率分别达到89.64%和81.57%。相对法计算求得MP与O3和羟基自由基(·OH)的速率常数分别为31.98L·(mol·s)-1和7.488×109 L·(mol·s)-1。活性污泥法的测试结果表明,MP经O3/Ti(IV)/H2O2(pH=3.3)和O3(pH=9.4)可提升含MP废水的可生化性,但与培养液体系相比仍具有一定的毒性。     

大型海藻孔石莼抑制浮游微藻生长的原因初探--种群密度及磷浓度的作用

本文以磷浓度和种群密度为变量 ,以亚心形扁藻为浮游微藻代表 ,采用实验生态学手段研究了大型海藻孔石莼与浮游微藻 (亚心形扁藻 )间的竞争。结果显示 ,不论营养盐浓度如何 ,高密度的孔石莼皆能显著抑制浮游微藻的生长。分析显示 ,高密度的孔石莼压制浮游微藻生长的原因 ,不是由于对氮、磷等营养盐的竞争所致 ,而可能是其他原因所致。     

长江口、杭州湾水域沉积物中磷的化学形态分布特征

污染物进入水体后,其最终的归宿行为与赋存状态是当今环境科学研究的重要方向.沉积物中磷形态的研究对了解磷在污水排放过程中的动态循环以及磷酸盐在水体-沉积物界面的迁移转化都具有十分重要的意义[1,2].目前在长江口、杭州湾水域已建成“上海市合流污水一期工程”、“星火开发区污水排海工程”、“上海市污水治理二期工程”等污水集中外排工程.针对该水域的竹园、白龙港和星火污水排放口附近沉积物中磷的化学形态和分布状况进行了研究.