外源水溶性有机物及温度对红壤铜形态的影响

利用模拟培养试验研究了外源水溶性有机物（DOM）添加量和培养温度对红壤中Cu形态的影响. 结果表明: 与不添加DOM比较, 添加不同量的DOM均可提高土壤中交换态Cu的含量、降低铁锰结合态Cu含量; 随着培养时间的延长,不同DOM添加量下土壤交换态Cu含量呈逐渐下降趋势;至试验结束时,DOM添加量为250 mg·L^-1时土壤交换态和碳酸盐结合态Cu含量最高, 添加量为500 mg·L^-1时铁锰结合态Cu含量最高;不同DOM添加量下, 土壤中有机结合态Cu含量较CK增加10.67%～23.66%. 在25 ℃和45 ℃温度条件下, 添加DOM后土壤交换态和铁锰结合态Cu含量均随培养时间的延长呈下降趋势, 但在5 ℃下变化趋势相反; 3种温度下添加DOM后土壤碳酸盐结合态Cu含量有随培养时间延长而增加的趋势. 随着培养温度的升高,土壤有机结合态Cu含量增加, 但在温度较低(5 ℃)时土壤残渣态Cu含量下降.     

水溶性有机物对水田土壤中水溶性氮磷含量及其利用率的影响

采用田间微区试验,研究了施用有机物料对土壤氮磷的变化动态及活性的影响.结果表明,水稻生长过程中土壤溶液中水溶性氮（铵态氮、硝态氮）及磷的含量都随着时间的延长而下降,且氮、磷含量的变化与施入的化学肥料量以及溶液中DOC含量有关;有机物料施用增加了水稻的生物量和对氮、磷的吸收利用;15N示踪显示,与对照的化肥处理相比,施用有机物料处理的微区氮肥利用率及土壤残留率明显增加,同时减少了土壤氮磷的损失.     

凋落物中水溶性有机物和残渣对亚热带森林土壤氮素转化的影响

设置60%和90%WHC两种土壤水分条件,并添加凋落物过滤液、剩余残渣和丙氨酸,进行为期36 d的室内培养(25 ℃),研究了凋落物中水溶性有机物和残渣对土壤氮素转化的影响.结果表明: 在60%和90%WHC条件下,丙氨酸在土壤中迅速矿化,该处理的土壤铵态氮(NH₄⁺-N)含量分别比对照显著提高5.4%～44.7%和16.1%～41.3%,净氮矿化和氨化速率在培养前期也高于对照,而凋落物过滤液和残渣添加处理则降低了土壤NH₄⁺-N含量,且残渣的降幅大于过滤液.试验期间,土壤硝态氮(NO₃^--N)含量呈直线增长趋势,培养结束时60%WHC条件下NO₃^--N含量显著高于90%WHC.土壤水分含量增多不利于土壤有机质的矿化;90%WHC条件下可溶性有机碳(SOC)含量明显低于60%WHC,而土壤氧化亚氮(N₂O)排放量比60%WHC提高1.5～63.0倍,且在60%WHC条件下凋落物残渣添加处理显著促进了土壤N₂O的排放.凋落物在分解过程中的可溶性物质和剩余物对土壤氮的影响存在差异,且这种差异随分解而发生动态变化.     

水溶性有机物电子转移能力及其生态效应

水溶性有机物(Dissolved organic matter,DOM)是生态系统最为活跃的有机物组分,参与众多物理、化学及生物过程.DOM具有电子转移能力,主要原因在于结构中包含的醌基官能团,通过醌、半醌和氢醌之间的可逆转化完成电子转移过程.DOM作为电子穿梭体,循环参与电子转移的能力是其发挥生态效应的重要体现.研究表明,DOM可以通过氧化还原反应介导环境中Cr(Ⅵ)、Hg(Ⅱ)等重金属及卤代烃、硝基芳香化合物等持久性有机污染物降解转化.综述了DOM电子转移能力机理、途径及可循环性,电子转移能力测定方法,以及DOM电子转移能力的生态效应并展望研究方向.     

重金属递进胁迫对黑麦草初期生长的影响

通过研究Cu²⁺、Zn²⁺、Cd²⁺与Pb²⁺胁迫对黑麦草初期生长的影响,结果表明：4种重金属对种子发芽率抑制效应相对较小,尤其Cu²⁺与Zn²⁺的抑制作用最小。高浓度Cu²⁺、Cd²⁺胁迫对株高、根系长度、地上生物量的抑制作用相对较大,尤其Cu²⁺对根系生长的抑制效应最大,在300 mg·L^-1下,与对照相比,根长最高下降了 85.48%。高浓度Cd²⁺胁迫显著降低了叶绿素含量,在300 mg·L^-1时比对照降低了45.51%;与对照相比,Cu²⁺与Zn²⁺所有处理都增加了叶绿素含量。从递进胁迫进程看,一些重金属对某一生长指标的影响往往表现在低浓度具有促进作用,而高浓度又存在明显的抑制效应。     

老化和风干处理对蚓粪微生物学性质和结构稳定性的影响

蚓粪水稳性团聚体含量是结构稳定性表征之一,蚓粪中水稳性团聚体含量与其微生物学性质是紧密联系的,并且受到老化时问和有机质等因素的影响。国内将蚓粪水稳性团聚体含量与其微生物学性质联系,并结合施用不同有机物处理的研究很少见报道。研究通过室内短期培养试验,研究了在不同碳氮比有机物施用下蚓粪老化和风干处理对其微生物生物量、微生物活性和结构稳定性变化的影响。研究结果表明蚓粪经过老化处理后真菌数量、微生物生物量碳和微生物活性都显著降低。不同有机物的施用对蚓粪微生物学性质的影响主要表现在施用牛粪的处理中蚓粪细菌数量高于施用秸秆的处理,真菌数量相反。新鲜蚓粪经过老化处理后总的水稳性团聚体含量（〉0．053mm）增加,主要表现在水稳性大型大团聚体（〉2mm）含量增加,且在施用牛粪的处理中达到显著,可能是与牛粪比秸秆能分解产生更多的粘结物质有关。蚓粪的风于处理也显著增加各个处理中总水稳性团聚体含量,且风干后蚓粪中水稳性团聚体主要以微团聚体（0．25～0．053mm）形式存在。施用秸秆的处理中,新鲜蚓粪0．25～0．053mm粒级的水稳性团聚体含量显著高于施用牛粪的处理。经风干后,施用秸秆的处理0．25～0．053mm的水稳性团聚体含量显著低于施用牛粪的处理,而水稳性大型大团聚体含量显著高于施用牛粪的处理。蚓粪的不同粒级水稳性团聚体含量和蚓粪的生物学性质之间存在良好的相关性。     

狮子山铜尾矿植物对铜的吸收及土壤特性的影响

我国铜矿储藏丰富,铜矿开采带来巨大经济利益的同时,也对生态环境造成极大的破坏,这种恶劣的环境严重阻碍了植物的定居,但是自然界物种繁多,总有一些植物能适应这种环境而生存下来。本文通过对狮子山优势植物吸收和积累铜的分析,发现这些植物均能富集较多的铜,在土壤铜含量很高的情况下,依然生长旺盛,没有出现受害症状,成为尾矿上的优势种,并形成了单优群落或多优小群落。这些植物的存在改变了土壤的理化特性,降低了土壤中的重金属的含量,提高了土壤的全N、全P、全K和有机质含量,一定程度上改善了土壤的不良环境,在尾矿的植被恢复和土壤修复中起着非常重要的作用。     

狮子山铜尾矿植物对铜的吸收及土壤特的影响

我国铜矿储藏丰富,铜矿开采带来巨大经济利益的同时,也对生态环境造成极大的破坏,这种恶劣的环境严重阻碍了植物的定居,但是自然界物种繁多,总有一些植物能适应这种环境而生存下来.本文通过对狮子山优势植物吸收和积累铜的分析,发现这些植物均能富集较多的铜,在土壤铜含量很高的情况下,依然生长旺盛,没有出现受害症状,成为尾矿上的优势种,并形成了单优群落或多优小群落.这些植物的存在改变了土壤的理化特性,降低了土壤中的重金属的含量,提高了土壤的全N、全P、全K和有机质含量,一定程度上改善了土壤的不良环境,在尾矿的植被恢复和土壤修复中起着非常重要的作用.     

水环境中重金属铜对异育银鲫肠道微生物的影响

【目的】了解水环境中重金属铜对异育银鲫肠道微生物组成及多样性的影响。【方法】采用试剂盒提取异育银鲫肠道总DNA,然后对总DNA进行16S r RNA进行扩增,构建异育银鲫肠道微生物16S r RNA基因克隆文库,最后进行数据分析。【结果】厚壁菌门、变形菌门和拟杆菌门为异育银鲫肠道中主要的细菌类群,在不同浓度的重金属铜胁迫处理后,厚壁菌门的含量明显降低。稀释性曲线、Venn图和多样性指数分析结果表明,重金属铜胁迫处理后异育银鲫肠道微生物多样性明显降低。【结论】重金属铜会使异育银鲫肠道微生物组成及多样性降低。此结果为研究重金属污染对异育银鲫健康状况的影响及异育银鲫养殖过程中病害的诊断奠定基础。     

铜铅被鱼吸收过程中的相互作用

在实验室条件下,研究了彩虹方头鱼（Ｐａｒａｃｈｅｉｒｏｄｏｎ ｉｎｎｅｓｖｕ）对人工河水中共存的Ｃｕ、Ｐｂ的吸收以及经过Ｃｕ驯化后的彩虹方头鱼对人工河水中Ｐｂ的吸收。研究结果表明,无论是Ｃｕ、Ｐｂ的混合体系,还是先经Ｃｕ预暴露后再投放到含Ｐｂ体系中,彩虹方头鱼对Ｃｕ和Ｐｂ的吸收均表现出明显的协同作用。     

水溶性有机质对土壤吸附菲的影响

研究了来源于稻草腐熟物的外源水溶性有机质(DOM)和土壤本身固有的内源DOM对有机碳含量不同的3种土壤吸附菲的影响.结果表明,不同处理土壤对菲的吸附曲线均为线性,其吸附系数(K_d)与土壤有机碳含量(f_oc)正相关.去除内源DOM后,黄棕壤、红粘田和黑土吸附菲的K_d值增加了7.08%～21.4%,增加量(ΔK_d)和增加幅度与f_oc正相关,表明土壤中存在的内源DOM抑制土壤对菲的吸附.而外源DOM对土壤吸附菲的影响与其浓度密切相关.在供试浓度范围(0～106 mg DOC·L^-1)内,红粘田吸附菲的K_d值随加入外源DOM浓度的提高先增大后减小.外源DOM浓度为28 mg DOC·L^-1时,红粘田吸附菲的K_d值增加了19.5%;而当外源DOM浓度≥52 mg DOC·L^-1时,则明显抑制菲的吸附.内源和外源DOM对土壤吸附菲的影响,主要与DOM和菲在溶液中的结合作用、在土壤中的累积吸附效应等有关.     

Effects of dissolved organic matter from sewage sludge on the atrazine sorption by soils

The effects of dissolved organic matter (DOM), water soluble organic matter derived from sewage sludge, on the sorption of atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-trazine) by soils were studied using a batch equilibrium technique. Six paddy soils, chosen so as to have different organic carbon contents, were experimented in this investigation. Atrazine sorption isotherms on soils were described by the linear equation, and the distribution coefficients without DOM (Kd) or with DOM (Kd*) were obtained. Generally, the values of Kd*/Kd initially increased and decreased thereafter with increasing DOM concentrations of 0-60 mg DOC ·L-1 in soil-solution system form. Critical concentrations of DOM (DOMnp) were obtained where the value of Kd* was equal to Kd. The presence of DOM with concentrations lower than DOMnp promoted atrazine sorption on soils (Kd* > Kd), whereas the presence of DOM with concentrations higher than DOMnp tended to inhibit atrazine sorption (Kd* < Kd). Interestingly, DOMnp for     

Effects of dissolved organic matter from sewage sludge on the atrazine sorption by soils

The effects of dissolved organic matter (DOM), water soluble organic matter derived from sewage sludge, on the sorption of atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-trazine) by soils were studied using a batch equilibrium technique. Six paddy soils, chosen so as to have different organic carbon contents, were experimented in this investigation. Atrazine sorption isotherms on soils were described by the linear equation, and the distribution coefficients without DOM (Kd) or with DOM (Kd*) were obtained. Generally, the values of Kd*/Kd initially insoil-solution system form. Critical concentrations of DOM (DOMnp) were obtained where the value of Kd* was equal to Kd. The presence of DOM with concentrations lower than DOMnp promoted atrazine sorption on soils (Kd* ＞ Kd), whereas the presence of DOM with concentrations higher than DOMnp tended to inhibit atrazine sorption (Kd* ＜ Kd). Interestingly, DOMnp for tested soils was negatively correlated to the soil organic carbon content, and the maximum of Kd*/Kd (i.e.Kmax) correlated positively with the maximum of DOM sorption on soil (Xmax). Further investigations showed that the presence of hydrophobic fraction of DOM evidently promoted the atrazine sorption on soils, whereas the presence of hydrophilic DOM fraction obviously tended to inhibit the atrazine sorption. Interactions of soil surfaces with DOM and its fractions were suggested to be the major processes determining atrazine sorption on soils. The results of this work provide a reference to the agricultural use of organic amendment such as sewage sludge for improving the availability of atrazine in soils.     

森林生态系统DOM的来源、特性及流动

可溶性有机物质（Dissolved Organic Matter)是森林生态系统主要的可移动碳库及重要的养分库。系统综述了森林生态系统DOM的来源,组成,性质,季节动态;DOM释放与存留机制及影响因素,森林生态系统DOM的流动及干扰对DOM动态影响等,已有研究表明DOM的森林生态系统C、N、P循环,成土作用,污染物迁移等方面起着重要作用。今后森林生态系统DOM的研究应集中于以几方面：（1）确定森林生态系统中DOM源和汇;（2）评价森林水文条件对DOM释放与存留的调节作用;（3）探讨全球气候变化对森林生态系统DOM的影响;（4）可溶性有机氮（Dissolved Organic Nitrogen),可溶性有机磷（Dissolved Organic Phosphorus)动态与可溶性有碳（Dissolved Organic Carbon）动态的差别。     

华南典型树种凋落叶的野外分解和溶解性有机质溶出动态

选用华南亚热带地区常见阔叶树种木荷和针叶树种湿地松的新近凋落叶,在野外分解0、30、60、90、150、210、240、365 d,分析溶出的溶解性有机质(DOM)浓度、组成和性质的变化,以及对土壤可溶性有机碳(DOC)的影响.结果表明: 随着分解的进行,尽管木荷叶片的DOM浓度高于松针,但是2种凋落叶DOM浓度、性质和物质组成变化规律一致;2种凋落叶的DOM浓度均呈下降趋势,芳香化程度和分子量增大,富里酸、腐殖酸类物质逐渐增多,可降解的简单芳烃蛋白(如酪氨酸)逐渐减少.在分解初期,DOM主要由亲水中性和酸性部分组成,易分解、易迁移,对表层土壤DOC影响不显著;在分解后期,DOM主要为腐殖酸和富里酸类物质,吸附性强,表层土壤DOC浓度显著下降.     

白洋淀沉水植物腐解释放溶解性有机物光谱特性

利用水生植物修复受污染水体中,水生植物在秋冬季节腐烂分解会释放大量溶解性有机物(DOM),DOM可影响水环境中污染物的迁移转化,对水体中的化学和生物过程产生一定影响。因此利用紫外可见光光谱(UV-vis)结合平行因子分析法(PARAFAC)和主成分分析法(PCA)来表征和分析水生植物腐解产物中DOM的组分及其特点。UV-vis的研究表明随着腐解时间的增加,样品中DOM的腐殖化程度逐渐升高,当腐殖化程度达到最高值时,腐解进入矿化阶段,此时腐殖化程度逐渐降低。通过PARAFAC分析可以分离出3种类蛋白组分(C1、C2和C5)和2种类腐殖酸组分(C3和C4)。由PCA可以得出在腐解初期,类蛋白组分占据主导地位;随着腐解时间的增加,类蛋白组分含量逐渐降低,而类腐殖酸组分含量逐渐升高。     

Influence of dissolved organic matter on copper binding, and calcium on cadmium binding, by gills of rainbow trout

Complexation of Cu by 5 mg Cl⁻¹ dissolved organic matter (DOM) from a marsh kept Cu from binding to gills of small rainbow trout Oncorhynchus mykiss in 9-day exposures to 0.5 μM Cu in soft water. The protective effect of DOM occurs because the formation of Cu-DOM complexes reduces the amount of free Cu in the water, so the disruptive effects of Cu on ionoregulation, such as inhibited Na uptake, cannot develop. The Cu-DOM complexes themselves do not bind to the gills. Calcium (1100 μm) reduced the accumulation of Cd by trout gills in short, 2-h exposures through competition for gill binding sites but not over longer, 7-day exposures to 0–14 μM Cd. However, the protective effect of Ca against Cd toxicity persisted throughout the longer experiment, likely due to the decrease in the electrochemical gradient for diffusive loss of Ca from the fish to the water. Rainbow trout and fathead minnows Pimephales promelas accumulated Cu and Cd on their gills in a similar manner; thus, binding constants for metal-gill interactions determined for one species of fish can be generalized to other fish species. When literature binding constants determined for fathead minnows were applied to our studies with rainbow trout, computer modelling of Cu-gill and Cu-DOM interactions simulated our results well. In contrast Cd-gill and Ca-gill modelling predicted the initial competitive effect of Ca against Cd accumulation by trout gills, but did not predict the longer-term accumulation of Cd by trout gills.     

Role of ultraviolet-B radiation on bacterioplankton and the availability of dissolved organic matter

Attenuation of ultraviolet (UV)-radiation into the water column is highly correlated with the concentration of the dissolved organic matter (DOM). Thus UV penetrates deeper into marine waters than into freshwater systems. DOM is efficiently cleaved by solar surface radiation levels consuming more oxygen than bacterial metabolism. This photolytically cleaved DOM exhibits higher absorbance ratios (250/365 nm) than untreated DOM. Natural bacterioplankton reach higher abundance if inoculated in previously solar-exposed DOM than in untreated DOM; during bacterial growth the absorbance ratio declines steadily indicating the utilization of the photolytically cleaved DOM. On the other hand, bacterioplankton are greatly reduced in their activity if exposed to surface solar radiation levels. Photoenzymatic repair of DNA induced by UV-A radiation, however, leads to an efficient recovery of bacterial activity once the UV-B stress is released. Turbulent mixing of the upper layers of the water column leads to a continuous alteration of the UV exposure regime. Close to the surface, bacteria and DOM are exposed to high levels of UV-B leading to a reduction in bacterial activity and to photolysis of DOM. Once mixed into deeper layers where UV-B is attenuated, but sufficient UV-A is remaining to allow photoenzymatic repair, the photolytically cleaved DOM is efficiently taken up by bacterioplankton leading to even higher bacterial activity than prior to the exposure. Thus, the overall effect of UV on bacterioplankton is actually an enhancement of bacterial activity despite their lack of protective pigments.     

Contrasting effects of solar UV radiation on dissolved organic sources for bacterial growth

The photochemical transformation of dissolved organic matter (DOM) in lakes and oceans has been shown to either reduce or enhance bacterial utilization. We compared the effects of UV radiation on the bacterial use of DOM in a wide range of lakes. Although complex DOM was converted in all irradiated samples into carboxylic acids that are readily utilized by bacteria, irradiation in several lakes resulted in a decreased ability of DOM to support bacterial growth. The effect of irradiation on the ability of DOM to promote bacterial growth was a positive function of the terrestrial humic matter, and a negative function of indigenous algal production. We suggest that the net effect of irradiation is a result of counteracting but concurrent processes rendering DOM either labile or recalcitrant. Humic DOM is predominantly transformed into forms of increased lability, whereas photochemical transformation into compounds of decreased bacterial substrate quality dominates in algal-derived DOM. Hence, solar-induced photochemical reactions interact with microbial degraders in different ways, depending on the origin and nature of the organic matter, affecting the transfer of energy within aquatic food webs, as well as the degradation and preservation of detrital organic matter, in different directions.