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101.
102.
Sorption by soil organic matter (SOM) is considered the most important process affecting the bioavailability of hydrophobic organic chemicals (HOCs)in soil.The sorption capacity of SOM for HOCs is affected by many environmental factors.In this study,we investigated the effects of soil pH and water saturation level on HOC sorption capacity of SOM using batch sorption experiments.Values of soil organic carbon-water partition coefficient (KOC) of six selected polycyclic aromatic hydrocar... 相似文献
103.
基于能值生态足迹法的山东省可持续发展分析 总被引:1,自引:0,他引:1
传统生态足迹方法自提出以来已广泛应用到可持续发展的研究中,但其改进方法能值生态足迹法在可持续发展中的运用还很少。简要介绍了传统生态足迹模型和基于能值分析理论的生态足迹模型,并运用这两种方法对山东省2002~2006年的生态足迹进行了计算与对比分析。在此基础上测算了衡量区域可持续发展程度的两个指标:生态足迹多样性指数和生态协调系数,计算结果均呈下降趋势,表明山东省对各种土地的需求越来越不平衡,需求与供给之间的差距越来越大,山东省处于不可持续发展状态。通过对比研究,与传统生态足迹模型相比,改进生态足迹模型的计算结果更能真实反映生态经济系统的环境状况。 相似文献
104.
Background River and lake sediments constitute complex and difficult analytical samples. On the other hand, sediments play a fundamental
role in the distribution of toxic compounds in aquatic systems and in the evaluation of the current state and the course of
changes taking place in the environment.
Among elements present in the environment in trace concentrations, but having well-elaborated toxic properties, one of most
dangerous is arsenic. The element occurs in the environment in several chemical forms, predominant are inorganic forms of
As(V) and As(III), and methylated forms such as monomethylarsonic acid (MMAA) and dimethylarsinic acid (DMAA).
Objectives Reported herein are experiments, which were undertaken with the aim of examining the dynamics of arsenic sorption in sediments
and its dependence on speciation of the element and the pH in the environment. Simultaneously, influence of organic matter
content and chemical composition of the sediments on As sorption, were investigated.
Methods Sediment samples (upper 10 cm layer) were collected from three sites located in the vicinity of Cracow:
Using XRD and IR methods, mineral composition of sediments was analysed. Concentrations of iron, manganese, aluminium and
arsenic as well as organic matter content in solid samples were analysed.
Sorption experiment 100 g of dry sediment sample was placed in a 400 ml volume glass beaker. 300 ml of arsenic containing solution was poured
into the beaker. Every 30 min (total experiment time span equalled 7 to 7.5 hours), 0.5 ml of the suspension’ (the beaker
content was constantly mixed) was collected and centrifuged, and the concentration of arsenic was determined in the supernatant.
In the series of experiments, solution contained about 0.05 μg/ml of arsenic in organic (DMAA) and inorganic forms, at different
pH values — 3, 5, 7 and 9.
Results and Discussion Examined sediments of Vistula river and Dobczyce Lake were characterised by relatively high concentrations of arsenic, iron,
manganese and aluminium.Rudawa river. At pH 3, the concentration of inorganic As in solution decreased from an initial value of 0.049 μg/ml to 0.012 μg/ml in
7.5 hours time. The same decreasing tendency was found at pH 5 (initial value 0.046 μg/ml, after 7.5 hours - 0.015 μg/ml).
Less distinct sorption effects were noted at pH 7 and 9.
Vistula river. At all pH values, a very significant decrease of inorganic As concentration up to 80% of the initial value, as well as a
short time of achieving an equilibrium state (1 – 2.5 hours), was found.
Dobczyce lake. Inorganic As was distinctly accumulated in sediments at pH 3 (decrease of As concentration in solution from 0.052 to 0.007
μg/ml after 7.5 hours of the experiment) and at pH 5. At pH 7, about 40% of As was accumulated in sediments (solution As concentration
decrease from 0.050 to 0.030). Only 20% of As adsorbed on sediments at pH 9.Very weak accumulation of organic form of As (DMAA)
was found in all examined sediments at pH 3 and 5. At higher pH values no sorption was registered.
Conclusions The following facts were established:
Recommendations The presented method of analysis of As sorption in sediments and results visualization (based on a newly defined coefficient)
provides a useful tool for the characterization of sorptive properties of sediments and may be used for other compounds as
well. Crucial, functional information — how much of a given element may be accumulated in sediments at a certain pH — is obtained
without digestion of the sediment sample, in an experiment taking less than one day. 相似文献
• | Rudawa river — 37 km long river, flowing mainly through the suburban area; |
• | Vistula river — heavily contaminated, main Polish river; |
• | Dobczyce reservoir — artificial reservoir on Raba river, total capacity of 125,000,000 m3, supplying about 60% of drinking water to the city of Cracow. |
• | inorganic form of arsenic was effectively accumulated in all analysed sediments; |
• | inorganic As sorption in sediments strongly depended on pH — for sediments of Rudawa river and Dobczyce lake, the highest sorption was found at pH 3, and a decrease of accumulated As was noted with an increase of pH (at pH 9, the lowest amount of As was immobilised in sediments); in the case of Vistula river sediments, a reverse tendency was found; |
• | organic form of arsenic (DMAA) was accumulated only at pH 3 in all sediments and less significantly at pH 5 (Vistula river sediments); no sorption of that form of As was found in the other sediment samples; |
• | state of equilibrium (no change in inorganic As concentration in liquid medium) was achieved in 1 hour for Vistula river sediments, after about 2 hours for Rudawa river and after about 4 hours for Dobczyce lake sediments. |
105.
以14个水稻品种及亲本为材料,通过检测各材料的Wx基因型,测定其直链淀粉含量(AC)、胶稠度(GC)和糊化温度(GT),对参试品种的Wx基因与AC、GC和GT的相关性进行了分析.结果表明,基因型为GG的品种具有较高的AC和较低的GC,而TT型品种具有中等的AC和较高的GC;AC与GC、GT呈极显著负相关,说明Wx除了控制稻米的AC之外,Wx与之紧密连锁的基因位点还可能影响GC的高低程度和GT的大小.对属于同一个恢复系的杂交组合的不育系和品种之间作偏相关性分析表明,优良品种的AC与不育系呈显著负相关,而品种的GC和GT与不育系之间的相关性却没有那么明显. 相似文献
106.
乳业产业系统发展状态测度研究——基于协同论的实证分析 总被引:1,自引:0,他引:1
科学测度乳业产业系统发展状态,是提升乳业竞争力和实现乳业可持续发展的内在要求。乳业产业系统具有复杂性和内部交互性,可划分为原料乳供应、乳制品加工、乳制品销售和乳制品消费4个子系统。基于协同理论,采用驰豫系数法,利用2006—2015年中国乳业数据,分析乳业产业系统发展状况和各子系统的有序发展状况,探讨其协调发展水平。结果表明,乳业产业系统协同度最高值仅为0.024,尚未形成良好的发展状态;各子系统有序度水平均处于较低水平,最高值为0.244,其中乳制品加工子系统有序度水平相对较高,但上升缓慢。乳业产业各子系统之间存在着相互作用,乳制品加工与乳制品消费子系统的相互影响最强,而原料乳供应与乳制品销售子系统的相互影响最弱。研究表明,要实现乳业产业系统高效协同发展,需要乳业产业所有子系统的运营状态都提高。因此,提出加强优质奶源基地和优质饲草体系建设;继续实行乳企兼并重组战略、丰富产品结构以深入开发国内外市场、加强乳企品牌建设;加强行业发展成就展示和消费引导等促进乳业可持续发展的政策建议。 相似文献
107.
108.
稻田土壤还原性物质特征及与甲烷排放的关联性分析 总被引:1,自引:0,他引:1
以南方稻田土壤的定位试验为研究对象,选取其中的五种不同施肥(无肥、化肥、猪粪+化肥、鸡粪+化肥、稻草+化肥)处理,监测了水稻生长期间土壤活性还原性物质、活性有机还原性物质、亚铁(Fe2+)含量、土壤Eh值和甲烷(CH4)排放的动态变化,分析还原性物质与CH4排放的关系。结果表明,水稻生长前期稻田CH4排放通量、土壤活性还原性物质、活性有机还原性物质和Fe2+含量均较高,并随水稻生长呈逐渐下降的趋势;而土壤Eh在水稻整个生育期介于-238至118 mv之间,且为水稻生长前期低,后期高。施用有机肥后的土壤活性还原性物质和Fe2+含量比化肥处理平均分别增加了13%和11%,而土壤Eh值则低于无肥和化肥处理。相关分析表明,CH4排放通量与土壤中活性还原性物质、Fe2+均呈极显著正相关关系,而与土壤Eh呈极显著负相关关系。通过逐步回归分析进一步表明,土壤中Fe2+含量显著影响稻田CH4排放,控制稻田土壤中Fe2+含量有利于稻田CH4的减排。 相似文献
109.
[目的]研究固氮功能菌株的生长特性,探索适地适菌原则。[方法]本研究以103株固氮功能细菌为研究对象,以p H值及培养温度为考量指标,分别研究了8个温度梯度、10个p H值梯度对菌株生长的影响。[结果]表明:经检测,含有nif H基因的菌株有103株;菌株的最适生长条件为温度28℃、p H=7,各菌株的温度适宜生长区为20、28、37℃,大量菌株生长的适宜p H值为4、5、7、8;在低温、碱性土中的适用菌株为6003,在高温、碱性土中的适用菌株有09ul27、1010、2024、2029、7002、lk2-1c(2)和zk3-1,在酸性及碱性土中均适宜生长的菌株为1012和2025。根据菌群不同生长特性,对所有菌株进行非层次聚类,使用SSI算法得出最优分类为9类,其中,第5类和第7类全部属于伯克霍尔德属,第2类基本为芽孢杆菌属,其它类别中各菌属没有出现明显的聚类现象,且生长条件分类与菌种的初步鉴定分类没有明显的相关性。[结论]固氮功能菌株的适宜生长环境较一致,最适宜的生长条件为温度28℃、p H=7。筛选出适合在特殊环境生长的固氮功能细菌10株,各菌株初步鉴定为枯草芽孢杆菌、蜡样芽孢杆菌、巨大芽胞杆菌、Chitinophaga pinensis、Burkholderia xenovorans、Burkholderia phymatum、Burkholderia bannensis。通过生长条件聚类分析及所有菌株的16S r DNA鉴定比对得出,菌株的生长特性与其生物学特征不完全相关。 相似文献
110.
为了分析迷宫型微小流道中沙粒沉积规律,通过计算流体动力学软件FLUENT对灌水器内部流场进行了分析,研究了灌水器中沙粒运动轨迹及沉积规律。研究表明:碰撞反弹系数对沙粒沉积规律影响很大,灌水器各流道单元速度场分布相似,压力场差异较大,沙粒运动轨迹基本不受各单元压力场变化的影响;粒径是影响沙粒沉积的最主要因素,粒径越大,沙粒的沉积危险系数越大;灌水器入口压力越大,沙粒的沉积危险系数越小。对沙粒沉积规律的研究,有利于深入地了解灌水器的堵塞机理,为灌水器抗堵塞设计提供一定的依据。 相似文献