天然多糖基水凝胶的制备及水体中重金属移除研究进展

水体中存在重金属会威胁到人类及其他生物体的健康,必须对水体中重金属离子进行去除.吸附法被认为是水体中重金属去除最有前景的技术之一,利用绿色、经济、可回收的天然材料吸附水体中的重金属离子是目前的热点研究话题.近年来,水凝胶材料由于其三维立体网络结构的特点及良好的金属离子吸附性能,使其在处理水体中重金属方面有了广泛应用.本...     

Stable lead isotopes as a tracer in coastal waters

The natural abundances of the stable isotopes of lead are used to identify natural and industrial sources of lead in the coastal waters of British Columbia, Canada. The (206)Pb/(207)Pb ratios, used to characterize the lead source, had values of approximately 1.24 for coastal oceanic water, approximately 1.22 for fjord waters receiving lead from mine tailings, and approximately 1.163 for waters near urban centers. The lead concentration data are in agreement with presently accepted seawater values.     

Fossil fuel combustion and the major sedimentary cycle

The combustion of the fossil fuels coal, oil, and lignite potentially can mobilize many elements into the atmosphere at rates, in general, less than but comparable to their rates of flow through natural waters during the weathering cycle. Since the principal sites of fossil fuel combustion are in the mid-latitudes of the Northern Hemisphere, changes in the composition of natural waters and air, as a consequence of this activity, will be most evident at these latitudes.     

内陆碳酸盐型盐碱水域移殖对虾的可能性试验

通过碱度对淡化南美白对虾幼虾的急性毒性试验和对虾在天然盐碱泡水域的生存能力观察,探讨内陆碳酸盐型盐碱水域移殖对虾的可能性。结果表明：碱度对淡化南美白对虾幼虾毒性作用的半有效浓度（EC50）为2．78mmol／L,24,48,96h的半致死浓度（屿）分别为12．94,11．89,11．65mmol／L,安全浓度（SC）为3．10mmol／L。淡化南美白对虾幼虾和中国对虾成虾在天然盐碱泡水域可分别存活5．5h和3h。盐度不是内陆碳酸盐型盐碱水域移殖对虾的限制因素,高碱度、高pH、主要离子组成及其比例不适和水质类型差别则是不可逾越的障碍。     

Upwelling of hydrothermal solutions through ridge flank sediments shown by pore water profiles

High calcium ion and low magnesium ion concentrations in sediment pore waters in cores from the Galápagos Mounds Hydrothermal Field on the flank of the Galápagos Spreading Center are believed to be due to a calcium-magnesium exchange reaction between circulating seawater and basement basalt. The nonlinearity of the calcium ion and magnesium ion gradients indicates that these discharging hydrothermal solutions on the ridge flank are upwelling at the rate of about 1 centimeter per year through the pelagic sediments of the Mounds Field and at about 20 centimeters per year through the hydrothermal mounds themselves.     

咪草烟在不同土壤和水体中的残留动态研究

采用HPLC法研究了咪草烟在不同土壤和不同自然水体中光化学降解动态。研究表明,在高压汞灯照射下,不同土壤中咪草烟的光解半衰期是砂姜黑土<黄潮土<黄褐土<砖红壤<红壤,半衰期分别为45.015、5.01、61.349、9.01和106.63 min;不同水体中咪草烟光解半衰期是湖水<井水<水库水<三蒸水<稻田水,半衰期分别为35.73、43.054、6.521、21.60和150.67 min。说明pH值、有机质及环境中的其他物质等环境条件对咪草烟降解速度有影响。     

植物释放负离子对室内空气质量影响分析

[目的]研究改善室内空气质量的新途径.[方法]在自然状态和放置植物源负离子发生器状态下,对玻璃室内的负离子、正离子和安倍指数等指标进行研究.[结果]在自然状态下,玻璃室内负离子浓度均值较低,为1 084 ion/cm3;在放置植物源负离子发生器状态下,负离子浓度均值为684 190 ion/cm3,是自然状态下的631倍.正离子在自然状态下的浓度均值为946 ion/cm3,在植物源负离子发生器开启状态下值为976 ion/cm3,两者差异不显著（P＞0.05）.从安倍指数看,植物源负离子发生器开启状态下值为685 457.62,是自然状态下的539 730倍.[结论]在玻璃室内放置植物源负离子发生器可显著提高室内空气质量.     

芜湖市区主要湖泊水体总有机碳的初步研究

本文利用总有机碳分析仪测定了芜湖市区几种典型地面水体总有机碳（TOC）含量。结果表明,市区景观水体镜湖和九连塘湖水中TOC含量分别为16．9±8．2和23．2±4．8mg／L;市郊自然河塘水中TOC含量在晴天和降雨后分别为35．9±22．6和24．5±3．2mg／L。两类水体中TOC含量的影响因素分别是市政绿化冲洗水及田间沟渠漫溢水的排入,降雨对河塘水TOC有明显的稀释作用。     

Regional ground-water mixing and the origin of saline fluids: midcontinent, United States

Ground waters in three adjacent regional flow systems in the midcontinent exhibit extreme chemical and isotopic variations that delineate large-scale fluid flow and mixing processes and two distinct mechanisms for the generation of saline fluids. Systematic spatial variations of major ion concentrations, H, O, and Sr isotopic compositions, and ground-water migration pathways indicate that each flow system contains water of markedly different origin. Mixing of the three separate ground waters exerts a fundamental control on ground-water composition. The three ground waters are: (i) dilute meteoric water recharged in southern Missouri; (ii) saline Na-Ca-Cl water in southeastern Kansas of far-traveled meteoric origin that acquired its salinity by halite dissolution; and (iii) Na-Ca-Cl brines in north-central Oklahoma that may have originated as Paleozoic seawater.     

Advection of pore fluids through sediments in the equatorial East pacific

Measurements of the ratio of helium-4 to helium-3 and of calcium ion in the pore waters of sediments at two locations in the eastern equatorial Pacific indicate that solution advection is occurring through the sediments. Both the helium ratio and the calcium ion profile yield velocity values for advective flow of about 20 centimeters per year. Mass balance constraints are also consistent with the interpretation presented. Flow appears to be occurring thorugh relatively thick sediments, on the order of 300 meters.     

Evidence for upwelling of corrosive "acidified" water onto the continental shelf

The absorption of atmospheric carbon dioxide (CO2) into the ocean lowers the pH of the waters. This so-called ocean acidification could have important consequences for marine ecosystems. To better understand the extent of this ocean acidification in coastal waters, we conducted hydrographic surveys along the continental shelf of western North America from central Canada to northern Mexico. We observed seawater that is undersaturated with respect to aragonite upwelling onto large portions of the continental shelf, reaching depths of approximately 40 to 120 meters along most transect lines and all the way to the surface on one transect off northern California. Although seasonal upwelling of the undersaturated waters onto the shelf is a natural phenomenon in this region, the ocean uptake of anthropogenic CO2 has increased the areal extent of the affected area.     

Methylated forms of arsenic in the environment

Environmental samples were analyzed for arsenate and arsenite ions and the methylarsenic acids in nanogram amounts. Dimethylarsinic acid and methylarsonic acid were found in natural waters, bird eggshells, seashells, and human urine.     

大曲预处理技术对天然酱油风味的影响

[目的]对成熟大曲进行预处理,提升天然酱油的风味。[方法]以正常大曲作为对照组,研究不同闷制时间后对应大曲的酶活及菌体自溶率;再向最佳闷制后的大曲中加入不同浓度的盐水进行发酵考察最适的盐水浓度。[结果]大曲闷制时间越长,其自溶率越高,但大曲酶活会先升高,后降低,最佳闷曲时间是使大曲温度接近40℃,即闷制5~6 h最佳,大曲酶活较对照组高5.5%。将闷制5~6 h的大曲加入不同浓度盐水发酵,盐水浓度越高,天然油氨基酸越低,当盐水的浓度为19.5 Be'时,对应天然油风味最好,且氨基酸提升6.1%。故大曲预处理最佳时间为5~6 h,最适盐水浓度为19.5 Be'。[结论]研究可为提升天然酱油品质提供参考。     

巢湖湖区底泥重金属污染状况评估

底泥是河湖的沉积物,是自然水域的重要组成部分,水体底泥污染是世界范围内的一个环境问题,当前对底泥的污染缺乏深入研究。以巢湖湖区底泥为研究对象,连续2年对湖区底泥中pH、Cd、Hg、As、Pb和Cr6项进行监测,选用标准值采用内梅罗综合污染指数法来评价监测点位的污染状况,通过方差分析法来评价两年数据的差异性;采用插值法绘出湖区底泥各重金属元素空间分布;采用地积累指数法来评价底泥中各重金属污染程度。评价结果显示,巢湖湖区底泥污染程度等级为清洁,2年的监测数据无显著性差异,湖区中部重金属含量相对较低,湖区底泥重金属污染程度总体不高,其中Hg的污染程度相对较大,Cd、Pb次之。     

明光市生态旅游资源现状与开发保护对策

明光市地处皖东,生态环境良好,山、水、林等自然景观兼备,生态旅游资源丰富.为了缓解未来旅游发展和环境保护之间的矛盾,为明光市旅游开发提供科学依据,在充分调研的基础上,对明光市旅游资源现状进行分析,探讨其生态旅游开发的可行性,并对明光市生态旅游资源的保护与开发提出了建议.     

Rate of Decomposition of GB in Seawater

The hydrolysis rate of isopropyl methylphosphonofluoridate (GB) in seawater can be predicted from known or extrapolated rate constants for the reaction between GB and the hydroxo-metal complexes of magnesium and calcium and between GB and the hydroxide ion. At 25 degrees C and pH 7.9 (typical values of many surface waters) the half-life of GB is approximately 30 minutes.     

Free-radical oxidants in natural waters

Photooxidation of cumene (isopropylbenzene) and pyridine in dilute solution in natural waters gives products characteristic of reactions with alkylperoxy (RO(2).) and hydroxyl (HO.) radicals. On the basis of the rates of formation of the products, the average concentrations of RO(2). and HO. are estimated to be about 10(-9) and 10(-17) mole per liter, respectively. The concentration of RO(2). is large enough that, for some classes of reactive chemicals, oxidation can be an important process in natural waters.     

Nitrogen Fixation in Lakes

Incorporation of N(15) into the fixed nitrogen fraction of natural lake waters has been studied for the purpose of estimating rates of primary nitrogen fixation. Experiments in Pymatuning Reservoir, Pennsylvania, in Lake Mendota, Wisconsin, and in two lakes in Alaska indicate that fixation occurs at measurable, sometimes high, rates.     

鳜亚科鱼类资源多样性的研究进展

近数十年来,随着内陆天然水域流量下降和水质受到不同程度的污染,加上江湖渔业的过度捕捞,使鳜类的野生资源受到严重威胁,其种类和数量逐渐减少。对近年来鳜类资源的物种多样性、分类地位和遗传多样性等方面的研究现状进行了综述。     

Arsenic in potable desert groundwater: an analysis problem

An accuracy investigation, initiated because of conflicting analytical data on the arsenic content for some 24 drinkinig water locations in the Mojave Desert, revealed that interference with the evolution of arsine in the American Public Health Association silver diethyldithiocarbamate method caused either color enhancement or arsine suppression. For certain types of natural waters this method is unreliable.