Einfluß einiger Umweltfaktoren auf die N2O-Bildung durch Belebtschlamm unter anoxischen Bedingungen Influence of Some Environmental Conditions on N2O-Release by Activated Sludge under Anoxic Conditions

The release of nitrous oxide during denitrification in activated sludge is influenced by various environmental factors. Experiments with different electron acceptors showed that under anoxic conditions increasing concentrations of nitrate as well as nitrite enhance the production of N₂O. The N₂O concentration in the gas phase increases for 2 h, then decreases. Nitrite causes a higher release of N₂O than nitrate. Acetate in high concentration can stimulate N₂O-release. Without addition of acetate nitrate and nitrite reduction are delayed, and hence N₂O-release and consumption are much slower. In activated sludge sulfide can play a role as an inhibitor of the nitrous oxide reductase (like in soil and pure cultures), but is inactivated very rapidly. Repeated addition of sulfide can cause a new release of nitrous oxide. At low pH (less than 6.5) denitrification is slightly inhibited and N₂O-release is 100 times higher than at pH 7.0 to 8.0. Under oxygen-limiting conditions N₂O-release and denitrification starts at 0.5–1.0 mg/L DO, but it is not always accompanied by accumulation of nitrite. Further reduction of the oxygen concentration reduces N₂O-release.     

Effects of nitrate on nitrite toxicity to Microcystis aeruginosa

The aim of this study was to investigate the effect of nitrate on nitrite toxicity to Microcystis aeruginosa. Short-term uptake experiment revealed nitrate could depress the nitrite active uptake. The long-term experiment of nitrate effects on nitrite toxicity showed a negative relationship between the growth and intracellular nitrite levels of M. aeruginosa. The net nitrite uptake displayed a decline in the range of 0-150 mg NO(3)(-)-NL(-1) and an elevation at 200mg NO(3)(-)-NL(-1), whereas the activities of nitrate reductase (NR) were more sensitive to nitrate than nitrite reductase (NiR). As a result, the total intracellular nitrite levels tended to decrease up to 100 mg NO(3)(-)-NL(-1) then increased at 150-200 mg NO(3)(-)-NL(-1). These results suggested the existence of external nitrate could affect the toxicity of nitrite to alga through changing intracellular nitrite content.     

我国水库综合养鱼的发展前景

本文从分析水库综合养鱼生态系统的生态关系入手,阐述了水库综合养鱼的内容、意义、理论依据以及发展水库综合养鱼的自然条件和实践基础,并对综合养鱼系统的鱼产潜力进行了预测。预测结果表明,水库发展综合养鱼比传统的粗养方式其单位面积鱼产量可获得大幅度提高。     

Eutrophic waters, algal bloom and fish kill in fish farming areas in Bolinao, Pangasinan, Philippines

The coastal waters of Bolinao, Pangasinan, Philippines experienced environmental changes over a 10-year period (1995-2005), the most significant effect of which was the major fish kill event in 2002 that coincided with the first reported Philippine bloom of a dinoflagellate Prorocentrum minimum. Days before the bloom, dissolved oxygen was < 2.0 mg/l in the waters that were stratified. These conditions may be linked to the uncontrolled proliferation of fish pens and cages to more than double the allowable limit of 544 units for Bolinao waters. Mariculture activities release organic matter from unconsumed feed and fecal material that accumulate in the water and sediments. In over 10 years, water quality conditions have become eutrophic with ammonia increasing by 56%, nitrite by 35%, nitrate by 90%, and phosphate by 67%. The addition of more fish pens and cages placed additional stress to this poorly flushed, shallow area that affected water quality due to changes in the water residence time.     

The Influence of a Teleost Clarias batrachus (L.) on the Behaviour of Different Species of Nitrogen in Water

Different experimental conditions (fed large, fed small, starved large, starved small groups, batch offered ration during experiment and low fish loading for a constant volume of water) of the carnivorous fish Clarias batrachus resulted in marked changes in the concentration of different N species (ammonium-N, nitrate-N, nitrate-N, organic-N as well as the sum of all forms of N) in aquaria water. Organic forms of nitrogen were the most important species of nitrogen excreted by the test fish. The maintenance nitrogen excretion rate was distinctly higher in larger fishes than in smaller ones. Different species of N were found to differ significantly depending upon the fed or starved conditions as well as small or large groups. A reduced level of oxygen in experimental aquaria inhibited the synthesis of nitrate which was maximum in control aquaria with considerably higher values of oxygen.     

Eutrophic waters,algal bloom and fish kill in fish farming areas in Bolinao,Pangasinan, Philippines

The coastal waters of Bolinao, Pangasinan, Philippines experienced environmental changes over a 10-year period (1995–2005), the most significant effect of which was the major fish kill event in 2002 that coincided with the first reported Philippine bloom of a dinoflagellate Prorocentrum minimum. Days before the bloom, dissolved oxygen was <2.0 mg/l in the waters that were stratified. These conditions may be linked to the uncontrolled proliferation of fish pens and cages to more than double the allowable limit of 544 units for Bolinao waters. Mariculture activities release organic matter from unconsumed feed and fecal material that accumulate in the water and sediments. In over 10 years, water quality conditions have become eutrophic with ammonia increasing by 56%, nitrite by 35%, nitrate by 90%, and phosphate by 67%. The addition of more fish pens and cages placed additional stress to this poorly flushed, shallow area that affected water quality due to changes in the water residence time.     

太湖梅梁湾藻蓝蛋白转录间隔区基因和伪空胞基因表达及其影响因子

以室内铜绿微囊藻7806(Microcystis aeruginosa 7806)为对照,运用反转录定量PCR技术研究太湖梅梁湾水体蓝藻藻蓝蛋白转录间隔区基因(PC-IGS)和伪空胞基因(gvp C)在2013年1月至2014年1月的相对表达量,并分析它们与环境因子的关系.结果表明,PC-IGS相对表达量在2013年1—5月逐渐上升,并在5月达到最大值;gvp C相对表达量从2013年1月开始持续上升并在3月达到最大值;gvp C的表达早于PC-IGS.相关分析表明,PC-IGS的相对表达量与硝态氮、溶解氧浓度均呈极显著正相关,与亚硝态氮、铵态氮以及正磷酸盐浓度均呈显著正相关,与p H值呈显著负相关,与温度、总氮和总磷浓度均无显著相关性;gvp C的相对表达量与硝态氮、铵态氮以及正磷酸盐浓度均呈极显著正相关,与总氮和亚硝态氮浓度呈显著正相关,与温度和p H值均呈显著负相关,与溶解氧和总磷浓度均无显著相关性.     

Shifts in the Processes of Oxygen and Nutrient Balances in the River Elbe since the Transformation of the Economic Structure

The reduction of pollution in the river Elbe since 1990 has resulted in changes in the processes taking place in the river. The heterotrophic degradation which dominated until 1990 was accompanied by a lack of oxygen, floating masses of sewage fungi, and sludge formation in the areas of still water. Since the early 1990s, autotrophic processes have come to dominate, with an increase in pH fluctuations and the oxygen production potential, but evidently not the chlorophyll level during the growing season. The degradable organic pollution of the Elbe is determined by algae production. The high levels of ammonium previously encountered in the Elbe were attributable to not only dischargers but also in particular the lack of oxygen in the water. Via heterotrophic nitrate assimilation, nitrate served as an oxygen reserve, resulting in high levels of nitrite. At present, when the oxygen contents are sufficient, the concentration reductions of nitrate and nitrite along the reach of the Elbe are approximately parallel, which in view of the lack of ammonium indicates the denitrification of microzones low in oxygen. The relative proportion of structurally bound substance turnover will become increasingly important for the Elbeπs material budget.     

三峡库区的入侵鱼类及库区蓄水对外来鱼类入侵的影响初探

三峡水库已于2010年10月完成175 m的蓄水目标,蓄水后三峡库区形成一个生态位严重空缺的人造湖泊生态系统.近年来,库区及长江上游外来入侵鱼类呈增长态势,已发现外来入侵鱼类23种,且部分已处于种群数量暴发阶段.水库蓄水初期营养盐输入增加和初级生产力的提高通常也利于广适性鱼类和外来种的生存,对外来鱼类的入侵和种群数量的扩散暴发产生一定的促进作用.外来鱼类在生态位竞争上与土著鱼类相比处于明显优势地位,可能将严重危害三峡库区的渔业资源及其水域生态系统的安全.因此,对于三峡库区的鱼类入侵及其所带来的相关效应等问题,应引起密切关注和重视,尽早建立三峡库区入侵鱼类的预警和防治体系,严格评估人为引种活动,深入研究外来鱼类得以成功入侵的原因与机理.     

太湖渔业资源现状(2009-2010年)及与水体富营养化关系浅析

根据2009-2010年的太湖鱼类资源调查,结合历年渔业资料和水环境监测数据,分析太湖渔业资源的发展趋势和结构特征.结果表明:本次调查共采集到鱼类47种,隶属10目14科37属,原常见鱼类种类数明显减少,鲤科等定居性鱼类成为主体;同时,太湖渔业产量近年来增长迅速,渔获物中湖鲚等小型鱼类比重增加,渔业资源的单一化和小型化趋势加剧.根据湖泊水体环境特征的空间差异,对太湖东部湖区、北部湖区和湖心区3个不同类型湖区间的渔业资源特征进行比较.其中在北部湖区和湖心区,浮游食性的湖鲚成为绝对优势种,2008年其产量分别占湖区总产量的70.7％和80.4％,其他主要鱼类所占比重仅为0.2％ -3.0％;而东部湖区草食性和肉食性鱼类的比例较高,鱼类结构相对合理,不同湖区间渔获物的组成差别反映出湖区鱼类组成与环境特征相适应的特点.针对太湖渔业资源与水体富营养化关系进行探讨,提出需加强渔业与湖泊环境功能之间关系的研究,重视水生植被在太湖渔业可持续发展中作用的建议.     

Lower thermospheric nitric oxide concentrations derived from WINDII observations of the green nightglow continuum at 553.1 nm

Vertical profiles of nitric oxide in the altitude range 90 to 105 km are derived from 553 nm nightglow continuum measurements made with the Wind Imaging Interferometer (WINDII) on the Upper Atmosphere Research Satellite (UARS). The profiles are derived under the assumption that the continuum emission is due entirely to the NO+O air afterglow reaction. Vertical profiles of the atomic oxygen density, which are required to determine the nitric oxide concentrations, are derived from coordinated WINDII measurements of the atomic oxygen OI 557.7 nm nightglow emission. Data coverage for local solar times ranging from 20 h to 04 h, and latitudes ranging from 42°S to 42°N, is achieved by zonally averaging and binning data obtained on 18 nights during a two-month period extending from mid-November 1992 until mid-January 1993. The derived nitric oxide concentrations are significantly smaller than those obtained from rocket measurements of the airglow continuum but they do compare well with model expectations and nitric oxide densities measured using the resonance fluorescence technique on the Solar Mesosphere Explorer satellite. The near-global coverage of the WINDII observations and the similarities to the nitric oxide global morphology established from other satellite measurements strongly suggests that the NO+O reaction is the major source of the continuum near 553 nm and that there is no compelling reason to invoke additional sources of continuum emission in this immediate spectral region.     

An investigation into the physico-chemical conditions of the coastal waters around the Gulf of Catania

The results are given of sea water sampling at 49 different stations around the Gulf of Catania. The main physico-chemical parameters are reported (temperature, pH, dissolved oxygen, salinity, BOD) as well as the concentrations of some nutritive salts (nitrite, nitrate, phosphate).     

Zum biochemischen Harnstoffabbau in wäßriger Lösung — Übersicht

Urea from natural and anthropogenic sources is one of the most interesting nitrogen compounds in an aquatic environment. Results of experimental investigations are presented for the successive biochemical urea transformation into nitrates via ammonium and nitrite species. Kinetic models based on a combination of Michaelis-Menten and Monod equations have been derived which describe reasonably well the course of the enzymatic reactions and the concentration-time profiles of different N oxydation states. Main factors affecting the rates of nitrogen metabolization are the initial concentration of ureolytic bacteria, the physical state of the nitrifying microorganisms, and the concentration of toxic organics added to the system under study.     

Estimation of atomic oxygen concentrations from measured intensities of infrared nitric oxide radiation

The vibrational distribution of nitric oxide in the polar ionosphere computed according to the one-dimensional non-steady model of chemical and vibrational kinetics of the upper atmosphere has been compared with experimental data from rocket measurement. Some input parameters of the model have been varied to obtain the least-averaged deviation of the calculated population from experimental one. It is shown that the least deviation of our calculations from experimental measurements depends sufficiently on both the surprisal parameter of the production reaction of metastable atomic nitrogen with molecular oxygen and the profile of atomic oxygen concentration. The best agreement with the MSIS-83 profile was obtained for the value of surprisal parameter corresponding to recent laboratory estimations. The measured depression of level v = 2 is obtained in the calculation that uses sufficiently increased concentrations of atomic oxygen. It is pointed out that similar measurements of infrared radiation intensities could be used to estimate the atomic oxygen concentrations during auroral disturbances of the upper atmosphere.     

The Uptake of Ammonium,Nitrite and Nitrate Ions by Hydrodictyon reticulatum

It has been found that ammonium ions belong together with potassium and sodium ions to the main cationic species in algal cells. The intracellular concentration of ammonium ions, which changes from 4 to 160 μmol. g^?1 wet weight, strongly influences the influx and reflux of different ions. Algal cells containing 4… 6 μmol of ammonium ions per gram cumulate ammonium ions in the light with a very high initial rate of 40… 80 pmol. cm^?2. s^?1, whereas the influx of nitrite or nitrate ions is slower by more than one order. Whereas ammonium ions simply displace potassium ions from the cell, the uptake of nitrite and nitrate ions is more complicated. These ions are rapidly reduced inside the cell into ammonium ions, which is connected with the reflux of potassium and hydroxyl ions. Ammonium ions formed take part in metabolic reactions releasing hydrogen ions.     

Physiological and genetical adaptation to temperature in fish populations

The physiological and genetical adaptation of fishes to environmental temperatures has been studied by analyzing data concerning: (i) the oxygen binding properties of haemoglobin recorded during growth experiments on Atlantic cod, and (ii) the primary structure of haemoglobin (Hb) and lactate dehydrogenase (LDH) of several fish species living in polar and temperate areas. The results on the oxygen binding properties of cod's haemoglobin indicate that for this species a temperature of around 12°C is the most favourable one, irrespective of the haemoglobin genotype, and are in line with recent evidence challenging the existence of significant evolutionary differences between cod stocks in North Atlantic. The primary structures of both Hb and LDH from species living under temperate environments show a higher variability as compared to that from polar species, although the difference in the recurrent patterns of hydrophobicity between the two areas is much larger for Hb. These results highlight the dominant role of physiological and genetical factors in shaping the adaptation to temperature at the individual and at the species level, respectively.     

Survey of Nitrate Contamination in Shallow Domestic Drinking Water Wells of the Inner Coastal Plain of Georgia

Beginning in 1990, 2,588 wells were sampled within the Inner Coastal Plain of Georgia in an effort to assess the quality of ground water in this major farm belt. The project was one aspect of an EPA-sponsored program to assess ground-water quality statewide. Several variables were measured, including pH, specific conductivity, dissolved oxygen, temperature, nitrate, nitrite, total hardness, calcium, magnesium, and bicarbonate. In some wells sulfate, chloride, potassium, iron, and manganese contents were also determined. Particular emphasis was placed, however, on pH, specific conductivity, temperature, and nitrite/nitrate content. Generally, pH was between 6 and 8, and temperatures were within a range of 18° and 24°Celsius. Measurements of specific conductivity varied, but averaged 250–275 microsiemens/cm. Nitrite contamination was negligible, and nitrate contamination of the ground water within the shallow aquifers did not appear to be significant. In fact, 56% of the wells sampled showed no detectable signs of nitrate or nitrite contamination. There were, however, a few isolated wells where nitrate as nitrogen measurements exceeded the EPA's Safe Drinking Water Standard of 10 ppm. The general lack of contamination may be the result of the nature of the agricultural practices used in this region and/or the effect of natural denitrification.     

Variations in the loadings and riverine transport of nitrate and nitrite in Latvia

The intra-annual and long-term variations in the nitrate and nitrite concentrations and transport are considered for the years 1948–1990. The nutrient loading on the Latvian rivers is subject to considerable intra-annual variations. Weak direct relationships with the fresh water inputs were observed for nitrite, while inverse ones were characteristic for nitrate. The nitrate and nitrite concentrations have been increasing since the late 1950s followed by an increase of the year-to-year variability. Non-point sources of anthropogenic impact (fertilizers leaching from agriculture and the reclamation) increase riverine concentrations of nitrogen compounds, and in particular of nitrate from 300–500 to 1300–1500%.     

Predicting summer hypoxia in the northern Gulf of Mexico: riverine N, P, and Si loading

We conducted a statistical analysis to discern the relative strengths of the loading of various forms of nitrogen, phosphorus, dissolved silicate and their molar ratios on the variance in the size of the summertime low oxygen zone found off the Mississippi River, northern Gulf of Mexico. A stable statistical model that included Year and riverine nitrate+nitrite loading for the 2 months prior to the measurement of hypoxic zone size described 82% of its variation in size from 1978 to 2004. The usefulness of the term Year is consistent with the documented increase in carbon stored in sediments after the 1970s, which is when the hypoxic zone is predicted to have become a regular feature on the shelf and to have expanded westward. The increased carbon storage is anticipated to cause a sedimentary respiratory demand influencing the size of the zone, and whose temporal influence is cumulative and transcends the annual variations in nitrogen loading. The variable Year is negatively correlated with the TN:TP ratio in a way that suggests N, not P, has become more important as a factor limiting phytoplankton growth in the last 20 years. Nitrogen, in particular nitrate+nitrite, and not phosphorus, dissolved silicate, or their molar ratios, appears to be the major driving factor influencing the size of the hypoxic zone on this shelf. This conclusion is consistent with cross-system analyses that conclude that the TN:TP ratio in the Mississippi River, currently fluctuating around 20:1, is indicative of nitrogen, not phosphorus, limitation of phytoplankton growth. Nutrient management that places stronger emphasis on reducing nitrogen loading as compared to phosphorus loading, is justified.     

Improved lakeshore sediment microenvironment and enhanced denitrification efficiency by natural solid carbon sources

At present, the high level of nitrate in tailwater of wastewater treatment plants(WWTPs) has continued to cause serious environmental problems. In current study, wood chips and bark, serving as natural solid carbon source(NSCS), were applied to enhance the denitrification capacity of lakeshore sediment to remove superabundant nitrate in tailwater. The results show that NSCS had a positive effect on denitrification process for lakeshore sediment and increased the total phosphorus removal capacity...