黑斑口虾蛄生态因子的试验观察

选用活力强、体长10cm左右的黑斑口虾蛄，进行海水盐度、水温、pH值等生态因子试验。结果表明：其生存的海水盐度为6．02％～38．64％，适宜的盐度是24．20‰～29．51‰；生存的水温为10～35℃，适宜的水温为22～30℃；存活的PH6～10，适宜的PH7～9。主要以摄食贝类、鱼类及虾类为生。     

Quantitative estimates of recent environmental changes in the Canadian High Arctic inferred from diatoms in lake and pond sediments

Diatoms were examined in three lacustrine sediment records from Alert, northern Ellesmere Island, and from Isachsen, Ellef Ringnes Island. Diatom assemblages changed markedly since the mid-19th century following relatively stable community composition that spanned centuries to millennia. Three different assemblages, primarily composed of Fragilaria pinnata, Diadesmis spp., or Pinnularia spp., dominated the pre-1850 period at the three sites, but were replaced with different, more diverse assemblages in recent sediments. These species shifts occurred in the mid- to late-19th century in the Isachsen sites, and in the mid- to late-20th century in our Alert site. This difference in timing appears to be a result of the different sensitivities of lakes and ponds to environmental change, rather than of site-specific chemical properties. Reconstructions of pH using diatom inference models indicated increases from 0.5 to 0.8 pH units at these sites over this period of assemblage change. The diatom-inferred pH record from Alert showed agreement with measured climate data from Alert over the last 30 years. These marked community changes suggest that these sensitive high arctic sites have recently crossed important ecological thresholds due to environmental change, most likely related to recent warming.     

Aqueous Oxidation of Sulfur(IV) Catalyzed by Manganese(II): A Generalized Simple Kinetic Model

The reaction kinetics of S(IV) autoxidation catalyzed by Mn(II) in the pH range 3–5 typical for atmospheric liquid water, was investigated. For reactions with pH maintained constant during the reaction course, the predictions obtained by a simple integral approach cover kinetic results only for concentrations of HSO ₃ ⁻ up to 0.2 mM at pH 4.5. Thus, a generalized simple kinetic model, which can be used for predicting the reaction kinetics in wider concentration, pH and temperature ranges, was derived. This model is based on the assumption that the reaction rate is proportional to the concentration of a transient manganese-sulfito complex formed in the initial step of a radical chain mechanism. In the proposed power law rate equation

Species Composition and Seasonal Variations of the Gastropoda in Upper Sakarya River System (Turkey) in Relation to Water Quality

Species composition, abundance, and seasonal distribution of the Gastropoda fauna and the physical and chemical variables of Upper Sakarya River System have been investigated between October 1998 and August 1999. Gastropod fauna in the Upper Sakarya River System was represented by 9 species of Prosobranchia and 7 species of Pulmonata. Diversity, dominance, and abundance of the Gastropoda species were recorded seasonally. The abundance of some of the 16 species was correlated positively with temperature, dissolved oxygen and negatively or positively with pH and nitrate. It was observed that Gyraulus albus (Müller, 1774), Physa acuta Draparnaud, 1805, Valvata pulchella Studer, 1820, and Oxyloma elegans (Risso, 1826) can tolerate a high level of NO‐N while V. piscinalis (Müller, 1774) spread out in unpolluted water. Although the species and their numbers change at the stations, the maximum numbers were found during autumn, while minimums were identified during the winter sampling. Gyraulus albus was the most widespread species in our research area. Only 5 species (Gyraulus albus, Physa acuta, Valvata cristata (Muller, 1774), Valvata pulchella, Melanopsis praemorsa costata (Olivier, 1804)) were determined each season. However, no Gastropoda were found at the station 3 that has high BOD, NO‐N, NO‐N, and NH₃ levels.     

环境因素对虎纹蛙胚胎发育的影响

就温度、盐度、pH值及水中溶氧四个环境因素对虎纹蛙胚胎发育的影响进行了系统研究.结果表明其适宜的孵化水温为20～30℃,在此温度范围内,随着温度的升高,胚胎发育速度加快,水温在(30±1)℃时,胚胎发育到鳃盖完成期需58.8h,孵化率为84.2%;水温(20±0.5)℃时,需203.9h,孵化率为89.0%;水温(25±1)℃时,需时84.0h,孵化率最高,达94.5%.盐度对虎纹蛙胚胎发育影响很大,盐度越高,胚胎畸形率越高,且发育经历时间越长,孵化水体的盐度应在1.9以下,最适宜用淡水孵化.pH过高或过低都对胚胎发育不利,孵化水体的pH值以6.5～8.5为宜.虎纹蛙胚胎发育的不同阶段对水中溶氧量要求不同,在肌肉效应期、鳃血循环期和鳃盖完成期,水中溶氧的半致死浓度分别为0.57mg/L、1.13mg/L和0.40mg/L.     

Saisonales Vorkommen von Arten der Saprolegniales und Leptomitales im Auesee und in der Fulda in Kassel (Hessen) unter Berücksichtigung fischpathogener Arten

Seasonal Occurrence of Species of Saprolegniales and Leptomitales in Lake Aue and the River Fulda in Kassel (Hesse) with Special Consideration of Fish Pathogenic Species In this study, we examined the occurrence of species of aquatic Oomycetes of Saprolegniales und Leptomitales in Lake Aue and the river Fulda in Kassel (Hesse, Germany) with special consideration of fish pathogenic species. We monthly collected water samples of both water bodies from July 2003 to June 2004. The baiting method was used to gain an insight into the specific seasonal occurrence of aquatic Oomycetes. Some species show a seasonal periodicity. Nine of 11 species of Saprolegniales isolated from the two water bodies, and Leptomitus lacteus (Roth) C. Agardh, one of the two species of Leptomitales, were already documented on fish according to references. Additionally, 7 of 10 species could according to references already be detected on fish species present in the two water bodies. Simultaneous measurements of limnological‐chemical parameters were done during the sampling of water for the isolation of aquatic Oomycetes. The results of some measurements, concerning the river Fulda, were additionally compared with the predetermined guideline values and limit values of water bodies of fish of the “Cyprinid region”.     

古海水pH值代用指标——海洋碳酸盐硼同位素研究进展

仪器测量的海水pH记录太短，无法评估海水pH自然变化的频率和幅度,并预测未来大气CO₂急剧增加后海水酸度的响应。海相碳酸盐的硼同位素是目前恢复古海洋pH的有效途径，倍受古气候—环境学家的重视。评述了近年来海洋碳酸盐的硼同位素的最新研究成果和研究现状，重点探讨了海相碳酸盐的硼同位素的测定方法、硼同位素—pH模型和古海水pH恢复等前沿内容，旨在提供一个系统的海洋碳酸盐硼同位素—pH系统的基本概念及研究思路，以利于气候学、地质学界了解这一交叉领域的发展动态。     

Tensile strength characteristics of contaminated and compacted sand-bentonite mixtures

A theoretical and experimental study of the unconfined penetration test (UP) method was conducted to determine the tensile strength of contaminated and compacted sand-bentonite mixtures, which are used widely in the landfill construction sites as a clay liner. To do this, the original UP device and experimental procedure were modified to reduce the measurement errors and named as the improved unconfined penetration (IUP) test. Experiments were carried out to examine the variation in tensile strength as a function of disk diameter, loading rate and pH level. The results of the experiments provided the following important findings. The tensile strength increases with an increase in the disk diameter. The tensile strength is not sensitive to the loading rate in the range of 0.1%/min–1.0%/min. A specimen compacted with a low pH value of water shows a high tensile strength, because a lower pH solution increases soil particle bonding stresses.     

Acid–base activity of microorganisms

In order to distinguish the buffering capacity associated with functional groups in the cell wall from that resulting from metabolic processes, the base or acid consumption of live and dead cells of the Gram-negative bacterium Shewanella putrefaciens was measured as a function of time in a pH stat system. Under neutral (pH 7) to basic (pH 8 and 10) conditions, base neutralization by suspensions of live bacteria beyond 1 h was clearly due to respiratory activity. At pH 4, however, proton neutralization ceased after 50 min due to cell death. Dead cells only produced or consumed protons during the very first minutes after exposure to pH 4, 8 or 10. From the time-dependent acid and base consumption curves of live cells, and the comparison of the acid–base activity of live and dead cells, the charging of ionizable groups in the cell wall was derived. From pH 4 to 10, cell wall charge increases from 0 to about − 4 × 10^− 16 mol cell^− 1.     

Inadvertent alkalization of a Florida lake caused by increased ionic and nutrient loading to its watershed

We evaluate the effects of land-use change since c.1890 on Little Lake Jackson in south-central Florida, USA. The lake currently is alkaline despite the prevalence of acidic lakes in the region. Watershed soils are acidic and poorly drained, but are underlain by limestone bedrock. Limnetic pH inferences, based on weighted-averaging tolerance regression of sedimented diatoms, indicate that Little Lake Jackson became significantly alkalized during the 1900s. Two driving forces that appear to be responsible for water-quality change are increased ionic loading and increased nutrient loading. Golf courses and residential lawns in the watershed receive substantial applications of lime, fertilizer, and irrigation with alkaline waters from deep wells, some of which reaches the lake in channelized runoff. Stormwater runoff and septic leachate also contribute to nutrient and solute loading. Sedimentary total P accumulation increased 5-fold and total N accumulation increased 3-fold since c. 1890. δ¹⁵N values suggest agricultural and septic sources for N loading. Sedimented pigments, inferred limnetic chlorophyll a values, and δ¹³C values of organic matter indicate that increased primary productivity occurred. Surface and subsurface inflow is nutrient-rich but low in hardness. Increased cation deposition in sediments indicates that ionic input might have reduced the lake’s natural resistance to alkalization. Lake waters remain low in ionic content, which suggests that the addition of base from carbonate sources is not responsible for all of the observed alkalization. Acid neutralization might have been facilitated by phosphate loading that led to increased base generation through greater nitrate assimilation. Inadvertent alkalization might occur commonly in regions where poorly buffered lakes are subject to significant ionic and nutrient loading from agriculture, turfgrass, and septic sources in their watersheds.