Sediment profile characterisation at contaminated and reference locations in the Windmill Islands, East Antarctica

Sediment profiles for pH, Eh, 28 elements, water and organic content are presented here for human impacted and reference locations in the Windmill Islands, East Antarctica. Variations in element concentrations are observed with increasing depth, especially at Brown Bay where the impact of past human activities is most pronounced in the top 10 cm. Spatial differences were observed between sediment profiles at reference and impacted locations and were largely explained by Pb variability in the top 5 cm. Median element concentrations from surface, middle and bottom regions of the sediment profile were compared to composite sample medians (no depth stratigraphy) for 11 elements at O’Brien Bay (reference) and Brown Bay (impacted). Pronounced differences were observed for Brown Bay, particularly surface and middle sections, implying that composite samples dilute the near surface anthropogenic signal by mixing with deeper uncontaminated sediment.     

Germination and establishment of the invasive cordgrass Spartina densiflora in acidic and metal polluted sediments of the Tinto River

Heavy metal pollution is common in rivers in the vicinity of mining areas. In these polluted environments, the survival of alien species with a high tolerance to metals may be favored. The Tinto River (Southwest Iberian Peninsula) is an excellent natural laboratory for the study of plants’ responses to acidic and metal polluted sediments. This work analyzes the tolerance of the alien species Spartina densiflora to low pH and high metal loads in the Tinto River. The main aim of this study was to determine if this alien species can invade landward along the banks of the Tinto River. S. densiflora seeds were able to germinate in heavy metal polluted aerobic sediments even at pH 2. However, these conditions decreased S. densiflora final germination, altered germination dynamics, decreased aerial and subterranean growth rates, and prevented its establishment.     

WA-PLS diatom-based pH, TP and DOC inference models from 42 lakes in the Abitibi clay belt area (Québec, Canada)

The relationship between surficial sediment diatom species and measured environmental variables was explored in lakes from the Abitibi region of western Quebec. Diatom assemblages in 42 lakes were identified and their relationship with measured environmental variables was examined using multivariate statistical methods. Canonical correspondence analysis with forward selection and Monte Carlo permutation tests revealed that the three environmental variables pH, TP and DOC each accounted for statistically significant fractions of the variation in diatom taxa. A training set with 164 modern diatom taxa was used to derive transfer functions for lake-water pH, TP and DOC using weighted-averaging-partial-least-squares (WA-PLS) techniques. The models were developed to infer lake water pH, TP and DOC within the ranges 4–8 for pH, 2.75–30.0 g l^–1 for TP, and 2.9–18.5 mg l^–1 for DOC. These quantitative inference models may now be used to help identify and estimate the effects of natural disturbances on the biogeochemistry of Abitibi lakes during their historical development.     

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.     

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。