盐碱池塘水生大型植物的研究

于1998 年4 月至1998 年9 月对高青盐碱池塘的水生大型植物种类组成、生产力及其影响因子进行了野外调查和试验研究。结果表明高青盐碱池塘共有水生植物12 种。常见的优势种有沉水植物:菹草、角果藻、金鱼藻;挺水植物:芦苇、荆三棱、莲和香蒲;漂浮植物:浮萍, 以及大型藻类布氏轮藻。种类少而优势种突出是盐碱池塘大型植物的显著特点。有水草池塘与无或少水草池塘相比, 透明度大、pH 值高、浮游植物生物量和叶绿素a 含量低、营养盐含量也低。在表层光照度7200lx、水温28~30℃的条件下, 菹草、角果藻和轮藻的毛产量分别为1.70、1.56 和1.50mgO₂·L^-1·h^-1·g^-1。除光照、水温、pH 等因素外, 含盐量和碱度对大型植物的初级生产力具有重要影响, 菹草和角果藻的生产力最高时的含盐量均为3g·L^-1, 前者适宜的碱度为6.69 mmol·L^-1, 而后者则为3.82 mmol·L^-1。菹草、角果藻、金鱼藻和浮萍对NH₄-N 的吸收速率相近, 而对PO₄-P 的吸收速率则角果藻 > 菹草 > 浮萍 > 金鱼藻。文后对盐水水体大型植物特点、菹草生产力及其影响因素、如何防止养鱼池大型植物危害及大型植物与浮游植物的关系进行了讨论。     

Effect of alkaline and saline substrates on ABA contents,distribution and transport in plant roots

The distribution of the phytohormone abscisic acid (ABA) between plant and soil and within plants growing on an alkaline substrate has been studied in order to separate the true effect of high soil pH from any effects that might be a result of the high salinity normally observed in alkaline soils. Leaves of a range of plants grown in an alkaline and saline solid substrate (municipal solid waste incinerator bottom slag) exhibited higher ABA levels than leaves of control plants. In contrast, roots of most plants grown on alkaline and saline substrates, particularly those without an exodermis (various species of Fabaceae), had slightly lower than or comparable ABA contents to control roots. However, in corn roots (Zea maysL. cv. Garant FAO 240) which possess a well-developed exodermis, alkaline and saline conditions in the rhizosphere did not reduce the endogenous ABA concentration, because the leaching of ABA from corn roots into the rhizosphere was lower than that from Vicia faba (variety Dreifache Weisse) roots. ABA efflux from corn and Vicia roots into the soil solution was observed only during the first days of the experiments and thereafter became substantially decreased. Because the leaching of ABA from Vicia faba roots into the rhizosphere was higher than that from corn roots, the leaves of Vicia plants grown in alkaline soil at low salinity no longer exhibited an elevated ABA concentration. However, whilst the roots of corn plants grown on desalted slag retained ABA levels that were higher than those of the control, the ABA content of leaves was not significant higher than the controls. For this reason, root ABA retention must be enough to induce tolerance to alkalinity in corn plants and there is no need to implicate changes in ABA concentrations in the aerial parts of the plant as having a role in this tolerance. In alkaline soil substrates, considerable portions of the ABA synthesised in the roots leached out into the soil solution of the rhizosphere according to the anion trap concept. An exodermis substantially reduces this leakage. The transient nature of ABA efflux into the rhizosphere was a result of the fact that the salt stress itself was only a transient phenomenon due to a washout of salt by irrigation. The results match predictions of mathematical models describing the effect of alkaline pH on the distribution of abscisic acid within plants and between roots and the rhizosphere. Species that can retain root ABA in the face of its tendency to leach into the more alkaline compartment are able to tolerate these normally harmful sites. This revised version was published online in June 2006 with corrections to the Cover Date.     

Radiolaria as a reflection of environmental conditions in the eastern and southern sectors of the Indian Ocean: A new statistical approach

Cluster analysis and species abundance plots of radiolarian abundance counts from core tops from the eastern Indian Ocean between 12° S and 31° S, and the southern Indian Ocean between 31° S and 62.5° S, demonstrate the existence of environmentally-related provinces supporting distinct taxa assemblages. These provinces are closely associated with currents in the eastern sector of the Indian Ocean and with fronts in the southern sector.The radiolarian assemblages correlate strongly with salinity-normalised total alkalinity (NTA) at the sea-surface, with temperature, salinity, and density from the sea-surface to 300 m, and with dissolved oxygen and nitrate and phosphate concentrations from the sea-surface to 100 m. Palaeo-reconstructions of these parameters at the sea-surface have been made for six Last Glacial Maximum (LGM) samples from five eastern Indian Ocean cores. The LGM sea-surface temperature estimates are comparable with those based on planktonic foraminiferal counts of the same samples obtained by other researchers. The reconstructions show that, since the LGM, density increased markedly along the Western Australian coast south of 20° S but changed little further from the Western Australian coast. By contrast, phosphate concentrations were marginally lower than modern values along the Western Australian coast south of 20° S but more than twice modern values in the other LGM samples.The utility of various regression and calibration techniques is discussed. It is concluded that, probably due to the effects of differences in radiolarian habitat, ocean currents, and/or environmental gradients, only one method, weighted averaging — partial least squares, is reliable in a study area of this size and complexity. If other methods are to be used, the study area must be partitioned into at least two separate regions with the major split between the eastern and southern sectors of the Indian Ocean.     

Benthos and macroinvertebrate drift in six streams differing in alkalinity

The productive capacity of aquatic systems often is equated with the ‘chemical richness’ of the water. A primary objective of the present study was to relate macroinvertebrate benthos and drift to a streams' productive capacity as indicated by absolute levels of alkalinity. We tested this relationship in six 2nd–3rd order tributaries of the Salmon River, Idaho that ranged in alkalinity from 50 to 360 mg 1⁻¹. Benthic density and biomass, drift biomass, and benthic organic matter increased with increasing levels of alkalinity, although not all relationships were significant. The proportion of drift biomass to benthic biomass was similar among study streams suggesting that drift was primarily passive during the study period. The data suggest that spatial variations in landscape-scale geology may indirectly affect spatial patterns of macroinvertebrate benthic and drift standing crops among streams within a single river basin by mediating lotic chemical richness as found among tributaries of the Salmon River basin. Author for correspondence     

Germination and Photosynthetic Responses to Salinity and Alkalinity in <i>Avicenna marina</i> Propagules

Avicenna marina (Forssk.) Vierh is a halophytic mangrove. The reproductive unit is green and has photosynthetic propagules. Mangroves are naturally exposed to fluctuations in some abiotic factors at the soil surface, including salinity and alkalinity. The objective of this study was to determine the effects of two salts including NaCl and NaHCO₃ on germination processes and discuss the relationships between cotyledon photosynthesis and embryo axis growth in A. marina propagules. These propagules came from Al Birk, located on the shoreline of the Saudi Red Sea. The results showed that the studied salts did not affect neither the final germination percentage nor the embryo axis growth. However, rooting and root growth were delayed by both salts at 300 mM and were strongly inhibited by 600 mM NaHCO₃. Both NaCl and NaHCO₃ reduced the photosynthetic activity. These two salts did not affect the other photosynthetic parameters, including stomatal conductance, net transpiration, and intercellular CO₂. Thereafter, the reduction in net photosynthesis was not related to any limitation of stomatal conductance. The early germination phase was independent of cotyledon photosynthesis, whereas rooting and root growth may be limited by reduced photosynthesis under NaCl and NaHCO₃.     

Is Coal Fly Ash a Suitable Alkaline Resource for Manufacturing New Calcium Carbonate–based Cements? A Systems Analytical Evaluation

At present, the production of cement contributes approximately 8% to global carbon dioxide (CO₂) emissions, whereas a further increase in the future is expected. To reduce these emissions, a prominent measure of the cement industry is to use materials such as coal fly ash (CFA) as a cement substitute, but the availability of qualified ash is limited. The development of “green cements” with lower CO₂ emissions attracts attention within the cement industry and politics. Recently, a new invention for a calcium carbonate (CaCO₃)‐based cement intends to use CFA as an alkaline resource during a manufacturing process based on CO₂ mineralization converting anthropogenic CO₂ into stable calcareous materials by using calcium‐bearing brines. In our systems analysis, we demonstrate that the alkalinity of CFA usable for mass production of cements is poor. The alkalinity of CFA primarily depends on the dissolution of free lime. For CO₂ mineralization, the resulting alkalinity is just sufficient to precipitate the calcium supplied by the CFA itself, and the capacity of CO₂ mineralization is low. Thus, CFA could only be used as a supplementary resource. Even at locations where exceptional calcium‐rich ash is available, very large amounts of ash must be processed. Globally, only a few million tonnes of calcium could be extracted in this way. Because qualified CFA is already used in the construction industry, the extraction of calcium from nonqualified, more polluted CFA is associated with a risk of unwanted environmental effects and implies an elaborated pollutant control.     

MORPHOLOGICAL AND PHYSIOLOGICAL EFFECTS IN PROBOSCIA ALATA (BACILLARIOPHYCEAE) GROWN UNDER DIFFERENT LIGHT AND CO2 CONDITIONS OF THE MODERN SOUTHERN OCEAN1

The combined effects of different light and aqueous CO₂ conditions were assessed for the Southern Ocean diatom Proboscia alata (Brightwell) Sundström in laboratory experiments. Selected culture conditions (light and CO_2(aq)) were representative for the natural ranges in the modern Southern Ocean. Light conditions were 40 (low) and 240 (high) μmol photons · m^?2 · s^?1. The three CO_2(aq) conditions ranged from 8 to 34 μmol · kg^?1 CO_2(aq) (equivalent to a pCO₂ from 137 to 598 μatm, respectively). Clear morphological changes were induced by these different CO_2(aq) conditions. Cells in low [CO_2(aq)] formed spirals, while many cells in high [CO_2(aq)] disintegrated. Cell size and volume were significantly affected by the different CO_2(aq) concentrations. Increasing CO_2(aq) concentrations led to an increase in particulate organic carbon concentrations per cell in the high light cultures, with exactly the opposite happening in the low light cultures. However, other parameters measured were not influenced by the range of CO_2(aq) treatments. This included growth rates, chlorophyll a concentration and photosynthetic yield (F_V/F_M). Different light treatments had a large effect on nutrient uptake. High light conditions caused an increased nutrient uptake rate compared to cells grown in low light conditions. Light and CO₂ conditions co‐determined in various ways the response of P. alata to changing environmental conditions. Overall P. alata appeared to be well adapted to the natural variability in light availability and CO_2(aq) concentration of the modern Southern Ocean. Nevertheless, our results showed that P. alata is susceptible to future changes in inorganic carbon concentrations in the Southern Ocean.     

新疆玛纳斯流域非农业种植地盐碱性空间变异特征

土壤盐渍化是导致干旱区土地退化的主要原因之一,也是影响干旱区可持续发展和环境改善的基本问题。充分挖掘不同分类体系下盐渍土空间变异性可以为实施开垦或恢复生态措施提供科学依据。以干旱区开垦近50a的玛纳斯流域为研究区,在不同分类体系下,以土壤盐度,p H值,离子类型为指标,分析该区域非农业种植地(弃耕地,盐碱地,裸地,沙地)盐渍土类型的空间分布特征。结果表明:(1)研究区68%的样本属于非盐渍化,不同类型的盐渍土主要以链状分布于泉水溢出带-冲积平原-干三角洲地带,由南向北,区域整体盐分大致遵循先升高后降低再升高趋势,半方差函数分析土壤盐分呈现弱变异,说明这种分布情况是受随机(人为)因素的影响;而p H整体由南向北递增,传统统计学和地统计学的分析结果都表明土壤碱化呈现中等变异,受结构(自然)因素和随机(人为)因素的共同影响。表层土壤除在溢出带为氯化物型盐渍土外,其他地区自南向北由硫酸-氯化物型逐渐变为氯化-硫酸盐型和硫酸盐土、苏打盐土,离子的半方差函数拟合模型结果均是弱变异和中等变异,与美国盐度实验室分类体系的变异性结果相同,此类分布特征也是结构因素和随机因素共同作用的结果。(2)分析五种典型地貌的盐渍土分布,方差分析结果表明,5种地貌类型均呈现盐分表聚特征,碱化度则由南向北递增;其中盐碱特征最为显著的是泉水溢出带。泉水溢出带的盐土垂直方向的变化趋势为由表层至深层,盐土类型由硫酸-氯化物盐土变为氯化盐土;冲积平原和干三角洲样点处全剖面为氯化物-硫酸盐土,冲积洪积扇和沙漠地区则包含所有阴离子盐土类型。对玛纳斯流域盐渍土特性的空间异质性进行分析,可以为下一步有针对性地治理与改善土壤盐渍化提供科学依据。