Trends in space occupation by the encrusting sponge Crambe crambe: variation in shape as a function of size and environment

The relationship between sponge size, habitat and shape was studied in the encrusting sponge Crambe crambe (Schmidt, 1862), which is distributed widely throughout the shallow Mediterranean littoral. Examination of sponge patches in shaded and well-illuminated habitats showed that the degree of peripheral irregularity of the edges of a patch is directly related to patch size. This relationship is valid only for sponges of >100 mm² in area. Photophilic and sciaphilous sponges display different growth forms. The pattern of growth is interpreted in terms of competition for space. The directional growth of sciaphilous sponges may be due to the presence of dominant neighbours that are good space competitors, and the irregular growth of photophilic sponges to the absence of such neighbours.     

Sediment accumulation rate and radiological characterisation of the sediment of Palmones River estuary (southern of Spain)

Chemical analyses and radioecological methods were combined in order to estimate the sediment accumulation rate in the upper 20 cm depth of the Palmones River estuary. Organic matter, total carbon, C:N and (137)Cs vertical profiles showed changes at 13 cm depth. These changes could be associated with the decrease in river input since 1987 when a dam situated in the upper part of the estuary started to store water. Using 1987 as reference to date the sediment, accumulation rate was 1.2 cm yr(-1). As alternative method, two layer model of (210)Pb(xs) vertical distribution showed a sedimentation rate of 0.7 cm yr(-1) with a surface mixing layer of 7 cm thickness. The high ammonium, potassium and sodium content in pore water and the strong correlation between (137)Cs activities and organic matter in dry sediment suggests that (137)Cs (the only anthropogenic product detected) is mainly accumulated in the estuary associated with the particulate organic material from the catchment area.     

Medium scale spatial structures of Polycyclic Aromatic Hydrocarbons in the topsoil of Tianjin area

The spatial distribution patterns of Polycyclic Aromatic Hydrocarbons (PAHs) in soil are important to regional environmental assessment. In this paper, the spatial structural features of sixteen prior PAH compounds in the topsoil of Tianjin area, as well as soil properties, were studied. Results shown that medium scale spatial autocorrelations were well revealed. Spherical models with sills could be used to fit all experimental variograms. The spatial structures of PAHs contents demonstrated significant anisotropy. Air precipitation caused by the combustion of coal was the key factor in the formation of the spatial structural patterns of PAHs in the topsoil of Tianjin area.     

Seasonal variation and background levels of heavy metals in two green seaweeds

Seasonal variation in the contents of different metals (Al, Cr, Cu, Fe, Mn, Ni and Zn) in two genera of macroalgae, Ulva and Enteromorpha was studied at 22 sites on the northwest coast of Spain. The seasonal variation in the different metals followed a similar pattern in both seaweeds and appeared to be caused by dilution during the period of maximum growth and concentration during periods of slow growth. Fluvial inputs of Al, Fe and Mn in autumn and winter appeared to accentuate the latter effect: the concentrations of these three metals in both macroalgae and of Cr in Enteromorpha were highest at those sites most influenced by inputs from rivers. The background levels of Cr, Cu, Ni and Zn in the algae in summer and winter were established.     

Effects of light quality on chlorophyll and biliprotein accumulation in seaweeds

The control of chlorophyll and biliprotein synthesis by different qualities of continuous light in four seaweeds, collected off the coast of Málaga (Spain) in the winter of 1986 and 1987, was investigated over the short term. In the green algaUlva rigida C. Aghardh, and in the red algaeCorallina elongata Ellis et Soland andPlocamium cartilagineum (L.), chlorophyll synthesis was induced by blue light. However, in the red algaPorphyra umbilicalis (L.), chlorophyll accumulation was primarily induced by red light. Phycoerythrin synthesis inCorallina elongata, Plocamium cartilagineum andPorphyra umbilicalis was stimulated primarily by green light, whilst phycocyanin synthesis was induced by red. The effect of light quality on the synthesis of photosynthethic pigments was rapid. The induction of chlorophyll synthesis of after 6 h in light was 11 to 20% higher than in the dark control. The induction of biliprotein synthesis was two times greater than that of chlorophyll. The results are discussed in terms of chromatic adaptation and as adaptative responses to the underwater light environment. The possible role of phytochrome, and of a blue-light photoreceptor, in the control of chlorophyll and biliprotein synthesis is discussed.Please address all correspondence and requests for reprint to Dr López-Figueroa at his present address: Botanisches Institut der Universität München, Menzingerstraße 67, D-8000 München 19, FRG     

Piggery waste treatment by anaerobic digestion and nutrient removal by ionic exchange

Piggery wastes must be treated before their disposal. The high solids content and high chemical oxygen demand of piggery wastes indicated that anaerobic biological treatment could be successfully applied as primary treatment. For that reason, a comparison between upflow anaerobic sludge bed reactor (UASB) and anaerobic fixed bed reactor (AFBR) at a similar organic volumetric loading rate of 5 kg DQO/m³ day was carried out. 60% of the piggery waste COD was removed with the AFBR compared to 40% with the UASB, thus showing a better performance of the AFBR. After 1-h sedimentation secondary process, both anaerobic effluents were treated by ionic exchange with natural zeolite due to their high values of ammoniacal nitrogen (NH⁺₄ plus free NH₃). The high removal of nutrients reported (90%) shows zeolite to be a good choice as tertiary treatment.     

Aluminium speciation in surface waters from a Welsh upland area

The complete aluminium speciation of surface waters from an acidified catchment, during dry weather and during storm episodes, is obtained. For the first time, estimates of adsorbed aluminium (Al(ad)) are reported together with other aluminium species. Al(ad) is calculated from the difference between monomeric aluminium content before and after separation of suspended solids by filtration (0.015 microm pore diameter). This fraction was very significant (Al(ad) >; 40 microg litre(-1)) for samples with high suspended solids content (ss >; 20 mg litre(-1)) collected during storm episodes. Plots of pAl(3+) versus pH for samples collected during dry weather are approximated by a straight line, close to the solubility line of synthetic gibbsite, and have a slope of 2.5, which suggests that these samples were saturated with respect to gibbsite. The cloud of pAl(3+) versus pH points for samples from storm episodes has a near zero slope, and shows a significant degree of undersaturation with respect to synthetic gibbsite. Various mechanisms of aluminium mobilisation are discussed.     

改进的层次分析法及其在自然灾害风险识别中的应用

自然灾害风险识别系统是由众多自然因素和社会经济因素组成的复杂系统 ,其主要问题之一就是如何将有关定性风险因素定量化。为此 ,本文进一步探讨了层次分析法用于自然灾害风险识别系统的具体途径。直接从判断矩阵的定义出发 ,提出了基于加速遗传算法的层次分析法 (AGA AHP)。利用该法 ,可同时确定层次各元素相对重要性的排序权值和进行判断矩阵的一致性检验。理论分析和实例分析的初步结果说明 ,AGA AHP法直观、可行而有效 ,其计算结果精度高于目前常用的基于特征根的层次分析法的相应结果 ,在各种自然灾害复杂系统分析中具有重要的理论意义和广泛的应用价值。     

Successfully applying sparging technologies

Air sparging is an innovative methodology for remediating organic compounds present in contaminated, saturated soil zones. In the application of the technology, sparging (injection) wells are used to inject a hydrocarbon-free gaseous medium (typically air) into the saturated zone below or within the areas of contamination. Two major mechanisms of remediation are engaged/enhanced due to the sparging process. First, volatile organic compounds are dissolved in the groundwater and sorbed on the soil partition into the advective air phase, effectively simulating an in-situ air stripping system. The stripped contaminants are transported in the air phase to the vadose zone, generally within the radius of influence of a standard vapor extraction and vapor treatment system. Second, with optimal environmental conditions, volatile and semivolatile organic compounds may be biodegraded by utilizing the sparging process to oxygenate the groundwater, thereby enhancing the growth and activity of the indigenous bacterial community. Air sparging is a complex multifluid phase process which has been applied successfully in Europe since the mid-1980s. Major design considerations include site geology, contaminant type, gas injection pressures and flow rates, injection interval (areal and vertical), and site-specific biofeasibility parameters. Site-specific geology and biofeasibility are the dominant design parameters. Pilot testing and full-scale design considerations should also be addressed. Mathematical models have been developed to simulate the air flow field during the sparging process and to examine the limitations imposed by site geology. Correct design and operation of this technology have been demonstrated to achieve groundwater cleanup to low part-per-billion contaminant levels. Incorrect design and operation can introduce significant pollution liability through undesirable contaminant migration in both the dissolved and vapor phases.