Antioxidant responses to variations in dissolved oxygen of Scapharca inaequivalvis and Tapes philippinarum, two bivalve species from the lagoon of Venice

The aim of the present work was to determine the activities of selected antioxidant enzymes (SOD, Se-GPX, CAT) in two species of bivalves, Scapharca inaequivalvis and Tapes philippinarum, from two sites of the lagoon of Venice that are characterized by different pO(2) (Marghera and Chioggia). The specimens were collected at four times during a 1-year period. In the two species studied, enzyme activities were found to be present in both digestive glands and gills, but with some species-specific differences that may also represent a different adaptation to seasonal variations. The presence of high SOD activities in the gills of both species may be related to their physiological role in respiration. Scapharca inaequivalvis is less sensitive than T. philippinarum to environmental changes, perhaps due to the presence of hemoglobins in this species. Moreover, in the digestive gland of T. philippinarum we found a significant negative correlation between the activities of SOD and GPX that may indicate the presence of oxidative stress. Some correlations between temperature/dissolved oxygen and antioxidant enzyme activity were present in specimens sampled in Marghera. Only GPX adequately responded to changes in dissolved oxygen and temperature, while the decrease in the activity of SOD and CAT in winter may be directly responsible for an enhanced susceptibility of mussels to oxidative stress during this period. We can conclude that the observed differences between Chioggia and Marghera are due to different concentrations of dissolved oxygen. Marghera is an appropriate location to study seasonal variations in water temperature. In fact, in this site, the differences between hot and cold months are quite evident.     

A study of the performance of a land surface process model (LSPM)

In this paper, a reliable Land-Surface Process Model (LSPM), which is a new version of the LPM of Ji and Hu (1989), is described. The LSPM has been validated with experimental data measured at two stations in the Po Valley (Northern Italy).     

Straw Blankets Sewn With Recycled Plastic Threads for Erosion and Urban Sediments Control

Soil erosion, transport and deposition of sediments represent invisible threats that along time can affect negatively the existing infrastructure of roads and dams, and the quality of air and water resources. In the last decades, a great number of researches were devoted to study erosion and sediments transportation processes. However, they addressed mostly areas of agriculture, water impoundments for dams, and land conservation. A lack of studies for erosion processes in urban areas is evident, in special those aiming to diminish the deposition of sediments originated from urban areas into the rivers and air, in special as airborne particulate. Traditionally, the costs associated in controlling erosion and sediments in urban areas are high and in some case, out of the range for most developing countries. Factors responsible for those high prices are the use of heavy equipments for soil grading and transportation, the use of costly building materials, and the need for employing more specialized personnel. In the case of gullies in urban areas, another concern is to ensure proper equipment access to the area for remediation operations. Hereby, it is presented a cost-effective method to recover an extensive gully erosion area of about 11,000 m² located in urban area. Estimated sediments released from this area to the water resources and air were estimated on about 66,000,000 tons. In this study area, bioengineering works were performed in 60 days, with hardly any sediment generated outside the work area resulting from bioengineering operations. A combination of bioengineering techniques were chosen for this study area, which was a mixture of rigid and biological products including biologs, silt fence, biodegradable straw blankets sewn with plastic threads derived from recycled PET bottles, among others. An efficient drainage system was implemented for preventing upland flow, sub-seepage and seepage. Biologs were used aiming to fulfill a double role, the first as barrier to soil sediments flow, and the second as filler for empty spaces, avoiding expensive grading operations. All engineering works were concluded in about 60 days at a cost of US0.89/m < sup > 2 < /sup > . This price is cost-effective if compared with the traditional engineering cost of approximately US 0.89/m². This price is cost-effective if compared with the traditional engineering cost of approximately US 2.92/m² because it includes extensive use of grading and soil transportation. An environmental advantage of the bioengineering method is the immediate reduction of airborne particulates. Furthermore, the overall visual aesthetics improved shortly after the implementation of the works because the bare ground was substituted by native vegetation. After 6 months the vegetation in the gully erosion area was totally established. Monitoring was performed after 12 months and no erosion and sediment transport was visually noticed. The ease implementation of this technique without the need for specialized workers in combination with low prices makes this method a model for developing countries.     

Aspetto elettrogeosmotico bidimensionale variabile col tempo

Riassunto Fino ad oggi sono apparse solo teorie elettrogeosmotiche transitorie unidimensionali. Quì risolviamo un problema del genere bidimensionale, con elettrodi verticali cilindrici. Le curve rappresentative delle portate d'acqua catodicaq _K a cui perveniamo, denotano diminuzioni abbastanza rapide fino ai tempi dell' ordine dei «tempi elettrodici », (t=), portate che poi diminuiscono in modo molto lento. Si riscontrano quì più estesi «pianerottoli»q _K che non quelli delle monodimensionalità (t=/9). Inoltre, col crescere dei rapporti distanze eteropolari-raggi catodici, o col diminuire dei raggi catodici, tali portate (che si compongono dei contributi dei singoli anodi) s'incrementano nel modo diagrammato.

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Summary Till now only mono-dimensional transient electro-geoosmotical theories have been published. In this paper a solution is given for a problem of bi-dimensional type, with vertical cylindrical electrodes. The plots which represent the amounts of cathodic waterq _K show quite rapid lowerings as far as to reach time durations of the order of «electrodic times » (t=) volumes which, after, diminish very slowly. In this case more extendedq _K «lobbies» are found than those in mono-dimensional case (t=/9). Furthermore increasing the ratios heteropolar spacings—cathodic radii, or diminishing the cathodic radii, water discharges (which result from the contribution of the single anods) increase as plotted in the diagrams.

     

The contribution of benthic macrofauna to the nutrient filter in coastal lagoons

Human activities in coastal areas have increased the occurrence of eutrophication events, especially in vulnerable ecosystems such as coastal lagoons. Although we have a general knowledge of the consequences of eutrophication in these ecosystems, some efforts need to be made to understand biotic feedbacks that could modify the response of the environment to nutrient enrichment. The plant-mediated 'coastal filter' is one of the main factors that determine lagoonal efficiency in processing excess nutrients. In this context, the present paper examined the relative contribution of benthic macrofauna to the 'coastal filter' of a Mediterranean lagoon. The analysis of macrofaunal assemblages in the Mar Menor lagoon led to a clear differentiation between shallow areas of net nutrient recycling and exportation and deeper areas of net retention. These differences enhance nutrient removal from the water column, thus increasing the ecosystem's resistance to eutrophication.     

Mapping soil pollution by spatial analysis and fuzzy classification

Spatial analysis and fuzzy classification techniques were used to estimate the spatial distributions of heavy metals in soil. The work was applied to soils in a coastal region that is characterized by intense urban occupation and large numbers of different industries. Concentrations of heavy metals were determined using geostatistical techniques and classes of risk were defined using fuzzy classification. The resulting prediction mappings identify the locations of high concentrations of Pb, Zn, Ni, and Cu in topsoils of the study area. The maps show that areas of high pollution of Ni and Cu are located at the northeast, where there is a predominance of industrial and agricultural activities; Pb and Zn also occur in high concentrations in the northeast, but the maps also show significant concentrations of Pb and Zn in other areas, mainly in the central and southeastern parts, where there are urban leisure activities and trade centers. Maps were also prepared showing levels of pollution risk. These maps show that (1) Cu presents a large pollution risk in the north–northwest, midwest, and southeast sectors, (2) Pb represents a moderate risk in most areas, (3) Zn generally exhibits low risk, and (4) Ni represents either low risk or no risk in the studied area. This study shows that combining geostatistics with fuzzy theory can provide results that offer insight into risk assessment for environmental pollution.     

Urbanization impacts upon catchment hydrology and gully development using mutli‐temporal digital elevation data analysis

Urbanization can change catchment hydrology, accelerating gully erosion and causing serious damage to urban structures like roads, bridges and buildings. Increased impervious surfaces lead to large, rapid increases in surface runoff in urban catchments during storm events, as well as changes in the upslope contributing area due to rerouting of urban runoff that can exacerbate erosion. Accounting for changes in surface drainage patterns Gama City, Brazil, is used to predict areas prone to accelerate gullying and develop a method of assessing the potential for gully erosion produced by urbanization. The method is based on the analysis and comparison of detailed digital elevation models (DEMs) of the natural condition before urbanization and the topography after urbanization. The study site is located in an area where changes in drainage patterns associated with rapid urbanization in the last 30 years have resulted in severe gullying. Our analysis identifies areas potentially susceptible to gullying and highlights the erosional influence of increased flow concentration caused by urban occupation, a finding that has implications and applications for strategies to prevent gully development in cities or areas undergoing urban expansion. Copyright © 2010 John Wiley & Sons, Ltd.     

The Space and Time Features of Global SST Anomalies Studied by Complex Principal Component Analysis

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El Nino的周期变化和空间特征——兼应用PC和CPC分析太平洋海温距平场

本文联合利用实主成分(以下简称PC)分析和复主成分(以下简称CPC)分析,探讨太平洋SST演变的时空特征.结果表明:这两种分析方法得到的第一个主成分都展示El Nino随时间周期性变化,在PC中表现为峰谷的变化,在CPC中表现为振幅和位相的变化;相应的荷载向量主要反映El Nino和La Nina事件时期空间分布特征,大振幅区域位于主要冷暖洋流活动中心.第一个复荷载向量可以认为在驻波上附加一个南北向传播的行波.第二个荷载向量为一驻波,第三个复荷载向量看上去像一个东西向传播的行波,后两个特征型各自强调不同El Nino和La Nina时期的空间特征.驻波峰、谷区域之间呈现反相关关系;这里虽然没有研究波群和群速度,但就行波而言,也初步看出能量传播的路径.与复荷载向量对应的实荷载向量仅显示驻波特征.     

How much past to see the future: a computational study in calibrating urban cellular automata

The objective of this computational study was to investigate to which extent the availability and the way of use of historical maps may affect the quality of the calibration process of cellular automata (CA) urban models. The numerical experiments are based on a constrained CA applied to a case study. Since the model depends on a large number of parameters, we optimize the CA using cooperative coevolutionary particle swarms, which is an approach known for its ability to operate effectively in search spaces with a high number of dimensions. To cope with the relevant computational cost related to the high number of CA simulations required by our study, we use a parallelized CA model that takes advantage of the computing power of graphics processing units. The study has shown that the accuracy of simulations can be significantly influenced by both the number and position in time of the historical maps involved in the calibration.