An integrated approach to environmental quality assessment in a coastal setting in Campania (Southern Italy)

The coastal region of Southern Italy’s Caserta province, known as the Litorale Domitio (Domitia coast) has been subjected to increasing pressure from unsustainably fast economic and urban growth in the last century, that resulted in a induced serious land degradation. To obtain a comprehensive picture of the ecological status of the Domitia coastal zone (Campania, Southern Italy), a holistic methodology has been applied. Sedimentological, geochemical, and biological analyses of the surface sediments and water samples were performed along the submerged beach. The data were integrated using a geographical information system, together with information on past and present land use and human activities along the coast and in inland regions. Heavy metal concentrations in sediments plus As and Se (Cd, Co, Cr, Cu, Hg, Ni, Pb, V, Zn) and their enrichment factors, which are important for identifying polluted areas in countries like Italy (where environmental legislation has not yet established intervention limits), indicate excesses Cd, Cr, Pb, and V of probable anthropogenic origin. A microbiological contamination of marine waters has been detected by the Regional Environmental Protection Agency of Campania. The Bacteriological Quality Index map shows that bathing areas must be classified as “contaminated” and “highly contaminated”. High levels of chemical and biological contamination are particularly common in both bathing seawater and sediments along the coastal zone south of the Volturno River, where the existing wastewater treatment plant is not properly working, to date. Factory farming, which is widespread in the area, is likely to be an additional important source of contamination. In accordance with these conclusions, analyses of the benthic diatom community revealed dominance of eutrophic species.     

Short-term changes in water chemistry in the Baccu Locci stream (Sardinia,Italy) affected by past mining

Short-term changes in water chemistry, and especially in dissolved trace element concentrations, associated with diel cycles during base-flow conditions at a specific sampling station in the Baccu Locci stream draining the homonymous old mine area in Sardinia (Italy) were investigated. Diel fluctuations in pH and alkalinity were correlated with the temperature-dependent CO₂ solubility and the biologically-induced CO₂ production, both of which were higher during the night. Adsorption/desorption to/from streambed material, in particular ferrihydrite, is believed to be the main in-stream mechanism causing the observed diel variations in dissolved concentrations of As and Zn. Arsenic was mainly affected by the dual action of temperature and competing carbonate ions, whereas pH seemed less important. Temperature acted in accordance with the exothermic feature of anion sorption onto hydrous metal oxide surfaces; aqueous carbonate species exerted their competitive effect in relation to alkalinity variation. Zinc was primarily affected by temperature, in accordance with the endothermic feature of metal cation sorption onto hydrous metal oxide surfaces, and secondly by pH. Co-precipitation of As and Zn with calcite is another possible mechanism, which requires further investigation involving examination of inorganic and biological materials coating the streambed. All these processes potentially controlling the diel cycles of trace elements should be carefully considered to assess the effectiveness of remediation actions currently in progress at Baccu Locci. A normalization method for data from asynchronous sampling has been developed and proposed in order to eliminate or at least attenuate the effect of sampling time and provide an additional tool to identify the processes/mechanisms involved in trace element concentration fluctuations observed along a contaminated stream during base-flow conditions.     

HYDROGEOMORPHIC CONDITIONS LIMITING THE DISTRIBUTION OF BALDCYPRESS IN THE SOUTHEASTERN UNITED STATES

Baldcypress is a dominant species in the alluvial valleys of the Coastal Plain of the southeastern United States. It is mostly absent, however, in the surrounding regions. An investigation of the northern boundary of baldcypress along streams flowing into the Coastal Plain indicates that a major factor limiting its distribution is high seasonal water-level fluctuations. Initial seedling establishment is dependent on water-level fluctuations. Seeds are dispersed by flood water, and germination occurs after their deposition on exposed surfaces as the water recedes. However, baldcypress seedlings are killed when completely submerged for longer than a few days. Seasonal water-level fluctuations increase with distance upstream, and eventually a point is reached along these streams where seedlings almost always are killed by high flood waters during the years following their establishment. This appears to be an important factor controlling the upstream boundary of baldcypress. The natural hydrology of most Coastal Plain streams has been altered by efforts to control flooding, mostly through dams and channelization. Baldcypress regeneration requires a narrow range of hydrologic conditions, and human-induced changes in seasonal water-level fluctuations likely will affect the northern boundary of baldcypress. [Key words: Coastal Plain, floodplain, Taxodium, wetland.]     

Is net ecosystem production higher in natural relative to constructed wetlands?

Ecosystem metabolism is an important measure of wetland restoration efficiency, and serves to indicate if the system is capable of processing energetic resources. Despite its value, ecosystem metabolism has rarely been included in monitoring programs. In this study, we aimed to achieve the following objectives: (i) compare net ecosystem production (NEP) rates of constructed vs. natural wetlands; (ii) identify the highest NEP rate habitats; and (iii) define the main environmental factors regulating NEP in different wetland types. Pelagic and benthic NEP rates and physicochemical features were measured in three natural and five constructed wetlands in the middle Ebro River floodplain (NE Spain). Statistical analyses showed pelagic NEP rates peaked in natural wetlands, which produced up to 187.5 mg C m^?3 h^?1 compared to lower rates in constructed wetlands (up to 46.2 mg C m^?3 h^?1). Pelagic NEP responded positively to temperature, total dissolved solids, and nutrients. Benthic NEP rates were 3 to 30-fold greater than pelagic in natural (up to 994.9 mg C m^?3 h^?1) and constructed (up to 1,551.5 mg C m^?3 h^?1) wetlands, and were heavily influenced by habitat type, with NEP peaking in areas dominated by submerged vegetation and fine organic sediment. Rapid recovery in aquatic communities (i.e. macroinvertebrate diversity) has been previously reported for the studied wetlands; however, our study suggests a slower recovery of functional processes (i.e. pelagic NEP) in constructed habitats. We therefore strongly advocate the inclusion of ecosystem function in the design and evaluation of restoration projects to optimise long-term wetland ecosystem sustainability.     

Groundwater quality assessment using data clustering based on hybrid Bayesian networks

Bayesian networks (BNs) have become a standard in the field of Artificial Intelligence as a means of dealing with uncertainty and risk modelling. In recent years, there has been particular interest in the simultaneous use of continuous and discrete domains, obviating the need for discretization, using so-called hybrid BNs. In these hybrid environments, Mixtures of Truncated Exponentials (MTEs) provide a suitable solution for working without any restriction. The objective of this study is the assessment of groundwater quality through the design and application of a probabilistic clustering, based on hybrid Bayesian networks with MTEs. Firstly, the results obtained allows the differentiation of three groups of sampling points, indicating three different classes of groundwater quality. Secondly, the probability that a sampling point belongs to each cluster allows the uncertainty in the clusters to be assessed, as well as the risks associated in terms of water quality management. The methodology developed could be applied to other fields in environmental sciences.     

A high-resolution stellar library for evolutionary population synthesis

We present a library of 1654 high-resolution stellar spectra, with a sampling of 0.3 Å and covering the wavelength range from 3000 to 7000 Å. The library was computed with the latest improvements in stellar atmospheres, incorporating non-local thermodynamic equilibrium (non-LTE) line-blanketed models for hot, massive  ( T _eff≥ 27 500 K)  and line-blanketed models for cool  (3000 ≤ T _eff≤ 4500 K)  stars. The total coverage of the grid is  3000 K ≤ T _eff≤ 55 000 K  and  −0.5 ≤ log g ≤ 5.5  , for four chemical abundance values: twice solar, solar, half solar and 1/10 solar. Evolutionary synthesis models using this library are presented in a companion paper. We tested the general behaviour of the library by calculating and comparing equivalent widths of numerous H and He  i lines, and some of the commonly used metallic indices. We also compared the library with the empirical libraries STELIB and Indo-US. The full set of the synthetic stellar spectra is available from our websites ( http://www.iaa.csic.es/~rosa and http://www.astro.iag.usp.br/~lucimara/library.htm ).