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1.
The coastal aquifer of Rome is hosted in the Tiber River Delta depositional sequence, in a densely populated area, which was reclaimed at the end of the 19th century. Moderate salinization processes characterize this aquifer. Hydrogeological and hydrochemical surveys were carried out in October 2012 and February 2013 in the southern sector of the Delta. Hydrogeological surveys updated knowledge of groundwater morphology and a detailed conceptual hydrogeological model of the coastal aquifer was realized. Hydrochemical analyses helped to identify the salinization spatial distribution and to specify the main groundwater types. The most salinized water was not detected close to the coastline, where seawater intrusion processes would be expected, but in the inner areas. Moreover, the salinization processes resulted to be slightly marked. Results so far suggest that the source of salinization may be related more to a combination of land use and historical development of the Tiber River Delta, rather than to seawater.  相似文献   

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3.
The life history of the bivalve-inhabiting hydroid Eugymnanthea inquilina was investigated in two different hosts, the mussel Mytilus galloprovincialis (collected from 1989–1991 from the Ionian Sea, Italy) and the clam Ruditapes decussatus (collected from 1991–1992, Ionian Sea, Italy). Hydroids living in mussels revealed a size selection for hosts longer than 40 mm, being almost completely absent in mussels below this size. This might be controlled by signals linked to the sexual maturity of the bivalve. The proportion of molluscs inhabited showed a seasonal trend in mussels only, with a sharp decline at the onset of medusoid liberation. Production of medusoids was high in mussels, whereas medusoids were rare and often abortive in clams. This indicates a higher degree of fitness of E. inquilina in mussels than in clams. The hydroid life cycle was not completed in clams, which therefore were presumably supplied by planulae from medusoids produced by mussel-inhabiting hydroids. Mussels played a key role in the stability and persistence of E. inquilina populations in the studied area. Selective ingestion of trematode sporocysts by E. inquilina hydroids indicated a protective role of the hydroid against mussel parasites, leading to reconsideration of this symbiotic association as a possible mutualism rather than a simple inquilinism.  相似文献   

4.
《Ecological modelling》2005,184(1):55-68
One of the most important sources of pollution in coastal zones (CZ) is certainly that one produced by human activities in the associated river basin. Understanding the linkage between water quality in CZ and river catchments is important in order to better assess CZ processes and to evaluate different management options aimed at improving the coastal ecosystem state. CZ water quality targets as identified by the Water Framework Directive (EC 2000/60) require an accurate study of the effects of pollutant loads coming from river discharge.In order to evaluate the impacts of human activities in river catchments on the associated coastal zone, a sound definition for this geographic area is needed. Many definitions for this area have been proposed in different contexts. The definition is generally built upon a particular goal, and is henceforth highly variable according to the different purposes. In this paper a general methodology allowing to discern those areas of the sea that are directly influenced by fluvial discharge is presented. The methodology is based on the variation pattern of sea water characteristics, and provides a numerical evaluation of this influence. In particular an analysis based on salinity as tracer, results in a sound definition of this area. The methodology has been applied on the case study of the Po river. Due to the significant nutrient loads discharged by the river, the CZ associated with Po is affected by severe eutrophication phenomena that have important consequences on the ecosystem and on the socio-economy of the area.In order to study the impacts of nutrients loads carried by the river, a water quality model (WASP6) has been implemented. The model simulates the seasonal variability of nutrient concentrations, phytoplankton biomass and dissolved oxygen. Using the CZ model is possible to compare the effects of variations of nutrient loads on the biochemical (short term) and ecological (long term) quality of the coastal environment. This is accomplished by feeding nutrients loads forecasted for different scenarios by the catchment model (MONERIS) as forcing functions to the CZ model. This way the effect of the different catchment management scenarios are propagated to the CZ model, and the trophic conditions of the coastal ecosystem evaluated using TRIX.This study has been developed in the context of the European project EUROCAT.  相似文献   

5.
It is necessary to identify the hydrogeochemical processes and analyze the causes of groundwater pollution due to the lack of knowledge about the groundwater chemical characteristics and the endemic diseases caused by groundwater pollution in the northern Ordos Cretaceous Basin. In this paper, groundwater chemical facies were obtained using the piper trilinear diagram based on the analysis of 190 samples. The hydrogeochemical processes were identified using ionic ratio coefficient, such as leaching, evaporation and condensation. The causes and sources of groundwater pollution were analyzed by correspondence analysis, and the spatial distribution and enrichment reasons of fluoride ion were analyzed considering the endemic fluorosis emphatically. The results show that leaching, evaporation and condensation, mixing, and anthropogenic activities all had significant impact on hydrogeochemical processes in the study area. However, cation exchange and adsorption effects were strong in the S2 and S3 groundwater flow systems, but weak in S1. Groundwater is mainly polluted by Mn and CODMn in the study area. The landfill leachate, domestic sewage, and other organic pollutants, excessive use of pesticides and fertilizers in agriculture, and pyrite oxidation from long-term and large-scale exploitation of coal are the sources of groundwater pollution. The S1 has the highest degree of groundwater pollution, followed by S2 and S3. High concentration of fluoride ion is mainly distributed in the north and west of study area. Evaporation and condensation and groundwater chemistry component are the most important causes of fluoride ion enrichment. The results obtained in this study will be useful for understanding the groundwater quality for effective management and utilization of groundwater resources and assurance of drinking water safety.  相似文献   

6.
The Industrial District (I.D.) of Messina was the first public authority to consider useful the application of the Strategic Environmental Assessment (SEA) procedure for the development of an Industrial Plan regarding a coastal area. At the moment the I.D. includes six areas, but the application of the SEA concerns only the area of Pace del Mela (along the north-eastern coast of Sicily), where a “District of the two Seas” will be created, based on the synergetic development between an industrialized niche (shipbuilding) and touristic development (port and hotels). The area in which this type of intervention will occur is not in use at the moment and it was not possible to collect environmental data. For this reason, in order to describe the environmental features of this territory, we took into consideration a few indicators which could be easily identified, necessary for a post evaluation which considers the Environmental Impact Assessment (EIA) of the industrial and suburban structures to be built.  相似文献   

7.
This study attempts to address the processes controlling the chemical composition of the Kavaratti aquifer system of Lakshadweep Island in India. Major ions and other physico-chemical parameters were determined for the premonsoon period in the Kavaratti of the Lakshadweep Island system. The trilinear diagram confirms the ingress of sea water into the shallow lens of freshwater in the islands by the changing water types. The abundance of major cations varied in the order Na>Ca>Mg>K and anions in the order Cl>HCO3>SO4. The ionic relations suggest that the higher concentration Na and Cl are the results of ion exchange and evaporation. The plots of data on the Gibbs diagram suggest that chemical weathering of rock-forming minerals and evaporation are the dominant factors controlling groundwater chemistry in the area. The hydrochemistry concept was deduced by the multivariate analysis for better understanding on the dynamic and complexity of the groundwater chemical processes. By the multivariate analytical techniques, the samples were grouped into two: one with saline water dominance and the other with freshwater characteristics. Thus proper management of these aquifers should be assured to retain their freshwater yield in the future.  相似文献   

8.
The reproduction of 9 species of littoral molluscs from the sub-Antarctic Macquarie Island was examined. The mode of larval development is reported for all species, and the reproductive patterns for 7 are described from collections taken monthly over a period of 1 year. Two species release gametes for external fertilization, whereas the other 7 have non-pelagic development via brooding or the laying of egg cases; some of these findings were deducted from examination of gonads rather than by direct observation. Features of reproduction important in any correlation between a littoral animal's reproduction and its habitat are discussed, and relationships between pelagic and non-pelagic development of the Macquarie molluscs and (a) distribution in the local environment and (b) habitat are drawn. The widely recognised correlation between species having a non-pelagic development and small number and large size of eggs is considered as a method for predicting the type of larval development (in terms of pelagic versus non-pelagic) from an examination of the ovary. It is suggested that further data on modes of development could be obtained from specimens of marine invertebrates collected throughout southern latitudes and that such data would enhance zoogeographical interpretations.  相似文献   

9.
The EI-Dabaa area is located on the northwestern coastal zone of Egypt and is considered to be one of the most important regions for land reclamation and agriculture. In addition, it has been selected as a potential site for constructing Egypt's first nuclear power plant.In April 1989, 14 groundwater samples were collected from the area as well as collecting samples from the Mediterranean sea and from local rainwater. These samples were subjected to chemical and environmental isotope analyses. The results of the analyses for stable isotopes (oxygen-18 and deuterium) indicate that the main recharge source of the groundwater in El-Dabaa is the local precipitation during the rainy season. Variation of the environmental tritium content as well as in the chemical composition of both major cations (Na,K,Ca,Mg) and major anions (Cl,SO4,HCO3) between different groundwaters in the studied area reflect the high degree of inhomogeneity of the aquifer and different recharging conditions due to permeability of the water bearing formation.The chemical water type of the El-Dabaa groundwater is sodium sulphate (Na2SO4) and the SAR values illustrate the suitability of these groundwaters for agricultural purposes.  相似文献   

10.
The ‘scope for growth’ (SFG) tool was used to study the growth performance of cultivated populations of Mytilus galloprovincialis (Lmk., 1819) in an oligotrophic area of the Southern Mediterranean Sea. The study was carried out between 1993 and 1996 by using data from four seasonal oceanographic cruises and from growth experiments. Water samples were collected and analysed for total suspended matter (TSM), particulate organic carbon (POC) and nitrogen (PON), particulate lipids, proteins and carbohydrates and chloropigments. The sum of the carbon equivalents of carbohydrates, proteins and lipids is indicated as the total biopolymeric particulate organic carbon (BPC) and was converted into a unit of energy in order to calculate the SFG of a theoretical mussel of 5 cm length. In order to test the performance of mussel growth at two depths (5 and 15 m water depth), mussel body size [as ash free dry weight (AFDW)] and the actual concentrations of BPC were used to calculate the monthly SFG using the physiological energetic relationships suggested in the current literature. Data from the field cruises led us to characterise the study site as ultra-oligotrophic (annual average of chloropigment concentration approximately 0.5 μg L−1). SFG calculations allowed us to identify a site where mussels grown successively were found to reach a commercial size in approximately 12 months. The good agreement obtained between energetic response and subsequent production response suggests that the available energy from particulate food could be fully available for organic production for maintaining “proportionate” growth trajectories, even in a ultra-oligotrophic system.  相似文献   

11.
Laura Joan Feyrer 《Marine Biology》2010,157(11):2461-2465
The ecological importance of mysid (Crustacea: Mysidacea) populations in coastal food webs is not well understood. Although the 10 or more species of epibenthic mysids found in Clayoquot Sound, BC, Canada, form the primary prey resource for seasonally abundant gray whales (Eschrichtius robustus), little is known about their life history. Here, Holmesmysis sculpta dominates multi-species swarms, however there are several potential routes to this state, one of which is higher embryo production. Reproductive capacity is key to the resiliency of local mysid populations and species diversity, in this study I compare one aspect, brood size for the four most commonly found species, H. sculpta, Neomysis rayii, Exacanthomysis davisi, and Columbiaemysis ignota. The number of embryos per brood was found to vary significantly between species; however, individual length is a stronger determinant of brood size. Here, I report previously unknown life history attributes of coastal mysid species, with important consequences for community structure and local marine food webs.  相似文献   

12.
A major influence on the environment of active volcanic areas is expected from continuous input of chemical species pertaining to fumarolic activities occurring during inter-eruptive intervals.

The systematic investigations carried out during thirteen years in the island of Vulcano (Italy) showed also substantial contributions to phreatic waters and soils of minor constituents and trace metals from volcanic rocks with no negligible influence on growing crops.

Greater extents of these phenomena have been observed for products of hydromagmatic volcanic activity or of long-lasting weathering processes.  相似文献   

13.
A major influence on the environment of active volcanic areas is expected from continuous input of chemical species pertaining to fumarolic activities occurring during inter-eruptive intervals.

The systematic investigations carried out during thirteen years in the island of Vulcano (Italy) showed also substantial contributions to phreatic waters and soils of minor constituents and trace metals from volcanic rocks with no negligible influence on growing crops.

Greater extents of these phenomena have been observed for products of hydromagmatic volcanic activity or of long-lasting weathering processes.  相似文献   

14.
Landslides affecting the north-western coast of the Island of Malta have been investigated and monitored for 10 years. As a result of a bathymetric survey, it was discovered the deposits continued out onto the seafloor, thus raising questions as to the timing of their development. Furthermore it was uncertain as to which environment they developed in and which factors controlled their movements. The aim of this paper is to investigate representative detachments to chronologically constrain these mass movement events and outline their spatial and temporal evolution. Samples for exposure dating using the cosmogenic nuclide 36Cl were collected from head scarps and blocks located within two long-term monitored landslides characterised by extensive block slides. The results indicate the oldest dated block detachment occurring in a subaerial environment at ca. 21 ka, when the sea level was about 130 m lower than at present. Mass movement possibly accelerated when sea level reached the landslide toe during the post-glacial marine transgression. Considering the timing of block movement, the landslide deposits observed today appear to be related to a first-time failure involving a large part of the slope, though and alternative hypothesis is also taken here into account. This main event is likely to have been followed by secondary movements influenced by toe undercutting and clay saturation due to rising sea level. However, further research on mass movement kinematics is required in order to model their evolution and explore whether this interpretation is widely applicable along the Maltese coast.  相似文献   

15.
Environmental Geochemistry and Health - A theoretical pattern for Fe and As co-precipitation was tested directly in a groundwater natural system. Several monitoring wells were sampled to identify...  相似文献   

16.
Geomorphologic information, topographic maps (dated 1967), aerial photographs (dated 1999 and 2008), and spatial analysis procedures were used to investigate a 90 km long coastal sector in South Sicily (Italy). Information was obtained on coastal erosion/accretion areas, general sediment circulation pattern and littoral cell distribution. Human-made structures and natural headlands constituted important artificial limits dividing littoral in morphological cells. Ports and harbours were observed at Scoglitti, Punta Secca, Marina di Ragusa, Donnalucata and Pozzallo. Most of them worked as “transit” limits which interrupted predominant, eastward directed sedimentary transport, this way generating accretion in updrift (west) side of mentioned structures and erosion in downdrift (east) side. During the 1967–2008 period, about 62,000 m2 and 42,000 m2 of beach surface were respectively formed updrift of Scoglitti and Donnalucata ports. The construction of Pozzallo port gave rise to the formation of a “convergent” limit which favoured large accretion (94,000 m2) east of port structure. Most important natural structures were observed at Punta Zafaglione, P. Braccetto and Cava d’Aliga. The knowledge of littoral cell distribution acquires a great importance for appropriate management of coastal erosion processes which may be mitigated installing by-passing systems in ports and harbours and carrying out nourishment works in eroding areas, often located downdrift of ports and harbours (when these structures work as transit limits) and in central part of littoral cells (when these structures work as convergent limits).  相似文献   

17.
Ammonium and nitrate concentrations have been investigated in water samples from the wells in the island of Vulcano, (Italy). Systematic observations, extended over a period of five years, have verified different trends in the changing concentrations of both species. Nitrate ion is considered as contributed to the unconfined upper ground aquifer by the surface environment, while for ammonium ion a deep origin appears more likely. Significant changes in the activity of the volcanic system appear to affect the distribution of ammonium only, while nitrate levels do not display any important variation.  相似文献   

18.
Environmental Geochemistry and Health - The Island of Ischia, one of the Italian active volcanoes, is a famous tourist resort for spa treatments. Spas are supplied by withdrawals from groundwaters...  相似文献   

19.
Management of coastal dunes on developed coasts could effectively take advantage of comprehensive and multitemporal georeferenced data collection, which offers the possibility to relate dune data with the natural and cultural characteristics of the beach and hinterland. The recent implementation of a coastal management geodatabase for the Veneto region provides the opportunity for improving knowledge on coastal dunes on developed littoral as well as a basis for appropriate future coastal planning in the study area. The geodatabase gathers data concerning different physical, evolutionary and human aspects of the coastal zone, with a special focus on coastal dunes. Established foredunes, human-altered dunes and relict dunes are irregularly distributed along 59 km, 38% of the entire coastal length. Their distribution and characteristics are the result of favourable natural conditions as well as long-lasting tourism exploitation (evaluated through an index of Land Use Pressure) and fragmentary and diversified uses of beaches (evaluated through an index of Tourism Pressure on the beach). At the same time, beach/dune nourishment intervention allowed the presence of artificial or sand fenced dunes along 17 km of coast. High dune elevation up to 8–10 m is promoted by the onshore exposition of the beach to dominant wind (from ENE), by stable-to-slowly negative sedimentary budget or by the re-activation of high relict foredunes in the case of shoreline retreat associated with strong negative budget. Present sedimentary budget (evaluated through the code ASPE – Accretion, Stable, Precarious, Erosive) is the tool used for dividing coasts in sedimentary compartments or cells. Past and present sedimentary budget and different human responses to erosive cases (hard and soft interventions) give the foredunes different means to form, grow, survive and evolve over time. The assessment of Human Impact and Active Management Practices on the dunes allows a first evaluation of the Management Effectiveness, which shows strong shortcomings for 81% of the dunes. The great variability of beach usage, human impact and management practises on the different dune stretches highlight the lack of effective and systematic management actions being correctly scheduled and performed.  相似文献   

20.
Phytoplankton productivity of the tidal estuaries and coastal waters of southern Nassau Country, Long Island, New York, USA was determined monthly at 28 stations during 1966. Diatoms alternated with dinoflagellates in dominating the standing crop in the coastal area. The estuaries were characterized by sustained blooms of green flagellates and dinoflagellates during the spring/summer period, 1966. Chlorophyll a ranged from 1.0 to 27.6 mg/m3 in the estuarine area, and 1.45 to 10.15 mg/m3 in adjacent coastal waters. Rate of phytosynthesis per unit weight chlorophyll a for surface samples in the region under study a veraged from 3.1 to 3.5 mgC/mg chlorophyll a/h. At light saturation, however, the ratio varied according to water temperature and species' composition. Primary productivity decreased seawards, with mean values for 1966 of 0.35, 0.22, and 0.16 gC/m3/d for the estuarine, nearshore and offshore areas, respectively.This study was carried out at the Lamont Geological Observatory of Columbia University Palisades; New York, USA.The study was conducted with financial assistance from Nassau County, New York, and the G. Unger Vetlesen Foundation.  相似文献   

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