1,720,955 research outputs found
Potentially Toxic Elements (PTEs) Distribution in Drainage Canal Sediments of a Low-Lying Coastal Area
Full text linkThis study examines the accumulation, distribution, and mobility of Potentially Toxic Elements (PTEs) in the sediments of a low-lying coastal drainage network (Ravenna, Italy). The aim is to understand the geochemical processes occurring between drainage water and canal bed sediments and assess factors affecting and driving PTE distribution and enrichment in these environments. A geochemical database resulting from the analysis of 203 drainage sediment samples was analyzed using Principal Component Analysis and compared to undisturbed near-surface sediment samples from the same depth and depositional environment. The results reveal PTEs exceeding national regulation limits. Distance from the sea, electrical conductivity of drainage water, and fertilizer use were identified as the main driving factors. The primary mechanisms for PTE precipitation (As, Co, Mo) and subsequent enrichment in the sediments is attributed to the absorption on Fe- and Mn-oxyhydroxides (HFO and HMO), particularly in high salinity areas near the coast. While Cu, Zn, Pb, Cr, and V also have affinity for HFO and HMO, their adsorption efficiency decreases due to the competition with salt-derived cations during ongoing salinization processes. Anthropogenic sources, including agriculture, hunting activities, traffic dust, and railways, contribute to the local abundance of other elements (Cr, Ni, Cu, Zn, Pb, and Sn). This paper's significant progress lies in assessing the concurrent interactions of chemical and physical processes that drive PTE distribution and accumulation in reclaimed low-lying coastal plains. The findings are significant for assessing PTE accumulation risks and sediment toxicity in coastal areas affected by water salinization, drainage, and subsidence, providing valuable information to water management institutions globally.This study investigates the presence of harmful substances called Potentially Toxic Elements (PTEs) in the sediment of the drainage canals in Ravenna's coastal area (Northern Italy). Researchers want to understand how these substances accumulate and spread in the sediment and what factors influence their distribution. They collected sediment samples from the bottom of the drainage canals and compared them to natural sediment samples. The results show that the PTE levels exceed the national and international limits. The distance from the sea, the water salinity, and the fertilizers are found to be the main factors affecting the distribution of PTEs. The researchers also discover that some PTEs (Arsenic, Cobalt, and Molybdenum) are absorbed by certain minerals in the sediment, especially in areas with high salinity close to the coast. However, other harmful elements, like copper, zinc, lead, chromium, and vanadium are not as strongly absorbed due to competition with salt-related substances. The abundance of other elements like chromium, nickel, copper, zinc, lead, and tin come from human activities like agriculture, hunting, traffic, and railways. These findings are important for understanding the risks associated with these substances in the sediment, particularly in low-lying coastal areas that have been reclaimed for human use.First study on Potentially Toxic Elements (PTEs) enrichment in drainage canal sediments of reclaimed low-lying coastal area Key roles of (i) Fe- and Mn-oxyhydroxides in PTE enrichments and (ii) salt-derived cations in adsorption efficiency Distance from the sea, salinity of drainage water, and use of fertilizers are the main factors affecting the distribution and enrichment of PTE
Different processes affecting long-term Ravenna coastal drainage basins (Italy): implications for water management
Full text linkThe low-lying coastal basins of Ravenna (Italy) are at or below mean sea level and currently undergoing land subsidence, which exposes the basins to frequent inundation and groundwater and soil salinization. The surface water drainage becomes necessary to lower the water table head and further prevent flooding and waterlogging. The study examines the evolution of drainage apropos to climate change and land subsidence in the three main Ravenna coastal basins. Our findings show that the evolution of drainage is influenced by land subsidence, climate change variability, droughts, vertical seepage, and local water management. Land subsidence causes an increase in upward-directed vertical seepage of saline water through the shallow unconfined aquifer into the drainage channels of the coastal basins, thus leading to an increase in drainage through time. At a seasonal timescale, the rate of pumping depends on antecedent rainfall and soil–water storage. The warming extremes indices, specifically drought indices, show to be more significant than rainfall indices trends to monitor drainage evolution. Drought indices permit easy comparison of dryness or wetness severity with drainage evolution along their time scale. The co-occurring anthropogenic and natural factors involving in the increasing drainage rate will affect decadal and seasonal water management policies in the area. The implications of increasing drainage rates, long periods of drought with limited rainfall, and increasing temperature will further worsen freshwater availability in this coastal area already experiencing soil and water salinization. However, drainage of this low-lying territory has effectively mitigated rising water tables and avoided flooding. Our study has shown that each coastal basin behaves differently in terms of sensitivity to land subsidence and climate extremes. Therefore, when using drainage data time series for water management purposes, one should account for past management practices and for the specific sensitivity of each basin to external factors
Factors affectingwater drainage long-time series in the salinized low-lying coastal area of Ravenna (Italy)
Full text linkThe low-lying coastal area of Ravenna (North-eastern Italy), like the majority of delta and coastal zones around the world, is affected by groundwater salinization due to natural processes (such as low topography, natural land subsidence, seawater encroachment along estuaries, etc.) and anthropogenic activities (i.e., increased anthropogenic subsidence rate, sea level rise, geofluids extraction, and drainage). Among all factors causing aquifer salinization, water drainage plays an important role in lowering the hydraulic head and favouring saltwater seepage in the Ravenna coastal aquifer. A network of drainage canals and water pumping stations first allowed for the reclamation of the low-lying territory and today are fundamental to keep land and infrastructures dry and maintain effective soil depth for agriculture practices. The aim of this work is to identify and assess factors affecting water drainage long-time series (1971-2017) of the most important mechanical drainage basin in this low-lying coastal area. Statistical analyses of drainage, climate, and land use change datasets help constrain the relative weight of each single factor potentially causing an increase of water drainage through time. The results show that, among these factors, subsidence rates and seepage processes are the most significant. The data trends also indicate that the climate, especially in terms of precipitation amount and extreme events, played no important role during the studied time interval. The process of infiltration soil capacity loss due to urbanization and consequent soil sealing probably has a small secondary effect. Moreover, an increase in pumping through time will exacerbate aquifer salinization and compromise freshwater availability in the coastal area
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
- …
