19 research outputs found
An attempt to use color as a tool for high resolution correlations between estuarine sedimentary cores from Algarve (Portugal)
Nowadays, paleoenvironmental and climatological researches focus on studying shortterm
climatic changes and one of the more sensitive environments for recording those
short-term climatic variations are the high sedimentation rate of coastal regions. Accordingly,
4 estuaries from the Algarve region, south of Portugal, have been cored
in order to study sedimentary and climatic variations during recent times (c.a. 5000
yrs). For this purpose, we applied sampling and analytical techniques from deep-sea
studies, allowing the acquirement of almost continuous data profiles, as the color data
obtained with the spectrophotometer Colortron
Correlation of estuarine sedimentary cores based on color analysis: an example from the Algarve region (Portugal)
Coastal zones play a significant role in the regional development and have been an important area for human occupation
through time. The study of estuarine sediments applied to sea level changes had always been of extreme importance, as it
reflects the coastal line evolution, either by local, regional or global changes
Is it possible to use "twin cores" as a unique sedimentary record? An experimental design based on sediment color
Sedimentary cores are widely used for studying Quaternary records. However, the
amount of sediment that is available is proportional to the diameter of the core, which is rarely
bigger than 15 cm. One way to obtain more sediment is to use two cores retrieved from almost
the same location and use them as if they represent a unique sedimentary record. In the present
work, an experimental design has been applied to verify if âtwin coresâ from an estuary can be
considered as representing the same sedimentary record with twice the amount of sediment to
study. Because sediment can be characterized based on its color, the variables used as
replicates in the experimental design are the three Lab CIE colors acquired with a X-Rite
Colortron spectrophotometer. Sediment cores were retrieved from the upper saltmarsh of GilĂŁo
Riverâs estuary, southern Portugal. Twin cores, with in between distances of 50 cm, 100 cm
and 200 cm, from two different sites were analysed. Results from a nested ANOVA show that
even for the closest twin cores (50 cm apart) there is at least one color variable that shows
significant variations between the profiles of both cores. These results clearly show that âtwin
coresâ cannot be used as a unique sedimentary record without any previous testing, at least in
such transitional regions
Regional sea level change study based on estuarine sediment color and biogeochemistry - preliminary results
Coastal zones play a significant role in the regional development and have been an important area for human occupation through time. The study of estuarine sediments applied to sea level changes had always been of extreme importance, as it reflects the coastal line evolution, either by local, regional or global changes
Algarve: a study case for global vs regional climatic changes in mid latitude estuaries during the Holocene
Located at the extreme southwestern end of the Iberian Peninsula, in the South of Portugal, the Algarve province is
bordered to the north by the Alentejo province, to the east by the Guadiana River, and to the west and south by the
Atlantic Ocean. Its coastal region can be divided into two different sectors: the eastern sector, which is mainly made of
barrier island and lagoon system named the Ria Formosa, and the western sector mainly represented by clastic and
carbonated cliffs. In each sector, we sampled long and short sedimentary cores (ca. 30m and 3m, respectively) in two
different estuaries. Therefore, the different sedimentary records obtained from the four estuaries should permit to identify
global vs. west-eastern regional climatic changes through the observation of several proxies. Two of these proxies are
sediment color and magnetic susceptibility, which have been acquired every five centimeters along core depth, using the
Colortron II spectrophotometer and SM-20 magneto-susceptometer, respectively. Sediment surfaces of short cores were
also digitized using the Mustek 1200 A3 PRO Scanner. Furthermore, short cores have been sampled every five centimeters
along depth in order to analyze the sediment for its major and minor elements content, its organic carbon content, and its
granulometry and mineralogy. Some shell fragments have also been sampled and sent for radiocarbon radiometry or AMS
dating, allowing therefore constructing some absolute chronologies for the several cores. Some relative chronologies based
on digital color profiles are also being used in order to correlate sedimentary sequences between cores. All the cores are
mainly composed of clay, with the existence of soil horizons at the top of the cores and frequent sand layers towards their
base. Several element profiles along depths are compared, namely those regarding Sr, Ca, F, Ba, Al and Ti, as well as
their ratios. First results indicate that geochemical and color data allow to identify similar sequences from west to east
probably related to major climate episodes. Although, pronounced differences in mineralogy and accumulation rates from
on site to another are probably due to differences, respectively, in the geochemistry of the drainage basin substratum and
in the flow rate of the rivers, and therefore to local precipitation. We acknowledge FEDER and OE that financed this study
through the Portuguese Foundation for Science and Technology (FCT) (POCTI/CTA/39733/2001)
An attempt to develop spectrophotometry as a proxy for sedimentary studies in estuarine environments
In deep-sea sediment studies, reïŹectance has been used as a proxy for high vs. low
productivity intervals for several years. This value of the white-black scale is obtained
through the use of spectrophotometers when using the CIE Lab color system, which
also gives values on green-red and blue-yellow scales. In estuarine/continental sediment studies, color data are still often based on Munsell Table which does not allow
to obtain numeric and continuous data and which is biased by the observerâs choice
Influence of particle size on ecotoxicity of low-density polyethylene microplastics, with and without adsorbed benzo-a-pyrene, in Clam Scrobicularia plana
This study investigated the ecotoxicological effects of differently sized (4â6 ”m and 20â25 ”m) low-density polyethylene (LDPE) microplastics (MPs), with and without adsorbed benzo-a-pyrene (BaP), in clam Scrobicularia plana. Biomarkers of oxidative stress (superoxide dismutaseâSOD; catalaseâCAT), biotransformation (glutathione-S-transferasesâGST), oxidative damage (lipid peroxidationâLPO) and neurotoxicity (acetylcholinesteraseâAChE) were analysed in gills and digestive glands at different time intervals for a total of 14 days of exposure. In order to have a better impact perspective of these contaminants, an integrated biomarker response index (IBR) and Health Index were applied. Biomarker alterations are apparently more related to smaller sized (4â6 ”m) MPs in gills and to virgin LDPE MPs in the digestive gland according to IBR results, while the digestive gland was more affected by these MPs according to the health index.info:eu-repo/semantics/publishedVersio
Identifying toxic impacts of metals potentially released during deep-sea mining - a synthesis of the challenges to quantifying risk
In January 2017, the International Seabed Authority released a discussion paper on the development of Environmental Regulations for deep-sea mining (DSM) within the Area Beyond National Jurisdiction (the "Area"). With the release of this paper, the prospect for commercial mining in the Area within the next decade has become very real. Moreover, within nations' Exclusive Economic Zones, the exploitation of deep-sea mineral ore resources could take place on very much shorter time scales and, indeed, may have already started. However, potentially toxic metal mixtures may be released at sea during different stages of the mining process and in different physical phases (dissolved or particulate). As toxicants, metals can disrupt organism physiology and performance, and therefore may impact whole populations, leading to ecosystem scale effects. A challenge to the prediction of toxicity is that deep-sea ore deposits include complex mixtures of minerals, including potentially toxic metals such as copper, cadmium, zinc, and lead, as well as rare earth elements. Whereas the individual toxicity of some of these dissolved metals has been established in laboratory studies, the complex and variable mineral composition of seabed resources makes the a priori prediction of the toxic risk of DSM extremely challenging. Furthermore, although extensive data quantify the toxicity of metals in solution in shallow-water organisms, these may not be representative of the toxicity in deep-sea organisms, which may differ biochemically and physiologically and which will experience those toxicants under conditions of low temperature, high hydrostatic pressure, and potentially altered pH. In this synthesis, we present a summation of recent advances in our understanding of the potential toxic impacts of metal exposure to deep-sea meio- to megafauna at low temperature and high pressure, and consider the limitation of deriving lethal limits based on the paradigm of exposure to single metals in solution. We consider the potential for long-term and far-field impacts to key benthic invertebrates, including the very real prospect of sub-lethal impacts and behavioral perturbation of exposed species. In conclusion, we advocate the adoption of an existing practical framework for characterizing bulk resource toxicity in advance of exploitation
A blueprint for an inclusive, global deep-sea Ocean Decade field programme
The ocean plays a crucial role in the functioning of the Earth System and in the provision of vital goods and services. The United Nations (UN) declared 2021â2030 as the UN Decade of Ocean Science for Sustainable Development. The Roadmap for the Ocean Decade aims to achieve six critical societal outcomes (SOs) by 2030, through the pursuit of four objectives (Os). It specifically recognizes the scarcity of biological data for deep-sea biomes, and challenges the global scientific community to conduct research to advance understanding of deep-sea ecosystems to inform sustainable management. In this paper, we map four key scientific questions identified by the academic community to the Ocean Decade SOs: (i) What is the diversity of life in the deep ocean? (ii) How are populations and habitats connected? (iii) What is the role of living organisms in ecosystem function and service provision? and (iv) How do species, communities, and ecosystems respond to disturbance? We then consider the design of a global-scale program to address these questions by reviewing key drivers of ecological pattern and process. We recommend using the following criteria to stratify a global survey design: biogeographic region, depth, horizontal distance, substrate type, high and low climate hazard, fished/unfished, near/far from sources of pollution, licensed/protected from industry activities. We consider both spatial and temporal surveys, and emphasize new biological data collection that prioritizes southern and polar latitudes, deeper (> 2000 m) depths, and midwater environments. We provide guidance on observational, experimental, and monitoring needs for different benthic and pelagic ecosystems. We then review recent efforts to standardize biological data and specimen collection and archiving, making âsampling design to knowledge applicationâ recommendations in the context of a new global program. We also review and comment on needs, and recommend actions, to develop capacity in deep-sea research; and the role of inclusivity - from accessing indigenous and local knowledge to the sharing of technologies - as part of such a global program. We discuss the concept of a new global deep-sea biological research program âChallenger 150,â highlighting what it could deliver for the Ocean Decade and UN Sustainable Development Goal 14
Estudo da biogeoquĂmica dos sedimentos estuarinos atravĂ©s da cor: Resultados preliminares
As zonas costeiras desempenham um papel importante no desenvolvimento das regiĂ”es e ao longo dos sĂ©culos foram locais privilegiados para a ocupação humana. O estudo de sedimentos estuarinos aplicado Ă evolução do nĂvel do mar ao longo dos tempos Ă© de extrema importĂąncia, pois reflecte avanços e recuos da linha de costa originados por variaçÔes climĂĄticas, quer a nĂvel mundial, quer a nĂvel regional e local