Marine ecosystem | EPFL Graph Search

Marine ecosystems are the largest of Earth's aquatic ecosystems and exist in waters that have a high salt content. These systems contrast with freshwater ecosystems, which have a lower salt content. Marine waters cover more than 70% of the surface of the Earth and account for more than 97% of Earth's water supply and 90% of habitable space on Earth. Seawater has an average salinity of 35 parts per thousand of water. Actual salinity varies among different marine ecosystems. Marine ecosystems can be divided into many zones depending upon water depth and shoreline features. The oceanic zone is the vast open part of the ocean where animals such as whales, sharks, and tuna live. The benthic zone consists of substrates below water where many invertebrates live. The intertidal zone is the area between high and low tides. Other near-shore (neritic) zones can include mudflats, seagrass meadows, mangroves, rocky intertidal systems, salt marshes, coral reefs, lagoons. In the deep water, hydroth

Mercury isotope evidence for Arctic summertime re-emission of mercury from the cryosphere

Jenny Thomas

During Arctic springtime, halogen radicals oxidize atmospheric elemental mercury (Hg0), which deposits to the cryosphere. This is followed by a summertime atmospheric Hg0 peak that is thought to resultmostly fromterrestrial Hg inputs to the ArcticOcean, followed by photoreduction and emission to air. The large terrestrial Hg contribution to the Arctic Ocean and global atmosphere has raised concern over the potential release of permafrost Hg, via rivers and coastal erosion,with Arctic warming. Here we investigateHg isotope variability of Arctic atmospheric,marine, and terrestrial Hg.We observe highly characteristic Hg isotope signatures during the summertime peak that reflect re-emission of Hg deposited to the cryosphere during spring. Air mass back trajectories support a cryospheric Hg emission source but nomajor terrestrial source. This implies that terrestrial Hg inputs to theArcticOcean remain in the marine ecosystem, without substantial loss to the global atmosphere, but with possible effects on food webs.

2022

Data mining in the context of urban metabolism: A case study of Geneva and Lausanne, Switzerland

Aristide Henri Roger Athanassiadis, Claudia Rebeca Binder Signer, Nicole Sophie Wiedmann

The highest share of the global population lives in cities. The current configuration of the latter requires considerable amounts of resource flows causing the degradation of local and global ecosystems. To face the complexity of these challenges, scientists use the concept of urban metabolism (UM), i.e. measuring urban input and output flows from a systemic perspective. This accounting method results in a large data collection from multiple sources that are often not harmonised. Metabolism of Cities Data Hub is an online platform which facilitates data collection, processing and visualisation in order to extract urban metabolism insights. This work highlights the challenges faced when mining urban metabolism data in the case of Lausanne and Geneva, as well as provides insights on how data could be best used from users and providers. Slight differences between the two case studies, in terms of data accessibility and availability where experienced but the main challenges revolved around data copyright, format and availability. As a conclusion, the used tool can enable harmonisation and standardisation of UM data. As such it could contribute to the use of data mining to streamline the environmental monitoring of cities as well as facilitate the creation of mitigation strategies.

IOP PUBLISHING LTD2021

The role of Organophosphate Esters Flame Retardants and plasticizers (OPEs) in Phosphorus Cycle in the atmosphere of the Mediterranean Sea

Athanasios Nenes, Christos Panagiotopoulos, Kalliopi Violaki

The atmosphere is considered as an important external nutrient source for the marine environment, especially in remote ocean waters or the oligotrophic Mediterranean Sea. Phosphorus (P) is a critical nutrient affecting primary productivity in large areas of oceanic ecosystems. Much has been placed on inorganic P, while the importance of organic P as potential pool of bioavailable P is not widely recognized. In this study we quantify and speciate the anthropogenic organic P in the West and East Mediterranean atmosphere. Several anthropogenic organophosphorus compounds are analyzed, including pesticides (Phosmet, Malathion, Ethoprophos, Diazinon, Chloropyrifos-Me, Chloropyrifos-e), organophosphorus flame retardants and plasticizers (OPEs) (Tris- (1-chloro-2-propyl) phosphate (TCPP), tris[2-chloro-1-(chloromethyl)ethyl]phosphate (TDCP), Tris-(2-chloroethyl)phosphate (TCEP), tri-n-butyl phosphate (TnBP), triphenyl phosphate (TPhP), 2-ethylhexyl diphenyl phosphate (EHDPP)). Our analysis applied to Total Suspended atmospheric Particles (TSP) collected in Eastern (Crete, n = 67) and Western (Marseille, n = 25) Mediterranean Sea by using high-volume air sampler. The analysis performed with the liquid chromatography coupled to mass spectrometry (Q–TOF–LC/MS) after optimization of the analytical protocol for the aerosol samples. Five pesticides were found during the sampling period in East Mediterranean in total of 27 samples. The most frequent were chlorpyrifos–e (n = 9) and phosmet (n = 10) with average concentration 0.24±0.38 pmol m–3 and 0.24±0.45 pmol m–3, respectively following by diazinon (n = 4) at 0.07±0.00 pmol m–3. Higher concentration was estimated in chlorpyrifos-me at 0.91±0.93 pmol m–3 (n = 3) while ethoprophos was detected only in one sample (0.002 pmol m m–3), malathion was below detection limit. In the West Mediterranean, the most abundant organophosphate pesticides were phosmet (n = 3) with an average concentration of 0.07±0.04 pmol m–3, followed by diazinon (0.05 pmol m–3, n = 1) and chloropyrifos-e (0.04 pmol m–3, n = 2). Malathion, chlorpyrifos-me and ethoprophos were not detected. The average contribution of organophosphate pesticides in atmospheric organic P detected during this study was 0.2% and 0.1% for East and West Mediterranean, respectively. OPEs analyses in the same samples revealed higher concentrations in the West than in East Mediterranean atmosphere especially for TCPP, TCEP and TDCP, which are considered as the most potentially hazardous. In the West Med. the most abundant detected OPEs were the EHDPP (3.04±4.17 pmol m-3) and the TCPP (1.71±1.28 pmol m-3). In East Mediterranean, the most abundant detected OPEs were the TCPP (0.36±0.29 pmol m-3) and the TCEP (0.24±0.20 pmol m-3) whereas the TDCP and the EHDPP were not detected. The percentage contribution of OPEs in atmospheric organic–P over the West Mediterranean was 9%, while over East was 0.4%. The total anthropogenic organic P deposited in East Mediterranean during stratification period (June-September) was calculated at 8 tons, which was 4 times lower comparing with West Mediterranean (29 tons of P) during the same period. Overall, the above anthropogenic compounds represented only 0.4% of the total anthropogenic P deposited during stratification period, however their toxicity and fate to the marine environment warrants further investigations.

2020

The role of Organophosphate Esters Flame Retardants and plasticizers (OPEs) in Phosphorus Cycle in the atmosphere of the Mediterranean Sea

Athanasios Nenes, Christos Panagiotopoulos, Kalliopi Violaki

2020