The Pennsylvanian Piauí Formation records the deposition of aeolian, fluvial and shallow marine systems accumulated in the cratonic sag Parnaíba basin. Characterization of the facies associations and ...sequence stratigraphic framework was done by detailed description and logging of outcrops. Six facies associations were recognized: aeolian dunes and interdunes, aeolian sandsheets, fluvial channels, tidally-influenced fluvial channels, shoreface and shoreface-shelf transition. Through correlation of stratigraphic surfaces, the facies associations were organized in system tracts, which formed eight high frequency depositional sequences, bounded by subaerial unconformities. These sequences are composed of a lowstand system tract (LST), that is aeolian-dominated or fluvial-dominated, a transgressive system tract (TST) that is formed by tidally-influenced fluvial channels and/or shoreface and shoreface-shelf transition deposits with retrogradational stacking, and a highstand system tract (HST), which is formed by shoreface-shelf transition and shoreface deposits with progradational stacking. Two low frequency cycles were determined by observing the stacking of the high frequency cycles. The Lower Sequence is characterized by aeolian deposits of the LST and an aggradational base followed by a progressive transgression, defining a general TST. The Upper Sequence is characterized by fluvial deposits and interfluve pedogenesis concurring with the aeolian deposits of the LST and records a subtle regression followed by transgression. The main control on sedimentation in the Piauí Formation was glacioeustasy, which was responsible for the changes in relative sea level. Even though, climate changes were associated with glacioeustatic phases and influenced the aeolian and fluvial deposition.
•The Piauí Formation is composed of aeolian, fluvial and shallow marine deposits.•A stratigraphic framework is presented, with 2 low frequency sequences and 8 high frequency sequences.•Ciclicity is controlled mainly by glacio-eustatic cycles.
During the late Neogene, the east Mediterranean margins of the Levant went through major morphological changes due to tectonic activity associated with the Dead Sea Transform Fault. The regional ...fluvial systems inverted their flow direction from westward towards the Mediterranean to eastward towards the Jordan Valley. Tectonic basins that developed at that time in northern Israel were filled by lakes with intermittent connections to the sea. The tectonic processes were accompanied by volcanism of alkali basalts. This study focuses on the evolution of sedimentary-volcanic sequences, mainly included in the Bira and Gesher Formations that were deposited in lacustrine and palustrine environments in northern Israel. The study presents a comprehensive dataset and interpretation integrating new and old lithological and paleontological records from outcrops and drill holes, together with new petrographic and mineralogical data. The Bira Formation of Tortonian age, which overlies the Lower Basalt unit, consists mainly of lacustrine littoral limestone and dolostone and basinal marl. Sporadic occurrences of marine macrofauna indicate pulses of marine ingressions that reached the Jordan Valley depocenter, where thick sequences of gypsum and salt were deposited. The overlying Gesher Formation of Messinian-early Zanclean age, which has a similar lithology to that of the Bira Formation, represents an environmental evolution from restricted shallow lakes into a larger lake, or lakes, and finally to shallow isolated water bodies. The latter stage coincides with the Messinian Salinity Crisis, when climate became more arid in the Levant. Pyroclasts and some lava flows recorded an ongoing volcanic activity during this period that intensified toward the eruption of the Cover Basalt unit, that overlies the Gesher Formation. Overall, the Bira and Gesher formations provide a detailed sedimentological, tectonic and volcanic history of the continental margins of the east Mediterranean and its connection to the tectonic evolution of basin associated with the Dead Sea Transform Fault.
In recent years, energy-related CO2 emissions embodied in international trade and the driving forces have been widely studied by researchers using the environmental input–output framework. Most ...previous studies however, do not differentiate different input structures in manufacturing processing exports and normal exports. Using China as an example, this paper exemplifies how implications of results obtained using different export assumptions differ. The study posits that the utilization of traditional I–O model results in an overestimation of emissions embodied in processing exports and an underestimation in normal exports. The estimate of CO2 emissions embodied in China's exports drops by 32% when the extended I–O model is used. The choice of export assumption has more impact on the decomposition results for processing exports. The study further highlights that for a country with an export structure similar to China, it is meaningful to look into the impact of export assumption in embodied emission studies.
► We study the issue of exports assumptions in embodied emission studies and structural decomposition analysis. ► The implications of the results obtained using two different exports assumptions are not the same. ► Utilization of traditional I–O model results in an overestimation of emissions embodied in processing exports. ► Utilization of traditional I–O model results in an underestimation of emissions embodied in normal exports. ► The choice of exports assumption has more impact on the decomposition results for processing exports.
Considering the strategic position of Algeria both in the global and regional economic complexities through economic liberalization, much has been said about oil shock and economic performance of ...Algeria but little has been done towards ascertaining the impact of natural resources and foreign direct investment inflow (FDI) on its environmental performance. For this purpose, we adopt Algeria 1970–2018 data to study its sustainable development with focus on its environmental performance. Nonlinear and long run asymmetric cointegration were utilized for a comprehensive research on this topic. Our findings are as follows: positive and negative shocks to the economic growth and fossil fuels on the Algerian environment increases and reduces carbon emission respectively, positive and negative shocks to FDI and natural resources decrease the carbon emission thereby impacting positively on the environment. Hence, pollution halo hypothesis is confirmed for Algeria meaning FDI is impacting positively on the environment and should be encouraged through policy framing and implementation for the case of Algeria.
•This is a nonlinear study of Algeria's environmental performance.•Natural Resource and foreign Direct Investment (FDI) were used to assess Algeria's environment performance.•Algeria's ambition towards mitigating carbon emission is confirmed with FDI and natural resources.•Pollution halo hypothesis was confirmed for Algeria.•Conclusion is based on policy inferences from Algeria's ability to curb emission.
New ichnological data from the Lower Triassic (Induan) Dongchuan Formation (Longmendong, South China) record the recovery interval of marginal-marine communities following the end-Permian mass ...extinction. Here, we document six ichnogenera from the upper part of the Dongchuan Formation of Dienerian (Early Triassic) age in the Longmendong area, Sichuan Province, South China. These are Cylindrichnus, Diplocraterion, Palaeophycus, Planolites, Siphonichnus, and Teichichnus, illustrating a depauperate Cruziana Ichnofacies. Facies analysis suggests that the depauperate Cruziana Ichnofacies is present in deposits recording the transition from fluvial to tide-dominated estuarine settings. Compilation of worldwide brackish-water ichnofaunas from Permian (average alpha ichnodiversity=6.2) to Triassic (average alpha ichnodiversity=5.5) suggests that no significant ichnodiversity decrease took place in these settings as a result of the mass extinction and further implies that the impact of the mass extinction may have been less severe in marginal-marine settings. Ichnofaunas in pre- and post-extinction marginal-marine environments are remarkably similar and tend to be dominated by facies-crossing ichnotaxa (e.g., Diplocraterion, Palaeophycus, Planolites) produced by opportunistic faunas.
•A depauperate Cruziana Ichnofacies in the Dinerian Dongchuan Formation•No ichnodiversity decrease in brackish-water ichnofaunas across the P–Tr•Overall similarities between pre- and post-extinction brackish-water ichnofaunas
Marine sediments, particularly those located in estuarine and coastal zones, are key locations for the burial of organic carbon (C). However, organic C delivered to the sediment is subjected to a ...range of biological C-cycling processes, the rates and relative importance of which vary markedly between sites, and which are thus difficult to predict. In this study, stable isotope tracer experiments were used to quantify the processing of C by microbial and faunal communities in two contrasting Scottish estuarine sites: a subtidal, organic C rich site in Loch Etive with cohesive fine-grained sediment, and an intertidal, organic C poor site on an Ythan estuary sand flat with coarse-grained permeable sediments. In both experiments, sediment cores were recovered and amended with 13C labelled phytodetritus to quantify whole community respiration of the added C and to trace the isotope label into faunal and bacterial biomass. Similar respiration rates were found in Loch Etive and on the Ythan sand flat (0.64 ± 0.04 and 0.63 ± 0.12 mg C m−2h−1, respectively), which we attribute to the experiments being conducted at the same temperature. Faunal uptake of added C over the whole experiment was markedly greater in Loch Etive (204 ± 72 mg C m−2) than on the Ythan sand flat (0.96 ± 0.3 mg C m−2), and this difference was driven by a difference in both faunal biomass and activity. Conversely, bacterial C uptake over the whole experiment in Loch Etive was much lower than that on the Ythan sand flat (1.80 ± 1.66 and 127 ± 89 mg C m−2, respectively). This was not driven by differences in biomass, indicating that the bacterial community in the permeable Ythan sediments was particularly active, being responsible for 48 ± 18 % of total biologically processed C. This type of biological C processing appears to be favoured in permeable sediments. The total amount of biologically processed C was greatest in Loch Etive, largely due to greater faunal C uptake, which was in turn a result of higher faunal biomass. When comparing results from this study with a wide range of previously published isotope tracing experiments, we found a strong correlation between total benthic biomass (fauna plus bacteria) and total biological C processing rates. Therefore, we suggest that the total C-cycling capacity of benthic environments is primarily determined by total biomass.
Abstract Objectives To estimate the proportion of children living within walking distance who walk to school in Toronto, Canada and identify built and social environmental correlates of walking. ...Methods Observational counts of school travel mode were done in 2011, at 118 elementary schools. Built environment data were obtained from municipal sources and school field audits and mapped onto school attendance boundaries. The influence of social and built environmental features on walking counts was analyzed using negative binomial regression. Results The mean proportion observed walking was 67% (standard deviation = 14.0). Child population (incidence rate ratio (IRR) 1.36), pedestrian crossover (IRR 1.32), traffic light (IRR 1.19), and intersection densities (IRR 1.03), school crossing guard (IRR 1.14) and primary language other than English (IRR 1.20) were positively correlated with walking. Crossing guard presence reduced the influence of other features on walking. Conclusions This is the first large observational study examining school travel mode and the environment. Walking proportions were higher than those previously reported in Toronto, with large variability. Associations between population density and several roadway design features and walking were confirmed. School crossing guards may override the influence of roadway features on walking. Results have important implications for policies regarding walking promotion.
Analysis of patterns of coastal circulation and sediment dispersal is an essential step for the study of controlling factors influencing the long-term dynamics of coastal systems. Modern settings ...offer the possibility to monitor relevant parameters over relatively short time spans. However, geological examples complement this perspective by providing a time-averaged record where longer trends and stratigraphically significant processes can be evaluated. This study investigates the shallow marine deposits of Le Castella terrace (Upper Pleistocene, southern Italy) to document how patterns of circulation influenced by coastline configuration can affect the preserved millennial-scale depositional record of a progradational shoreline system. The regressive portion of the Le Castella terrace deposits, developed during a relative sea-level highstand and falling stage, consists of a progradational wedge mainly composed of redistributed skeletal particles of a coeval shallow water carbonate factory. Preservation of the morphology of the paleocoastline and abundant current-related sedimentary structures allow reconstruction of the predominant sediment dispersal dynamics responsible for the formation of this sedimentary wedge. Facies and paleocurrent analysis indicate offshore and alongshore sediment transport modes, consistent with coastal circulation driven by storms normally incident to the shoreline and a sharp change in coastline orientation. This coastal inflection influenced circulation patterns causing flow separation and eddy formation in the lee of the curved coastline. Syndepositional tectonic deformation also affected the architecture of the preserved deposits, controlling the nucleation and development of a clinostratified body and determining localized lateral stratigraphic variability. This study illustrates how transient but recurrent circulation patterns associated with changes in coastal orientation and related to high-energy storm events can leave a predominant signature in the stratigraphic record of microtidal shallow-marine successions.
•We report data on facies and paleocurrents of a microtidal progradational bioclastic wedge•Storm-related deposition dominates millennial-scale record of a shallow-marine succession•Coastline orientation affects inner shelf sediment distribution patterns•Tectonically-generated submarine paleotopography controls stratal geometry
•We summarized and discussed about As in drinking water for all territories in China.•Possible natural As sources in drinking water, were documented.•Typical environmental conditions for occurrence ...of geogenic high-As waters.•Anthropogenic As contaminations in China were summarized.
Chronic endemic arsenicosis areas have been discovered in China since 1960s. Up to 2012, 19 provinces had been found to have As concentration in drinking water exceeding the standard level (0.05mg/L). Inner Mongolia, Xinjiang and Shanxi Province are historical well-known “hotspots” of geogenic As-contaminated drinking water. The goal of this review is to examine, summarize and discuss the information of As in drinking water for all provinces and territories in China. Possible natural As sources for elevating As level in drinking water, were documented. Geogenic As-contaminated drinking water examples were taken to introduce typical environmental conditions where the problems occurred: closed basins in arid or semi-arid areas and reducing aquifers under high pH conditions. Geothermal water or mineral water in mountains areas can be high-As water as well. For undiscovered areas, prediction of potential As-affected groundwater has been carried out by some research groups by use of logistic regression. Modeled maps of probability of geogenic As contamination in groundwater are promising to be used as references to discover unknown areas. Furthermore, anthropogenic As contaminations were summarized and mining, smelters and chemical industries were found to be major sources for As pollution in China.
We compile a multi-proxy Holocene record from North Raft Lake located in the sub-Arctic Hudson Bay Lowlands, Canada. Specifically, we use subfossil chironomid, diatom, and pollen assemblages, ...non-pollen palynomorphs, sedimentary chlorophyll
a
, magnetic susceptibility, and organic matter content to characterize terrestrial and lake processes and to track paleoclimate following land emergence from the postglacial Tyrrell Sea. Following recession of the Tyrrell Sea (~ 6600 cal yr BP), pollen assemblages are indicative of a salt marsh environment with the establishment of an opportunistic chironomid assemblage. By ~ 6200 cal yr BP, isostatic uplift reduced the marine influence and pollen and palynomorph assemblage changes indicate that North Raft Lake became a closed-basin freshwater system. At this time, pollen assemblages signify the establishment of a forested peatland dominated by
Picea
, and chironomid taxa indicate warming water temperatures. The North Raft Lake pollen/palynomorph record captures a warm and moist mid-Holocene (Holocene Thermal Maximum) period starting ~ 6200 cal yr BP. During this period, an increase in pollen concentration and a shift to higher abundances of
Larix
indicate watershed-scale succession and enhanced local ecosystem productivity. Shifts in chironomid taxa at ~ 5000 cal yr BP are indicative of abrupt limnological changes suggesting wet conditions that caused an expansion of littoral habitat. The gradual transition into Neoglacial cooling is signaled by an increase in the abundances of cold-stenothermal chironomid taxa and a small decline in pollen-reconstructed temperatures. Marked changes occur in the mid-twentieth century with the appearance of diatoms in notable abundances for the first time in the lake’s sedimentary record, the arrival of new chironomid littoral taxa, and unprecedented increases in sedimentary chlorophyll
a
and organic matter content. Throughout the North Raft Lake Holocene sediment record, the pollen trends suggest slow centennial-scale changes in temperature and precipitation, whereas chironomid assemblages indicate abrupt mid-Holocene and twentieth century limnological changes, stressing that biota in lakes of the Hudson Bay Lowlands may change substantially under future scenarios of global climate warming.
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