A study of the photocatalytic degradation of methomyl by UV light

The photocatalytic degradation of insecticide methomyl in water, using TiO2 and ZnO (Merck), under UV (366 nm) was studied. The influence of the catalyst concentration and pH was investigated. The optimal concentration of the catalyst was found to be 2.0 g/l. It was found that ZnO is a better catalyst than TiO2 under the same reaction conditions. Also, the influence of NaCl was studied. The presence of Cl− significantly affects the photodegradation of the pollutant

Slab tearing in non-collisional settings: Insights from thermo-mechanical modelling of oblique subduction

The propagation of slab break-off (slab tearing) is usually attributed to laterally variable plate convergence systems with a spatial transition between simultaneous oceanic subduction and continental collision. To study the process of slab tearing in a non-collisional geodynamic context, here we use a 3D thermo-mechanical numerical approach to model the oblique subduction of a homogeneous oceanic plate. We investigate the effects of the following parameters: (1) subduction obliquity angle, (2) age of oceanic slab, and (3) partitioning of boundary velocities (i.e., the ratio between the subduction component and the advance of the overriding plate in the total convergence). In our simulations, the retreat of the subduction zone leads to a thinning of the fore-arc and back-arc lithosphere, which are decoupled from the subducting slab by the rise of the hot asthenosphere from the underlying mantle wedge. As a consequence of the initial obliquity of the active plate margin, slab roll-back velocities are subject to progressive along-trench variations. Consistent with the gradual rotation of the trench, the front of the decoupling between the overriding and downgoing plates (together with predicted magmatic activity and topographic uplift) migrates in a horizontal direction. In the experiments with low angles of subduction obliquity ( 50 Ma), and in the absence of the subduction component in the overall shortening, slab detachment either develops simultaneously along the entire length of the subduction zone or does not occur at all. In contrast, with higher subduction obliquity (≥ 15°), younger slabs (≤ 50 Ma) and in the presence of a boundary push on the oceanic side, the initial slab break-off is followed by the gradual growth of the “tear” window in the direction opposite to the migration path of the previously established plates decoupling. The sharp contrast in trench retreat rates between subduction zone segments affected and unaffected by slab detachment results in the arcuate shape of the trench. Furthermore, the direction of slab tearing may change from horizontal to vertical, eventually leading to the formation of a transform fault on the subducting plate. Our results show striking similarities with several features – such as trench curvature, subduction zone segmentation, magmatic production, lithospheric stress/deformation fields, and associated topographic changes – observed in many subduction zones (e.g., Marianas, New Hebrides, Mexico, Calabrian)

Integrated records of tectonic and climate interactions in the Northern Alpine Foreland Basin sedimentary architecture

Peripheral foreland basins form due to flexural subsidence of the downgoing plate driven by topographic- and slab loading. Their architecture records lithospheric- and crustal-scale processes, and the climate history of the adjacent growing orogen. Previous geological and geophysical observational studies revealed that many foreland basins show along-strike heterogeneous sedimentary architecture, implying that mechanisms controlling basin evolution varied laterally. In the Northern Alpine Foreland Basin (NAFB, also known as Molasse Basin) the along-strike heterogeneity in basin architecture is represented by eastward shallowing of depositional environments during Oligocene-Miocene times. This coincided with the suggested two slab break-off and/or tearing events occurring below the Alps. In this project, we test the hypothesis of whether slab break-off and tearing can control along-strike variable foreland basin architecture. We do this by combining tectonostratigraphic analysis of the NAFB fill and numerical models. Tectonostratigraphic analysis includes interpretation of the 2D/3D seismic data located in the transitional zone of the NAFB (German Molasse) connecting the western and eastern parts of the basin. To investigate the effect of the slab-break off and tearing on the foreland basin evolution we combine 3D thermomechanical- and stratigraphic forward models. The results of the tectonostratigraphic analysis reveal a northward younging trend of syn-flexural normal fault nucleation which agrees with forebulge migration driven by the advance of the Alpine thrust front during the Oligocene-Miocene. Furthermore, the eastward increase in the magnitude of syn-flexural normal fault offsets suggests an increase in the magnitude of flexural bending of the lower plate. This may have been controlled by lateral variations in the architecture of the lower plate and/or spatiotemporal variations in slab breakoff/tearing. The observed along-strike seismic facies integrated with the published data suggests that the north-south trending intrabasinal coastline migrated from west to east at an average rate of ~ 6 cm/yr. Furthermore, 3D thermomechanical models show that slab tearing will initiate either at the location of a subducted continental terrain (if present along the slab) or where collision starts first in the case of oblique convergence. Subsequently, tearing propagates along the strike at velocities ranging from ~35 cm/yr to 120 cm/yr depending on the margin obliquity, slab age and mantle rheology. The surface expression of slab tearing is the orogen parallel migration of uplift, affecting both the orogen and peripheral foreland basin. In the peripheral foreland basins associated with the collision of oblique margins, this uplift leads to a gradual along-strike decrease of accommodations space followed by shallowing of depositional environments. However, during the collision of irregular margins, the size and rheology of irregular terrains exert a key influence on the along-strike distribution of the surface uplift during tearing. Typically, this yields a more stepwise distribution of the accommodation space along the peripheral foreland, i.e. lower above the previously accreted terrain. Currently, we are focusing on integrating thermomechanical- and forward stratigraphic models to estimate the effect of environmental factors such as sea-level variations, and precipitation rates on the preservation of the slab break-off and tearing signals in the stratigraphic record of peripheral foreland basins

Relationships among hygiene indicators in take-away foodservice establishments and the impact of climatic conditions

AimsThis paper examined the relationships among hygiene indicators in take-away foodservice establishments and the impact of climatic conditions. Methods and ResultsA total of 7545 samples were collected encompassing 2050 from food handlers' (HF) hands, 3991 from stainless steel food contact surfaces (FCS) and 1504 samples from plastic FCS. The study covered a period of 43months. Hygiene-indicator bacteria (total plate count, Enterobacteriaceae Staphylococcus) were determined from the samples collected from 559 different take-away establishments. Climatic conditions were evaluated in respect to the outside temperature, pressure, humidity and precipitation. Logistic regression confirmed that the presence of precipitation was associated with an increased likelihood of exhibiting both Enterobacteriaceae and Staphylococcus on HF' hands as well as exhibiting Enterobacteriaceae on both types of FCS. Numerable Enterobacteriaceae and Staphylococcus levels on HF' hands were detected when higher outside temperatures and higher precipitations occurred. Higher outside temperatures were observed when Enterobacteriaceae were detected on both plastics (P lt 005) and stainless steel (P>005). Higher precipitation was observed when Enterobacteriaceae was detected on stainless steel while in contrast, this indicator was detected on plastics in periods with lower precipitation. ConclusionsThis research confirms relationships between hygiene indicators in take-aways and climatic conditions, mostly temperature and precipitation. Significance and Impact of the StudyThis study provides another perspective into the possible nature of cross-contamination and foodborne outbreaks originating in foodservice establishments and brings to attention the necessity of analysing various climatic conditions

Signals of slab breakoff- and tearing in the stratigraphic architecture of a foreland basin

A significant change in the architecture of peripheral pro-foreland basins observed in all natural examples is the flysch to molasse transition (i.e., shift from underfilled- to overfilled conditions). Forcing mechanisms for pro-foreland basin architecture include changes in sediment supply from the adjacent growing orogen and flexural subsidence in the basin. As these forcing mechanisms themselves are driven by orogenic processes in the adjacent mountain range, the flysch to molasse transition can be regarded as the sedimentary fingerprint of hinterland tectonics. Slab breakoff of the foreland plate leading to isostatic rebound of both the pro-foreland basin and adjacent orogen (leading to increased sediment supply) has been suggested to be a driver of the flysch to molasse transition. However, this cause-and-effect relationship between slab breakoff and the flysch to molasse transition is based on qualitative assessments. This raises the question whether other external forcings may have masked the contribution of slab breakoff to the flysch to molasse transition. In this study we investigate the stratigraphic signal of slab breakoff in a pro-foreland basin. To quantitatively assess the relationship between slab breakoff and the flysch to molasse transition, we coupled 2D geodynamic models (GMs) of slab breakoff using LaMEM with 2D forward stratigraphic modelling (FSM) using the GPM software (SLB). To better understand the influence of slab breakoff on pro-foreland basin architecture, we tested slab breakoff scenarios in our GMs for varying 1) slab bending angles and 2) slab necking durations (depending on slab rheology). To test whether the stratigraphic signal of slab breakoff may be masked by other external forcings, we introduced eustatic sea level changes (50 m amplitude with a 1 My period). From our FSMs we generated sediment thickness maps used to reconstruct sediment supply rates, grain size distribution- and facies maps and synthetic seismic data to compare with observed seismic data. Our preliminary results indicate that vertical uplift due to isostatic rebound in the pro-foreland basin (1.5 – 7 cm/yr, where fast necking of steep slabs yields higher values) decreases the accommodation space, leading to a stratigraphically upward shallowing. Furthermore, isostatic rebound of the adjacent mountain range (2-5 cm/yr, same relationship with slab dynamics as pro-foreland basin) results in up to 2.5x increased rates of sediment supply with very little lag time, adding to the stratigraphically upward shallowing. The eustatic sea level changes do not mask the stratigraphic signal of slab breakoff. Lastly, the facies of the flysch to molasse transition in our synthetic seismics looks similar to that observed on seismics of the Austrian Molasse which occurred coeval with slab breakoff under the Eastern Alps

Urban deciduous tree leaves as biomonitors of trace element (As, V and Cd) atmospheric pollution in Belgrade, Serbia

Leaves of common deciduous trees: horse chestnut (Aesculus hippocastanum) and linden (Tilia spp.) from three parks within the urban area of Belgrade were studied as biomonitors of trace element (As, V, and Cd) atmospheric pollution. The May–September trace element accumulation in the leaves, and their temporal trends, were assayed in a multi-year period (2002–2006). Significant accumulation in the leaves was evident for As and V, but not so regularly for Cd. Slightly decreasing temporal trends of V and As ac-cumulated in the leaf tissues were observed over the years. During the time span, the concentrations of Cd remained approximately on the same level, except in May 2002 and September 2005, when a rapid increase was observed. The May–September accumulations of As and V were higher in horse chestnut than in linden, although both may be used as biomonitors for these elements, and optionally for Cd in conditions of its high atmospheric loadings

Aflatoxins in milk and dairy products: Occurrence and exposure assessment for the serbian population

The main objective of this study was to assess the exposure associated with aflatoxin M1 (AFM1) of the adult population in Serbia from consumption of milk and dairy products. This assessment was performed using concentration values of AFM1 in raw milk (385 samples) and dairy products (556 samples) based on the analyses conducted in the period between 2015 and 2018. In parallel, a dairy products consumption survey was completed during 2018 based on ‘one-day’ and ‘seven-day’ recall methods. In order to estimate the intake of AFM1 from the consumption of dairy products for both recall methods, a Monte Carlo simulation was conducted. The study revealed that pasteurized milk and yogurt are dairy products mostly consumed by the Serbian adult population. Estimated daily intake of AFM1 was in the range of 62-74 × 10-3 ng/kg bw/day, depending on the recall methods and scenarios employed. Although the results show moderate exposure risks compared to similar studies worldwide, climatic conditions and weather extremes that have occurred recently may have negatively influenced the contamination of feed and, consequently, AFM1 contamination of milk. As a result, it is justifiable to promote continuous monitoring in feed and dairy supply chains in Serbia and provide an update of exposure assessment

Slab tearing in non-collisional settings: Insights from thermo-mechanical modelling of oblique subduction

The propagation of slab break-off (slab tearing) is usually attributed to laterally variable plate convergence systems with a spatial transition between simultaneous oceanic subduction and continental collision. To study the process of slab tearing in a non-collisional geodynamic context, here we use a 3D thermo-mechanical numerical approach to model the oblique subduction of a homogeneous oceanic plate. We investigate the effects of the following parameters: (1) subduction obliquity angle, (2) age of oceanic slab, and (3) partitioning of boundary velocities (i.e., the ratio between the subduction component and the advance of the overriding plate in the total convergence). In our simulations, the retreat of the subduction zone leads to a thinning of the fore-arc and back-arc lithosphere, which are decoupled from the subducting slab by the rise of the hot asthenosphere from the underlying mantle wedge. As a consequence of the initial obliquity of the active plate margin, slab roll-back velocities are subject to progressive along-trench variations. Consistent with the gradual rotation of the trench, the front of the decoupling between the overriding and downgoing plates (together with predicted magmatic activity and topographic uplift) migrates in a horizontal direction. In the experiments with low angles of subduction obliquity (< 15°), relatively old subducting plates (> 50 Ma), and in the absence of the subduction component in the overall shortening, slab detachment either develops simultaneously along the entire length of the subduction zone or does not occur at all. In contrast, with higher subduction obliquity (≥ 15°), younger slabs (≤ 50 Ma) and in the presence of a boundary push on the oceanic side, the initial slab break-off is followed by the gradual growth of the “tear” window in the direction opposite to the migration path of the previously established plates decoupling. The sharp contrast in trench retreat rates between subduction zone segments affected and unaffected by slab detachment results in the arcuate shape of the trench. Furthermore, the direction of slab tearing may change from horizontal to vertical, eventually leading to the formation of a transform fault on the subducting plate. Our results show striking similarities with several features – such as trench curvature, subduction zone segmentation, magmatic production, lithospheric stress/deformation fields, and associated topographic changes – observed in many subduction zones (e.g., Marianas, New Hebrides, Mexico, Calabrian)

Plume‐Induced Sinking of Intracontinental Lithospheric Mantle: An Overlooked Mechanism of Subduction Initiation?

Although many different mechanisms for subduction initiation have been proposed, only few of them are viable in terms of consistency with observations and reproducibility in numerical experiments. In particular, it has recently been demonstrated that intra-oceanic subduction triggered by an upwelling mantle plume could greatly contribute to the onset and operation of plate tectonics in the early and, to a lesser degree, modern Earth. On the contrary, the initiation of intra-continental subduction still remains underappreciated. Here we provide an overview of 1) observational evidence for upwelling of hot mantle material flanked by downgoing proto-slabs of sinking continental mantle lithosphere, and 2) previously published and new numerical models of plume-induced subduction initiation. Numerical modeling shows that under the condition of a sufficiently thick (>100 km) continental plate, incipient downthrusting at the level of the lowermost lithospheric mantle can be triggered by plume anomalies of moderate temperatures and without significant strain- and/or melt-related weakening of overlying rocks. This finding is in contrast with the requirements for plume-induced subduction initiation within oceanic or thinner continental lithosphere. As a result, plume-lithosphere interactions within continental interiors of Paleozoic-Proterozoic-(Archean) platforms are the least demanding (and thus potentially very common) mechanism for initiation of subduction-like foundering in the Phanerozoic Earth. Our findings are supported by a growing body of new geophysical data collected in various intra-continental areas. A better understanding of the role of intra-continental mantle downthrusting and foundering in global plate tectonics and, particularly, in the initiation of “classic” ocean-continent subduction will benefit from more detailed follow-up investigations

Plume‐Induced Sinking of Intracontinental Lithospheric Mantle: An Overlooked Mechanism of Subduction Initiation?

Although many different mechanisms for subduction initiation have been proposed, only few of them are viable in terms of consistency with observations and reproducibility in numerical experiments. In particular, it has recently been demonstrated that intra‐oceanic subduction triggered by an upwelling mantle plume could greatly contribute to the onset and operation of plate tectonics in the early and, to a lesser degree, modern Earth. On the contrary, the initiation of intra‐continental subduction still remains underappreciated. Here we provide an overview of 1) observational evidence for upwelling of hot mantle material flanked by downgoing proto‐slabs of sinking continental mantle lithosphere, and 2) previously published and new numerical models of plume‐induced subduction initiation. Numerical modeling shows that under the condition of a sufficiently thick (>100 km) continental plate, incipient downthrusting at the level of the lowermost lithospheric mantle can be triggered by plume anomalies of moderate temperatures and without significant strain‐ and/or melt‐related weakening of overlying rocks. This finding is in contrast with the requirements for plume‐induced subduction initiation within oceanic or thinner continental lithosphere. As a result, plume‐lithosphere interactions within continental interiors of Paleozoic‐Proterozoic‐(Archean) platforms are the least demanding (and thus potentially very common) mechanism for initiation of subduction‐like foundering in the Phanerozoic Earth. Our findings are supported by a growing body of new geophysical data collected in various intra‐continental areas. A better understanding of the role of intra‐continental mantle downthrusting and foundering in global plate tectonics and, particularly, in the initiation of “classic” ocean‐continent subduction will benefit from more detailed follow‐up investigations