Factors triggering landslide occurrence on the Zemun loess plateau,Belgrade area,Serbia

Among the numerous factors that trigger landslide events, the anthropogenic impact caused by inadequate planning and faulty land use in urban areas is increasing. The Zemun settlement on the northern outskirts of Belgrade has experienced a number of landslides in the last three decades, endangering buildings and roads, and claiming human lives, particularly in the case of the 2010/2011 landslides. Selected meteorological parameters were used to calculate rainfall erosivity indices such as Precipitation Concentration Index and Modified Fournier Index over the period 1991–2015. Drought indices, Lang aridity index and Palfai Drought Index were calculated as well. Mann–Kendall trend test was applied to identify potential rising and/or declining trends both in meteorological parameters and calculated indices. Trend analysis of the annual and seasonal scales yielded a statistically significant trend in the spring time series. Stable arid and pronounced drought conditions were recorded. The modified Fournier index based on monthly mean values yields moderate aggressiveness, with several extreme values indicating very high erosivity classes, especially for 2010/2011. The geological substrate is predominantly loess and hence highly susceptible to erosion and slope failure when climatological conditions are suitable. Accelerated urbanization at the end of the last century reduced vegetation cover, intensified pressure on the vertical loess slope, and lacked suitable rain drainage systems so that surface-water runoff was directed into the porous loess, thereby endangering slope stability. We proposed a geomorphic model to describe the nature of the erosional processes on the loess cliffs of the Zemun loess plateau. Results from this study have implications for mitigation strategies.     

The political roots of divergence in carbon market design: implications for linking

There is a substantial literature on optimal emissions trading system (ETS) designs, but relatively little on how organized political interests affect the design and operation of these economic instruments. This article looks systematically at the political economy of the diffusion of ETS designs and explores the implications for carbon-market linking. Contrary to expectations of convergence – as has been observed in many areas where economic policy diffuses across markets – we found substantial divergence in the design and implementation of ETS across the nine systems examined. The architects of these different systems are aware of other designs, but they have purposely adjusted designs to reflect local political and administrative goals. Divergence has sobering implications for visions of ubiquitous linkages and the emergence of a global carbon market that, to date, have been predicated on the assumption that designs would converge. More such ‘real world’ political economy analysis is needed to understand how political forces, mainly within countries, act as strong intervening variables that affect instrument design, implementation and effectiveness.

Key policy insights

• Our finding of design divergence indicates that policy efforts aimed at achieving integrated international markets are unlikely to be successful.

• Visions of carbon market linkage will need to confront the reality that there are well-organized political coalitions, anchored in the status quo, that prefer divergence.

• In linking ETS, policy-makers should devote more attention to preventing excessive capital flows that can undermine political support for linkage, while also creating incentives for convergence in trading rules over time.

     

On Empirical Correlations for Normalised Shear Strengths from Fall Cone and Direct Simple Shear Tests in Soft Swedish Clays

Empirical correlations provide valuable information in early design stages, and they help to validate or discard single values from site investigations. This paper presents a multivariate database from commercial projects consisting of evaluated shear strengths obtained from direct simple shear tests and fall cone tests (which are calibrated to the field vane test), including index tests. The multivariate database is used to investigate the performance of common transformation models and to test the recommended correction for fall cone tests. It is found that the measured normalised shear strength evaluated from direct simple shear tests and fall cone tests is correlated to the liquid limit and that the results conform to Swedish and Norwegian recommendations. However, the scatter is large, more for fall cone tests than for direct simple shear tests, which is thought to depend mainly on sample disturbance. It can however be concluded that the trend of normalised shear strengths increases with increasing plasticity.

     

Application of the self-calibrated palmer drought severity index and standardized precipitation index for estimation of drought impact on maize grain yield in Pannonian part of Croatia

Recent global warming and more frequent droughts are causing significant damage to maize production. A reliable estimate of drought intensity and duration is essential for testing maize hybrids to drought tolerance. For this purpose, the self-calibrating 10-day palmer drought severity index (scPDSI) and standardized precipitation index (SPI) for 1, 2, 3, 6, 9, 18, 27, and 36 10-day scales were used to estimate the effects of drought on grain yield of 32 maize hybrids evaluated in 2017 and 2018 at eight experimental locations in the Pannonian part of Croatia. Time series of observed 10-day mean air temperature, relative humidity, and precipitation totals for a set of “reference” weather stations of the croatian meteorological and hydrological service (DHMZ) for the period 1981–2018 were used to calculate the scPDSI and SPI indices. According to the 10-day scPDSI and SPI for different time scales, 2018 proved to be a “normal year,” while 2017 experienced a “mild to moderate drought,” which resulted in a 13% reduction in maize grain yield at eight experimental locations compared to 2018. The correlation between grain yield and drought indices for summer months was the highest for the 10-day scPDSI. To some extent, correlations between summer months’ SPI for the 3 10-day time scale and maize grain yield were comparable to the corresponding correlations for the 10-day scPDSI. However, for other SPI time scales considered, the corresponding correlations were weaker and less informative. The dependence of grain yield on scPDSI values was not the same for all hybrids, indicating their different tolerance to drought. The reduction in grain yield due to drought was primarily caused by insufficient grain filling (lower 1000-grain weight) and, to some extent, by a reduction in the number of grains. In this study, application of 10-day scPDSI data proved to be more relevant in detecting effects of drought on agronomic traits than application of SPI data for the most time scales.

     

The peat bog at Zinnwald-Georgenfeld revisited after 25 years: Geochemical investigation of water,Sphagnum moss and peat cores

From 1992 to 1994, trace metal concentrations of bog water, Sphagnum mosses and peat cores of the bog “Georgenfelder Hochmoor” at Zinnwald-Georgenfeld in the Eastern Ore Mountains (Germany) were investigated. A sampling campaign in September 2019 allows the comparison of the older measurements with today's trace metal concentrations. No changes were found in the bog waters, while the trace metal concentrations of the Sphagnum mosses have decreased significantly. Due to the low growth rate of the peat and despite certain heterogeneity between the peat cores, the investigated elemental data for the peat sampled in the 1990s and in 2019 are in the same concentration range. The maximum concentrations are measured in the upper samples of all peat cores for the analysed elements (except sulphur). Compared to upper crustal data, a different behaviour of the elements is observed: Cr, Sc, Ti, and V, rare earth elements show crustal ratios, while Al and Si are also influenced by crust-air fractionation. Cd, Cu, Ni, Pb, and Zn are additionally enriched by anthropogenic atmospheric inputs from industry and transport. These results confirm the assumption that peat cores record past atmospheric deposition.     

Magmatic source and metamorphic grade of metavolcanic rocks from the Granjeno Schist: was northeastern Mexico a part of Pangaea?

The geochemistry of the metavolcanic rocks from the Granjeno Schist in northeastern Mexico indicates an origin in different tectonic environments: mid‐ocean ridge and ocean island. High ratios of Hf/Th and Th/Nb (4.4–14 and 0.08–0.15), low ratios of LaN/YbN and LaN/SmN (0.74–1.7 and 0.60–1.4) and depleted LREE patterns in metabasalt display mid‐ocean ridge characteristics. In contrast, the pattern of trace‐element ratios and REEs in metabasalt and metapillow lava 60 km to the west indicates a magma source with ocean‐island basalt characteristics. Both areas were metamorphosed during the Late Carboniferous (300 ± 4 Ma). Estimated metamorphic conditions deduced from white mica and chlorite compositions, distinguish greenschist facies (350 °C and 4 kbar) for the mid‐ocean ridge basalt, and prehnite–pumpellyite facies (250 °C and 2.5 kbar) for the ocean‐island‐type basalt. This metamorphism took place at an active continental margin during Pennsylvanian time. Our new tectonic model, which differs from earlier models, suggests that the origin of the Granjeno Schist is related to a subduction zone located at the western margin of Pangaea, active after Laurentia–Gondwana collision. Copyright © 2015 John Wiley & Sons, Ltd.