Variation in the rate of land subsidence induced by groundwater extraction and its effect on the response pattern of soil microbial communities

Excessive extraction of groundwater leads to (irreversible) changes in the physical soil properties, causing land subsidence associated with soil compaction to occur. Using a combined image processing and field approach, we examined: (1) how variation in the land subsidence rate induces different soil compaction degrees; and (2) the response patterns of microbial communities to such variations. By using Sentinel Synthetic Aperture Radar image processing, we selected three locations that exhibited different land subsidence rates, including high (HSR), moderate (MSR), and low (LSR). Then, soil sampling was undertaken within these representative locations. Indicators of soil compaction, including total porosity, air-filled porosity, water-filled porosity, and bulk density, were measured. The soil microbial community was determined using qPCR and sequencing. The highest and lowest values for bulk density were observed in the HSR–MSR and LSR zones, respectively. The greatest values of total porosity and macropore volume were displayed in the LSR zone compared to other zones. Bacterial abundance in the LSR zone was significantly greater than that in the HSR and MSR zones. The relative abundances of bacterial taxa indirectly demonstrated that the anaerobic phyla were significantly increased (by 10–13%), and the aerobic phyla decreased (by 30–40%) in the HSR zone compared to the LSR zone. This result demonstrates that the aerobes declined as larger volumes of the soil became more anaerobic. Indeed, the increased abundance of anaerobes was not able to compensate for the larger decrease in the abundance of aerobes. Our work showed that at the increased rates of land subsidence, the abundance distribution of the microbial community critically declined. These findings highlight the critical impacts of increasing the land subsidence rate on the emergence of high soil compaction degrees, which can significantly affect the resilience thresholds of the microbial communities in dryland soils.     

A Comparative Study of Radiation Fog and Quasi-Fog Formation Processes During the ParisFog Field Experiment 2007

Fog is an atmospheric phenomenon that has important environmental consequences related to visibility, air quality and climate change on local and regional scales. The formation of radiation fog results from a complex balance between surface radiative cooling, turbulent mixing in the surface layer, aerosol growth by deliquescence and activation of fog droplets. During the ParisFog field experiment, out of 16 events forecasted for radiation fog, activated fog materialized in seven events, while in five other events the visibility dropped to 1–2 km but haze particle size remained below the critical size of activation. To better understand the conditions that lead to or do not lead to sustained fog droplet activation, we performed a comparative study of dynamic, thermal, radiative and microphysical processes occurring between sunset and fog (or quasi-fog) onset. We selected two radiation fog events and two quasi-radiation fog events that occurred under similar large-scale conditions for this comparative study. We identified that aerosol growth by deliquescence and droplet activation actually occurred in both quasi-fog events, but only during <1 h. Based on ParisFog measurements, we found that the main factors limiting sustained activation of droplets at fog onset in the Paris metropolitan area are (1) lack of mixing in the surface layer (typically wind speed <0.5 ms^?1), (2) relative humidity exceeding 90 % throughout the residual layer, (3) low cooling rate in the surface layer (typically less than ?1 °C per hour on average) due to weak radiative cooling (0 to ?30 Wm^?2) and near zero sensible heat fluxes, and (4) a combination of the three factors listed above during the critical phase of droplet activation preventing the transfer of cooling from the surface to the liquid layer. In addition, we found some evidence of contrasted aerosol growth by deliquescence under high relative humidity conditions in the four events, possibly associated with the chemical nature of the aerosols, which could be another factor impacting droplet activation.     

The plane symmetric vacuum solutions of modified field equations in metric f(R) gravity

The f(R) theories of gravity have been interested in recent years. A considerable amount of work has been devoted to the study of modified field equations with the assumption of constant Ricci scalar which may be zero or nonzero. In this paper, the exact vacuum solutions of plane symmetric spacetime are analyzed in f(R) theory of gravity. The modified field equations are studied not only for R=constant but also for general case R≠constant. In particular, we show that the Novotný-Horský and anti-de Sitter spacetimes are the exact solutions of the field equations with the non-zero constant Ricci scalar. Finally, the family of solutions with R≠constant is obtained explicitly which includes the Novotný-Horský, Kottler-Whittaker, Taub and conformally flat spacetimes.     

Application of the FMEA in insurance of high-risk industries: a case study of Iran's gas refineries

The purpose of this paper is to categorize and analyze various risk factors in Irans gas refineries for insurance purposes. Using the failure modes and effects analysis method as a subset of probability risk assessment technique and gas refineries data for the period March 2011 till March 2012, risk priorities numbers are calculated from the perspectives of both the insured party (gas industries) and the insurer (insurance companies). Our empirical results indicate that various property damage risk factors embodied in gas refineries including fire, explosion, error and omission, and machinery breakdown are insurable risks. Risks of pressurized vessels defects are in safe category and can be tolerated by the industry owner. The policy implication of this paper for Iranian policy makers in the energy sector is that, gas refineries are insurable in the market with reasonable risk premium. Insuring gas refineries will definitely reduce capital losses which can otherwise be enormous for the economy in general and for oil and gas industries in particular.     

Empirical seismic vulnerability analysis for masonry buildings based on school buildings survey in Iran

School facilities in Iran, in particular masonry schools, have shown poor performance during past earthquakes and can be identified as one of the parts of the country’s infrastructure that is most vulnerable to earthquakes. Hence, in this paper a method to perform index-based damage assessment for brick masonry schools located in the province of Yazd, the central region of Iran, using a comprehensive database of school buildings, is proposed. The database was obtained from the field survey forms applied for each observed school to collect the features of and damage to the structure. The results of a vulnerability index method developed in Iran are employed as input data to obtain empirical fragility curves for the school inventory. The Macroseismic model and GNDT II level method are two empirical methods combined in this procedure. Finally, the procedure is verified using damage survey data obtained after recent earthquakes (1990 Manjil–Rudbar earthquake and 2003 Bam earthquake) that occurred in Iran.     

Collapse of a nonductile concrete frame: Evaluation of analytical models

The current paper presents nonlinear dynamic analyses that simulate shaking table tests performed on a four‐column reinforced concrete frame described in a companion paper. The frame consists of two ductile and two nonductile columns interconnected by a stiff beam. In order to validate existing analytical models for nonductile concrete columns, a blind comparison of the test data and results of the analysis is performed. The analysis adequately captures the drift response and correctly detects collapse of the structure; however, strength degradation due to cover spalling is exaggerated in the analytical model. Refinement of the analysis by changing the concrete cover model results in an excellent agreement between the test data and analysis results at the initiation of shear failure and collapse of the frame. The experimental data are further compared with lumped‐plasticity nonlinear models used in engineering practice. The results suggest that the sudden strength degradation used in ASCE/SEI 41‐06 results in an exaggerated estimate of the displacement demands. It is also observed that ignoring the strength degradation, using an elastic‐perfectly‐plastic model, provides a good estimate of the displacement demands when strength degradation is not severe. Copyright © 2008 John Wiley & Sons, Ltd.     

Nematode community structure in relation to metals in the southern of Caspian Sea

Spatial distribution and structure of nematode assemblages in coastal sediments of the southern part of the Caspian Sea were studied in relation to environmental factors. By considering metals, organic matter, Shannon diversity index(H), maturity index(MI) and trophic diversity(ITD), ecological quality status of sediment was also determined. Fifteen nematode species belonging to eleven genera were identified at the sampling sites. Average density of nematode inhabiting in sediment of the studied area was 139.78±98.91(ind. per 15.20 cm~2). According to redundancy analysis(RDA), there was high correlation between metals and some species. Based on biological indicators, the studied area had different environmental quality. Generally, chemical and biological indices showed different results while biological indices displayed similar results in more sites.     

Assessing and Modeling the Impacts of Wetland Land Cover Changes on Water Provision and Habitat Quality Ecosystem Services

Natural Resources Research - Understanding the spatial–temporal dynamics of wetland land cover (LC) changes and their impacts on ecosystem services (ESs) is essential for wetland conservation...     

The influence of experimental sewage pollution on lagoon phytoplankton

In a sewage pollution experiment in the lagoon system at Strunjan, Yugoslavia, an artificially polluted lagoon showed significantly lower chlorophyll a biomass and cell density, and the relationship between these two variables was altered.