Comparative Re-Estimation of Environmental Degradation and Population Density in China: Evidence from the Maki’s Regime Shift Approach

Numerous studies have estimated the linkage of economic growth and environmental degradation in the framework of EKC theory with typical CO2 emissions proxy. However, the complexity of environmental degradation (ED) is better measured by ecological footprint (ECF) in any geographical territory. Against this background, the present study is an effort to contribute to the existing literature by re-investigating the EKC hypothesis with ecological footprint and CO2 emissions proxy in the largest population of the world. Moreover, the role of population density is also considered with maximum data available from 1961 to 2016 for China. To estimate the said linkage, we apply first, second, and third-generation econometric approaches i. e. Augmented Dickey-Fuller unit root test, Zaviot Andrew’s unit root test with structural breaks, and Carrion-i-Silvestre’s general least-squares based test with several structural breaks. Likewise, the co-integration relationship is examined by applying Maki’s co-integration econometric approach with multiple structural breaks. Furthermore, the autoregressive distributive lag model is applied to investigate the long-run and short-run relationships by incorporating year dummies highlighted by MBk.  The results report the U-shaped EKC for China, which means economic growth is helping to clean the environment while the population density (PD) is found to be a cause of increasing ED. Findings have robust policy implications for China

Phytochemical screening and antibacterial activity of different fractions of Operculina turpethum root and leaf

ABSTRACT In Bangladesh, the herb Operculina turpethum is used for otitis media, suppurative sores, burns, conjunctivitis and skin diseases (eczema, abscesses, acne, scabies and warts) although the compounds responsible for the medicinal properties have not been identified. The present study has been undertaken for antibacterial activity of the ethanol, ether and chloroform extract of O. turpethum root and leaf. Antibacterial activity has been investigated against Shigella boydii, Shigella flese, Shigella dysenteriae, Escherichia coli, Proteus vulgaris, Salmonella typhi, Hafnia alvei, Staphylococcus epidermidis, Streptococcus pyogenes, Staphylococcus aureus, Enterococcus faecalis by disc diffusion and broth macro-dilution assay. The zone of inhibition has been observed with almost all bacteria with some exceptions. Minimum inhibitory concentrations (MIC) of the extracts were found to be significant

Foulant Identification and Performance Evaluation of Antiscalants in Increasing the Recovery of a Reverse Osmosis System Treating Anaerobic Groundwater

The objectives of this study are to assess the performance of antiscalants in increasing the recovery (≥85%) of a reverse osmosis (RO) plant treating anaerobic groundwater (GW) in Kamerik (the Netherlands), and to identify scalants/foulant that may limit RO recovery. Five different commercially available antiscalants were compared on the basis of their manufacturer-recommended dose. Their ability to increase the recovery from 80% to a target of 85% was evaluated in pilot-scale measurements with anaerobic GW and in once-through lab-scale RO tests with synthetic (artificial) feedwater. A membrane autopsy was performed on the tail element(s) with decreased permeability. X-ray photoelectron spectroscopy (XPS) analysis indicated that calcium phosphate was the primary scalant causing permeability decline at 85% recovery and limiting RO recovery. The addition of antiscalant had no positive effect on RO operation and scaling prevention, since at 85% recovery, permeability of the last stage decreased with all five antiscalants, while no decrease in permeability was observed without the addition of antiscalant at 80% recovery. In addition, in lab-scale RO tests executed with synthetic feed water containing identical calcium and phosphate concentrations as the anaerobic GW, calcium phosphate scaling occurred both with and without antiscalant at 85% recovery, while at 80% recovery without antiscalant, calcium phosphate did not precipitate in the RO element. In brief, calcium phosphate appeared to be the main scalant limiting RO recovery, and antiscalants were unable to prevent calcium phosphate scaling or to achieve a recovery of 85% or higher.Sanitary Engineerin

Postseismic coastal development in Aceh, Indonesia: Field observations and numerical modeling

We model postseismic changes to the shoreline of West Aceh, Indonesia, a region largely affected by the December 2004 Sumatra-Andaman earthquake and ensuing Indian Ocean tsunami, using a cross-shore morphodynamic model. Subsidence of 0.5–1.0 m and tsunami scouring during the 2004 event caused the complete destruction of the beach and the landward displacement of the western coast of Aceh by an average of 110 m. Comparing a series of satellite images and topographic surveys, we reconstruct the build-up of a new beach ridge along a 6 km long stretch of coastline in the years following the event. We then use the cross-shore model UNIBEST-TC developed for a wave-dominated sandy shoreline to determine the controlling factors of shoreline recovery. Input parameters include bathymetric data measured in 2015, grain size characteristics of offshore sediment samples, modeled wave data, tidal elevations from a nearby tide-gauge station as well as measured and modeled postseismic uplift data. After establishing a cross-shore profile in equilibrium with the prevailing hydrodynamic conditions, we simulate the post-tsunami recovery, the effect of the monsoon seasons, as well as the influence of postseismic land level changes for up to 10 years and compare them to the observed coastal development. Our modeling results indicate that the recovery of the western Acehnese shoreline after the 2004 tsunami was quick with littoral sediment transport normalizing to pre-tsunami conditions within two to four years following the event. However, field data shows that the shoreline stabilized 50–90 m landward of its pre-2004 tsunami position, most likely due to the build-up of a prominent higher beach ridge in response to coseismic subsidence. Observed variability in shoreline position in the order of a few tens of meters since 2009 can be attributed to seasonal wave climate variability related to the monsoon cycle. The effect of postseismic uplift on shoreline position is small and in the order of only a few meters over 10 years, which is 3 to 5 times smaller than long-term coastal progradation rates that are driven by abundant sediment supply to the littoral zone. This overall progradational trend will promote preservation of seismically modified beach ridges, which can serve as paleoseismic indicators.Applied Geolog