Abundance and Breeding of the Common Skittering Frog(Euphlyctis cyanophlyctis)and Bull Frog(Hoplobatrachus tigerinus)at Rawal Lake,Islamabad,Pakistan

The population density and breeding of two frog species, i. e., the Skittering Frog （Euphlyctis eyanophlyctis） and the Bull Frog （Hoplobatrachus tigerinus） were studied at Rawal Lake, Islamabad, Pakistan, by using visual encounter method from September 2009 to August 2010. Mean population density for the two frogs was 1.55 ± 0.44 frogs per ha, with that for the Skittering Frog being 1.09 ± 0.33 frogs/ha and that of the Bull Frog 0.46 ± 0.11 frog/ha, respectively. It is concluded that both frog species are explosive breeders, i. e., their breeding activities were confined to the first showers of the monsoon season. The mean spawn weight of the Skittering Frog was 1.5 g with more than 1000 eggs in each spawn, while that of the Bull Frog was 0.26 g with less than 1000 eggs in a spawn. The spawning sites of the two species were investigated in detail. Generally, no threat to their populations was observed. However, the opening of the spillway of Rawal Dam following the torrential rain destroyed the breeding sites of the frogs. It is maintained that the event did not produce any significant impact on their populations and breeding as the two species were quite common.

Compositional characteristics and toxicological responses of human lung epithelial cells to inhalable particles (PM_(10)) from ten typical biomass fuel combustions

As the primary component of haze,atmospheric inhalable particulate matters(PMio)are highly detri-mental to human health.Biomass combustion is one of China's most pivotal sources to aerosols pollution,inducing non-negligible emissions and uncertain risks.PMio samples directly from 10 representative biomass fuel combustion sources(2 groups covering the reality widely:straws of rice,wheat,corn,corncob,soybean,peanut,rape,sesame;and branches of pine,peach)were collected using the dilution channel sampler and analyzed for chemical compositions and in vitro cytotoxicity to human lung epithelial cell lines A549.The components of PMio are dominated by organic carbon(OC),followed by Water-soluble K+and Cl,and rich in metals Fe,Zn,Cr,and Ni.Generally,PMio emitted from biomass fuel combustions can weaken the antioxidant capacity of cells,and straws emissions,especially rape and peanut straws,show stronger ability to further induce oxidative stress and inflammatory damage than fuelwoods,owing to the key toxic roles of Cr,Ni,and Co.Therefore,reducing the specific source emis--sions of PMio from crop straw combustions rich in heavy metals could be an effective oriented strategy to improve environmental air quality and control aerosols pollution precisely for protecting public health.

Transformation mechanism and fate of dissolved organic nitrogen(DON) in a full-scale drinking water treatment

Dissolved organic nitrogen(DON) has attracted much attention in drinking water treatment due to its potential to produce nitrogenous disinfection by-products(N-DBPs). This work was designed to explore the transformation and fate of DON and dissolved inorganic nitrogen(DIN) in drinking water treatment. The changes of DON and formation of N-DBPs were evaluated along the water treatment route(i.e., pre-ozonation and biologicalcontact oxidation, delivery pipes’ transportation, coagulation-sedimentation, sand filtration, post-ozonation, biological activated carbon, ultrafiltration and disinfection) of drinking water treatment plant(DWTP). The transformation mechanism of DON was comprehensively investigated by molecular weight fractionation, three-dimensional fluorescence, LCOCD(Liquid Chromatography-Organic Carbon Detection), total free amino acids. A detailed comparison was made between concentrations and variations of DON and DIN affected by seasons in the drinking water treatment. Regardless of seasonal variation in raw water concentration, the DON removal trends between different treatment processes remain constant in the present study. Compared to other treatment processes, pre-ozonation and coagulation-sedimentation exhibited the dominant DON removal in different seasons, i.e.,11.13%-14.45% and 14.98%-22.49%, respectively. Contrary, biological-contact oxidation and biological activated carbon negatively impacted the DON removal, in which DON increased by 1.76%-6.49% in biological activated carbon. This may be due to the release of soluble microbial products(SMPs) from bacterial metabolism, which was further validated by the rise of biopolymers in LC-OCD.

Hot corrosion of surface-modified Sm_(2)Co_(17) high-temperature magnet with Ni and Ni/Cr bilayer coatings in 75 wt% Na_(2)SO_(4)–NaCl mixture

Hot corrosion behavior of Sm_(2)(Co, Fe, Cu,Zr)17-type high-temperature magnetic alloy without and with a protective coating of Ni and Ni/Cr bilayer at 500 ℃ in a corrosive mixture of 75 wt% Na_(2)SO_(4)–NaCl for 100 h was reported in this paper. The obtained results of timedependent weight change established the parabolic growth of oxidized surface of bare magnets(8.87 mg·cm^(-2)),which caused a rapid loss of magnetic properties measured both at room and high temperatures(500 ℃). X-ray diffraction(XRD) analysis revealed the growth of oxides for bare magnet and Cr–oxides(Cr_(2) O_(3)), top layer of Ni/Cr bilayer coating, but in the case of single coating, Ni–sulfides formation indicated penetration of sulfur, which is further verified by electron probe microanalysis with energy dispersive spectroscopy(EPMA/EDS) study.Results showed that bilayer-coated samples(Ni/Cr) performed better than Ni-coated and bare samples.