Purpose Serpentine soils derived from ultramafic rocks release elevated concentrations of toxic heavy metals into the environment. Hence, crop plants cultivated in or adjacent to serpentine soil may experience reduced growth due to phytotoxicity as well as accumulate toxic heavy metals in edible tissues. We investigated the potential of biochar (BC), a waste byproduct of bioenergy industry in Sri Lanka, as a soil amendment to immobilize Ni, Cr, and Mn in serpentine soil and minimize their phytotoxicity. Materials and methods The BC used in this study was a waste byproduct obtained from a Dendro bioenergy industry in Sri Lanka. This BC was produced by pyrolyzing Gliricidia sepium biomass at 900°C in a closed reactor. A pot experiment was conducted using tomato plants (Lycopersicon esculentum L.) by adding 1, 2.5, and 5 % (w/w) BC applications to evaluate the bioavailability and uptake of metals in serpentine soil. Sequential extractions were utilized to evaluate the effects of BC on bioavailable concentrations of Ni, Cr, and Mn as well as different metal fractionations in BCamended and BC-unamended soil. Postharvest soil in each pot was subjected to a microbial analysis to evaluate the total bacterial and fungal count in BC-amended and BCunamended serpentine soil. Results and discussion Tomato plants grown in 5 % BCamended soil showed approximately 40-fold higher biomass than that of BC-unamended soil, whereas highly favorable microbial growth was observed in the 2.5 % BC-amended soil. Bioaccumulation of Cr, Ni, and Mn decreased by 93-97 % in tomato plants grown in 5 % BC-amended soil compared to the BC-unamended soil. Sequentially extracted metals in the exchangeable fraction revealed that the bioavailabile concentrations of Cr, Ni, and Mn decreased by 99, 61, and 42 %, respectively, in the 5 % BC-amended soil. Conclusions Results suggested that the addition of BC to serpentine soil as a soil amendment immobilizes Cr, Ni, and Mn in serpentine soil and reduces metal-induced toxicities in tomato plants.

Reports on malformations in amphibians due to trematode infections prompted this study on an endemic frog species in Sri Lanka. The effect of an infection with a monostome-type cercaria is reported here. Ten days post-hatch, tadpoles (Gosner stage 27) of the common hourglass treefrog Polypedates cruciger (Anura: Ranidae), were exposed to a monostome-type cercaria, in a dose-dependent manner, under laboratory conditions. Malformations, survival and growth of the tadpoles were monitored for four treatments having different doses of cercariae (control = 0, low= 16, intermediate = 32 and high = 48). The severity and the number of malformations varied depending on the dose of the infection. A higher percentage (90%) of malformations was observed at higher doses of cercariae. Overall, malformations in the limbs, spine and skin pigmentation were common after parasite exposure. Survival declined with increasing doses of parasite infections, declining to 88% in the high treatment group, although not statistically significant. The growth rates of tadpoles as measured by weight and snout to vent length showed that exposed individuals were significantly smaller and had higher variance in growth compared with that of the controls. Thus, this trematode infection significantly affected the growth and induced severe malformations in P. cruciger, under laboratory conditions. Such malformed tadpoles and adults may face high predation under natural conditions. Here, we present the first empirical evidence of the effect of a trematode infection on the development of malformations, growth and survivorship in an endemic amphibian species in Sri Lanka.

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IntroductionRecords on gallstones and associated ailments in Sri Lankan community are scarce, despite frequent detection of gallstone disease. Identification of the chemical composition of gallstones in the local setting is important in defining aetiopathogenic factors which in turn are useful in implementing therapeutic and preventive strategies. This study aimed to describe the chemical composition of gallstones and the socio-demographic factors of a cohort of Sri Lankan patients with gallstone disease.Materials and MethodsData on clinical and socio-demographic factors, and gallstones removed at surgery were collected from patients with cholelithiasis admitted to Teaching Hospital, Peradeniya, Sri Lanka from May 2011 to December 2012. External and cross sectional morphological features of gallstones were recorded by naked eye observation. Compositional analysis was carried out by Fourier Transform Infrared Spectroscopy, X - ray Powder Diffraction, and Atomic Absorption Spectrophotometry. Scanning Electron Microscopy was used to identify the microstructure of gallstones.ResultsData of 102 patients were analyzed. Of them majority (n = 77, 76%) were females with a female: male ratio of 3:1. Mean age of the study group was 46.1±11.6 years. All the patients had primary gallbladder stones. According to the physical and chemical analysis, majority (n = 54, 53%) were pigment gallstones followed by mixed cholesterol gallstones (n = 38, 37%). Only 10 (9%) had pure cholesterol gallstones. Calcium bilirubinate, calcium carbonate and calcium phosphate were the commonest calcium salts identified in pigment gallstones and core of mixed cholesterol gallstones.ConclusionPresence of a pigment nidus in gallstones is a common feature in majority of Sri Lankan patients denoting the possible role of elevated unconjugated bilirubin in bile on the pathogenesis of GS. Hence it is imperative to explore this further to understand the aetiopathogenesis of GS among Sri Lankans.

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