Structural alterations in compound eye of Drosophila melanogaster in response to sodium fluoride treatment

Sodium fluoride, used as a pesticide in agriculture, is also an ingredient of toothpastes which help to fight dental problems. In this study, Drosophila melanogaster, a non-target organism, is used to explore morphological changes in the adult compound eye as a function of exposure to fluoride at 20, 40, 80, 100 and 150 mg L^?1, using scanning electron microscopy. The experimental concentrations were much lower than the ones used in the studies of the British Association of Community Dentistry. Distinct morphological alterations in the eye of the treated insects revealed ommatidial ridges and disoriented mechanosensory bristles which were most prominent in the 40 and 80 mg L^?1 treatment groups. Since humans and Drosophila share homology in many genes that are involved in developmental pathways, the present findings raise concern on the use of sodium fluoride as a pesticide.     

Livestock carrying capacity evaluation in an integrated farming system: A case study from the mid-hills of Nepal

The crop livestock integrated farming system practiced in hilly regions of developing countries largely depends on the ecosystem as a whole. More especifically, the livestock component of the farming system relies heavily on natural resources such as forest, grazing and agricultural land for the supply of feed and fodder. The importance of animals as agents of nutrient recycling, sources of rural energy in terms of draft power and fuel, as well as being major contributors to the farm economy, has resulted in an increased population of ruminants in these regions, creating a threat to the sustainability and productivity of these land resources. This paper is an attempt to evaluate the livestock carrying capacity of land resources and to formulate the optimum herd size compatible with the differently resourced farm categories within the sub-watershed region of the mid-hills in Nepal. Our analysis reveals that the livestock carrying capacity of the land resources at the watershed level is 11696 Livestock Units (LU), whereas current stocking is 12985 LU, suggesting an overstocking of 1289 LU at the watershed level. Total feed supply from different sources is 12668 mt/yr whereas current Total Digestive Nutrient (TDN) demand is 14060 mt/yr, a negative balance of 1393 mt/yr. The excess livestock at the sub-watershed level directly implies excess livestock holding, producing a poor nutritional status for the farm household. Linear programming analysis reveals that the farmers of large, medium and small category farms can optimize their livestock holding by a combination of 3 LU buffaloes and 4 LU goats, 2 LU buffaloes and 4 LU goats and 1 LU buffaloes and 4.4 LU goats, thus giving maximum return to the farm family without exerting pressure on fragile natural resources.     

Investigating the complex relationship between in situ Southern Ocean pCO_{2} and its ocean physics and biogeochemical drivers using a nonparametric regression approach

The objective in this paper is to investigate the use of a non-parametric approach to model the relationship between oceanic carbon dioxide \((pCO_2)\) and a range of ocean physics and biogeochemical in situ variables in the Southern Ocean, which influence its in situ variability. The need for this stems from the need to obtain reliable estimates of carbon dioxide concentrations in the Southern Ocean which plays an important role in the global carbon flux cycle. The main challenge involved in this objective is the spatial limitation and seasonal bias of the in situ data. Moreover, studies have also reported that the relationship between \(pCO_2\) and its drivers is complex. As such, in this paper, we use the non-parametric kernel regression approach since it is able to accurately capture the complex relationships between the response and predictor variables. In this analysis we use the in situ data obtained from the SANAE49 return leg journey between Antarctic to Cape Town. To the best of our knowledge, this is the first time this data set has been subjected to such analysis. The model variants were developed on a training data subset, and the ‘goodness’ of the models were assessed on an “unseen” test data subset. Results indicate that the nonparametric approach consistently captures the relationship more accurately in terms of mean square error, root mean square error and mean absolute error, over a standard parametric approach (multiple linear regression). These results provide a platform for using the developed nonparametric regression model based on in situ measurements to predict \(pCO_2\) for a larger spatial region in the Southern Ocean based on satellite biogeochemical measurements of predictor variables, given that satellites do not measure \(pCO_2\) .     

Nanoweapon: control of mosquito breeding using carbon-dot-silver nanohybrid as a biolarvicide

Health issues induced by mosquito illnesses highlight the need for effective control. Here, we developed an efficient carbon-dot-silver nanohybrid to control Anopheles stephensi and Culex quinquefasciatus mosquito species. The nanohybrid was synthesized using a thermal method without addition of any toxic-reducing agent. Monohybrids are found within the ranges of 2–6 nm for carbon-dot and 10–35 nm for silver nanoparticles with uniform distribution. The uniformly dispersed nanohybrid solutions show excellent larvicidal activity within the concentration range of 0.5–1.0 ppm. Morphological studies evidence the presence of strong bonds between nanohybrid and sulphur- or phosphorus-containing compounds such as proteins and DNA present in the larval body. This explains tissue damage at very low concentrations of nanohybrid. Therefore, this nanoweapon has high potential for field applications.     

Chlorine leakage from bonnet of a valve in a bullet—a case study

This paper deals with the accidental release of chlorine from bonnet of a valve in a bullet installed in a chloro-alkali industry, and the probable causes of the accident and the ensuing sequence of events. Emergency procedures are also discussed. Finally, in the conclusions reached at some useful recommendations, which has been drawn for industrial facilities handling chlorine.     

Arsenic concentrations in rice, vegetables, and fish in Bangladesh: a preliminary study

Arsenic contaminating groundwater in Bangladesh is one of the largest environmental health hazards in the world. Because of the potential risk to human health through consumption of agricultural produce grown in fields irrigated with arsenic contaminated water, we have determined the level of contamination in 100 samples of crop, vegetables and fresh water fish collected from three different regions in Bangladesh. Arsenic concentrations were determined by hydride generation atomic absorption spectrophotometry. All 11 samples of water and 18 samples of soil exceeded the expected limits of arsenic. No samples of rice grain (Oryza sativa L.) had arsenic concentrations more than the recommended limit of 1.0 mg/kg. However, rice plants, especially the roots had a significantly higher concentration of arsenic (2.4 mg/kg) compared to stem (0.73 mg/kg) and rice grains (0.14 mg/kg). Arsenic contents of vegetables varied; those exceeding the food safety limits included Kachu sak (Colocasia antiquorum) (0.09-3.99 mg/kg, n=9), potatoes (Solanum tuberisum) (0.07-1.36 mg/kg, n=5), and Kalmi sak (Ipomoea reptoms) (0.1-1.53 mg/kg, n=6). Lata fish (Ophicephalus punctatus) did not contain unacceptable levels of arsenic. These results indicate that arsenic contaminates some food items in Bangladesh. Further studies with larger samples are needed to demonstrate the extent of arsenic contamination of food in Bangladesh.     

Proximity to forests drives bird conservation value of coffee plantations: implications for certification

Widespread loss of primary habitat in the tropics has led to increased interest in production landscapes for biodiversity conservation. In the Western Ghats biodiversity hotspot in India, shade coffee plantations are located in close proximity to sites of high conservation value: protected and unprotected forests. Coffee is grown here under a tree canopy that may be dominated by native tree species or by nonnative species, particularly silver oak (Grevillea robusta). We investigated the influence of properties at the local scale and the landscape scale in determining bird communities in coffee plantations, with particular emphasis on species of conservation priority. We used systematic point counts in 11 coffee plantation sites and analyzed data in a randomized linear modeling framework that addressed spatial autocorrelation. Greater proportion of silver oak at the local scale and distance to contiguous forests at the landscape scale were implicated as factors most strongly driving declines in bird species richness and abundance, while increased basal area of native tree species, a local-scale variable, was frequently related to increased bird species richness and abundance. The influence of local-scale variables increased at greater distances from the forest. Distance to forests emerged as the strongest predictor of declines in restricted-range species, with 92% reduction in the abundance of two commonly encountered restricted-range species (Pompadour Green Pigeon and Yellow-browed Bulbul) and a 43% reduction in richness of bird species restricted to Indian hill forests within 8 km of forests. Increase in proportion of silver oak from 33% to 55% was associated with 91% reduction in the abundance of one commonly encountered restricted-range species (Crimson-fronted Barbet). One conservation strategy is providing incentives to grow coffee in a biodiversity-friendly manner. One implication of our study is that plantations located at varying distances to the forest cannot be compared fairly for biodiversity friendliness by existing certification methodology. Another is that conservation of existing forests at the landscape scale is essential for maintaining higher biodiversity in coffee plantations. Incentive schemes that promote conservation of remnant forests at the landscape scale and biodiversity-friendly practices locally and that relate to coffee communities as a whole rather than individual planters are likely to be more effective.