Carnivorous plants of the genus Nepenthes supplement their nutrient deficiency by capturing arthropods or by mutualistic interactions, through their leaf-evolved biological traps (pitchers). Though there are numerous studies on these traps, mostly on their prey capture mechanisms, the gas composition inside them remains unknown. Here we show that, Nepenthes unopened pitchers are CO2-enriched ‘cavities’, when open they emit CO2, and the CO2 gradient around open pitchers acts as a cue attracting preys towards them. CO2 contents in near mature, unopened Nepenthes pitchers were in the range 2500–5000 ppm. Gas collected from inside open N. khasiana pitchers showed CO2 at 476.75 ± 59.83 ppm. CO2-enriched air-streaming through N. khasiana pitchers (at 619.83 ± 4.53 ppm) attracted (captured) substantially higher number of aerial preys compared to air-streamed pitchers (CO2 at 412.76 ± 4.51 ppm). High levels of CO2 dissolved in acidic Nepenthes pitcher fluids were also detected. We demonstrate respiration as the source of elevated CO2 within Nepenthes pitchers. Most unique features of Nepenthes pitchers, viz., high growth rate, enhanced carbohydrate levels, declined protein levels, low photosynthetic capacity, high respiration rate and evolved stomata, are influenced by the CO2-enriched environment within them.

Urban Heat Island (UHI), a measure of the near surface air temperature contrast between urbanised and adjoining rural areas, is the most pronounced effect of urbanisation. The definition of 'urban' varies in different contexts, which makes it difficult for direct comparison between cities in different regions. Local climate zone (LCZ) classification based method was adopted in Kochi in Southern India to study its UHI. Twelve mobile surveys were carried out from January 2011 to March 2013 to quantify UHI intensity. Pre-dawn UHI there was more intense than early night UHI, and its intensity in winter was stronger than in summer. UHI observed during winter were 4.6 o C and 3.7 o C in pre-dawn and early night respectively. The study area was classified into ten different local climate zones based on the standard zone properties. Thermal gradient between different zones and cooling rates observed in these zones were computed, which validates the LCZ classification. Maximum intensity was seen in Compact Midrise zones which cover the central part of the city. Most intense cooling was observed in openset and sparsely built regions in all seasons. Standard zone properties alone were inadequate to explain variation of UHI intensity of same classes with different surface area and diverse adjacent zones. Two more zone properties, radial distance to adjacent zone called Zone Boundary Distance, and the Nearest Adjacent Zone, are proposed here to overcome this. The use of these additional parameters gives a better understanding of the intra zone variation of UHI intensity of the same classes with different coverage area and diverse adjacent zones.

Bamboos are one of the fastest growing plants on Earth, and are widely considered to have high ability to capture and sequester atmospheric carbon, and consequently to mitigate climate change. We tested this hypothesis by measuring carbon dioxide (CO2 ) emissions from bamboo culms and comparing them with their biomass sequestration potential. We analysed diurnal effluxes from Bambusa vulgaris culm surface and gas mixtures inside hollow sections of various bamboos using gas chromatography. Corresponding variations in gas pressure inside the bamboo section and culm surface temperature were measured. SEM micrographs of rhizome and bud portions of bamboo culms were also recorded. We found very high CO2 effluxes from culm surface, nodes and buds of bamboos. Positive gas pressure and very high concentrations of CO2 were observed inside hollow sections of bamboos. The CO2 effluxes observed from bamboos were very high compared to their carbon sequestration potential. Our measurements suggest that bamboos are net emitters of CO2 during their lifespan.

Urban regions are hotspots of greenhouse gas emissions which include CO(2), CH(4), N(2)O, etc. Methane is a strong greenhouse gas which is produced from a number of sources including fossil fuel combustion, municipal waste, and sewage processing, etc. Ground level mixing ratio of methane in the tropical coastal city of Thiruvananthapuram in South India, during calm early morning period was measured. Measurements were done during both winter and summer seasons. Concentrations were significantly higher than global average value. Intra-city variation in ground level mixing ratio was also significant. Ground level methane concentration at Thiruvananthapuram urban area showed maximum value of 3.16 ppmV. Under stable atmospheric conditions in early morning, ground level mixing ratio of methane was 2.79 ppmV in winter and 2.54 ppmV during summer. The spatial distribution of methane concentration shows correlation with urban heat island.

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Industrialisation and urbanization leads to an increase in concentration of greenhouse gases, which eventually alters the radiation balance of the climate system. Urban regions are hotspots of greenhouse gas emissions which include CO 2 , CH 4 , N 2 O, etc. Methane emitting sources hosted by cities include fossil fuel combustion, municipal waste and sewage management, blocked drains and pools etc. Waste discharges from the residences, food wastes, market places etc., contribute to the methane production. Urban heat island causing warm nights in the city is also a suitable condition for the generation of methane.Ground level mixing ratio of methane in the tropical coastal city of Cochin in South India, during calm early morning periods was measured in this study. A mobile traverse method was employed from January 2011 to March 2013. Measurements were taken during both winter and summer seasons. It was observed that the ground level methane concentrations were significantly higher than the global average value. Intra-city variation in ground level mixing ratio was also significant. The maximum value of ground level methane in winter and summer were 3.85 ppm and 3.21 ppm respectively. The study reveals that the city acts as a source of atmospheric methane.

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