The Tropical Peatland Plantation-Carbon Assessment Tool: estimating CO2 emissions from tropical peat soils under plantations

Land use change on Indonesian peatlands contributes to global anthropogenic greenhouse gas (GHG) emissions. Accessible predictive tools are required to estimate likely soil carbon (C) losses and carbon dioxide (CO₂) emissions from peat soils under this land use change. Research and modelling efforts in tropical peatlands are limited, restricting the availability of data for complex soil model parameterisation and evaluation. The Tropical Peatland Plantation-Carbon Assessment Tool (TROPP-CAT) was developed to provide a user friendly tool to evaluate and predict soil C losses and CO₂ emissions from tropical peat soils. The tool requires simple input values to determine the rate of subsidence, of which the oxidising proportion results in CO₂ emissions. This paper describes the model structure and equations, and presents a number of evaluation and application runs. TROPP-CAT has been applied for both site specific and national level simulations, on existing oil palm and Acacia plantations, as well as on peat swamp forest sites to predict likely emissions from future land use change. Through an uncertainty and sensitivity analysis, literature reviews and comparison with other methods of estimating soil C losses, the paper identifies opportunities for future model development, bridging between different approaches to predicting CO₂ emissions from tropical peatlands under land use change. TROPP-CAT can be accessed online from www.redd-alert.eu in both English and Bahasa Indonesia.     

Photocatalytic reduction of organic pollutant under visible light by green route synthesized gold nanoparticles

We report a rapid method of green chemistry approach for synthesis of gold nanoparticles(AuNPs)using Lagerstroemia speciosa leaf extract(LSE). L. speciosa plant extract is known for its effective treatment of diabetes and kidney related problems. The green synthesis of Au NPs was complete within 30 min at 25°C. The same could also be achieved within 2 min at a higher reaction temperature(80°C). Both UV–visible spectroscopy and transmission electron microscopy results suggest that the morphology and size distribution of Au NPs are dependent on the pH of gold solution,gold concentration,volume of LSE,and reaction time and temperature. Comparison between Fourier transform infrared spectroscopy(FT-IR)spectra of LSE and the synthesized Au NPs indicate an active role of polyphenolic functional groups(from gallotannins,lagerstroemin,and corosolic acid)in the green synthesis and capping of Au NPs. The green route synthesized Au NPs show strong photocatalytic activity in the reduction of dyes viz.,methylene blue,methyl orange,bromophenol blue and bromocresol green,and 4-nitrophenol under visible light in the presence of Na BH_4. The non-toxic and cost effective LSE mediated Au NPs synthesis proposed in this study is extremely rapid compared to the other reported methods that require hours to days for complete synthesis of Au NPs using various plant extracts. Strong and stable photocatalytic behavior makes Au NPs attractive in environmental applications,particularly in the reduction of organic pollutants in wastewater.     

Spatial patterns reveal negative density dependence and habitat associations in tropical trees

Understanding how plant species coexist in tropical rainforests is one of the biggest challenges in community ecology. One prominent hypothesis suggests that rare species are at an advantage because trees have lower survival in areas of high conspecific density due to increased attack by natural enemies, a process known as negative density dependence (NDD). A consensus is emerging that NDD is important for plant-species coexistence in tropical forests. Most evidence comes from short-term studies, but testing the prediction that NDD decreases the spatial aggregation of tree populations provides a long-term perspective. While spatial distributions have provided only weak evidence for NDD so far, the opposing effects of environmental heterogeneity might have confounded previous analyses. Here we use a novel statistical technique to control for environmental heterogeneity while testing whether spatial aggregation decreases with tree size in four tropical forests. We provide evidence for NDD in 22% of the 139 tree species analyzed and show that environmental heterogeneity can obscure the spatial signal of NDD. Environmental heterogeneity contributed to aggregation in 84% of species. We conclude that both biotic interactions and environmental heterogeneity play crucial roles in shaping tree dynamics in tropical forests.     

Impact of paper mill effluent on growth and development of certain agricultural crops

The physico-chemical characteristics of paper mill industry effluent were measured and some were found to be above the permissible limits prescribed by Indian irrigation water standard. A study was conducted in pots to investigate the effects of different concentrations (10, 20, 30, 40, 50, 60, 70, 80 and 100%) of paper mill effluent on growth and production of rice, mustard and peafor three years. The study reveals that the paper mill effluent has deleterious effect on the growth of crop at higher concentrations. However, at lower concentration (viz. 10 to 40% in rice, 10 to 50% in mustard and 10 to 60% in pea) of effluent, beneficial impact on general welfare of the crops was noticed. Growth and development was increased with increasing the concentration of the effluent up to 30% in rice, 40% in mustard and 50% in pea. Investigation showed that the growth and production of rice, mustard and pea was found maximum at a concentration of 30, 40 and 50% effluent respectively.     

Seasonal variations in abundance of nitrifying bacteria in fish pond ecosystem

Seasonal changes in abundance of nitrifiers (ammonia-oxidizing and nitrite-oxidizing bacteria) in surface and bottom water of freshwater ponds were examined with respect to temperature, DO, pH as well as concentration of ammonia and nitrite. The most probable number (MPN) of ammonia-oxidizers in different ponds varied from 1297 +/- 3.6 to 1673.23 +/- 0.36 ml(-1) in bottom and 720.5 +/- 8.1 to 955.3 +/- 10.8 ml(-1) in surface water during the rainy season while the MPN ranged from 1074 +/- 1.07 to 1372.17 +/- 4.6 ml(-1) in bottom and 515 +/- 10.1 to 678 +/- 11.8 ml(-1) in surface water in winter. However, the MPN were greatly reduced in summer and ranged from 435.05 +/- 15.7 to 547.54 +/- 2.12 ml(-1) in bottom and 218.7 +/- 7.3 to 368.4 +/- 9.32 ml(-1) in surface water. Similar seasonal trends were also observed in MPN of nitrite-oxidizers. Among all the physico-chemical parameters, abundance of nitrifiers was more positively correlated with ammonia and nitrite concentration in all the seasons. The abundance of nitrifiers in surface and bottom water was highest in rainy season followed by winter and modest in summer. The potential nitrification activities and oxidation rates were shown to be linear and activity of ammonia-oxidizing and nitrite-oxidizing bacteria was highest during rainy season.     

Does iodine gas released from seaweed contribute to dietary iodine intake?

Thyroid hormone levels sufficient for brain development and normal metabolism require a minimal supply of iodine, mainly dietary. Living near the sea may confer advantages for iodine intake. Iodine (I₂) gas released from seaweeds may, through respiration, supply a significant fraction of daily iodine requirements. Gaseous iodine released over seaweed beds was measured by a new gas chromatography–mass spectrometry (GC–MS)-based method and iodine intake assessed by measuring urinary iodine (UI) excretion. Urine samples were obtained from female schoolchildren living in coastal seaweed rich and low seaweed abundance and inland areas of Ireland. Median I₂ ranged 154–905 pg/L (daytime downwind), with higher values (~1,287 pg/L) on still nights, 1,145–3,132 pg/L (over seaweed). A rough estimate of daily gaseous iodine intake in coastal areas, based upon an arbitrary respiration of 10,000L, ranged from 1 to 20 μg/day. Despite this relatively low potential I₂ intake, UI in populations living near a seaweed hotspot were much higher than in lower abundance seaweed coastal or inland areas (158, 71 and 58 μg/L, respectively). Higher values >150 μg/L were observed in 45.6% of (seaweed rich), 3.6% (lower seaweed), 2.3% (inland)) supporting the hypothesis that iodine intake in coastal regions may be dependent on seaweed abundance rather than proximity to the sea. The findings do not exclude the possibility of a significant role for iodine inhalation in influencing iodine status. Despite lacking iodized salt, coastal communities in seaweed-rich areas can maintain an adequate iodine supply. This observation brings new meaning to the expression “Sea air is good for you!”     

Assessment of acute toxicity of ��-cyhalothrin to a freshwater catfish, Clarias batrachus

Acute static bioassays were conducted for 96 h period with λ-cyhalothrin to determine its acute toxicity to a freshwater catfish, Clarias batrachus. The 96 h LC₅₀ value was estimated to be 5.00 μg l⁻¹ (95% confidence limit: 4.114–5.712). The alterations in behavioral pattern, such as change in the color of skin, hyperactivity, loss of balance, rapid swimming, increased surfacing activity, enhanced rate of opercular activity, as well as prominent rates of convulsions in treated fish were observed with the increasing concentrations of insecticide as compared to the control fish. The results indicate that λ-cyhalothrin is highly effective even at very low concentrations.