Crop residues as soil amendments and feedstock for bioethanol production

Traditional solid fuels account for more than 90% of the energy supply for 3 billion people in developing countries. However, liquid biofuels (e.g., ethanol) are perceived as an important alternative to fossil fuel. Global crop residue production is estimated at about 4 billion Mg for all crops and 3 billion Mg per annum for lignocellulosic residues of cereals. One Mg of corn stover can produce 280L of ethanol, compared with 400L from 1Mg of corn grains; 1Mg of biomass is also equivalent to 18.5GJ of energy. Thus, 3 billion Mg of residues are equivalent to 840 billion L of ethanol or 56x10(9)GJ of energy. However, removal of crop residues exacerbates soil degradation, increases net emission of CO2, and aggravates food insecurity. Increasing the SOC pool by 1 Mg C ha(-1)yr(-1) through residue retention on soil can increase world food grain production by 24-40 million Mg yr(-1), and root/tuber production by 6-11 million Mg yr(-1). Thus, identifying alternate sources of biofuel feedstock (e.g., biofuel plantations, animal waste, municipal sold waste) is a high priority. Establishing biofuel plantations on agriculturally marginal or degraded lands can off-set 3.5-4 Pg Cyr(-1).     

Mechanism of enzymatic dehairing of skins using a bacterial alkaline protease

In the conventional dehairing process of leather manufacture, animal skins are subjected to a drastic chemical treatment using lime and sodium sulfide. Sulfide reduces disulfide bonds in keratin present in hair and epidermis and thereby detaches them from skin. Lime, being an alkali, contributes to opening up of collagen fiber structure by cleaving a major portion of the glycosaminoglycans from proteoglycans, the interfibrillar elements of skin connective tissue. Currently, as an alternative to chemical dehairing, enzyme based dehairing processes using proteases avoiding the use of lime and sulfide are being developed because of their environmental benefits. Though both chemical as well as enzymatic dehairing processes are aimed at removing noncollagenous proteins and proteoglycans in addition to fiber opening, the mechanism of enzymatic process is distinct from that of the chemical process. In this study, we attempt to study in detail the mechanism of hair saving enzymatic dehairing process for skins using a bacterial protease against the customary hair burn chemical dehairing process. Quantitative analysis shows that the collagen content remains unaffected in both treatments but there is a marked reduction of proteoglycan constituents from dehaired pelts in the enzymatic process when compared to lime-sulfide process. This is further substantiated by histochemical examination of the sections of dehaired pelts using different stains as well as immunohistochemical studies on the removal of decorin. HPLC profile shows that decorin is extensively degraded by the bacterial protease. This study conclusively demonstrates that proteolytic degradation of decorin and subsequent removal of proteoglycan aggregates play an important role in the opening up of the collagen fiber bundles during enzymatic dehairing.     

The effect of malathion and gamma-BHC on the lipid metabolism in relation to reproduction in the tropical teleost, Clarias batrachus

In the present study, female Clarias batrachus were exposed to two sublethal concentrations of gamma-BHC (2 and 8 microg litre(-1)) and malathion (1 and 4 microl litre(-1)) for 4 weeks during different phases of their reproductive cycle. Impact of these pesticides on free fatty acids, monoglycerides, diglycerides, triglycerides, phospholipids, free and esterified cholesterol in the liver, plasma, ovary and muscle was assessed. During the pre-vitellogenic and regressed phases, they suppressed the levels of fatty acids and glycerides in the liver, but had no effect on their levels in the plasma, ovary and muscle. However, in the vitellogenic phase, fatty acids in the liver and plasma were increased, but were decreased in the ovary and muscle. Glycerides were also decreased in the studied tissues. In the post-vitellogenic phase, these pesticides increased the levels of fatty acids and glycerides in the liver and ovary, but decreased their levels in the plasma. Both pesticides decreased hepatic phospholipids in the pre-vitellogenic phase, while in the vitellogenic phase only gamma-BHC reduced its levels in the liver. These pesticides also restricted their mobilisation to the ovary. Cholesterol biosynthesis seemed unaffected, but the hydrolysis of esterified cholesterol to free cholesterol was adversely affected during the period of estrogen biosynthesis.     

Bioconcentration and metabolism of DDT, fenitrothion and chlorpyrifos by the blue-green algae Anabaena sp. and Aulosira fertilissima

Anabaena and Aulosira fertilissima showed a marked ability to accumulate DDT, fenitrothion and chlorpyrifos. Although the maximum accumulation of DDT was almost the same in both organisms, there were significant differences in their abilities to accumulate fenitrothion and chlorpyrifos. Patterns of uptake of DDT under different treatments were also similar in both Anabaena and Aulosira, but there were significant differences in the patterns of accumulation of fenitrothion between these two organisms. In Aulosira the maximum accumulation of fenitrothion was observed on the second day, whereas, in Anabaena, maximum accumulation was noticed on the first day. A completely different pattern of accumulation of chlorpyrifos was observed in Aulosira, which continued to accumulate chlorpyrifos throughout the experimental period. Bioconcentration of DDT in Anabaena and Aulosira ranged from 3 to 1568 ppm (microg g(-1)) and 6 to 1429 ppm, respectively. Bioconcentration of fenitrothion and chlorpyrifos in Anabaena varied from 53 to 3467 ppm and 7 to 6779 ppm, respectively. In Aulosira the bioconcentration varied from 100 to 6651 ppm and 53 to 3971 ppm for fenitrothion and chlorpyrifos, respectively. Anabaena and Aulosira metabolised DDT to DDD and DDE. Amounts of these DDT metabolites detected in the organisms were dependent on the concentration of treatment. DDD was the major, and DDE the minor, metabolite. These organisms were not able to metabolise the organophosphorus insecticides, fenitrothion and chlorpyrifos.     

Heavy metal concentration and distribution in a dated sediment core of Nainital Lake in the Himalayan region

The concentrations and distribution of the elements, including heavy metals such as As, Ba, Br, Co, Cr, Cs, Fe, Ga, K, Mn, Na, Rb, Sc, Sr, Th and Zn, were investigated in dated sediment cores of Nainital Lake located in the Himalayan region, in Uttar Pradesh state of India, which is considered as a remote background area. The concentrations of the elements were measured by instrumental neutron activation analysis using the k0 method. The International Atomic Energy Agency certified reference material SL-3 was used to evaluate the accuracy of the method. The normalized data for a series of elements were used to understand the source of loading. Elements like Br, Co, Cr, Fe, K, Mn and Zn show a negative correlation with increasing depth whereas elements like As, Ba, Cs, Na and Rb show a positive correlation with increasing depth. By considering the concentration for the bottom segments of the core as close to the baseline concentration, recent flux values for different elements were calculated. An increase in the flux value was observed for Br, Cr, Fe, K, Mn and Zn, which can be attributed to anthropogenic contribution in recent years.     

Nitrate leaching from a free-draining volcanic soil irrigated with municipal sewage effluent in New Zealand

Land application of municipal sewage effluent is becoming increasingly popular worldwide as a means of disposal, treatment, nutrient recycling, irrigation to meet plants' water requirements, and groundwater recharge. Nitrate leaching from a volcanic soil (Typic Udivitrand) was investigated under a Pinus radiata plantation near Rotorua, New Zealand, which had received, on average, 0, 29, and 88 mm per week of tertiary-treated municipal sewage effluent for the previous 4 years. Four replicates of undisturbed soil monolith lysimeters (200 mm diameter×200 mm depth) from surface soil from each treatment were used to study the influence of the three different rates of effluent application on N leaching. A rapid emergence of nitrate–N occurred in the drainage samples, and indicated that approximately up to half of soil nitrate was readily leached beyond the topsoil. Nitrate–N concentrations in the drainage water increased substantially with effluent application rate, almost reaching the World Health Organisation recommended limits (approximately 10 g m⁻³) in plots receiving effluent at the highest rate. Given that nitrate leaching from the soils may threaten the viability of the land treatment system, due to large N loads being observed in streams which drain irrigated catchments during winter periods, possible strategies for minimising nitrate leaching losses under effluent irrigation may need to be considered.     

Role of traditional conservation practice: highlighting the importance of Shivbari sacred grove in biodiversity conservation

Recognizing the importance of sacred groves in biodiversity conservation and management, and the recent threats to them, the present study was conducted in Shivbari sacred grove of Himachal Pradesh. The study aimed at documenting the floral wealth of Shivbari and promoting plantation of indigenous species in participation with local people. For this, systematic field surveys in different seasons were conducted in Shivbari from April 2005 to November 2009, and liaison was maintained with the local community and temple management authority for gaining insight into the history and problems of Shivbari and initiating plantation activities. A total of 69 flowering plant species were identified inside the grove, which include 14 trees, 9 shrubs, 3 lianas and 43 herbs. This represents almost 2% of the total flowering plant species occurring in the state of Himachal Pradesh. Mallotus philippensis followed by Putranjiva roxburghii was the most dominant tree species. Adhatoda zeylanica was the most common shrub species, while Achyranthes aspera was the most common herb species. The grove harbours 23 plants species that are in high demand in the market, and at the same time also influences the microclimate of the area. The temperature inside the grove was significantly lower than the temperature outside the grove. The recent changes in socio-economic status of the local people and a shift towards market-oriented economy have threatened the survival of Shivbari. However, the deeply held beliefs of the pilgrims, local people and priest offer a ray of hope. During the course of the study, 3,000 plants were planted inside the grove out of which 60% have survived.     

ESTIMATING THE LOCAL COST OF PROTECTING KOSHI TAPPU WILDLIFE RESERVE, NEPAL: A CONTINGENT VALUATION APPROACH

We estimate the compensation required by the local communities to forego access to the natural resources within the Koshi Tappu Wildlife Reserve (KTWR), Nepal using the contingent valuation method (CVM). In addition to contributing a CVM application from a seldom studied location to the literature, this case illustrates the sensitivity of WTA estimates to the analytical technique adopted. We analyze households’ willingness to accept (WTA) compensation using Tobit and double-hurdle regression models that account for the censored distribution of WTA and nested yes/no decision implicit in the WTA responses. The average WTA of a household residing in the vicinity of KTWR is estimated to be US $238, which amounts to nearly $ 1.64 million for the neighboring region. The results provide a basis to address local people’s concerns in the process of sustainable management of natural resources and wetland ecosystems in KTWR, Nepal.