Effect of biopolymer on the dewatering characteristics of autothermal thermophilic aerobic digestion of sludges.

Autothermal thermophilic aerobic digestion of sludge is known to produce poorly dewatering sludges. Laboratory studies were conducted to investigate the reasons for the poor dewatering. It was found that, during digestion, proteins and polysaccharides were released into solution, and that these could be linked to the deterioration in dewatering. The biopolymer release was accompanied by an increase in the monovalent-to-divalent (M/D) cation ratio. The degree to which the M/D caused deterioration of the sludges depended on the presence of iron in sludge. When the iron content was high, the release of protein and polysaccharides was low. When iron was low, the release of protein and polysaccharides increased linearly with the M/D ratio. The dose of conditioning chemicals, cationic polymer or ferric chloride, was related to the amount of colloidal biopolymer present in solution. The findings suggest that the addition of iron during the digestion process has the potential to produce better dewatering sludges.     

Distribution of lindane in plasma and brain after a single administration to cats

The distribution of lindane and its metabolites in the plasma and brain of the cats after 30 minutes, 1, 2, 4 and 8 hours of administration of lindane (2mg/kg, i.v.) was investigated. The compound distributes differentially in the CNS and this pattern changes with time. The pattern of distribution shows that although lindane concentration is higher in areas with a high myelin content, it disappears more rapidly from gray matter. The plasma levels were also high at 30 minutes interval and then gradually decreased. The rate of formation of the metabolite 2,4,6‐Trichlorophenol appeared to be maximum in the first 4 hours. The accumulation of the compound and its metabolite in brain during the experimental period was not evident.     

Contrasting temporal trends and relationships of total organic carbon, black carbon, and polycyclic aromatic hydrocarbons in rural low-altitude and remote high-altitude lakes

Historical records of total organic carbon (TOC), black carbon (BC), and polycyclic aromatic hydrocarbons (PAHs) were reconstructed in dated sediment cores from four nearby lakes in central Switzerland. In the sub-Alpine Lake Thun, located at 558 m a.s.l., the proximity to anthropogenic emission sources is reflected in higher input of BC and PAHs into sediments with fluxes only slightly decreasing during the last decades. PAH/BC ratios are relatively high and correlation between levels of total PAHs and BC is almost inexistent in Lake Thun, probably due to the presence of less condensed forms of the BC spectrum (char BC) that is underestimated with the chemothermal oxidation method applied in this study. The sediment profiles of TOC, BC, and PAHs are noticeably different in the mountain lakes located around 2000 m a.s.l. In Lake Engstlen, the PAH/BC ratios, as well as the correlation between PAHs and BC, point towards appreciable amounts of predominantly light soot particles. Light soot particles have higher mobility and can, therefore, be efficiently transported to this remote site. The proglacial Lake Oberaar is shown to be a receptor of BC and PAHs released by the fast melting adjacent glacier acting as a secondary source for these conservative species temporarily stored in the glacier ice. Finally, Lake Stein is in strong contrast to all other lakes. High flux of BC into Lake Stein, combined with constant temporal evolutions of BC and PAHs, and in particular BC/TOC ratios approaching 100% are all strong indications for a geogenic presence of graphite in its catchment area.     

Dissipation and leaching of (14)C-monocrotophos in Soil Columns under subtropical climate

Dissipation and leaching behavior of 14C-monocrotophos was studied for 365 days under field conditions using PVC cylinders. The first set (24 cylinders) was spiked with 1.0 microCi 14C-labeled monocrotophos along with 1.06 mg unlabeled monocrotophos to give a concentration of 2 mg kg -1 in the soil up to 15 cm depth. The second set (24 cylinders) received 14C-labeled monocrotophos along with other non-labeled insecticides viz., dimethoate @ 300 g a.i ha-1, deltamethrin @ 12.5 g a.i ha-1, endosulfan @ 750 g a.i ha-1, cypermethrin @ 60 g a.i ha-1, and triazophos @ 600 g a.i ha-1 at an interval of 15 days each as recommended for the cotton crop. 14C-monocrotophos dissipated faster, up to 45% in first 90 days in columns treated with only monocrotophos compared to 25% in columns that received monocrotophos along with other insecticides. However, both the columns showed similar residues 180 days onward. After 180 days of treatment, 46% radiolabeled residues were observed, which reduced up to 39.6% after 365 days. Leaching of 14C-monocrotophos to 15-30 cm soil layer was observed in both the experimental setups. In the 15-30 cm soil layer of both soil columns, up to 0.19 mg 14C-monocrotophos kg-1d. wt. soil was detected after 270 days.     

Effect of weed extracts on seedling growth of some varieties of wheat

Allelopathic effect ofAvena fatua L., Cyperus rotundus L., Polygonum hydropiper L., and Solanum nigrum L. were examined on seedling growth of certain commonly used varieties of wheat (Triticum aestivum L.) in the Tarai region of U.P. state. The weed extracts inhibited the length of plumule in all the varieties (100%) with Solanum and it was in 12 (92%), 10 (77%) and 06 (46%) varieties with Polygonum, Avena and Cyperus, respectively. In radicle length, it was in 92% with both Polygonum and Solanum; and 85% and 69% of the varieties with Avena and Cyperus, respectively. However, all the four weed extracts reduced the dry weight of plumule, radicle and total seedling in all the varieties (100%) of wheat except in HD--2329 with Cyperus, in which it was positive. The percent reduction (percentage of control) was more than 50% in 92%, 77%, 54% and 39% of the varieties, respectively with Solanum, Polygonum, Avena and Cyperus. Among the weed extracts, the inhibitory effect on seedling growth in different varieties followed the order: Solanum > Polygonum > Avena and > Cyperus. On the basis of the present results, UP--2003 and WH--542 followed by PBW--226, Sangam and HD--248 were more susceptible to all the four weed extracts compared to the rest of the varieties of wheat.     

Groundwater Quality Assessment of Tehsil Kheragarh, Agra (India) with Special Reference to Fluoride

Fluoride concentration and other parameters in groundwater from 261 villages in Tehsil Kheragarh of District Agra were assessed and attempts were made to observe the relationship between fluoride and other water quality parameters. Of 658 groundwater samples (collected from separate sources) analysed for fluoride, 27% were in the range of 0–1.0 mg/L, 25% in 1.0–1.5 mg/L, 32% in1.5–3.0 mg/L and 16% above 3.0 mg/L. The highest fluoride concentration recorded was 12.80 mg/L. Significant correlation of fluoride with pH, alkalinity, Na, SiO₂ and PO₄ were observed. Factor analysis was also attempted in order to identify the contributing sources.