Monitoring of Phenol in Wastewater Bioremediation by HPLC

Bioremediation emphasizes the detoxification and destruction of toxic substances by microorganisms. Wastewater obtained from an industrial concern was solvent extracted with methyl alcohol and dichloromethane and analysed by GC/MS. Besides phenol, a large variety of organic compounds were detected. Under controlled laboratory conditions, the wastewater was innoculated with a mixed culture of microorganisms specially selected for their abilities to degrade phenol. Samples were collected at regular intervals from the stirred tank bioreactor and analysed for phenol by reverse phase HPLC with a C18 column. Results shows that from an initial phenol concentration of 987 ppm, slightly more than 50% was destroyed within 163 hours. The dry weight of the microorganisms and the plate count (CFU/ml) shows a steady increase from 0.5238 gms to 0.5355 gms and from 1.1E+9 to 1.94E+13 respectively over the same period. This suggested that the phenol was consumed by the microorganisms as the sole carbon source.     

Changes in polybrominated diphenyl ether (PBDE) levels in cooked food

Food surveys for levels of toxic chemicals frequently report the levels on an uncooked basis. It is known that cooking may in some conditions decrease the amount of dioxins and related chemicals in food. Surveys of polybrominated diphenyl ether (PBDE) levels in food to date show data from uncooked food only. In this article, it was shown that broiling, with fat dripped from the foods reported here, ground beef, ground lamb, catfish, trout, and salmon, reduces the amount of PBDEs in these foods. This suggests that calculations of food intake need to take into consideration levels in the cooked food rather than in the uncooked food.     

Assessing links between crop diversity and food self-sufficiency in three agroecological regions of Nepal

Increasing on-farm crop diversity is one agroecological approach to enhancing food self-sufficiency that helps small-scale farmers keep their food systems stable by reducing risks associated with stressors, such as a pest outbreaks or droughts. But understanding how crop diversity and food self-sufficiency are related is unknown. To explore this complex relation, this study presents household data (n = 1664) from Nepal to test the hypothesis that families with high crop diversity enjoy greater household food self-sufficiency. Data are presented for three districts that are representative of three distinct agroecological regions of the country: (1) Sarlahi, which is affluent, market-oriented, and on the plains; (2) Makwanpur District in the hills, which has well-developed integrated farm production; and (3) the mountainous District of Humla, which has the poorest quality environment and is the most remote. Results show that in the Humla District, families with greater crop diversity were more self-sufficient. In contrast, farmers in Makwanpur, who have already established a high degree of crop diversity based on vegetable production, do not benefit from additional crop diversity in terms of their ability to provide for themselves. Finally, data from Sarlahi show that families’ food self-sufficiency benefits from crop diversification. We conclude that boosting crop diversity is a viable strategy for maintaining stability in food systems, but this varies depending on the accessibility of a farm and, in particular, access to markets.     

Isotopic evidence of nitrate sources and denitrification in the Mississippi River, Illinois

Anthropogenic nitrate (NO3-) within the Mississippi-Atchafalaya River basin and discharge to the Gulf of Mexico has been linked to serious environmental problems. The sources of this NO3- have been estimated by others using mass balance methods; however, there is considerable uncertainty in these estimates. Part of the uncertainty is the degree of denitrification that the NO3- has undergone. The isotopic composition of NO3- in the Mississippi River adjacent to Illinois and tile drain (subsurface drain) discharge in agricultural areas of east-central Illinois was examined using N and O isotopes to help identify the major sources of NO3- and assess the degree of denitrification in the samples. The isotopic evidence suggests that most of the NO3- in the river is primarily derived from synthetic fertilizers and soil organic N, which is consistent with published estimates of N inputs to the Mississippi River. The 1:2 relationship between delta18O and delta15N also indicate that, depending on sample location and season, NO3- in the river and tile drains has undergone significant denitrification, ranging from about 0 to 55%. The majority of the denitrification appears to have occurred before discharge into the Mississippi River.     

Environmental Monitoring of Benzene and Alkylated Benzene from Vehicular Emissions

The volatile organic pollutants from direct vehicular exhaust were trapped with activated charcoal, desorbed with carbon disulphide and analysed by GC/MS with tert-butyl benzene as an internal standard. A comparative study was made from the exhaust of 1000 cc, 1300 cc, 1600 cc cars, pickup, lorry(diesel), 125 cc and 70 cc motorbikes. The level of pollutants emitted were in the following order, motorbike(petrol) car(petrol) pickup(petrol) lorry(diesel). The range of highest emission (125 cc motorbike) to the lowest emission (lorry(diesel)) was of the order of 102 for benzene, 6×102 for ethyl benzene, 5×102 for toluene and 3×102 for xylenes. Among cars, those fitted with catalytic convertors emitted a lower level of benzene (2 to 3 times) when compared with those without catalytic convertors. Similar studies on the air in air-conditioned buses, non air-conditioned buses and three metres from the edge of the road shows that they have the same pollutant level. The level of these pollutant as compared to those from direct car exhaust are of the order of 102 times less for benzene, xylene and toluene and 103 times less for ethylbenzene. The levels of benzene, toluene, ethylbenzene and xylenes by the road side and in the buses were found to be lower than the exposure limits of ACGIH, OSHA and EH40.     

Seasonal variation in male-female competition,cooperation and selfish hoarding in a monogamous songbird

Both cooperation and conflict between the sexes are commonplace in monogamous mating systems. However, little is known about how cooperation and competition varies seasonally in monogamous species that maintain permanent territories. We presented territorial pairs of male and female New Zealand robins (Petroica australis) with a large supply of insect prey at monthly intervals for 2 years. Behavioural observations after food presentation were then made to quantify seasonal and sexual differences in aggressive interactions over prey, prey acquisition rates, mate provisioning, offspring provisioning, selfish food hoarding and cache retrieval. Data were used to evaluate sex-specific behavioural strategies of mediating competition for food. Results showed that males aggressively excluded females from experimental food sources year-round. Females only accessed food sources when males left them unattended. Consequently, females acquired fewer prey than males. After controlling for differences in prey acquisition, both sexes consumed similar amounts of prey in the non-breeding season. Even though males aggressively excluded females from accessing food sources directly, males fed large amounts of prey to females during the breeding season. Both sexes provisioned young at similar rates. Males cached less prey than females in the breeding season but more prey than females in the non-breeding season. Females showed similar caching intensities year-round. Although males tried to defend their hoards, females frequently retrieved male-made caches. Overall, results showed that although New Zealand robins cooperate to raise offspring during the breeding season, conflict between the sexes occurs year-round. Males and females display different behavioural strategies to gain access to experimental food sources, which appear to lessen male–female competition for food and evenly distribute food resources between the sexes.     

Challenges for physical characterization of silver nanoparticles under pristine and environmentally relevant conditions

The reported size distribution of silver nanoparticles (AgNPs) is strongly affected by the underlying measurement method, agglomeration state, and dispersion conditions. A selection of AgNP materials with vendor-reported diameters ranging from 1 nm to 100 nm, various size distributions, and biocompatible capping agents including citrate, starch and polyvinylpyrrolidone were studied. AgNPs were diluted with either deionized water, moderately hard reconstituted water, or moderately hard reconstituted water containing natural organic matter. Rigorous physico-chemical characterization by consensus methods and protocols where available enables an understanding of how the underlying measurement method impacts the reported size measurements, which in turn provides a more complete understanding of the state (size, size distribution, agglomeration, etc.) of the AgNPs with respect to the dispersion conditions. An approach to developing routine screening is also presented.