Systematic evaluation of dissolved lead sorption losses to particulate syringe filter materials

Distinguishing between soluble and particulate lead in drinking water is useful in understanding the mechanism of lead release and identifying remedial action. Typically, particulate lead is defined as the amount of lead removed by a 0.45-μm filter. Unfortunately, there is little guidance regarding selection of filter membrane material and little consideration to the possibility of the sorption of dissolved lead to the filter. The objective of this work was to examine the tendency of 0.45-μm syringe filter materials to adsorb lead. Tests were performed with water containing 40 and 24 μg/L soluble lead at pH 7 buffered with 50 mg C/L dissolved inorganic concentration (DIC). The amounts of lead sorbed greatly varied by filter, and only two filter types, polypropylene and mixed cellulose esters, performed well and are recommended. Great care must be taken in choosing a filter when filtering soluble lead and interpreting filter results.     

The Effect of Building Fan Operation on Indoor-Outdoor Dust Relationships

As part of an energy conservation program recently implemented by the Bell System, fans in many telephone equipment buildings now operate only when necessary to bring the temperature within allowable limits, rather than continuously. In the study reported here the effects of fan operation on indoor-outdoor dust relationships were monitored at 2 representative telephone offices. Automatic dichotomous samplers were used to collect fine and coarse aerosol particles inside telephone equipment buildings at Wichita, KS and Lubbock, TX. At both sites, outdoor samples (roof top) were collected at the same time as the indoor samples. During the tests the building fans were repetitively cycled between 2-week intervals of continuous fan operation and 2-week intervals of intermittent fan operation. The indoor dust concentrations typically increased when the fans were off. The results indicate that this increase was due to loss of constant filtration, but not due to loss of building pressurlzation (i.e., filtration of the recirculated air is largely responsible for the lower dust levels when the fans are running continuously). An expression is derived for the relative dust increase when the building fans are switched off. Among other factors, the relative increase is directly proportional to the efficiency of the building filters and to the rate at which air is recirculated through them. The present findings can be extended to similar buildings.     

Examples of the role of analytical chemistry in environmental risk management research

Analytical chemistry is an important tier of environmental protection and has been traditionally linked to compliance and/or exposure monitoring activities for environmental contaminants. The adoption of the risk management paradigm has led to special challenges for analytical chemistry applied to environmental risk analysis. Namely, methods developed for regulated contaminants may not be appropriate and/or applicable to risk management scenarios. This paper contains examples of analytical chemistry applied to risk management challenges broken down by the analytical approach and analyte for some selected work in our laboratory. Specific techniques discussed include stable association complex electrospray mass spectrometry (cESI-MS), gas chromatography-mass spectrometry (GC-MS), split-flow thin cell (SPLITT) fractionation and matrix-assisted laser desorption time of flight mass spectrometry (MALDI-ToF-MS). Specific analytes include haloacetic acids (HAA9), perchlorate, bromate, triazine degradation products, metal-contaminated colloids and Cryptosporidium parvum oocysts.     

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.     

Assessment of Residential Rain Barrel Water Quality and Use in Cincinnati,Ohio1

The collection, storage, and reuse of rainwater collected in rain barrels from urban rooftop areas assists municipalities in achieving stormwater management objectives and in some areas also serves as an adjunct resource for domestic water supplies. In this study, rainwater reuse and levels of select microbial indicators were monitored for six residential rain barrels located in the Shepherd Creek watershed of Cincinnati, Ohio. Water from rain barrels typically had poor microbial quality and was used for watering indoor and outdoor plants. Rain barrel water chemistry was slightly acidic, exhibited wide ranges in conductivity, turbidity, and total organic carbon (TOC) concentrations and gave no evidence of the presence of cyanobacterial microcystin toxins. Selected microbial water‐quality indicators indicated that counts of total coliform and enterococci were consistently above U.S. Environmental Protection Agency standards for secondary recreational contact water‐quality standards. Residential rain barrels can provide water appropriate for low‐contact reuses (such as plant watering), although there may be transient periods of high levels of indicator bacteria in the collected water.     

Reduction of stem growth and site dependency of leaf injury in Massachusetts black cherries exhibiting ozone symptoms

Leaf ozone symptoms in natural ecosystems are increasingly reported but ozone effects on tree growth and the mediation of site conditions are still little documented. This study tests two hypotheses: (1) leaf injury in black cherry is associated with decline in radial growth, (2) symptoms are more prevalent on mesic sites. On sites supporting black cherry across Massachusetts, tree growth and leaf ozone injury were surveyed in 1996 using a randomized plot network established in the 1960s. Forty-seven percent of 120 trees sampled for ozone symptoms were symptomatic with generally low levels of injury. Over a 31-year period symptomatic trees had 28% lower stem growth rates than asymptomatic trees. Ozone symptom expression was enhanced in well growing stands on moister, cooler and more elevated sites. Ozone appeared to increase environmental stress and had a more pronounced effect on growth in better growing black cherry stands. This complicates management decisions as thinning increases growth and moisture availability.     

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.     

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.