Florida seagrass habitat evaluation: a comparative survey for chemical quality

Contaminant concentrations were determined for media associated with 13 Florida seagrass beds. Concentrations of 10 trace metals were more commonly detected in surface water, sediment and two seagrass species than PAHs, pesticides and PCBs. Concentrations of copper and arsenic in surface water exceeded Florida aquatic life criteria more frequently than other trace elements. Total organic carbon, mercury, chromium, zinc, total chlordane, total PAHs, total PCBs, DDD and DDE were significantly greater in seagrass-rooted sediments than adjacent non-vegetated sediments. Total DDT, DDD, DDE, total chlordane, arsenic, copper and nickel exceeded proposed sediment quality guidelines at six of 13 grass beds. Pesticides, PAHs, and PCBs were below detection in seagrass tissues. Mercury, cadmium, nickel, lead and silver were detected in 50% or more of the tissues for Thalassia testudinum (turtle grass) and Halodule wrightii (shoal grass). Spatial, interspecific and tissue differences were usually an order of magnitude or less.     

Effects of soil biota from different ranges on Robinia invasion: acquiring mutualists and escaping pathogens

The net effects of soil biota on exotic invaders can be variable, in part, because net effects are produced by many interacting mutualists and antagonists. Here we compared mutualistic and antagonistic biota in soils collected in the native, expanded, and invasive range of the black locust tree, Robinia pseudoacacia. Robinia formed nodules in all soils with a broad phylogenetic range of N-fixing bacteria, and leaf N did not differ among the different sources of soil. This suggests that the global expansion of Robinia was not limited by the lack of appropriate mutualistic N-fixers. Arbuscular mycorrhizal fungi (AMF) from the native range stimulated stronger positive feedbacks than AMF from the expanded or invasive ranges, a biogeographic difference not described previously for invasive plants. Pythium taxa collected from soil in the native range were not more pathogenic than those from other ranges; however, feedbacks produced by the total soil biota were more negative from soils from the native range than from the other ranges, overriding the effects of AMF. This suggests that escape from other pathogens in the soil or the net negative effects of the whole soil community may contribute to superior performance in invaded regions. Our results suggest that important regional evolutionary relationships may occur among plants and soil biota, and that net effects of soil biota may affect invasion, but in ways that are not easily explained by studying isolated components of the soil biota.     

Chlorinated components in lime used in production contaminated citrus pulp pellets from Brazil

In order to further understand the contamination of the citrus pulp pellets (CPP) that were exported to Europe in 1997 we examined both contaminated lime and CPP samples for the distribution of polychlorinated biphenyls (PCBs) and chlorinated benzenes (tri–hexa). Standard isotope dilution techniques were applied for all samples, which were analysed by selected ion monitoring high resolution GC–MS. Lime that is used in the production of CPP product is highly contaminated with PCBs and chlorobenzenes.     

Beyond the medicine cabinet: an analysis of where and why medications accumulate

Active pharmaceutical ingredients (APIs) from medications can enter the environment as trace contaminants, at individual concentrations generally below a part per billion (microg/L). APIs enter the environment primarily via the discharge of raw and treated sewage. Residues of unmetabolized APIs from parenteral and enteral drugs are excreted in feces and urine, and topically applied medications are washed from skin during bathing. These trace residues may pose risks for aquatic life and cause concern with regard to subsequent human exposure. APIs also enter the environment from the disposal of unwanted medications directly to sewers and trash. The relative significance of this route compared with excretion and bathing is poorly understood and has been subject to much speculation. Two major aspects of uncertainty exist: the percentage of any particular API in the environment originating from disposal is unknown, and disposal undoubtedly occurs from a variety of dispersed sources. Sources of disposal, along with the types and quantities of APIs resulting from each source, are important to understand so that effective pollution prevention approaches can be designed and implemented. Accumulation of leftover, unwanted drugs poses three major concerns: (i) APIs disposed to sewage or trash compose a diverse source of potential chemical stressors in the environment. (ii) Accumulated drugs represent increased potential for drug diversion, with its attendant risks of unintentional poisonings and abuse. (iii) Leftover drugs represent wasted healthcare resources and lost opportunities for medical treatment. This paper has four major purposes: (1) Define the processes, actions, and behaviors that control and drive the consumption, accumulation, and need for disposal of pharmaceuticals. (2) Provide an overview of the diverse locations where drugs are used and accumulate. (3) Present a summary of the first cataloging of APIs disposed by a defined subpopulation. (4) Identify opportunities for pollution prevention and source reduction.     

The reuse of biosludge as an adsorbent from a petrochemical wastewater treatment plant

Biosludge was obtained from a petrochemical industry's biological wastewater treatment plant. Zinc chloride (ZnCl2) was used as a sludge activation agent during the pyrolytic process. Scanning electron microscope (SEM) image photographs, element composition, surface functional group, and pore structure were analyzed for the sludge adsorbent characteristics. Results indicated the proper ZnCl2-immersed concentration, pyrolytic temperature, and time could produce adsorbent from the biosludge. The optimal conditions for a larger surface area adsorbent were 3 M ZnCl2-immersed sludge pyrolyzed at 600 degrees C for 30 min and washed with 3 N hydrochloric acid (HCl) solution and distilled water. The predominant pore size of the sludge adsorbent was the mesopore.     

Isolation of coliphages specific to enterotoxigenic E. coli (ETEC)

Bacteriophages specific to Enterotoxigenic E. coli (ETEC) are reported for the first time. Out of 15 isolated phages only 10 were specific to strains of ETEC. All ten phages of dsDNA could be grouped into three different genotypes based on their RAPD patterns observed and it is likellly that they belong to only 3 different strains. The three phages yielded clear plaques on 10 strains of ETEC within 4-6 h at 37 degrees C.     

Field demonstration of surfactant-enhanced solubilization of DNAPL at Dover Air Force Base, Delaware

This study reports on a surfactant-based flood for tetrachloroethylene (PCE) removal from a control test cell at the Dover National Test Site. The surfactant formulation (sodium dihexyl sulfosuccinate (Aerosol-MA or AMA), isopropanol and calcium chloride) was able to achieve a high concentration of PCE in swollen micelles (supersolubilization) without vertical PCE migration. The hydraulic system included eight screened wells that were operated in both vertical circulation and line drive configurations. After 10 pore volumes of flushing, the overall PCE removal was 68% (65% of which corresponded to the surfactant flooding alone). In addition, the residual PCE saturation was reduced from 0.7% to 0.2%, and the concentration of PCE in the groundwater was reduced from 37-190 mg/L before the flushing to 7.3 mg/L after flooding. Recycling the surfactant solution reduced the required surfactant mass (and thus cost, and waste) by 90%. Close to 80% of the total PCE removal was obtained during the first five pore volumes which were operated in an upward vertical circulation flow scheme. No free oil phase was observed during the test. Further analysis of multilevel sampler data suggests that most of the trapped oil remaining in the cell was likely localized in secluded regions of the aquifer, which helps explain the lower PCE groundwater concentration after remedial activities. In summary, this field study demonstrated the feasibility of surfactant-enhanced remediation to reduce the mass in the source zone and significantly reduce the PCE aqueous concentration and therefore the risk associated with the contaminant plume.     

Indian-Asian Relationship: mtDNA Reveals More

 Recent studies on human mtDNA have identified continent-specific restriction enzyme sites and resultant haplogroups among populations from different regions of the world. Such studies have helped in elaborating the models for human migrations. We have studied Indian mtDNAs to identify the recognized world ethnic elements present in it. The results presented here are based on the study of DdeI 10394 site along with the associated Asian-specific AluI 10397 site in the mtDNA sequences of the Indian samples. On examining all the related haplogroups, this study suggests that the apparent affinities of Indians and East Asians (comprising Chinese, Japanese, Southeast Asians etc.) could be due to a proto-Asiatic element present in Indians. Received: 12 April 1999 / Accepted in revised form: 13 January 2000     

Effect of petroleum-containing wastewater irrigation on bacterial diversities and enzymatic activities in a paddy soil irrigation area

Effects of petroleum contamination on bacterial diversities and enzymatic activities in paddy soils were investigated in the Shenfu irrigation area, the largest area irrigated by oil-containing wastewater for more than 50 yr in northeastern China. Bacterial diversities were determined by conventional colony morphology typing techniques and 16S rDNA polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE). Dehydrogenase, hydrogen peroxidase, polyphenol oxidase, urease, and substrate-induced respiration (SIR) were measured to evaluate the effects of petroleum-containing wastewater irrigation on soil biochemical characteristics. Results showed that paddy soil total petroleum hydrocarbon (TPH) concentration in the irrigation area varied from 277.11 to 5213.37 mg kg(-1) dry soil. Soil TPH concentration declined along the gradient of the irrigation channel from up- to downstream. At the current pollution level, the paddy soil TPH concentration was positively correlated with the colony forming units (CFU) of aerobic heterotrophic bacteria (AHB) (r = 0.928, p < 0.001) and the genetic diversity based on DGGE profiles (r = 0.655, p < 0.05). The bacterial diversities in the soils based on colony morphotypes of AHB also increased with TPH concentration (r = 0.598), but not significant statistically (p = 0.052). Analysis of soil enzyme activities indicated a significant positive correlation between soil TPH concentration and activities of dehydrogenases (r = 0.974, p < 0.001), hydrogen peroxidases (r = 0.957, p < 0.001), polyphenol oxidases (r = 0.886, p < 0.001), and SIR (r = 0.916, p < 0.001). On the contrary, the urease activity showed a negative correlation with paddy soil TPH concentration (r = -0.814, p = 0.002), and could be used as a sensitive indicator of petroleum contamination.