Twenty-five years of biomonitoring lead in the Frankfurt/Main area

The present study is an example of the historical monitoring of heavy metals. The specific question it aims to explore is: to what extent has the lead content of selected organisms used for biomonitoring in Frankfurt/Main—one of the cities in Germany most heavily affected by automobile traffic—changed as a result of legislation on leaded gasoline?

Data on the lead content of the moss speciesBryum argenteum Hedw. from the years 1974, 1975 and 1978 and data on the lead content of the outer bark of the ash speciesFraxinus excelsior L. from 1973 served as the basis for the repeated measurements. Remeasurement was successful in 76.5% (i.e. 124 trees at 26 growth sites). The study produced the following results:

• ? As was expected, the lead content of the short-term accumulatorBryum argenteum Hedw. was distinctly lowered with a decreasing particulate lead concentration. However, the reduction factor varied greatly between the different growth sites.
• ? On the other hand, the lead content measured in the outer bark layers ofFraxinus excelsior L. has risen markedly during the past two decades. Whereas in 1973 nearly all trees examined displayed very low concentrations of lead (< 38 ppm), only 9.5% were still in this category in 1997 and nearly 30% exhibited high or even unacceptable lead concentrations (< 150 ppm → > 225 ppm). Various factors have to be taken into account to explain this increase. First of all, bark is a long-term accumulator for heavy metals like lead and its enrichment capacity could have increased as the surface becomes rougher over time. Furthermore, lead is most probably leached out of the bark to a lesser degree now than in the 1970s, owing to the reduced concentration of sulphuric acid in the rain. The dramatic growth of automobile traffic in the Frankfurt/Main area during the period covered by the study undoubtedly plays an important role as well.

     

Convergent-flow tracer tests in heterogeneous media: combined experimental-numerical analysis for determination of equivalent transport parameters

In modeling transport within naturally heterogeneous aquifers, it is usually assumed that the transport equations valid at local scales can also be applied at larger scales. At larger scales, the heterogeneous domain is represented by an equivalent homogeneous medium. Convergent-flow tracer tests constitute one of the most frequently used field tests to estimate effective input parameters of equivalent homogeneous aquifers. Traditionally, statistical approaches applied to groundwater flow and solute transport have provided tools to estimate these equivalent parameters. These approaches are based on a number of simplifications including the assumption that the point transmissivity values follow a multilog-normal random function. Several investigators have found that this assumption may not be valid in many field cases. In order to study the applicability of the equivalent homogeneous formulation in a nontraditional stochastic field, a number of experimental and numerical studies were conducted. The results are used to determine the apparent values of porosity and dispersivity that would be obtained if convergent-flow tracer tests were conducted in a deterministically generated heterogeneous transmissivity field displaying anisotropy in the correlation structure. It is shown that in this particular heterogeneous media, apparent porosity strongly depends on connectivity rather than on transmissivity. This dependence on connectivity questions the theoretical results obtained in continuum equivalent fields to estimate effective porosity.     

Metallothionein induction and cadmium uptake in Bufo arenarum embryos following an acclimation protocol

Bufo arenarum embryos at the end of their embryonic development were acclimated to cadmium (Cd) by means of a 10-day treatment protocol. Embryos were processed for metallothionein (Mt) isolation and Cd and zinc (Zn) contents were measured. The results showed that: (1) the uptake of Cd in the experimental embryos was 7 microg/g embryo (wet weight) representing a bioaccumulation of Cd 255 times higher than in the maintaining medium; (2) a major Mt-like fraction was Cd-induced 7.8 times that in control embryos; two other protein fractions also bound Cd and Zn but were induced by Cd only about 2 and 1.4 times; (3) the Zn concentration was about 44 microg Zn/g embryo (wet weight) and did not change significantly (p>0.01) in the experimental embryos with respect to controls, but in acclimated embryos the essential metal was released from the Mts. The enhanced Mt synthesis and release of Zn from the native Mts are discussed in relation to the acclimation phenomenon.     

Overview of the U.S. Environmental Protection Agency's Hazardous Air Pollutant Early Reduction Program.

Under provision of the Clean Air Act Amendments of 1990 Title III, the EPA has proposed a regulation (Early Reduction Program) to allow a six-year compliance extension from Maximum Achievable Control Technology (MACT) standards for sources that voluntarily reduce emissions of Hazardous Air Pollutants (HAPs) by 90 percent or more (95 percent or more for particulates) from a base year of 1987 or later. The emission reduction must be made before the applicable MACT standard is proposed for the source category or be subject to an enforceable commitment to achieve the reduction by January 1, 1994 for sources subject to MACT standards prior to 1994. The primary purpose of this program is to encourage reduction of HAPs emissions sooner than otherwise required. Industry would be allowed additional time in evaluating emission reduction options and developing more cost-effective compliance strategies, although, under strict guidelines to ensure actual, significant and verifiable emission reductions occur.     

Degradation of chlorobenzenes by a strain of Acidovorax avenae isolated from a polluted aquifer

A subsurface microbial community was isolated from a polluted site of Suquía River (Córdoba-Argentina), acclimated during 15 days in aerobic conditions using 1,2-dichlorobenzene (1,2-DCB) as the sole carbon source. From this acclimated community, we isolated and identified by 16S rDNA analysis a strain of Acidovorax avenae, which was able to perform the complete biodegradation of 1,2-DCB in two days affording stoichiometric amounts of chloride. This pure strain was also tested for biodegradation of chlorobenzene (CB); 1,3-DCB and 1,4-DCB, giving similar results to the experiments using 1,2-DCB. The aromatic-ring-hydroxylating dioxygenase (ARHDO) alpha-subunit gene core, encoding the catalytic site of the large subunit of chlorobenzene dioxygenase, was detected by PCR amplification and confirmed by DNA sequencing. These results suggest that the isolated strain of A. avenae could use a catabolic pathway, via ARHDO system, leading to the formation of chlorocatecols during the first steps of biodegradation, with further chloride release and subsequent paths that showed complete substrate consumption.     

ERD of Residual TCE DNAPL Achieving Nondetect from a Single Injection of Food‐Grade Waste

Residual dense nonaqueous phase liquid (DNAPL) composed of trichloroethene (TCE) was identified in a deeper interval of an overburden groundwater system at a manufacturing facility located in northern New England. Site hydrostratigraphy is characterized by two laterally continuous and transmissive zones consisting of fully‐saturated fine sand with silt and clay. The primary DNAPL source was identified as a former dry well with secondary contributions from a proximal aboveground TCE storage tank. A single additive‐injection mobilization in 2001 utilizing a food‐grade injectate formulated with waste dairy product and inactive yeast enhanced residual TCE DNAPL destruction in situ by stimulating biotic reductive dechlorination. The baseline TCE concentration was detected up to 97,400 μg/L in the deeper interval of the overburden groundwater system, and enhanced reductive dechlorination (ERD) achieved >99 percent reduction in TCE concentrations in groundwater over nine years with no evidence of sustained rebound. TCE concentrations have remained nondetect below 2.0 μg/L for the last five consecutive sampling rounds between 2013 and 2015. ERD utilizing a food‐grade injectate is a green remediation technology that has destroyed residual DNAPL at the site and achieved similar results at other residual DNAPL sites during both pilot‐ and full‐scale applications. ©2016 Wiley Periodicals, Inc.     

Conversion of Mixed Low-Density Polyethylene Wastes into Liquid Fuel by Novel CaO/SiO<Subscript>2</Subscript> Catalyst

Plastic wastes disposal can be done by various methods such as landfill, incineration, mechanical and chemical recycling but these are restricted due to some environmental, economic and political problems. Conversion of these plastic wastes into valuable products by degradation is the best option. In the present work waste low density polyethylene was degraded by catalytic process using CaO/SiO₂ as mixed catalyst. The conditions for catalytic degradation were optimized for the production of maximum liquid fuel. It was found that the yield of liquid product was up to 69.10 wt% at optimum condition of temperature (350 °C), time (90 min) and catalyst feed ratio (1:0.4). Liquid fuels obtained from the catalytic degradation were further separated into various fractions by fractional distillation. Composition of liquid fuels was analyzed by FTIR spectroscopy, which showed that the liquid fuels mostly consist of paraffinic and naphthenic hydrocarbons. Different fuel properties such as density, specific gravity, American petroleum institute gravity (API gravity), viscosity, kinematic viscosity, refractive index, refractive intercept and flash point of both the parents and various fractional fuels were determined. All the properties of the obtained fuels are in close agreement with the fuel properties of gasoline, kerosene and diesel. It was found that our catalyst is very much efficient in terms of time, degradation temperature and amount of catalyst.     

Photochemical Degradation of Aqueous Polyvinyl Alcohol in a Continuous UV/H<Subscript>2</Subscript>O<Subscript>2</Subscript> Process: Experimental and Statistical Analysis

Polyvinyl alcohol (PVA), being a dominant contributor of total organic carbon (TOC) in textile wastewater, is not easily degradable by conventional methods of wastewater treatment. This study investigates the degradation of aqueous PVA in a continuous UV/H₂O₂ photoreactor since the feeding strategy of hydrogen peroxide proves to have considerable effects on the process performance. Response surface methodology involving the Box–Behnken method is adopted for the experimental design to study the effects of operating parameters on the process performance. Experimental analysis shows that the TOC removal varies from 16.11 to 42.70 % along with a reduction of the PVA molecular weights from 56.7 to 95.3 %. The TOC removal is significantly lower than the molecular weight reduction due to the generation of the intermediate products during oxidation. Operating the UV/H₂O₂ process in a continuous mode facilitates the degradation of highly concentrated polymeric solutions using a relatively small hydrogen peroxide concentration in the feed with a small residence time ranges from 6.13 to 18.4 min.     

Heavy metal mobility and potential availability in animal manure: using a sequential extraction procedure

In this study, dairy cow manure, goat manure, and chicken manure were collected from three farms and analyzed to find out the concentration of Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn. The concentration and potential of mobility and availability of heavy metals were studied in the animal manure samples. BCR Sequential extraction procedure was used to determine the binding forms of the metals. In this study, pseudo total concentrations of Mn and Zn were found out to be predominant in all the types of animal manure samples. According to the results, it was traced that Cr, Cu, and Ni were observed to be at the second highest level while Cd, Co, and Pb were seen at the lowest level in all the manure samples. When extractable amounts of heavy metals are taken into consideration, it is seen that the amount of the mobile fractions of heavy metals except for Cr and Ni are higher in comparison with that of immobile fraction in all the animal manure samples. It was also viewed that Mn, Cd, and Zn are more available in dairy cow manure and chicken manure whereas Cd, Co, and Mn are more available in goat manure.