The Effect of Masterbatch Addition on the Mechanical, Thermal, Optical and Surface Properties of Poly(lactic acid)

There has been considerable interest in the use of the biodegradable polymer poly(lactic acid) (PLA) as a replacement for petroleum derived polymers due to ease of processability and its high mechanical strength. Other material properties have however limited its wider application. These include its brittle properties, low impact strength and yellow tint. In an attempt to overcome these drawbacks, PLA was blended with four commercially available additives, commonly known as masterbatches. The effect of the addition of 1.5 wt% of the four masterbatches on the mechanical, thermal, optical and surface properties of the polymer was evaluated. All four masterbatches had a slight negative effect on the tensile strength of PLA (3–5% reduction). There was a four fold increase in impact resistance however with the addition of one of the masterbatches. Differential scanning calorimetry demonstrated that this increase corresponded to a decrease in the polymer crystallinity. However there was an associated increase in polymer haze with the addition of this masterbatch. The clarity of PLA was improved through the addition of an optical brightener masterbatch, but the impact resistance remained low. The glass transition and melting temperatures of PLA were not affected by the addition of the masterbatches, and no change was observed in surface energy. Some delay in PLA degradation, in a PBS degradation medium at 50 °C, was observed due to blending with these masterbatches.     

The contemporary cement cycle of the United States

A country-level stock and flow model for cement, an important construction material, was developed based on a material flow analysis framework. Using this model, the contemporary cement cycle of the United States was constructed by analyzing production, import, and export data for different stages of the cement cycle. The United States currently supplies approximately 80% of its cement consumption through domestic production and the rest is imported. The average annual net addition of in-use new cement stock over the period 2000–2004 was approximately 83 million metric tons and amounts to 2.3 tons per capita of concrete. Nonfuel carbon dioxide emissions (42 million metric tons per year) from the calcination phase of cement manufacture account for 62% of the total 68 million tons per year of cement production residues. The end-of-life cement discards are estimated to be 33 million metric tons per year, of which between 30% and 80% is recycled. A significant portion of the infrastructure in the United States is reaching the end of its useful life and will need to be replaced or rehabilitated; this could require far more cement than might be expected from economic forecasts of demand for cement.     

Evaluation of Caging Designs and a Fingernail Clam for Use in an In Situ Bioassay

Two cage designs and fingernail clams(Sphaerium fabale) were evaluated for theirsuitability for use in in situ bioassays toassess the ecological condition of a stream andpredict ecological recovery potential. One design(referred to as tray design) was a modified plastictray about one-fourth full of small gravels andcovered with 1 mm fiberglass mesh. The second design(referred to as tube-plates) consisted of shortplexiglass tubes about one-third full of small gravelsand attached horizontally to a plexiglass plate. Oneend of each tube faced into the current; both endswere covered with mesh. Cages containing clams weredeployed at reference and impacted (test) sites forperiods of 70 to 135 d. Growth and survival were theprimary endpoints evaluated, but the tube-platesallowed isolation of individual clams so that natalityalso could be evaluated as an endpoint. Results ofbenthic macroinvertebrate surveys, performed foranother study, were included to help validate bioassayresults. Both cage designs yielded good quantitative,site-specific results for clam survival and growth;results for natality, though, were less conclusive. Clam survival and growth results were in good generalagreement with the results for the benthicmacroinvertebrate community surveys. At a site wherethe macroinvertebrate community was the mostdepauperate, clam mortality was always rapid. At asite where the condition of the macroinvertebratecommunity was only slightly less impacted than themost impacted site, clam growth was almost alwayssignificantly lower than at reference sites. Survivalof clams was significantly reduced in <25 d at thissite in some trials, but in other trials there waslittle mortality. At a minimally impacted site, clamsurvival was similar to that found at reference sites,and differences in clam growth were not detectableuntil after 40 to 50 d of exposure. The tube-platedesign was easier to use, allowed more flexibility inselection of response parameters, and required lesshandling time of test animals, thus, this was thepreferred design. Our results demonstrated thateither in situ bioassay design can be used toaugment monitoring and assessment programs. Their useas a predictor of ecological recovery, however,requires further evaluation.     

Adaptation Scenarios of Agriculture in Poland to Future Climate Changes

This paper demonstrates the ability of Polish agriculture to adapt to predicted climate change according to GISS and GFDL scenarios. Both climate-change scenarios will significantly affect farming conditions in Poland through water deficit, shifts in planting and harvesting seasons, changes in crop yields and crop structure. Neither scenario seems to endanger the self-sufficiency of Poland as long as preventative measures are taken. Moreover, the realization of GISS creates the possibility of a surplus in production. It must be emphasized that regardless of the scenario, the adaptation of agriculture to an expected climate change cannot be handled by the farming community itself.     

Numerical Simulations of the Urban Roughness Sub-Layer : A First Attempt

Most of the mesoscale models use roughness parameters to characterise the ground and to compute the surface stress. As the experimental determinations of the urban roughness parameters are rare and not very reliable, a new methodology based on microscale numerical simulations is presented here and the first results from two-dimensional simulations with different roof shapes are analysed.Firstly, it appears that the roof shape has a large influence : large difference in the Reynolds stress profile and in the roughness sub-layer thickness, enhancement of the exchanges at the roof level by buildings with attic. It also appears that the fetch necessary to obtain a constant flux layer is unrealistic compared to the real spatial homogeneity of quarters in European cities. Consequently, a new parameterisation of the urban ground-induced friction is to be developed without reference to the constant flux layer theory.     

Application of fuzzy sets and cognitive maps to incorporate social science scenarios in integrated assessment modelsA case study of urbanization in Ujung Pandang, Indonesia

Decision–support systems in the field of integrated water management could benefit considerably from social science knowledge, as many environmental changes are human-induced. Unfortunately the adequate incorporation of qualitative social science concepts in a quantitative modeling framework is not straightforward. The applicability of fuzzy set theory and fuzzy cognitive maps for the integration of qualitative scenarios in a decision–support system was examined for the urbanization of the coastal city of Ujung Pandang, Indonesia. The results indicate that both techniques are useful tools for the design of integrated models based on a combination of concepts from the natural and social sciences. This revised version was published online in July 2006 with corrections to the Cover Date.     

Soil contamination of heavy metals in the Katedan Industrial Development Area, Hyderabad, India

Studies on quantitative soil contamination due to heavy metals were carried out in Katedan Industrial Development Area (KIDA), south of Hyderabad, Andhra Pradesh, India under the Indo-Norwegian Institutional Cooperation Programme. The study area falls under a semi-arid type of climate and consists of granites and pegmatite of igneous origin belonging to the Archaean age. There are about 300 industries dealing with dyeing, edible oil production, battery manufacturing, metal plating, chemicals, etc. Most of the industries discharge their untreated effluents either on open land or into ditches. Solid waste from industries is randomly dumped along roads and open grounds. Soil samples were collected throughout the industrial area and from downstream residential areas and were analysed by X-ray Fluorescence Spectrometer for fourteen trace metals and ten major oxides. The analytical data shows very high concentrations of lead, chromium, nickel, zinc, arsenic and cadmium through out the industrial area. The random dumping of hazardous waste in the industrial area could be the main cause of the soil contamination spreading by rainwater and wind. In the residential areas the local dumping is expected to be the main source as it is difficult to foresee that rain and wind can transport the contaminants from the industrial area. If emission to air by the smokestacks is significant, this may contribute to considerable spreading of contaminants like As, Cd and Pb throughout the area. A comparison of the results with the Canadian Soil Quality Guidelines (SQGL) show that most of the industrial area is heavily contaminated by As, Pb and Zn and local areas by Cr, Cu and Ni. The residential area is also contaminated by As and some small areas by Cr, Cu, Pb and Zn. The Cd contamination is detected over large area but it is not exceeding the SQGL value. Natural background values of As and Cr exceed the SQGL values and contribute significantly to the contamination in the residential area. However, the availability is considerably less than anthropogenic contaminants and must therefore be assessed differently. The pre- and post-monsoon sampling over two hydrological cycles in 2002 and 2003 indicate that the As, Cd and Pb contaminants are more mobile and may expect to reach the groundwater. The other contaminants seem to be much more stable. The contamination is especially serious in the industrial area as it is housing a large permanent residing population. The study not only aims at determining the natural background levels of trace elements as a guide for future pollution monitoring but also focuses on the pollution vulnerability of the watershed. A plan of action for remediation is recommended.     

Soil and vegetation carbon stocks in Brazilian Western Amazonia: relationships and ecological implications for natural landscapes

The relationships between soils attributes, soil carbon stocks and vegetation carbon stocks are poorly know in Amazonia, even at regional scale. In this paper, we used the large and reliable soil database from Western Amazonia obtained from the RADAMBRASIL project and recent estimates of vegetation biomass to investigate some environmental relationships, quantifying C stocks of intact ecosystem in Western Amazonia. The results allowed separating the western Amazonia into 6 sectors, called pedo-zones: Roraima, Rio Negro Basin, Tertiary Plateaux of the Amazon, Javari-Juruá-Purus lowland, Acre Basin and Rondonia uplands. The highest C stock for the whole soil is observed in the Acre and in the Rio Negro sectors. In the former, this is due to the high nutrient status and high clay activity, whereas in the latter, it is attributed to a downward carbon movement attributed to widespread podzolization and arenization, forming spodic horizons. The youthful nature of shallow soils of the Javari-Juruá-Purus lowlands, associated with high Al, results in a high phytomass C/soil C ratio. A similar trend was observed for the shallow soils from the Roraima and Rondonia highlands. A consistent east–west decline in biomass carbon in the Rio Negro Basin sector is associated with increasing rainfall and higher sand amounts. It is related to lesser C protection and greater C loss of sandy soils, subjected to active chemical leaching and widespread podzolization. Also, these soils possess lower cation exchangeable capacity and lower water retention capacity. Zones where deeply weathered Latosols dominate have a overall pattern of high C sequestration, and greater than the shallower soils from the upper Amazon, west of Madeira and Negro rivers. This was attributed to deeper incorporation of carbon in these clayey and highly pedo-bioturbated soils. The results highlight the urgent need for refining soil data at an appropriate scale for C stocks calculations purposes in Amazonia. There is a risk of misinterpreting C stocks in Amazonia when such great pedological variability is not taken into account.     

Extraction of labile metals from solid media by dilute hydrochloric acid

Extraction of labile metals from solid media is environmentally more meaningful than a total digestion. A variety of reagents have been introduced in the literature, but dilute HCl has received the greatest attention. We compare metal concentrations liberated by a dilute HCl leach with the sum of the 3-step optimized (standardized) BCR sequential extraction procedure. This is the first study to compare these procedures over a range of grain sizes. Road-deposited sediments from 10 sites in Honolulu were fractionated into six grain size classes. Aliquots of individual fractions were digested with dilute HCl, the 3-step BCR procedure (‘labile’), and a 4-acid (total) procedure. Results indicated that the weighted labile concentrations of Al, Cu, Fe, Mn, Ni, Pb and Zn were statistically greater than those from the dilute HCl leach. However, regression analysis indicated strong statistically significant relationships between the two partial extraction procedures for all metals. On a whole-sample basis, the toxicity classifications for anthropogenic-enhanced metals (Cu, Pb and Zn) were similar between extractions. Taken together, results suggest that the application of dilute HCl to solid media provides a rapid, cost-effective, and environmentally meaningful approach for contaminant monitoring.     

Is PM10 mass measurement a reliable index for air quality assessment? An environmental study in a geographical area of north-eastern Italy

The aim of this study was to measure the concentration of some metals (Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Ti) in PM(10) samples collected in one urban and one industrial site and to assess that PM(10) total mass measurement may be not sufficient as air quality index due to its complex composition. Metals were determined by inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and differential pulsed anodic stripping voltammetry (DPASV). The measured concentrations were used to calculate the content of metals in the PM(10) total mass, and to estimate the enrichment factors and the correlations between PM(10), metal concentrations and meteorological data for the two sites. The mean PM10 concentration during the sampling period in the urban site exceeded the annual European Union (EU) standard (40 microg/m(3)) and, for some sampling days, the daily EU standard (50 microg/m(3)) was also exceeded. In opposite, both EU standards were never exceeded in the industrial site. The overall metal content was nearly double in the industrial site compared to the urban one, and the mean Ni concentration exceeded the EU annual limit value (10 ng/m(3)). The metals with the highest enrichment factor were Cd, Cu, Ni and Pb for both sites, suggesting a dominant anthropogenic source for these metals. Metal concentrations were very low and typical of rural background during Christmas holidays, when factories were closed. PM(10) total mass measurement is not a sufficient air quality index since the metal content of PM(10) is not related to its total mass, especially in sites with industrial activities. This measurement should be associated with the analysis of toxic metals.