Slip safety risk analysis of surface properties using the coefficients of friction of rocks

This study was conducted to determine the most appropriate surface processing techniques (SPT), environmental conditions (EC) and surface roughness (SR) to minimize the risk of slipping when pedestrians walk on a floor covering of rocks barefoot and with shoes. Coefficients of friction (COFs) and values of SR were found using five different types of rocks, four SPT and two (ramp and pendulum) tests. Results indicate that the parameters which affect the COF values of rocks include SR, EC and SPT. Simple linear regression was performed to examine the relationship between the values of the COF and the SR. The value of the COF was identified as R²?≥?0.864. Statistical results, which are based on experimental measurements, show that rocks are classified according to their safe use areas depending on their COF and SR values.     

Donax trunculus and Venus verrucosa as bioindicators of trace metal concentrations in Mauritanian coastal waters

Trace-metal concentrations (Cd, Cu, Fe, Mn and Zn) were investigated in two species of abundant filter-feeding molluscs from Mauritania, the wedge shell Donax trunculus L. and the clam Venus verrucosa L. D. trunculus were collected on the beach of Nouakchott at low tide and V. verrucosa were sampled at the Banc d'Arguin at depths varying from 10 to 20 m, in mid-February 1987. D. trunculus contains significantly higher Fe and Zn concentrations than the clam. Total trace-metal content per individual (Y) in D. trunculus could be related to body weight (W) as the power function Y=aW ^b . The subsequent regression coefficient b was >1 for Cu, Fe, Mn and Zn and >1 for Cd. Metal concentrations in both species decreased in the order: Fe>Zn>Mn>Cu>Cd. Comparison of trace-metal concentrations in the small D. trunculus and the large V. verrucosa revealed lower contents in V. verrucosa, except for Cd. The trace-metal distribution in the various organs of V. verrucosa indicates that gills seem to concentrate metals, except Cu, to a greater degree than the other organs (visceral mass and remainder). The relatively elevated content of Fe in D. trunculus and of Cd, Fe and Zn in the gills of V. verrucosa seem to be of natural origin. In view of the scarcity of Mytilus sp. along the Mauritania coast, the molluscs D. trunculus and V. verrucosa are proposed as useful bioindicators of trace-metal concentrations.     

Chemical Changes in Agricultural Soils of Korea: Data Review and Suggested Countermeasures

The monitoring of chemical properties, including heavy metals, in soils is necessary if better management and remediation practices are to be established for polluted soils. The National Institute of Agricultural Science and Technology initiated a monitoring study that investigated fertility and heavy metal contents of the benchmarked soils. The study covered paddy soils, upland soils, and horticultural soils in the plastic film houses, and orchard soils throughout the Korea from 1990 to 1998. Likewise,4047 samples of paddy and 2534 samples of plastic house in 1999 and 2000 were analyzed through the Soil Environment Conservation Act. Soil chemical properties such as pH, organic matter, availablephosphate and extractable calcium, magnesium and potassium contents, and heavy metal contentssuch as cadmium, copper, lead, zinc, arsenic, mercury, and cobalt contents were analyzed. The studyshowed that the average contents of organic matter, available phosphate, and extractable potassiumrapidly increased in plastic house soils than in upland or paddy soils. Two kinds of fertilizer recommendation systems were established for the study: the standard levels by national soil average data for 77 crops and the recommendation by soil test for 70 crops. Standard nitrogen fertilizer application levels for cereal crops changed from 94 kg/ha in 1960s, 99 kg/ha in 1970s, 110 kg/ha in 1980s to 90 kg/ha in 1990s. The K₂O-fertilizer also changed from 67 kg/ha in 1960s, 76 kg/ha in 1970s, 92 kg/ha in 1980s, andonly 44 kg/ha in 1990s. In rice paddy fields, the average contents of Cd, Cu, Pb, and Zn in surface soils(0–15 cm depth) were 0.11 mg kg^–1(ranged from 0 to 1.01), 4.70 mg kg^–1(0–41.59), 4.84 mg kg^–1(0–66.44), and 4.47 mg kg^–1(0–96.70), respectively. In the uplands, the average contents of Cd, Cu, Pb, Zn,and As in surface soils (0–15 cm depth) were 0.135 mg kg^–1(ranged from 0 to 0.660), 2.77 mg kg^–1(0.07–78.24), 3.47 mg kg^–1(0–43.00), 10.70 mg kg^–1(0.30–65.10), and 0.57 mg kg^–1(0.21–2.90), respectively. In plastic film houses, the average contents of Cd, Cu, Pb, Zn, and As in surface soil were 0.12 mg kg^–1(ranging from 0 to 1.28), 4.82 mg kg^–1(0–46.50), 2.68 mg kg^–1(0–46.50), 31.19 mg kg^–1(0.19–252.0), and 0.36 mg kg^–1(0–4.98), respectively. In orchard fields, the averagecontents of Cd, Cu, Pb, Zn, As, and Hg in surface soils (0–20 cm depth) were 0.11 mg kg^–1(ranged from 0–0.49), 3.62 mg kg^–1(0.03–45.30), 2.30 mg kg^–1(0–27.80), 16.60 mg kg^–1(0.33–105.50),0.44 mg kg^–1(0–4.14), and 0.05 mg kg^–1(0.01–0.54), respectively. For polluted soils with over thewarning content levels of heavy metals, fine red earth application, land reconsolidation and soilamelioration such as lime, phosphate, organic manure, and submerging were recommended. For the countermeasure areas, cultivation of non-edible crops such as garden trees, flowers, and fiber crops; landreformation; and heavy application of finered earth (up to 30 cm) were strongly recommended. Landuse techniques should be changed to beharmonious with the environment to increase yield andincome. Soil function characteristics should betaken into account.     

The effect of cadmium on antioxidant responses and the susceptibility to oxidative stress in the hydrothermal vent mussel Bathymodiolus azoricus

Hydrothermal vents are a unique environment of extreme physical–chemical characteristics and biological species composition. Cd is a toxic non-essential metal present in high concentrations in the hydrothermal vent environment, contrary to those found in marine coastal areas. Cd toxicity has been related, among other things, with reactive oxygen species production, even though this is a non-redox metal. Bathymodiolus azoricus is a deep-sea Mytilid bivalve very common in the Mid Atlantic Ridge (MAR) hydrothermal vent fields and very little is known about the antioxidant defence system in this specie. Because lethal Cd concentration in B. azoricus is unknown, the aim of this study was to assess the effects of a Cd concentration higher than that found in the hydrothermal vents on oxidative stress biomarkers, such as antioxidant enzymes. Mussels were exposed to 100 μg l⁻¹ Cd during 24, 48 and 144 h, respectively, in a pressurized aquarium (IPOCAMP). Superoxide dismutase (SOD), catalase (CAT), glutathione peroxidases (GPx), total oxyradical scavenging capacity (TOSC), metallothionein (MT) and lipid peroxidation (LPO) were measured in the gills and mantle of B. azoricus. The results indicate that gills are first affected by Cd toxicity. This may be due to different physiological functions of the tissues and by the presence of thio and methanotrophic symbiotic bacteria in the gills. The SOD and CAT are inhibited during the first day of exposure in the gills, although TOSC and MT concentrations were the same in control and exposed mussels. In the mantle, enzymatic activation only occurred after 6 days, and no significant differences in MT concentrations were found in the control and exposed mussels during the first day, as observed in the gills.     

Organochlorine pesticides accumulation and degradation products in vegetation samples of a contaminated area in Galicia (NW Spain)

The content of 21 organochlorine pesticides were studied in vegetation samples of a highly contaminated area by isomers of hexachlorocyclohexane (HCH) located close to a former industrial area in Galicia (NW Spain). Five species of plants were collected at different points of the contaminated area and the different parts of the plants were separated in order to study differences in accumulation capabilities. Samples were extracted employing microwave energy followed by a clean-up step using solid phase extraction and finally determined by GC–ECD. The results obtained show that the most abundant pesticides are HCHs isomers, being the main isomers β-HCH and -HCH in all samples whereas δ-HCH and γ-HCH were at lower levels. Some other pesticides such as p,p′-DDT, p,p′-DDD and p,p′-DDE were also present in much lower amount in some of the samples. Several degradation products of HCH were also identified in some samples by GC–MS.     

Toxicity of hexahydro-1,3,5-trinitro-1,3,5-triazine to larval zebrafish (Danio rerio)

Hexahydro-1,3,5-trinitro-1,3,5-triazine, a cyclonitramine commonly known as RDX, is used in the production of military munitions. Contamination of soil, sediment, and ground and surface waters with RDX has been reported in different places around the world. Acute and subacute toxicities of RDX have been relatively well documented in terrestrial vertebrates, but among aquatic vertebrates the information available is limited. The objective of this study was to characterize the acute toxicity of RDX to larval zebrafish. Mortality (LC50) and incidence of vertebral column deformities (EC50) were two of the end points measured in this study. The 96-h LC50 was estimated at 22.98 and 25.64 mgl(-1) in two different tests. The estimated no-observed-effective-concentration (NOEC) values of RDX on lethality were 13.27+/-0.05 and 15.32+/-0.30 mgl(-1); and the lowest-observed-effective-concentration (LOEC) values were 16.52+/-0.05 and 19.09+/-0.23 mgl(-1) in these two tests, respectively. The 96-h EC50 for vertebral deformities on survivors from one of the acute lethality tests was estimated at 20.84 mgl(-1), with NOEC and LOEC of 9.75+/-0.34 and 12.84+/-0.34 mgl(-1), respectively. Behavioral aberrations were also noted in this acute toxicity study, including the occurrence of whirling movement and lethargic behavior. The acute effects of RDX on survival, incidence of deformities, and behavior of larval zebrafish occurred at the high end of the most frequently reported concentrations of RDX in aquatic environments. The chronic effects of RDX in aquatic vertebrates need to be determined for an adequate assessment of the ecological risk of environmental RDX.     

Evaluation of biomarkers in caged fishes and mussels to assess the quality of waters in a bay of the NW Mediterranean Sea

Specimens of sea bass (Dicentrarchus labrax) were placed in cages for 1 month in spring and autumn at different locations in the Bay of Cannes (NW Mediterranean). Biochemical markers evaluated were: ethoxyresorufin O-deethylase (EROD) and glutathione S-transferase (GST) activities in fish livers and acetylcholinesterase (AChE) activity in fish muscle. EROD and GST activities were higher in front of the outlet for the wastewater plant of Cannes and in the harbour than outside the marina. High EROD and GST activities may be induced by petrol hydrocarbons and/or polychlorinated biphenyls (PCBs). AChE was low in the muscles of the fish caged in the harbour compared with samples from the other cages. Low AChE activity could suggest the presence of organophosphorus and carbamate compounds in seawater from the harbour. Mussels (Mytilus galloprovincialis) were caged off Cannes for the same periods as the fishes. Heavy metal, metallothionein (MT) concentrations and lysosomal membrane stability were evaluated in the digestive gland of the mussels. Results show low heavy metal and MT concentrations, implying low metal concentrations in the surrounding waters. High lysosomal membrane stability revealed a good physiological status of these animals after caging. The whole set of data indicates that seawater in the Bay of Cannes appeared to be unpolluted as regards pollutants which may induce the measured biomarkers, except in restricted areas.     

Improvement of coagulation-flocculation process using anionic polyacrylamide as coagulant aid

A physicochemical treatment (coagulation-flocculation) was applied to a slaughterhouse wastewater, using anionic polyacrylamide as coagulant aid to improve the settling velocity of the flocs formed with the coagulants used: ferric sulphate, aluminium sulphate and polyaluminium chloride. The optimum speed and stirring time for the flocculation stage were ascertained along with the optimum pH and coagulant and coagulant aid doses. The speed and coagulation time were initially set according to recommendations in the literature concerning the treatment of this type of water. Chemical oxygen demand (COD), biochemical oxygen demand at 5 days (BOD5) and total suspended solids (TSS) were recorded at the beginning and end of each experiment in order to monitor the process. Once the optimal conditions had been established, several parameters were measured in order to assess the coagulation-flocculation process: particle number and size, sludge volume, nutrients (ammonia nitrogen, total Kjeldahl nitrogen, albuminoid nitrogen, orthophosphate, total phosphorus) and the residual concentration of iron and aluminium in clarified water. Anionic polyacrylamide, when added with ferric sulphate or polyaluminium chloride led to a significant increase in the settling speed.     

Solubility of volatile organic compounds in aqueous ammonia solution

The Ostwald solubility coefficient, L of 17 volatile organic compounds (VOCs) from the gas phase into water and dilute aqueous ammonia solutions was determined by the equilibrium partitioning in closed system-solid phase micro extraction (EPICS-SPME) method at 303 K and at 0-2.5 mol dm(-3) ammonia concentrations. Ammonia increased the solubility of all VOCs nearly linearly, but to a different extent. The difference in the solubility values in aqueous ammonia solutions (Lmix) compared to pure water (L) is explained on the basis of a Linear Solvation Energy Relationship (LSER) equation made applicable for solvent mixtures, logLmix - logL = x((sNH3 - sH2O)pi2H + (aNH3 - aH2O)Sigma2H + (bNH3 - bH2O)Sigmabeta2H + (vNH3 - VH2O)Vx). sNH3 - sH2O, aNH3 - aH2O, bNH3 - bH2O, vNH3 - vH2O are the differences of solvent parameters, x is the mole fraction, pi2H is the solute dipolarity-polarizability, Sigmaalpha2H is the effective hydrogen bond acidity of the solute, Sigmabeta2H is the effective hydrogen bond basicity of the solute and Vx, the McGowan characteristic volume. The most significant term was v, the phase hydrophobicity. The solubility behavior was explained by the change in structure of the aqueous solution: the presence of ammonia reduces the cavity effect. These findings show that the presence of compounds such as ammonia, frequently observed in environmental waters, especially wastewaters, affect the fugacity of VOCs, having consequences for the environmental partitioning of VOCs and having technical consequences towards wastewater treatment technologies.     

Carbon and hydrogen isotope effects during sorption of organic contaminants on carbonaceous materials

Stable carbon and hydrogen isotopes can be an efficient means to validate biodegradation of organic contaminants in groundwater since it results in an isotopic fractionation. A prerequisite in applying this method in the field is the proof that other processes decreasing the contaminant concentration are conservative with respect to isotope effects. In this paper we show for carbon isotopes of halogenated hydrocarbon compounds [trichloroethene (TCE), cis-dichloroethene (c-DCE), vinylchloride (VC)] and carbon and hydrogen isotopes of BTEX compounds (benzene, toluene, p-xylene) that no significant fractionation occurs during equilibrium sorption onto activated carbon, lignite coke and lignite. In general, effects were in the range of the reproducibility limit of the analytical instrument (0.5 per thousand for delta13C, and 8 per thousand for delta2H). This observation was made for fractions sorbed of less than 5% to more than 95%. Also for rate-limited sorption of TCE onto activated carbon, no significant fractionation in carbon isotopes could be observed. These findings support the assumption that for these classes of compounds, sorption processes in aquifer systems are conservative with respect to isotope effects.