Evaluation of various tests for the diagnosis of soil contamination by 2,4,5-trichlorophenol (2,4,5-TCP)

Soil response to contamination with 2,4,5-triclorophenol was studied to test the validity of the concept of Generic Reference Levels (GRL), the main criterion used to define soil contamination. Soil samples were artificially contaminated with doses between 0 and 5000 mg kg⁻¹ of 2,4,5-triclorophenol, and analysed by various tests. Where possible, the response of soils to the contaminant was modelled by a sigmoidal dose-response curve in order to estimate the ED₅₀ values. The tests provided different responses, but only microbial biomass-C and dehydrogenase and urease activities demonstrated soil deterioration in response to contamination. The results suggest that the diagnosis of soil contamination has been greatly simplified in the legislation by the provision of a single figure for each compound, and that the GRL concept could perhaps be substituted by measurement of ED₅₀ values, which better reflect the alteration of a soil due to the presence of a xenobiotic substance.     

Human health risks of petroleum-contaminated groundwater

BACKGROUND, AIM AND SCOPE: The volatile organic compounds Benzene, Toluene, Ethylbenzene and Xylene (BTEX) are commonly found in petroleum derivatives and, at relatively high levels, can be associated with human health risks. Due to industrial activities, accidental petroleum spills are the main route of soil and groundwater contamination. The aim of the present study was to evaluate the indoor health risks due to tap water consumption contaminated by BTEX. MATERIALS AND METHODS: BTEX indoor exposure can occur through three principal pathways: inhalation, ingestion and dermal absorption. A multiphase and multicomponent model was used to simulate BTEX transport in groundwater. For evaluation of human risks due to the use of contaminated tap water, a mathematical model was elaborated. RESULTS: BTEX concentrations in a drinking well were obtained as a function over time. These concentrations were used to obtain the exposure due to the use of water from the contaminated drinking well. In addition to showing the highest concentration in water, benzene was the compound that remained for a longer period before being completely degraded. For all the evaluated BTEX, oral ingestion was also the main pathway of exposure for adults, whereas the contribution of inhalation and oral exposition in children were seen to be of the same magnitude. The sensitivity analysis of BTEX total dose for adults showed that direct ingestion was the most significant factor, followed by shower time, volume of the shower room, inhalation rate, and shower flow rate. For children, the most significant variable was also direct ingestion, followed by shower time, volume of the shower room, and body weight. DISCUSSION: In the current design situation, there would not be any health risks by the use of BTEX-contaminated water to the general population living in the neighborhood of the petroleum spill. Therefore, no remediation measures in the area of the spill would be necessary. CONCLUSIONS: The present results indicate that the design of a good scenario can perform an accuracy risk assessment. This model can serve as a useful tool for predicting indoor exposure to substances for which no direct data are available, reducing monitoring efforts and observing how different processes affect outcomes. RECOMMENDATIONS AND PERSPECTIVES: These preliminary data allow the establishment of a basis for further investigations focusing on efficiently recovering petroleum from contaminated sites.     

Development of a harmonised phosphorus extraction procedure and certification of a sediment reference material

A harmonised procedure for the determination of the forms of phosphorus in freshwater sediments, developed in the frame of the European Programme, Standards, Measurements and Testing (SMT) has been used for a certification campaign for a reference material. This operationally defined scheme is a good compromise between method performance and reproducibility. Furthermore, the method is rather simple to implement and could be used by water managers on a routine basis. A homogeneous and stable sediment reference material has been prepared and will be available before mid 2001. The so-called SMT protocol, together with the reference material, are useful tools in the field of water management, especially at a time when quality assurance is of paramount importance in laboratory analyses. Knowledge of the bioavailable forms of phosphorus is important not only for analysis of sediments but also for sludge and soils. Therefore, the SMT protocol could be extended to these materials.     

In vivo effects of deltamethrin on some biochemical parameters of carp (Cyprinus carpio L.)

Thein vivo effects of deltamethrin (DM) on the blood sugar level, the acetylcholinesterase (AChE, EC 3.1.1.7) activities of the blood serum and various organs (heart, liver and intestine), the lactate dehydrogenase (LDH, EC 1.1.2.3), glutamic-oxaloacetic transaminase (GOT, EC 2.6.1.1), and glutamic-pyruvic transaminase (GPT, EC 2.6.1.2) activities of the blood serum, the adenosine triphosphatases (EC 3.6.1.3; Na⁺/K⁺-ATPase and Mg²⁺-ATPase) activities of the erythrocyte plasma membrane and the catalase (EC 1.11.1.6) activity of the liver were examined throughout 96 h in adult carp (Cyprinus carpio L.) Two sublethal concentrations, 1.0 and 1.5 µg/l of deltamethrin, were used. All fish survived the experiment except one, in an aquarium containing 1.5 ppb of DM, which died after 72 h.The AChE specific activity was significantly inhibited in the heart and intestine after 96 h at both concentrations compared to that in the control animals (P<0.05, Student'st-test), while there was no detectable difference between the two treatment. At the same time there was no detectable change in the liver. In the serum, the AChE activity almost remained unchanged; the only significant decrease could be measured after 96 h at 1.5 µg/l deltamethrin concentration. The blood glucose content exhibited interesting changes: after 24 h fish exposed at 1 µg/l DM seemed to be stressed, although this increase was not significant. When these fish became used to the new conditions (in practice this meant the presence of DM), the glucose level decreased, especially after 72 h. At the same time the control animals kept in similar circumstances showed a small insignificant decrease. Meanwhile fish in aquaria containing 1.5 µg/l DM reacted to the treatment with an increased blood glucose level after 48 h, and this did not change until the end of the treatment. The Na⁺/K⁺-ATPase activity decreased in a dose-dependant manner, while Mg²⁺-ATPase was less affected. A small increase in LDH level was observed, indicating damage of different muscle tissues. However, this phenomenon appeared only with the small dosage after 24 h (P<0.05). It has to be mentioned that the individual values varied to a large extent among of the eight fish.The GOT activities of the serum increased during the treatment. However, significant changes were only expressed after 72 and 96 h at 1 µg/l DM concentrations (P<0.01 andP<0.05), and after a similar long treatment at the high dosage (P<0.05, 72 and 96 h). The GPT did not change significantly in aquaria containing 1 µg/l DM. The only larger increase was measured after 96 h at 1.5 µg/l DM concentration (P<0.05). The catalase activity in the liver of treated carp remained practically at the same level compared to that in control fish.All these changes (concerning the primary effects of this compound) demonstrate the effect of DM on different fish enzymes, at low concentrations under laboratory conditions, which might be useful in practice for biomonitoring using fish.     

The evaluation of stability and maturity during the composting of cattle manure

We examined chemical, microbiological and biochemical parameters in order to assess their effectiveness as stability and maturity indicators during the composting process of cattle manure. The composting material obtained after 15 d in trenches and at different times during the maturation phase (i.e. 80, 180 and 270 d) were analyzed. We found that the material collected at the end of the active phase was inadequate to be applied to soil as organic amendment due to its high content of NH4+, its high level of phytotoxicity and the low degree of organic matter stability. After a maturation period of 80 d, the stability of the sample increased. This was shown by a reduction in the dissolved organic carbon (DOC) content and NH4+ concentration and also by a reduction in the microbial activity and biomass; however, 180 d of composting were not sufficient to reduce the phytotoxicity to levels consistent for a safe soil application. Among the various parameters studied, the change in DOC with composting time gave a good indication of stability.     

Immobilization of heavy metals in polluted soils by the addition of zeolitic material synthesized from coal fly ash

The use of zeolitic material synthesized from coal fly ash for the immobilization of pollutants in contaminated soils was investigated in experimental plots in the Guadiamar Valley (SW Spain). This area was affected by a pyrite slurry spill in April 1998. Although reclamation activities were completed in a few months, residual pyrite slurry mixed with soil accounted for relatively high leachable levels of trace elements such as Zn, Pb, As, Cu, Sb, Co, Tl and Cd. Phytoremediation strategies were adopted for the final recovery of the polluted soils. The immobilization of metals had previously been undertaken to avoid leaching processes and the consequent groundwater pollution. To this end, 1100 kg of high NaP1 (Na6[(AlO2)6(SiO2)10] .15H2O) zeolitic material was synthesized using fly ash from the Teruel power plant (NE Spain), in a 10 m3 reactor. This zeolitic material was manually applied using different doses (10000-25000 kg per hectare), into the 25 cm topsoil. Another plot (control) was maintained without zeolite. Sampling was carried out 1 and 2 years after the zeolite addition. The results show that the zeolitic material considerably decreases the leaching of Cd, Co, Cu, Ni, and Zn. The sorption of metals in soil clay minerals (illite) proved to be the main cause contributing to the immobilization of these pollutants. This sorption could be a consequence of the rise in pH from 3.3 to 7.6 owing to the alkalinity of the zeolitic material added (caused by traces of free lime in the fly ash, or residual NaOH from synthesis).     

Reduction of the movement and persistence of pesticides in soil through common agronomic practices

Laboratory and field studies were conducted in order to determine the leaching potential of eight pesticides commonly used during pepper cultivation by use of disturbed soil columns and field lysimeters, respectively. Two soils with different organic matter content (soils A and B) were used. Additionally, soil B was amended with compost (sheep manure). The tested compounds were cypermethrin, chlorpyrifos-methyl, bifenthrin, chlorpyrifos, cyfluthrin, endosulfan, malathion and tolclofos-methyl. In soil B (lower organic matter content), only endosulfan sulphate, malathion and tolclofos-methyl were found in leachates. For the soil A (higher organic matter content) and amended soil B, pesticide residues were not found in the leachates. In addition, this paper reports on the use of common agronomic practices (solarization and biosolarization) to enhance degradation of these pesticides from polluted soil A. The results showed that both solarization and biosolarization enhanced the degradation rates of endosulfan, bifenthrin and tolclofos-methyl compared with the control. Most of the studied pesticides showed similar behavior under solarization and biosolarization conditions. However, chlorpyrifos was degraded to a greater extent in the solarization than in biosolarization treatment. The results obtained point to the interest in the use of organic amendment in reducing the pollution of groundwater by pesticide drainage and in the use of solarization and biosolarization in reducing the persistence of pesticides in soil.     

Factors influencing the food transition in riverine communities in the Brazilian Amazon

The objective of this study was to determine the main patterns and factors influencing food transition in riverine people in the Brazilian Amazon. Through interviews with a semi-structured questionnaire, we inferred their food habits and provide information about general demographic, socioeconomic, resource use and environmental context. Data from the questionnaires were categorized and analyzed using a logistic regression model to assess the relative influence of socioeconomic and environment factors on the local diet. Based on a logistic regression data analysis, it was found a greater consumption of processed food significantly associated with multiple factors such as market participation, sex (female and male), government aid to forest conservation and environment context (upland and wetland). Although the local diet is composed mainly of local resources such as fish and cassava flour, increasing incomes due to direct government subsidy programs and marketing of cassava flour have influenced these local practices and habits. Through the analysis of factors influencing food transition, it was possible to evaluate those having the greatest effect on this Amazon region and propose an alternative method to subsidy food policy grounded in local opinion surveys.