Effects of dissolved organic carbon on sorption and mobility of imidacloprid in soil

To evaluate the effects of dissolved organic carbon on sorption and mobility of the insecticide imidacloprid [1-(6-chloro-3-pyridinyl) methyl-N-nitro-2-imidazolidinimine] in soils, adsorption and column experiments were performed by using a typical calcareous soil from southeastern Spain and two different types of dissolved organic carbon, that is, dissolved organic carbon extracts from a commercial peat (DOC-PE) and high-purity tannic acid (DOC-TA). The experiments were carried out from a 0.01 M CaCl2 aqueous medium at 25 degrees C. The results obtained from the sorption experiments show that the presence of both DOC-PE and DOC-TA, over a concentration range of 15 to 100 mg L(-1), produces in all cases a decreasing amount of imidacloprid adsorbed in the soil studied. From the column experiments the retardation coefficients (RC) were calculated for imidacloprid by using either 0.01 M CaCl2 aqueous solution (RC = 2.10), 0.01 M CaCl2 DOC-PE solution (RC = 1.65), or 0.01 M CaCl2 DOC-TA solution (RC = 1.87). The results indicate that mobility of imidacloprid is increased 21.4 and 11.0% in the presence of DOC-PE and DOC-TA solutions, respectively. Dissolved organic carbon reduces imidacloprid sorption by competing with the pesticide molecules for sorption sites on the soil surface, allowing enhanced leaching of imidacloprid and potentially increasing ground water contamination.     

Study of 222Rn concentrations in drinking water in the north-eastern hydroregions of Poland

This paper presents the results of radon concentration measurements in the drinking water from the municipal water supply system and private wells located in the north-eastern part of Poland. The measurements were carried out on 643 samples using a liquid scintillation method. The mean value was found to be 5262 Bq m-3 with a maximum of 38347 Bq m-3. The samples were obtained from different water-bearing levels, i.e. surface water, deep borehole water and well water and have respective mean values of 3398, 5178 and 6155 Bq m-3. In 57 water samples, a guideline maximum level of 11,000 Bq m-3 was found to be exceeded. The observed radon concentration in water can contribute to a 2% increase in indoor radon concentration.     

Phosphogypsum amendment effect on radionuclide content in drainage water and marsh soils from southwestern Spain

Phosphogypsum (PG) is a residue of the phosphate fertilizer industry that has relatively high concentrations of 226Ra and other radionuclides. Thus, it is interesting to study the effect of PG applied as a Ca amendment on the levels and behavior of radionuclides in agricultural soils. A study involving treatments with 13 and 26 Mg ha(-1) of PG and 30 Mg ha(-1) of manure was performed, measuring 226Ra and U isotopes in drainage water, soil, and plant samples. The PG used in the treatment had 510 +/- 40 Bq kg(-1) of 226Ra. The 226Ra concentrations in drainage waters from PG-amended plots were similar (between 2.6 and 7.2 mBq L(-1)) to that reported for noncontaminated waters. Although no significant effect due to PG was observed, the U concentrations in drainage waters (200 mBq L(-1) for 238U) were one order of magnitude higher than those described in noncontaminated waters. This high content in U can be ascribed to desorption processes mainly related to the natural adsorbed pool in soil (25 Bq kg(-1) of 238U). This is supported by the 234U to 238U isotopic ratio of 1.16 in drainage waters versus secular equilibrium in PG and P fertilizers. The progressive enrichment in 226Ra concentration in soils due to PG treatment cannot be concluded from our present data. This PG treatment does not determine any significant difference in 226Ra concentration in drainage waters or in plant material [cotton (Gossipium hirsutum L.) leaves]. No significant levels of radionuclides except 40K were found in the vegetal tissues.     

Untreated abandoned mercury mining works in a scenic area of Asturias (Spain)

Mercury mining was a large and thriving industry during the last century in Asturias (NW Spain). At Bra?alamosa, mining activity introduced significant quantities of wastes in spoil heaps located close to the mining operations. In these mining wastes, in addition to mercury, high concentrations of other potentially dangerous elements like As have been found. As a consequence, pollution and dereliction of the local environment occurred. This paper focuses on the environmental impact of these old mining operations and describes a preliminary assessment of the extent of contamination. This includes analytical data from systematic sampling of soils, stream sediments, wastes from spoil heaps, water and herbaceous plants in areas affected by mining activities. The potential risk that spoil materials imply for human health and the environment is documented on the basis of the application of EPA Risk Assessment methodology.     

Persistent organochlorine contaminants in eggs of northern goshawk and Eurasian buzzard from northeastern Spain: temporal trends related to changes in the diet

Persistent organochlorine compounds (pesticides and polychlorinated biphenyls) were determined in 24 northern goshawk (Accipiter gentilis) and eight Eurasian buzzard (Buteo buteo) samples of eggs collected between 1988 and 1999 in La Segarra (northeast Spain), in order to evaluate the changes in exposure and detrimental effects during this period. In the study area, both species exhibited similar levels of contamination, which may be related to their similar diet, mainly based on European rabbits (Oryctolagus cuniculus) in terms of biomass. The buzzard showed contamination levels similar to those found in other Spanish areas, but the levels found in the goshawk were much lower. The shell index in goshawk eggs was inversely correlated to concentration of p,p'-DDE. In late eighties, the concentrations of p,p'-DDE and heptachlor-epoxide in goshawk eggs were positively correlated to the biomass percentage of passeriforms in the diet. In goshawk samples, a decline in HCB concentration in the 1990s as compared to the 1980s was detected. Surprisingly, p,p'-DDE concentrations did not decline, as could be expected from the ban on DDT use. On the contrary, the highest p,p'-DDE concentrations were detected in some samples from the nineties, which also showed the lowest shell indices. This may be related to a severe reduction of rabbit population after 1989 that produced an increase in the consumption of passeriformes, which are known to accumulate higher levels of organochlorine compounds. Our study suggests that monitoring programs aiming to detect temporal trends in chemical contamination should take into account changes in diet composition before any conclusion can be drawn.     

Irrigation of broccoli and canola with boron- and selenium-laden effluent

Selenium (Se), boron (B), and salinity contamination of agricultural drainage water is potentially hazardous for water reuse strategies in central California. To demonstrate the feasibility of using plants to extract Se from drainage water, Se accumulation was determined in canola (Brassica napus L.) and broccoli (Brassica oleracea L.) irrigated with drainage effluent in the San Joaquin Valley, California. In the 2-yr field study, both crops were irrigated with a typical drainage water containing Se (150 microg L(-1)), B (5 mg L(-1)), and a sulfate dominated salinity (EC of 7 dS m(-1)). Total dry matter yields were at least 11 Mg ha(-1) for both canola and broccoli, and plant tissue Se concentrations did not exceed 7 mg kg(-1) DM for either crop. Based on the amount of soluble Se applied to crops with drainage water and the estimated amount of soluble Se remaining in soil to a depth of 90 cm at harvest, both canola and broccoli accumulated at least 40% of the estimated soluble Se lost from the soil for both years. Applied Se not accounted for in plant tissue or as soluble Se in the soil was presumably lost by biological volatilization. This study suggests that irrigating two high value crops such as canola and broccoli with Se-laden effluent helps manage Se-laden effluent requiring treatment, and also produces economically viable Se-enriched crops. Future research should focus on managing residual salt and B in the soil for sustaining long time water reuse strategies.     

Building disaster-resilient communities: The road to the second World Conference on Disaster Reduction, January 2005, Kobe, Hyogo, Japan

The statistics paint a shocking picture: Over the past ten years around 7,000 ‘natural’ disasters have occurred, killing more than 300,000 people and resulting in over US$800 billion in economic losses (Munich Re, 2003). Increasing interest in global warming has provoked intense debate on the issue of climate change and its implications for more frequent and intense extreme weather events, placing more people at risk than ever. While all countries may be threatened by natural hazards, experience shows that developing countries are disproportionately affected, with losses sometimes exceeding years of hard‐won and desperately needed economic development. The World Conference on Disaster Reduction,1 to be held in Japan in 2005, aims to address these and other crucial issues that are posing an unprecedented challenge to the international community.     

Influence of Fibers on the Mechanical Properties of Cassava Starch Foams

The utilization of renewable resources in packaging can provide solutions to ecological problems such as waste quantity. Agricultural resources are alternative raw materials, among which there is starch, a natural polysaccharide that can be used to form resistant foam under wet and warm conditions. The starch foam is obtained by thermo pressing process where cassava starch, water and additives are processed to form a rigid structure by swelling, gelatinization and network formation. Natural fibers can be used to improve the mechanical properties of starch foams. In this project was investigated the influence of the addition of fibers in the levels of 1, 2 and 3% of cassava (short fiber) and 1, 2 and 3% of wheat fiber (powered fiber) in the starch dough. The foams were characterized by physical methods of strength, flexibility, density and by Scanning Electron Microscopy (SEM). The increase in fibers quantity has resulted in foams with higher density and less flexibility, whatever the fiber type. Most fibers quantity did not improve the foam strength. Foam made with 1% of cassava fiber showed higher compression strength; by increasing the percentage quantity there was a decrease on the compression resistance. Foam made with wheat fiber presented a lower result in 2%. The fiber type had no statistical significance in strength, flexibility and density foam. Only the fiber quantity was significant. The results showed that both fibers presented limited dimensions to improve the reinforcement of the starch foams up to 1%.     

The dispersion of 137Cs and 239,240Pu in the Rhone River plume: a numerical model

A numerical three dimensional model to simulate the transport of Cs and Pu by the Rhone River plume has been developed. The model solves the hydrodynamic equations, including baroclinic terms (that account for density variations) and a turbulence model, the suspended matter equations, including several particle classes simultaneously, settling, deposition and erosion of the sediment, and the radionuclide dispersion equations. Exchanges of radionuclides between the liquid and solid phases are described in terms of kinetic transfer coefficients. The dependence of these coefficients with water salinity is explicitly included in the model since it changes from freshwater to seawater values in the model domain. Computed activity levels in water, suspended matter and bed sediments are, in general, in agreement with measurements in the area. The model can also give a wide amount of information, as distribution coefficients for total suspended matter and sediments and for each particle class, fractions of radionuclides fixed to solid particles, and vertical profiles of radionuclides and distribution coefficients.     

Reconstruction of 137Cs signal in Cuba using 7Be as tracer of vertical transport processes in the atmosphere

Levels of 137Cs and 7Be in aerosols have been measured in the region of Cienfuegos (Cuba) during the period 1994-1998. 137Cs showed the same seasonal trend as 7Be and the monthly regimes of precipitation seemed to be responsible for the observed pattern. The 137Cs/7Be ratio obtained in Cienfuegos and Miami (FL) in this period was used to calibrate the long-term database of 137Cs concentrations recorded in Miami (250 km from Cienfuegos). The database was then employed to reconstruct the 137Cs monthly concentrations in Cienfuegos since 1957.