Influence of urbanization and tourist activities on the water quality of the Potrero de los Funes River (San Luis – Argentina)

A study of the water quality of the Potrero de los Funes River (San Luis – Argentina) was carried out in order to evaluate the possible effect of the anthropogenic activities on the river developed in the homonymous town. Samples were collected during the period March 2000–November 2005 at three selected sampling sites (RP₁, RP₂ and RP₃). Different physicochemical and bacteriological parameters (turbidity, pH, conductivity, suspended solids, alkalinity, potassium, sodium, calcium, magnesium, chlorides, nitrates, phosphates, sulphates, chemical oxygen demand (COD), 5-day biological oxygen demand (BOD₅), dissolved oxygen, total coliforms, Escherichia coli and total heterotrophic bacteria) were analysed according to the Standard Method for the Examination of Water and Wastewater. When comparing the values of total coliforms, E. coli, total heterotrophic bacteria, COD, BOD₅ and phosphates from the zone without anthropogenic influence (RP₁) and the urban zones (RP₂ and RP₃) an important variation in the parameters was observed. These results indicate that the urban activity produces a serious and negative effect on the water quality, thus constituting a sanitary risk and may have a major impact on the trophic status of the Potrero de los Funes dam. As case study, we report on the use of General Quality Index (GQI) to evaluate spatial and seasonal changes in the water quality of Potrero de los Funes River. Results revealed a significant degradation of the water quality at RP₂ and RP₃.     

Investigations of ash fouling with cattle wastes as reburn fuel in a small-scale boiler burner under transient conditions

Fouling behavior under reburn conditions was investigated with cattle wastes (termed as feedlot biomass [FB]) and coal as reburn fuels under a transient condition and short-time operation. A small-scale (30 kW or 100,000 Btu/hr) boiler burner research facility was used for the reburn experiments. The fuels considered for these experiments were natural gas (NG) for the ashless case, pure coal, pure FB, and blends of coal and FB. Two parameters that were used to characterize the ash "fouling" were (1) the overall heat-transfer coefficient (OHTC) when burning NG and solid fuels as reburn fuels, and (2) the combustible loss through ash deposited on the surfaces of heat exchanger tubes and the bottom ash in the ash port. A new methodology is presented for determining ash-fouling behavior under transient conditions. Results on the OHTCs for solid reburn fuels are compared with the OHTCs for NG. It was found that the growth of the layer of ash depositions over longer periods typically lowers OHTC, and the increased concentration of ash in gas phase promotes radiation in high-temperature zones during initial periods while decreasing the heat transfer in low-temperature zones. The ash analyses indicated that the bottom ash in the ash port contained a smaller percentage of combustibles with a higher FB percentage in the fuels, indicating better performance compared with coal because small particles in FB burn faster and the FB has higher volatile matter on a dry ash-free basis promoting more burn out.     

Chlorinated naphthalene formation from the oxidation of dichlorophenols

Polychlorinated naphthalenes (PCNs) formed along with dibenzo-p-dioxin and dibenzofuran products in the slow combustion of dichlorophenols (DCPs) at 600 degrees C were identified. Each DCP reactant produced a unique set of PCN products. Major PCN congeners observed in the experiments were consistent with products predicted from a mechanism involving an intermediate formed by ortho-ortho carbon coupling of phenoxy radicals; polychlorinated dibenzofurans (PCDFs) are formed from the same intermediate. Tautomerization of the intermediate and H2O elimination produces PCDFs; alternatively, CO elimination to form dihydrofulvalene and fusion produces naphthalenes. Only trace amounts of tetrachloronaphthalene congeners were formed, suggesting that the preferred PCN formation pathways from chlorinated phenols involve loss of chlorine. 3,4-DCP produced the largest yields of PCDF and PCN products with two or more chlorine substituents. 2,6-DCP did not produce tri- or tetra-chlorinated PCDF or PCN congeners. It did produce 1,8-DCN, however, which could not be explained.     

Application of two organic amendments on soil restoration: effects on the soil biological properties

One method for recovering degraded soils in semiarid regions is to add organic matter to improve soil characteristics, thereby enhancing biogeochemical nutrient cycling. In this paper, we studied the changes in soil biological properties as a result of adding a crushed cotton gin compost (CCGC) and a poultry manure (PM) for 4 yr to restore a Xerollic Calciorthid located near Seville (Guadalquivir Valley, Andalusia, Spain). Organic wastes were applied at rates of 5, 7.5, and 10 Mg organic matter ha(-1). One year after the assay began, spontaneous vegetation had appeared in the treated plots, particularly in that receiving a high PM and CCGC dose. After 4 yr, the plant cover in these treated plots was around 88 and 79%, respectively, compared with 5% for the control. The effects on soil microbial biomass and six soil enzymatic activities (dehydrogenase, urease, BBA-protease, beta-glucosidase, arylsulfatase, and alkaline phosphatase activities) were ascertained. Both added organic wastes had a positive effect on the biological properties of the soil, although at the end of the experimental period and at high dosage, soil microbial biomass and soil enzyme activities were generally higher in the PM-amended soils compared to the CCGC-amended soils. Enzyme activity from the PM-amended soil was 5, 15, 13, 19, 22, 30, and 6% greater than CCGC-amended soil for soil microbial biomass, urease, BBA-protease, beta-glucosidase, alkaline phosphatase, arylsulfatase, and dehydrogenase activities, respectively. After 4 yr, the percentage of plant cover was > 48% in all treated plots and 5% in the control.     

Long term changes in atmospheric N and S throughfall deposition and effects on soil solution chemistry in a Scots pine forest in the Netherlands

In a Scots pine forest the throughfall deposition and the chemical composition of the soil solution was monitored since 1984. (Inter)national legislation measures led to a reduction of the deposition of nitrogen and sulphur. The deposition of sulphur has decreased by approximately 65%. The total mineral-nitrogen deposition has decreased by ca. 25%, which is mainly due to a reduction in ammonium-N deposition (−40%), since nitrate-N deposition has increased (+50%). The nitrogen concentration in the upper mineral soil solution at 10 cm depth has decreased, leading to an improved nutritional balance, which may result in improved tree vitality. In the drainage water at 90 cm depth the fluxes of NO₃⁻ and SO₄²⁻ have decreased, resulting in a reduced leeching of accompanying base cations, thus preserving nutrients in the ecosystem. It may take still several years, however, before this will meet the prerequisite of a sustainable ecosystem.     

Atrazine sorption and fate in a Ultisol from humid tropical Brazil

This study combined laboratory based microcosm systems as well as field experiments to evaluate the mobility of atrazine on a Ultisol under humid tropical conditions in Brazil. Results from sorption experiments fit to the Freundlich isotherm model [K(f) 0.99 mg kg(-1)/(mg l(-1))(1/n)], and indicate a low sorption capacity for atrazine in this soil and consequently large potential for movement by leaching and runoff. Microcosm systems using (14)C-atrazine to trace the fate of the applied herbicide, showed that 0.33% of the atrazine was volatilized, 0.25% mineralized and 6.89% was recorded in the leachate. After 60 d in the microcosms, 75% of the (14)C remained in the upper 5 cm soil layer indicating atrazine or its metabolites remained close to the soil surface. In field experiments, after 60 d, only 5% of the atrazine applied was recovered in the upper soil layers. In the field experiments atrazine was detected at a depth of 50 cm indicating leaching. Simulating tropical rain in field experiments resulted in 2.1% loss of atrazine in runoff of which 0.5% was adsorbed onto transported soil particles and 1.6% was in solution. Atrazine runoff was greatest two days after herbicide application and decreased 10 fold after 15 d. The use of atrazine on Ultisols, in the humid tropics, constitutes a threat to water quality, causing surface water and ground water pollution.     

CHemical and Biological Assessment of an Urban, Estuarine marsh in Northeastern New Jersey USA

Oritani Marsh in the Hackensack Meadowlands of urbanized northeastern New Jersey USA was assessed in 2000 for vegetation, soil/sediment chemistry, abundance/diversity of benthic invertebrates, and bird and mammal usage. Vegetatively, both marsh and uplands are dominated by tall, dense Phragmites australis. Small patches (less than 2 hectares total) dominated by Spartina spp. were found at the lowest elevations. Soil/sediment cores were sliced into 5 intervals and analyzed for metals, pesticides and volatile/semivolatile organic compounds. Thirteen locations had at least one chemical above Long et al.’s [Environmental Management, 19, 1995, 81--97] “Effects Range-Median” (ERM). Seven metals and nine organics exceeded ERM in at least one sample, with mercury showing the most exceedances. The surface 15 cm interval was generally more contaminated with metals than the 15 to 30 cm interval; the reverse was true for semivolatile organic compounds. Twenty taxa of benthic macroinvertebrates were collected, with each location producing from 1 to 9 taxa. Abundance ranged from 11 to 3,889 individuals/m². Number of taxa was moderately (r ² between 0.40 and 0.70) negatively correlated with zinc, beryllium, nickel and arsenic concentrations; no other chemical’s r ² was above 0.25. Diversity was moderately negatively correlated with arsenic and beryllium. These correlations were unexpected: zinc, beryllium, nickel and arsenic were not the chemicals found at the highest concentrations relative to benchmarks. Number of taxa, abundance and diversity were moderately (negatively) correlated with elevation; organic carbon was moderately (positively) correlated with abundance. All other correlations were weak (r ² < 0.35). Live traps captured only one mammal species, the meadow jumping mouse. Bird observations revealed 39 species, dominated by a few common species.