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At least 595 records · Page 33Linked to original sources
PubMed2006

Arsenic leaching from mulch made from recycled construction and demolition wood and impacts of iron-oxide colorants.

Mulch made from recycled construction and demolition (C&D) wood has been reported to contain elevated levels of arsenic from inadvertent inclusion of chromated copper arsenate (CCA)-treated wood. Such mulch is also commonly colored with iron oxide, a compound known to bind arsenic. The objectives of this study were to quantify the releases of arsenic from mulch made from C&D wood, to evaluate the impacts of an iron-oxide colorant in potentially decreasing arsenic leaching rates, and to evaluate the relative significance of additional variables on leachate concentrations. Atotal of 3 sets of mulch samples (0%, 5%, or 100% CCA-treated wood) were prepared containing a sample either with or without colorant addition. Each sample was subjected to two tests: a field leaching test and the Synthetic Precipitation Leaching Procedure (SPLP). Results showed that arsenic concentrations in the field leachate from the 0% treated wood mulches were consistently low (<0.003-0.013 mg/L) whereas leachates from 5 and 100% treated wood mulches were characterized by higher arsenic concentrations (0.059-2.23 mg/L for 5%; 0.711-22.7 mg/L for 100%). The mass of arsenic leached from the field samples during the 1-year monitoring period was between 10 and 15% of the initial mass of arsenic. The colorant reduced the leaching of arsenic by more than 20% for the field leachate and 50% for the SPLP leachate, on average. However, the study showed that the effect may not last for long periods. Besides colorant addition other factors were observed to affect the amount of arsenic leached from contaminated mulch. These include the proportion of CCA-treated wood in the mulch, time, and pH of rainfall.

Arsenates↗
PubMed2003

Is there a relationship between soil and groundwater toxicity?

Part IIA of the Environmental Protection Act 1990 requires environmental regulators to assess the risk of contaminants leaching from soils into groundwater (DETR, 1999). This newly introduced legislation assumes a link between soil and groundwater chemistry, in which rainwater leaches contaminants from soil into the saturated zone. As the toxicity of both groundwater and overlying soils is dependent upon the chemicals present, their partitioning and their bioavailability, similar patterns of soil, leachates and groundwater toxicity should be observed at contaminated sites. Soil and groundwater samples were collected from different contaminated land sites in an urban area, and used to determine relationships between soil chemistry and toxicity, mobility of contaminants, and groundwater chemistry and toxicity. Soils were leached using water to mimic rainfall, and both the soils and leachates tested using bioassays. Soil bioassays were carried out using Eisenia fetida, whilst groundwater and leachates were tested using the Microtox test system and Daphnia magna 48 h acute tests. Analysis of the bioassay responses demonstrated that a number of the samples were toxic to test organisms, however, there were no significant statistical relationships between soil, groundwater and leachate toxicity. Nor were there significant correlations between soil, leachates and groundwater chemistry.

Animals↗
PubMedDate not supplied

Optimum nitrogen use and reduced nitrogen loss for production of rice and wheat in the Yangtse Delta region.

A long-term field and lysimeter experiment under different amount of fertilizer-N application was conducted to explore the optimal N application rates for a high productive rice-wheat system and less N leaching loss in the Yangtse Delta region. In this region excessive applications of N fertilizer for the rice-wheat production has resulted in reduced N recovery rates and environment pollution. Initial results of the field experiments showed that the optimal N application rate increased with the yield. On the two major paddy soils (Hydromorphic paddy soil and Gleyed paddy soil) of the region, the optimal N application rate was 225-270 kg N hm(-2) for rice and 180-225 kg N hm(-2) for wheat, separately. This has resulted in the highest number of effective ears and Spikelets per unit area, and hence high yield. Nitrogen leaching in the form of NO(3-)-N occurs mainly in the wheat-growing season and in the ponding and seedling periods of the paddy field. Its concentration in the leachate increased with the N application rate in the lysimeter experiment. When the application rate reached 225 kg N hm(-2), the concentration rose to 5.4-21.3 mgN l(-1) in the leachate during the wheat-growing season. About 60% of the leachate samples determined contained NO(3-)-N beyond the criterion (NO(3-)-N 10 mg l(-1)) for N pollution. In the field experiment, when the N application rate was in the range of 270-315 kg hm(-2), the NO(3-)-N concentration in the leachate during the wheat-growing season ranged from 1.9 to 11.0 mg l(-1). About 20% of the leachate samples reached close to, and 10% exceeded, the criterion for N pollution. Long-term accumulation of NO(3-)-N from leaching will no doubt constitute a potential risk of N contamination of the groundwater in the Yangtse Delta Region.

Agriculture↗
PubMed2004

Laboratory simulation of anaerobic digestion of municipal solid waste.

Landfill processes were simulated in lab-scale bioreactors--lysimeters. The changes in leachate characteristics as well as the influence of the leachate recirculation on the processes taking place in the landfill were investigated. Lysimeters were filled with material simulating municipal waste in the city of Lodz, Poland. Compost in the amount of 30% w/w and the methanogens inoculum were added in order to enhance a development of methanogenic phase. Leachate produced in lysimeters was recirculated once, twice a week, or everyday. The leachate composition and biogas changes showed trends confirming that the bench-scale lysimeters appeared suitable to simulate processes taking place in the landfill. It was also proved that leachate recirculation accelerate these processes.

Bacteria, Anaerobic↗
PubMed2004

Water flows of MSW landfills and implications for long-term emissions.

A test landfill served for experiments to describe the water and material household of municipal solid waste (MSW) landfills. Special emphasis was given to the determination of the influence of the water flow on the substance balance. Therefore, a water balance was measured and the discharge was modeled by means of a mathematical model. A model, which separates the landfill into an area of preferential flow and an area of matrix flow fits best water flow data measured from 1987 to 1989 in the Breitenau landfill of 95,000 t MSW. This test landfill consists of three compartments C1, C2 and C3 with different covering systems. Leachate amount was highest in C1 with a permeable cover of silt and gravel. The lowest amount of leachate was found in C3 with a less permeable cover of gravel, humus, and plants. The values for C2 lie in between. An input-output balance for the substances C, N, S, P, Cl, Na, Ca, Fe, Zn, Pb, Cd and Cu was prepared. Contrary to the expectations the output of some substances was higher for C2 than for C1 with more leachate. Possibly a higher flow rate leads to preferential water flows that contact only small parts of the landfill body while most part of the landfill stays more or less dry. The substance balance reveals that most of the substances still remain in the landfill after 15 years of leaching. Hence, focusing on leachate concentrations only results in underestimating the after-care period of MSW landfills. Leachate concentrations reflect just a small part of a landfill. Understanding water flows and measuring substance balances improve considerably the assessment of the long-term emission potentials of landfills.

Environmental Monitoring↗
PubMed2005

The increased incidence of pure red cell aplasia with an Eprex formulation in uncoated rubber stopper syringes.

BACKGROUND: The incidence of pure red cell aplasia (PRCA) in chronic kidney disease patients treated with epoetins increased substantially in 1998, was shown to be antibody mediated, and was associated predominantly with subcutaneous administration of Eprex. A technical investigation identified organic compounds leached from uncoated rubber stoppers in prefilled syringes containing polysorbate 80 as the most probable cause of the increased immunogenicity. METHODS: This study investigated whether the incidence of PRCA was higher for exposure to the product form containing leachates than for leachate-free product forms. Antibody-mediated PRCA cases were classified according to indication, product form, and route of administration. Exposure estimates were obtained by country, indication, route of administration, and product form. RESULTS: For 2001 to 2003, the PRCA incidence rate for patients with subcutaneous exposure to Eprex in prefilled syringes with polysorbate 80 and uncoated rubber stoppers (leachates present) was 4.61/10,000 patient years (95% CI 3.88-5.43) versus 0.26/10,000 patient years (95% CI 0.007-1.44) for syringes with coated stoppers (leachates absent). The rate difference was 4.35/10,000 patient years (95% CI 3.44-5.26; P < 0.0001); the rate ratio was 17 (95% CI 3.14-707). A substantial rate difference remained in sensitivity analyses that adjusted for exposure to multiple product forms. CONCLUSION: The epidemiologic data, together with the chemical and immunologic data, support the hypothesis that leachates from uncoated rubber syringe stoppers caused the increased incidence of PRCA associated with Eprex. Currently, all Eprex prefilled syringes contain fluoro-resin coated stoppers, which has contributed to decreased incidence of PRCA with continued surveillance.

Chemistry, Pharmaceutical↗
PubMedDate not supplied

Characterization and identification of na-cl sources in ground water.

Elevated concentrations of sodium (Na+) and chloride (Cl-) in surface and ground water are common in the United States and other countries, and can serve as indicators of, or may constitute, a water quality problem. We have characterized the most prevalent natural and anthropogenic sources of Na+ and Cl- in ground water, primarily in Illinois, and explored techniques that could be used to identify their source. We considered seven potential sources that included agricultural chemicals, septic effluent, animal waste, municipal landfill leachate, sea water, basin brines, and road deicers. The halides Cl-, bromide (Br), and iodide (I) were useful indicators of the sources of Na+-Cl- contamination. Iodide enrichment (relative to Cl-) was greatest in precipitation, followed by uncontaminated soil water and ground water, and landfill leachate. The mass ratios of the halides among themselves, with total nitrogen (N), and with Na+ provided diagnostic methods for graphically distinguishing among sources of Na+ and Cl- in contaminated water. Cl/Br ratios relative to Cl- revealed a clear, although overlapping, separation of sample groups. Samples of landfill leachate and ground water known to be contaminated by leachate were enriched in I and Br; this provided an excellent fingerprint for identifying leachate contamination. In addition, total N, when plotted against Cl/Br ratios, successfully separated water contaminated by road salt from water contaminated by other sources.

Bromides↗
PubMed1996

Wool and grain dusts stimulate TNF secretion by alveolar macrophages in vitro.

OBJECTIVE: The aim of the study was to investigate the ability of two organic dusts, wool and grain, and their soluble leachates to stimulate secretion of tumour necrosis factor (TNF) by rat alveolar macrophages with special reference to the role of lipopolysaccharide (LPS). METHODS: Rat alveolar macrophages were isolated by bronchoalveolar lavage (BAL) and treated in vitro with whole dust, dust leachates, and a standard LPS preparation. TNF production was measured in supernatants with the L929 cell line bioassay. RESULTS: Both wool and grain dust samples were capable of stimulating TNF release from rat alveolar macrophages in a dose-dependent manner. The standard LPS preparation caused a dose-dependent secretion of TNF. Leachates prepared from the dusts contained LPS and also caused TNF release but leachable LPS could not account for the TNF release and it was clear that non-LPS leachable activity was present in the grain dust and that wool dust particles themselves were capable of causing release of TNF. The role of LPS in wool dust leachates was further investigated by treating peritoneal macrophages from two strains of mice, LPS responders (C3H) and LPS non-responders (C3H/HEJ), with LPS. The non-responder mouse macrophages produced very low concentrations of TNF in response to the wool dust leachates compared with the responders. CONCLUSIONS: LPS and other unidentified leachable substances present on the surface of grain dust, and to a lesser extent on wool dust, are a trigger for TNF release by lung macrophages. Wool dust particles themselves stimulate TNF. TNF release from macrophages could contribute to enhancement of inflammatory responses and symptoms of bronchitis and breathlessness in workers exposed to organic dusts such as wool and grain.

Animals↗
PubMed2003

A risk factor analysis of municipal domestic refuse landfills using a reactor with high water input.

Collapse, explosion and water pollution by leachate have been three major problems in confining the development of sanitary landfilling technology as an economical method for disposal of municipal refuse. Potential risk factors including settlement of landfilled refuse, the generation of methane, carbon dioxide and other gases from landfill, the dynamic changes in temperature within the landfill and its ambient environment, as well as COD(Cr), BOD5, nutrients (TKN, TP and organic matter), heavy metals (Cu, Pb and Zn) and pH in landfill leachate were simulated using a reactor with high water input. It was indicated that high content of organic components in landfilled refuse is a key risk factor to cause abrupt collapse and accidental explosion in the landfill because they have impact not only on the settlement, but also on the release of methane and other gases. Elevated temperatures coincided with maximum generation of methane and other gases, thus increasing the risk of accidental explosion. Leachate quality was closely related with the release of COD(Cr) and BOD5 and heavy metals such as Cu, Pb and Zn, as well as organic pollutants, there was less release of TKN and TP. The mass balance analysis for the reactor showed that 36% of organic carbon reduction in the refuse during the simulations was discharged into leachate as soluble organic carbon, and 3% was converted to methane and carbon dioxide as gas production. Mixing of refuse with soil and sand particles, the so-called drill-a-hole method and recycling leachate were measures suggested in order to mitigate and avoid potential accidents.

Carbon Dioxide↗
PubMed2003

Biomarker responses and chemical analyses in fish indicate leakage of polycyclic aromatic hydrocarbons and other compounds from car tire rubber.

Rubber tire material contains toxic compounds including oils rich in polycyclic aromatic hydrocarbons (PAH), so-called highly aromatic (HA) oils, as well as other reactive additives used as antioxidants, antiozonants, and vulcanization accelerators. The toxicity of rubber tire leachates to aquatic organisms has been demonstrated before. However, previous studies have focused on lethal rather than sublethal effects. We kept rainbow trout (Oncorhynchus mykiss) in tanks with two types of tires: a tire containing HA oils in the tread or a tire free of HA oils in the tread. After 1 d of exposure, an induction of cytochrome P4501A1 (CYP1A1) was evident in both exposed groups, measured as elevated ethoxyresorufin-O-deethylase (EROD) activity and increased CYP1A1 mRNA levels. After two weeks of exposure, EROD activity and CYP1A1 mRNA were still high in fish exposed to leachate from HA oil-containing tire, whereas the effect was somewhat lower in fish exposed to leachate from HA oil-free tread tire. Compounds in the tire leachates also affected antioxidant parameters. Total glutathione concentration in liver as well as hepatic glutathione reductase, glutathione S-transferase, and glucose-6-phosphate dehydrogenase activities were markedly elevated after two weeks of exposure in both groups. The responses were greater in the group exposed to leachate from HA oil-free tread tire. Vitellogenin measurements did not indicate leakage of estrogenic compounds from the tires. Chemical analyses of bile from exposed fish revealed the presence of hydroxylated PAH as well as aromatic nitrogen compounds indicating uptake of these compounds by the fish.

Animals↗
PubMed2005

Fertilizer, tillage, and dairy manure contributions to nitrate and herbicide leaching.

Few studies have examined the water quality impact of manure use in no-tillage systems. A lysimeter study in continuous corn (Zea mays L.) was performed on Maury silt loam (fine, mixed, semiactive, mesic Typic Paleudalf) to evaluate the effect(s) of tillage (no-till [NT] and chisel-disk [CD]), nitrogen fertilizer rate (0 and 168 kg N ha(-1)), and dairy manure application timing (none, spring, fall, or fall plus spring) on NO3-N, atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine), and alachlor [2-chloro-2'-6'-diethyl-N-(methoxymethyl)acetanilide] concentrations in leachate collected at a 90-cm depth. Herbicides were highest immediately after application, declining to less than 4 mug L(-1) in about two months. Manure and manure timing by tillage interactions had little effect on leachate herbicides; rather, the data suggest that macropores rapidly transmitted atrazine and alachlor through the soil. Tillage usually did not significantly affect leachate NO3-N, but no-tillage tended to cause higher NO(3)-N. Manuring caused higher NO3-N concentrations; spring manuring had more impact than fall, but fall manure contained about 78% of the N found in spring manure. Nitrate under spring "only fertilizer" treatment exceeded 10 mg L(-1) 38% of the time, compared with 15% for spring only manure treatment. After three years, manured soil leachate NO3-N exceeded that for soil receiving only N fertilizer. Soil profile (90 cm) NO3-N after corn harvest exceeding 22 kg N ha(-1) was associated with winter leachate NO3-N greater than 10 mg N L(-1). Manure can be used effectively in conservation tillage systems on this and similar soils. Accounting for all N inputs, including previous manure applications, will be important.

Agriculture↗
PubMed2006

Identification of prevalent microbial communities in a municipal solid waste landfill.

To identify the microbial communities in Istanbul, Odayeri Municipal Solid Waste Landfill, leachate samples were collected from different sections at different stabilization phases. In identification of microbial communities in leachate samples, molecular techniques such as FISH, DGGE and cloning based on 16S rRNA and mcrA genes were used. As the chemical and microbiological compositions of the samples were compared, obvious correlations were found between the stability of the landfill section and abundance of active methanogens. On the other hand, there were considerable differences between acidogenic and mature leachate samples in DGGE profiles of archaeal and bacterial 16S rRNA genes. Moreover, in acidogenic leachate samples having BOD5/COD ratio of about 0.5 acetate utilizing Methanosarcina and Methanosaeta species were intensively detected in FISH. Although only very few H2-utilizing methanogens were identified with FISH analysis, most of the clones isolated from mature leachate samples clustered within H2-utilizing Methanobacteriales and Methanomicrobiales according to phylogenetic analysis of 16S rRNA and mcrA clones, respectively.

Archaea↗
PubMed2006

Enhancing waste decomposition and methane production in simulated landfill using combined anaerobic reactors.

The design of leachate recirculation to enhance municipal solid waste decomposition, methane production and microbial activities was taken into account in this study by using the combined anaerobic reactors of a simulated high organic content landfill reactor and a stabilized fixed film anaerobic reactor. The latter aimed to treat high strength leachate from the simulated landfill reactor before recirculation back to the former reactor. The results showed the possibility to apply this technique to high organic waste landfill where rapid and accumulative acids formed in the leachate were removed and treated by a fixed film anaerobic reactor. In addition, the treated leachate when circulated back to the simulated bioreactor landfill helps accelerate waste decomposition and methane production by providing buffer capacity as well as diluting organic content in the leachate to achieve the favourable conditions for acidogen and methanogen, respectively, to rapidly enter into the methanogenesis phase.

Acids↗
PubMed2003

Conversion of organic carbon in the decomposable organic wastes in anaerobic lysimeters under different temperatures.

The quantitative fractions of conversion of organic carbon in the decomposable organic wastes with initial moisture of 70% sorted from municipal solid wastes (MSW) in lysimeters into biogas, leachate and solid residue were characterized, under temperatures of 25, 30 and 41 degrees C, respectively, and circulation of leachate generated within the lysimeter. It is found that 27% of organic carbon in the wastes are conversed into gases, 0.8% into leachate, and the other 72% remained in the decomposable solid residues, after 180 days' degradation at 41 degrees C. Higher temperature will lead to more rapid degradation and result to higher conversion of the organic carbon to biogas and lower to both solid residues and leachate, while the pollutant concentrations in leachate will be lower at a higher temperature and the values of COD are quite consistent with TOC.

Bacteria, Anaerobic↗
PubMed2003

Evaluation of the current status of operating and closed landfills in Russia, Finland and Ireland with regard to water pollution and methane emission.

The annual production of municipal solid wastes (MSW) in Russia, Finland and Ireland in the late 1990s accounts for 37.5, 2.5 and 2.05 min. tonnes or 252, 488 and 566 kg per capita, respectively. 96.5, 64 and 91% of these wastes (for Russia, Finland and Ireland, correspondingly) are currently disposed of via landfilling. However, nowadays, MSW management in these countries is undergoing drastic changes (source separation, closure of old landfills, reduction of the number of landfills etc.) forced by recent legislation set by the European Union and Russian authorities. This paper evaluates the current status of MSW landfills, as well as information on current leachate and methane emissions in the three above mentioned countries. Landfill leachates are highly variable in each country and between different countries due to different rainfall and climatic conditions and also due to poor landfill top insulation/cover. Leachates in poorly structured landfills are very dilute, whereas leachates with total COD and nitrogen contents as high as 33,700 mg COD/l and 4,030 mg N/l, respectively, have been detected from state-of-the-art sites. Currently, on-site treatment of leachates exists at only a few landfills in Russia, Finland and Ireland but this situation will be considerably improved during the next years. The annual methane emissions from landfills are estimated as 500-900 and 77 ktonnes for Russia and Finland, respectively. Recent estimates from Ireland suggest an annual landfill methane emission of c. 2.1 Mt CO2 equivalent. Several systems of methane recovery have been developed in all three countries and these are currently in different stages of implementation.

Environmental Monitoring↗
PubMed1999

Mobility of the organochlorine compound dicofol in soil promoted by Pseudomonas fluorescens.

The genetic modified Pseudomonas fluorescens Br 12, resistant to kanamycin and rifampycin, was used to follow the cotransport of the organochlorine acaricide dicofol through a nonsterilized soil column. P. fluorescens was found to bioaccumulate dicofol with the highest bioconcentration factor of 279 within 30 min. Separate soil column experiments where applied P. fluorescens or [14C]dicofol were submitted to heavy rain simulation did not reveal any correlation between the distribution patterns of P. fluorescens and [14C]dicofol in the leachate fractions (r = 0.3). Similar experiments with P. fluorescens that previously had bioaccumulated [14C]dicofol demonstrated a high correlation of these bacteria and radioactivity in the leachate fractions (r = 0.8). The total recovery of radioactivity in the leachate, when [14C]dicofol was previously bioaccumulated in bacteria, was more than two times higher (4.5%) than the total recovery of radioactivity in the leachate when [14C] dicofol was directly applied in the soil (2%). This indicates cotransport by Pseudomonas. Fractionation and analysis of soil columns indicated that most of the bioaccumulated dicofol was rapidly released and adsorbed in soil, while bacteria moved down by leaching.

Carbon Radioisotopes↗
PubMed1991

Combined use of open-air and indoor fumigation systems to study effects of SO2 on leaching processes in Scots pine litter.

Both an open-air fumigation system and a laboratory-based system were used to expose decomposing Scots pine (Pinus sylvestris L.) needles to controlled concentrations of SO(2) (arithmetic mean </= 48 nl litre(-1)) during a period, in total, of 301 days. The experimental design involved reciprocal litter transplants from 'clean' to 'polluted' air and vice versa, using the two fumigation systems. The objectives were (1) to observe the effects of SO(2) on leachate and litter chemistry, (2) to assess whether pollution-induced changes are reversible in clean air, and (3) to test the suitability of small-scale fumigation chambers (litter microcosms) compared with open-air systems in soil studies. Through the formation of SO(4)(2-) ions, dry-deposited SO(2) exhibited a marked capacity to remove 'base' cations (Ca(2+), Mg(2+) and K(+)) from decomposing pine needles, and also to acidify litter leachates (as indicated by proton fluxes from the litter). When litter was transferred from polluted air (48 nl litre(-1) SO(2), in the open-air system) to either clean or polluted air in the laboratory, the effects of prior exposure to SO(2) on leachate composition were still evident even after 86 days: the role of base cation depletion within the litter, caused by SO(4)(2-)-induced leaching, is discussed. Data for SO(4)(2-) fluxes in leachates collected from the small-scale chambers indicated that dry deposition velocities for SO(2) were not anomalously high within this fumigation system. It is therefore concluded that microcosm studies can provide information complementary to the open-air fumigation approach in soils research.

Journal Article↗
PubMed1989

Biocompatibility testing of a posterior composite and dental cements using a new organ culture model.

Mandibular first molars from day 14 and 17 mouse embryos were cultured in vitro for 7 days in chemically defined Pratt's medium in a submerged culture system. Ameloblast and odontoblast polarization and morphogenesis occurred in the control tooth germs. Discs of Occlusin, Silicate, ChemFil, IRM and Dycal were exposed to the culture system as either fresh material, leached discs (by pre-incubation in media) or the leachate from the incubated discs. Their effects on dental differentiation were assessed histologically. Day 17 tooth germs were slightly more sensitive to the effects of the exogenous agents than day 14 tooth germs. In general, silicate and ChemFil were toxic, IRM was slightly less toxic and the major effect was from the leachate. Dycal was toxic but most of this effect resulted from pH changes in the leachate. Occlusin was the most biocompatible material tested. Only a very mild adverse effect was detected, and this appeared to be caused by an agent (not a pH change) released into the leachate.

Aluminum Silicates↗