Toxic substances in rivers and streams

Many of the toxic substances entering freshwaters today are those which were present several decades ago, but others have become significant recently. The effects of toxicants in flowing waters are modified by unidirectional transport and dispersion which afford the potential for a degree of 'self-purification'. The chemical quality of the receiving water also affects toxicity. Biological factors also contribute to the ultimate effect of pollutants. The potential for accumulation of toxic substances within tissues increases the significance of certain pollutants which may be present in water even though ambient concentrations are very low. The biota of flowing waters may be restored, following catastrophic entry of pollutants, by drift from unaffected regions upstream. The range of potential toxic substances is very extensive and includes inorganic poisons, organic poisons, heavy metals, pesticides and PCBs. Metals, pesticides and PCBs have the greatest potential for bioaccumulation. Few generalisations can be made regarding the effects of toxic substances on the biota. Each species tends to respond to different toxicants in different ways and even at different stages in its life-history. Toxicity tests conducted under controlled laboratory conditions sometimes produce conflicting results: it is not then to be unexpected that field observations should sometimes vary widely. Determinations of toxicity in laboratory tests must be applied with caution to field conditions and it is not wise to extrapolate findings to other species or environments.     

Evaluation of the cytotoxic effects of glyphosate herbicides in human liver,lung, and nerve

Glyphosate-based herbicides are broad-spectrum pesticides widely used in the world, which is considered a highly safe pesticide due to their target specificity, but recently, there has been an ongoing controversy regarding their carcinogenicity and possible side effects of glyphosate on human health. Commercial glyphosate-based herbicides (GBHs) consist of declared active ingredient (glyphosate salts) and a number of formulants such as ethoxylated formulants (4130®, 3780^®, and A-178^®). The aim of our study is to investigate whether the toxicity of GBHs is related to formulants. The effects of GBHs on human health were studied at the cellular level based on their toxicity to liver, lungs and nerve tissue. The inhibitory toxicity to cell viability by GBHs was examined with cell-based systems using three human cell lines: HepG2, A549, and SH-SY5Y. Data obtained showed that all tested ethoxylated formulants and their mixtures with declared active ingredient glyphosate isopropylamine salt (GP) have significant inhibitory effect on cell proliferation, while the declared active ingredient has no significant toxicity. Our study demonstrates that the toxic effect of GBH is primarily due to the use of formulants. This result suggests that GP is relatively safe and a new approach for the assessment of toxicity should be made.     

Characteristics of mercury speciation in Minnesota rivers and streams

Patterns of mercury (Hg) speciation were examined in four Minnesota streams ranging from the main-stem Mississippi River to small tributaries in the basin. Filtered phase concentrations of methylmercury (MeHg), inorganic Hg (IHg), and dissolved organic carbon (DOC) were higher in all streams during a major summertime runoff event, and DOC was enriched with MeHg but not with IHg. Particulate-phase MeHg and IHg concentrations generally increased with total suspended solids (TSS) concentrations but the event data did not diverge greatly from the non-event data, suggesting that sources of suspended sediments in these streams did not vary significantly between event and non-event samplings. The dissolved fractions (filtered concentration/unfiltered concentration) of both MeHg and IHg increased with increasing DOC concentrations, but varied inversely with TSS concentrations. While MeHg typically constitutes only a minor portion of the total Hg (THg) in these streams, this contribution is not constant and can vary greatly over time in response to watershed inputs.     

Occurrence and risk assessment of organophosphate esters in urban rivers from Piracicaba watershed (Brazil)

Environmental Science and Pollution Research - Organophosphate esters (OPEs) are substances globally used as flame retardants and plasticizers that have been detected in all environmental...     

Occurrence and potential toxicity of pyrethroids and other insecticides in bed sediments of urban streams in central Texas

Despite heavy insecticide usage in urban areas, only a few studies have investigated the impact of current-use insecticides on benthic invertebrates in urban streams. The objective of this study was to measure the presence and concentration of current-use pesticides in sediments of residential streams in central Texas. Additionally, toxicity of these sediments to Hyalella azteca was evaluated. Sediment samples were collected from several sites in urban streams over the course of a year, of which, 66% had greater than one toxic unit (TU) of insecticide. Bifenthrin was the greatest contributor accounting for 65% of the TUs, and sediment toxicity to H. azteca correlated with the magnitude of total insecticides and bifenthrin TUs. The results of this study further raise concerns over the environmental consequences posed by many current-use insecticides, especially pyrethroids, in urban settings.     

Sorption and leaching potential of acidic herbicides in Brazilian soils

Leaching of acidic herbicides (2,4-D, flumetsulam, and sulfentrazone) in soils was estimated by comparing the original and modified AF (Attenuation Factor) models for multi-layered soils (AFi). The original AFi model was modified to include the concept of pH-dependence for Kd (sorption coefficient) based on pesticide dissociation and changes in the accessibility of soil organic functional groups able to interact with the pesticide. The original and modified models, considering soil and herbicide properties, were applied to assess the leaching potential of selected herbicides in three Brazilian soils. The pH-dependent Kd values estimated for all three herbicides were observed to be always higher than pH-independent Kd values calculated using average Koc data, and therefore the original AFi model overestimated the overall leaching potential for the soils studied.     

Occurrence and determination of organic oxidants in rivers and wastewaters

Two iodometric methods for the concentration and analysis of water samples containing organic oxidants were applied to rivers and wastewaters in Illinois, Delaware, and Pennsylvania. Oxidant concentrations detected were as high as 2.5 § 10⁻⁵ M; the methods were capable of detecting as little as 10⁻⁸ M. Compounds possibly responsible for the observed oxidizing activity include N-chloro compounds, organic peroxides, or quinones.     

Occurrence of benzotriazoles in the rivers Main,Hengstbach, and Hegbach (Germany)

Background, aim, and scope  

Benzotriazoles (BT) as 1H-benzotriazole (1H-BT), 5-methyl-1H-benzotriazole (5Me-BT), and 4-methyl-1H-benzotriazole (4Me-BT) are frequently used as corrosion inhibitors in dish washer detergents, aircraft de-icing/anti-icing fluids (ADAF), automotive antifreeze formulations, brake fluids, fluids for industrial cooling systems, metal-cutting fluids, and in solid cooling lubricants. Discharge of treated municipal waste water and controlled over-runs of combined waste water sewers are potential point sources for BT in rivers. The aim of this monitoring study was to yield an overview on exposure concentrations and loads of BT in the German rivers Main, Hengstbach, and Hegbach.     

Sorption, desorption and mineralisation of the herbicides glyphosate and MCPA in samples from two Danish soil and subsurface profiles

The vertical distribution of the sorption, desorption and mineralisation of glyphosate and MCPA was examined in samples from two contrasting soil and subsurface profiles, obtained from a sandy agricultural site and a non-agricultural clay rich site. The highest mineralisation of [14C-methylen]glyphosate, with 9.3-14.7% degraded to 14CO2 within 3 months was found in the deepest sample from the clay site. In the deeper parts of the sandy profile high sorption and low desorption of glyphosate coincided with no or minor mineralisation indicating a limited glyphosate bioavailability. MCPA was readily mineralised except in the deepest samples from both sites. The highest MCPA mineralisation was detected just below the surface layers with 72% or 44% degraded to 14CO2 at the sandy or the clay sites, respectively. MCPA sorped to a minor extent in all samples and no indications of sorption-controlled mineralisation was revealed. None of the herbicides were mineralised under anoxic conditions.     

Volatile organic compounds in urban rivers and their estuaries in Osaka, Japan

The levels and distribution of 55 volatile organic compounds (VOCs) were determined by purge and trap GC-MS on water samples from 30 sites within the urban rivers and estuaries of Osaka, a populated industrialized city of Japan. Forty of 55 target VOCs listed in the US EPA Method 524.2 were detected. Dichloromethane (DCM) was found at higher levels at all of the sampling sites. The distribution of dominant VOCs followed four different patterns. First, the most common VOCs (DCM, toluene, trichloroethene and tetrachloroethene) showed concentration maxima in the river segments, and the sites of maximum concentration fluctuated due to irregular large spills and/or loadings. Second, one VOC (cis-1,2-dichloroethene) was evenly distributed in particular rivers due to fixed loadings. Both of these patterns were found in the upper and middle reaches. Third, some of VOCs (1,2,3-trichloropropane and benzene) were specific to a single industrial site and truceable to those sources. Finally, some VOCs showed no concentration maxima along the rivers and entered from multiple sources (chloroform and bromodichloromethane). Diurnal variations of VOCs at the border of the city area, receiving domestic and industrial discharges, provided information to interpret their observed downstream distribution and possible sources.     

Comparative environmental impacts of glyphosate and conventional herbicides when used with glyphosate-tolerant and non-tolerant crops

The introduction of glyphosate-tolerant (GT) crops is expected to mitigate the environmental contamination by herbicides because glyphosate is less persistent and toxic than the herbicides used on non-GT crops. Here, we compared the environmental balances of herbicide applications for both crop types in three French field trials. The dynamic of herbicides and their metabolites in soil, groundwater and air was simulated with PRZM model and compared to field measurements. The associated impacts were aggregated with toxicity potentials calculated with the fate and exposure model USES for several environmental endpoints. The impacts of GT systems were lower than those of non-GT systems, but the accumulation in soils of one glyphosate metabolite (aminomethylphosphonic acid) questions the sustainability of GT systems. The magnitude of the impacts depends on the rates and frequency of glyphosate application being highest for GT maize monoculture and lowest for combination of GT oilseed rape and non-GT sugarbeet crops.     

Glyphosate adsorption in soils compared to herbicides replaced with the introduction of glyphosate resistant crops

Use of glyphosate resistant crops was helpful in addressing observed increases in environmental contamination by herbicides. Glyphosate is a broad-spectrum herbicide, and its behaviour-as well as that of other herbicides-in soils is an important consideration for the overall environmental evaluation of genetically resistant crop introduction. However, few data have been published comparing glyphosate behaviour in soil to that of the herbicides that would be replaced by introduction of glyphosate resistant crops. This work compares glyphosate adsorption in soil with that of other herbicides frequently used in rape (trifluralin and metazachlor), sugarbeet (metamitron) and corn (sulcotrione). Herbicide adsorption was characterised in surface soils and in the complete soils profiles through kinetics and isotherms using batch equilibration methods. Pedological and molecular structure factors controlling the adsorption of all five herbicides were investigated. Glyphosate was the most strongly adsorbed herbicide, thus having the weakest potential for mobility in soils. Glyphosate adsorption was dependent on its ionisable structure in relation to soil pH, and on soil copper, amorphous iron and phosphate content. Trifluralin adsorption was almost equivalent to glyphosate adsorption, whereas metazachlor, metamitron and sulcotrione adsorption were lower. Trifluralin, metazachlor and metamitron adsorption increased with soil organic carbon content. Sulcotrione was the least adsorbed herbicide in alkaline soils, but its adsorption increased when pH decreased. Ranking the adsorption properties among the five herbicides, glyphosate and trifluralin have the lowest availability and mobility in soils, but the former has the broadest spectrum for weed control.     

Concentrations and specific loads of glyphosate, diuron, atrazine, nonylphenol and metabolites thereof in French urban sewage sludge

Indirect soil pollution by heavy metals and organics may occur when sewage sludge is used as fertilizer. It is essential to define the nature and amounts of pollutants contained in sewage sludge in order to assess environmental risk. Here, we present results from a one-year monitoring of herbicides (glyphosate, diuron and atrazine) and their major degradates in sewage sludge sampled from three wastewater treatment plants and one composting unit in the vicinity of Versailles, France. The concentrations of these compounds were determined, as well as these of the surfactant nonylphenol. We demonstrated the presence of glyphosate and aminomethylphosphonic acid at the mg kg(-1) (dry matter) level in all samples. Diuron was detected at the microg kg(-1) (d.m.) level, whereas its degradate and triazine compounds were below the limits of quantification. Nonylphenol amounts were higher than the future European limit value of 50 mg kg(-1) (d.m.).     

Occurrence of organotin compounds in water and sediment in Canada

Water and sediment samples from 265 locations across Canada were analyzed for butyltin and methyltin species, and inorganic tin. In 10% of the water samples the highly toxic tributyltin species was found at concentrations which could cause growth retardation upon chronic exposure to a sensitive organism, rainbow trout yolk sac fry. High concentrations of tributyltin were found in some sediments (up to 10 mg Sn/kg dry weight), but the biological availability of sediment-associated tributyltin is unknown. Tributyltin was mainly found in areas of heavy boating and shipping traffic, which is consistent with its use as an antifouling agent in some paints for boats, ships and docks. The methyltin species were found much less frequently in water and sediment than tributyltin and its degradation products.     

Isolating the impact of sediment toxicity in urban streams

Several factors can contribute to the ecological degradation of stream catchments following urbanization, but it is often difficult to separate their relative importance. We isolated the impact of polluted sediment on the condition of an urban stream in Melbourne, Australia, using two complementary approaches. Using a rapid bioassessment approach, indices of stream condition were calculated based on macroinvertebrate field surveys. Urban stream reaches supported impoverished macroinvertebrate communities, and contained potentially toxic concentrations of heavy metals and hydrocarbons. Using a field microcosm approach, a bioassay was carried out to assess sediment pollution effects on native macroinvertebrates. Sediment from urban sites substantially altered the microcosm macroinvertebrate community, most likely due to elevated heavy metal and hydrocarbon concentrations. Macroinvertebrate surveys combined with a bioassay approach based on field microcosms can help isolate the effect of stream pollutants in degraded ecosystems.     

城市河流与湖库中痕量有机污染物的研究

通过采用ＧＤＸ－５０２富集,ＧＣ－ＭＳ分析,对城市河流、湖库中的痕量有机污染物进行分析,共检出５８种有机污染物,其中含有多种美国ＥＰＡ公布的重点污染物,从而为痕量有机污染物的研究建立了灵敏度高,分辨率好的测试方法。     

Indoor- and outdoor-derived contaminants in urban and rural homes in Ottawa, Ontario, Canada

Indoor and outdoor air contaminants have largely been treated separately in studies of their respective effects on respiratory and nonrespiratory health. In this paper, we report the results of a comprehensive study of key contaminants in 10 urban and 10 rural homes in Ottawa, Ontario, Canada. The analyses included house dust mite and cat allergens along with the fungal inflammatory polysaccharide beta1,3-D-glucan in settled dust and fine particulate matter, coarse particulate matter, ergosterol, glucan, and endotoxin from air samples. In addition, black carbon was continuously measured for 7 days. A detailed physical assessment of the house and patterns of use were undertaken, including a careful inspection for mold and water damage, as well as measurements of air leakage. The performance of the houses and the range and distribution of the contaminants measured were largely similar to that of previous Canadian studies. For certain combinations, it is thought that the presence of both allergen and inflammatory materials increases asthma symptoms. House-by-house comparisons of airborne concentrations of inflammatory compounds measured (endotoxin, fine particulate matter, and fungal glucan) with dust mite allergens indicated that certain houses had relatively higher amounts of both kinds of materials.     

Occurrence of butyltin compounds in the waters of selected lakes, rivers and coastal environments from China

The presence of butyltin compounds was investigated for the first time in selected lakes, rivers and coastal environments of China. Aqueous samples were pretreated by the technique of headspace solid phase micro-extraction after hydride generation with sodium tetrahydroborate (NaBH4). Quantitative measurement of tributyltin (TBT), dibutyltin (DBT) and monobutyltin (MBT) concentrations were accomplished by capillary gas chromatography with flame photometric detector using quartz surface-induced luminescence. Experimental data demonstrated the widespread occurrence of butyltin compounds in the Chinese aquatic environment. In some locations, the concentrations of TBT were higher than the acute and chronic toxicity threshold of sensitive fresh water or marine organisms. Although DBT and MBT (which mainly come from the degradation of TBT), are less toxic, their occurrence can still affect the ecosystem over a long time frame.     

Electrochemical degradation of chlorophenoxy and chlorobenzoic herbicides in acidic aqueous medium by the peroxi-coagulation method

The degradation of 4-chlorophenoxyacetic acid (4-CPA), 4-chloro-2-methylphenoxyacetic acid (MCPA), 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) as chlorophenoxy herbicides, as well as of 3,6-dichloro-2-methoxybenzoic acid (dicamba) as chlorobenzoic herbicide, has been studied by peroxi-coagulation. This electrochemical method yields a very effective depollution of all compounds in acidic aqueous medium of pH 3.0 working under pH regulation, since they are oxidized with hydroxyl radicals produced from Fenton's reaction between Fe(2+) and H(2)O(2) generated by the corresponding Fe anode and O(2)-diffusion cathode. Their products can then be removed by mineralization or coagulation with the Fe(OH)(3) precipitate formed. Both degradative paths compete at low currents, but coagulation predominates at high currents. The peroxi-coagulation process of dicamba at I>or=300 mA leads to more than 90% of coagulation, being much more efficient than its comparative electro-Fenton treatment with a Pt anode and 1 mM Fe(2+), where only mineralization takes place. For the chlorophenoxy compounds, electro-Fenton gives a slightly lower depollution than peroxi-coagulation, because more easily oxidable products are produced. Oxidation of chlorinated products during peroxi-coagulation is accompanied by the release of chloride ion to the solution. The efficiency of this method decreases with increasing electrolysis time and current. The decay of all herbicides follows a pseudo-first-order reaction, with a similar constant rate for 4-CPA, MCPA, 2,4-D and 2,4,5-T, and a higher value for dicamba.     

Determination of acidic herbicides in cereals by QuEChERS extraction and LC/MS/MS

A simple and rapid method has been studied for the determination of acidic herbicides (2,4-D, Dichlorprop, Dichlorprop-p, Fluazifop, Fluroxypyr, MCPA, Mecoprop and Mecoprop-p) on cereals (rye). The method involves an alkaline hydrolysis with sodium hydroxide in order to release covalently bound compounds, prior to QuEChERS extraction, followed by neutralization and analysis via liquid chromatography-double mass spectrometry LC/MS/MS. The performance of the method either with or without alkaline hydrolysis was studied in terms of recovery rates and limit of quantification (LOQ). In either case, recoveries were determined at four spiking levels (0.02 mg/kg, 0.05 mg/kg, 0.1 mg/kg and 0.5 mg/kg) with 5 replicates for each level. Mean recoveries ranged from 90 to 120 %, whereas relative standard deviations (RSD %) proved to be less than 20 %. Quantitative analysis was carried out by the internal standard (Nicarbazin) and the LC/MS/MS analysis was performed in electrospray ionisation (ESI) negative mode using a Zorbax XCB Eclipse column. The developed method was applied to the analysis of several cereals commercially available like as rye flour, oat meal, oat flakes and dehusked oat. Residue levels were found below the limit of quantification (LOQ) of the method. The method has been tested in EU Proficiency Tests for cereals with good results.