Comparison of spray drift- and runoff-related input of azinphos-methyl and endosulfan from fruit orchards into the Lourens River, South Africa.

Spray drift and edge-of-field runoff are regarded as important routes of nonpoint-source pesticide input into aquatic surface waters, with current regulatory risk assessment in Europe focussing largely on spray drift. However, the two routes of entry had rarely been compared directly in the same catchment. To this end, the concentrations and loads of the current-use insecticides azinphos-methyl (AZP) and endosulfan (END) were monitored in the Lourens River, South Africa downstream of a 400-ha fruit orchard area during normal farming practice. Spray drift-related peak pesticide levels in the tributaries were in the range of 95th-percentiles of standard drift values according to regulatory risk assessment procedures. Resulting concentrations in Lourens River water samples (n = 3) at a discharge of 0.28 m3/s were as high as 0.04 +/- 0.01 microg/l AZP and 0.07 +/- 0.02 microg/l END. Pesticide levels at the same site during runoff following 3 storm events varying in rainfall between 6.8 and 18.4 mm/d (discharge: 7.5-22.4 m3/s) were considerably higher: by factors between 6 and 37 for AZP (0.26-1.5 microg/l) and between 2 and 41 for END (0.13-2.9 microg/l). Levels of pesticides associated with suspended particles were increased during runoff only up to 1247 microg/kg AZP and 12082 microg/kg END. A possible reason for the relative importance of runoff is that runoff largely integrates potential pesticide input over both time and space, because the prerequisites for the occurrence of runoff in terms of application and plot characteristics as well as meteorological conditions are far less specific than for spray drift. A probability analysis based on pesticide application patterns and 10-yr rainfall data indicates that the frequencies of rainfall events > or = 10 and > or = 15 mm/d are 3.4 and 1.7 per spraying season, respectively.     

A comparison of predicted and measured levels of runoff-related pesticide concentrations in small lowland streams on a landscape level

Short-term pollution events via runoff are typical of streams in agricultural areas. Existing runoff models that simulate pesticide loss from agricultural fields require extensive input of information. There is thus a need for a simple model that can predict runoff-related pesticide concentrations in many streams on a landscape level when only limited data are available. To validate such a model, the runoff-related pesticide load of 18 small lowland streams was predicted with an extended version of the model "simplified formula for indirect loadings caused by runoff" (available from the Organisation for Economic Cooperation and Development, OECD). The authors suggest that the model presented here is suitable for use in routine exposure assessment of pesticides on a landscape level, as all input data (soil, slope, precipitation, pesticide application) are readily available from public authorities or could be generated by simple regional flood hydrograph curves. The predicted concentrations were compared with measured concentrations obtained by runoff-triggered sampling. Fungicides, insecticides and herbicides were detected in 17 streams, with max. concentrations measuring up to 29.7 microg/l for the fungicide azoxystrobin and 0.3 microg/l for the insecticide parathion-ethyl. Herbicides were detected in 16 streams, with max. concentrations between 13.7 and 1.2 microg/l. The linear regression between the predicted and measured concentrations (log-values) shows significant correlations for the following pesticides: azoxystrobin: r2=0.43; p=0.03; epoxiconazole: r2=0.71; por=0.5 microg/l).     

Constructed wetlands for mitigation of atrazine-associated agricultural runoff

Atrazine was amended into constructed wetlands (59-73x14x0.3 m) for the purpose of monitoring transport and fate of the pesticide to obtain information necessary to provide future design parameters for constructed wetlands mitigation of agricultural runoff. Following pesticide amendment, a simulated storm and runoff event equal to three volume additions was imposed on each wetland. Targeted atrazine concentrations were 0 microg/l (unamended control), 73 microg/l, and 147 microg/l. Water, sediment, and plant samples were collected weekly for 35 days from transects longitudinally distributed throughout each wetland and were analyzed for atrazine using gas chromatography. Between 17 and 42% of measured atrazine mass was within the first 30-36 m of wetlands. Atrazine was below detection limits (0.05 microg/kg) in all sediment and plant samples collected throughout the duration of this study. Aqueous half lives ranged from 16 to 48 days. According to these data, conservative buffer travel distances of 100-280 m would be necessary for effective runoff mitigation.     

Assessment of insecticide contamination in runoff and stream water of small agricultural streams in the main soybean area of Argentina

The first- and second-order streams, Brown and Horqueta, respectively, which are located in the main area of soybean production in Argentina were examined for insecticide contamination caused by runoff from nearby soybean fields. The insecticides most widely used in Argentina (chlorpyrifos, cypermethrin and endosulfan) were detected in sediments, suspended particles and water. Highest concentrations in suspended particles were 318 microg/kg for endosulfan in the stream Horqueta, while 226 microg/kg chlorpyrifos and 13.2 microg/kg cypermethrin were measured in the stream Brown. In the Horqueta stream 150 and 53 microg/kg chlorpyrifos and cypermethrin were detected in runoff sediments, respectively. Whereas cypermethrin concentrations in the suspended particles were relatively low, levels in the floodwater of Brown reached 0.7 microg/l. The highest chlorpyrifos concentration in floodwater was 0.45 microg/l in Brown. However, endosulfan was not detected in the water phase. In runoff water the highest concentrations measured were 0.3 microg/l for chlorpyrifos in Horqueta and 0.49 microg/l for cypermethrin in the Brown stream. On five sampling dates during the pesticide application period in Brown stream (2002/2003) the concentration of chlorpyrifos and cypermethrin in runoff and/or floodwater exceeded the water quality criteria for freshwater mentioned in this study. In three cases this insecticide concentration was measured in stream water, indicating an acute risk to aquatic life. The acute toxicity-exposure-ratio (TER) for chlorpyrifos and cypermethrin also shows an acute risk for aquatic invertebrates in the Brown stream. In the Horqueta chlorpyrifos concentrations in the runoff exceeded the safety levels three times during the application period (2001/2002), potentially endangering the aquatic fauna. Effects on aquatic macroinvertebrates after insecticide contamination were reported in earlier studies in Horqueta stream.     

Oil spill in the Rio de la Plata estuary, Argentina: 1. Biogeochemical assessment of waters, sediments, soils and biota

Aliphatic (ALI) and aromatic (ARO) hydrocarbon concentrations, composition and sources were evaluated in waters, sediments, soils and biota to assess the impact of approximately 1000 tons of oil spilled in Rio de la Plata coastal waters. Total ALI levels ranged from 0.4-262 microg/l in waters, 0.01-87 microg/g in sediments, 5-39 microg/g in bivalves, 12-323 microg/g in macrophytes to 948-5187 microg/g in soils. ARO varied from non-detected 10 microg/l, 0.01-1.3 mug/g, 1.0-16 microg/g, 0.5-6.9 microg/g to 22-67 microg/g, respectively. Offshore (1, 5, 15 km) waters and sediments were little affected and contained low background hydrocarbon levels reflecting an effective wind-driven transport of the slick to the coast. Six months after the spill, coastal waters, sediments, soils and biota still presented very high levels exceeding baseline concentrations by 1-3 orders of magnitude. UCM/resolved aliphatic ratio showed a clear trend of increasing decay: coastal waters (3.3) < macrophytes (6.7) < soils (9.4) < offshore sediments (13) < coastal sediments (17) < clams (52). All environmental compartments consistently indicated that the most impacted area was the central sector close to Magdalena city, specially low-energy stream embouchures and bays which acted as efficient oil traps. The evaluation of hydrocarbon composition by principal component analysis indicated the predominance of biogenic (algae, vascular plant cuticular waxes), background anthropic, pyrogenic and diagenetic hydrocarbons, offshore and in non-impacted coastal sites. In contrast, polluted stations presented petrogenic signatures characterized by the abundance of isoprenoids, low molecular weight n-alkanes and methylated aromatics in different stages of alteration. The petrogenic/biogenic ratio ( n-C23) and petrogenic/pyrogenic relationship (methylated/unsubstitued PAH) discriminated the samples according to the different degree of impact. The following paper present the results of the study of the progress of hydrocarbon disappearance in sediments and soils 13 and 42 months after the spill.     

Use of oxytetracycline and tylosin in intensive calf farming: evaluation of transfer to manure and soil

Antibiotics may enter soils with manure from treated animals. Because of their biological effects, antibiotics are regarded as potential micropollutants. The levels of oxytetracycline and tylosin over time were followed in faeces, bedding and manure, and then in the soil of a manured field and surrounding drainage courses, after oral treatment of calves. Fifty Simmental calves were treated for 5 days with 60 mg/kg/day of oxytetracycline. After 15 days the animals were treated for 5 days with 20 mg/kg/day of tylosin. Tylosin degraded rapidly, and was no longer detected in manure 45 days after cessation of treatment and no trace of the compound was detected in soil or surrounding water (detection limits 10 microg/l). The half-life of oxytetracycline in manure was 30 days and the compound was still detectable in this matrix (820 microg/kg) after 5 months maturation. In the manured soil oxytetracycline was detected at concentrations at least 10 times lower than the European Agency for the Evaluation of Medicinal Products threshold (100 microg/kg) requiring phase II environmental risk assessment. Oxytetracycline was not detected in the water courses (detection limit 1 microg/l). These results demonstrate that the processes occurring between faeces production and application of manure to the soil are very effective in reducing the load of TYL and OTC in the environment. For both drugs a toxicity test was performed using the alga Selenastrum capricornutum. The EC50 was 4.18 mg/l for oxytetracycline and 0.95 mg/l for tylosin. A worst-case hazard assessment for the aquatic environment was performed comparing the ratio between the measured concentrations (LOD) and effect data from previous work (OTC) or from this work (TYL). This showed ratio between toxicity levels (bacteria) (EC50=0.14 mg/l) and measured concentrations (LOD=1 microg/l) for OTC to be 140. The corresponding value for TYL (LOD=10 microg/l) was 95.     

Individual and mixture toxicity of three pesticides; atrazine,chlorpyrifos, and chlorothalonil to the marine phytoplankton species Dunaliella tertiolecta

This study analyzed the toxicity of three pesticides (the herbicide atrazine, the insecticide chlorpyrifos and the fungicide chlorothalonil) individually, and in two mixtures (atrazine and chlorpyrifos; atrazine and chlorothalonil) to the marine phytoplankton species Dunaliella tertiolecta (Chlorophyta). A standard 96 h static algal bioassay was used to determine pesticide effects on the population growth rate of D. tertiolecta. Mixture toxicity was assessed using the additive index approach. Atrazine and chlorothalonil concentrations > or = 25 microg/L and 33.3 microg/L, respectively, caused significant decreases in D. tertiolecta population growth rate. At much higher concentrations (> or = 400 microg/L) chlorpyrifos also elicited a significant effect on D. tertiolecta population growth rate, but toxicity would not be expected at typical environmental concentrations. The population growth rate EC50 values determined for D. tertiolecta were 64 microg/L for chlorothalonil, 69 microg/L for atrazine, and 769 microg/L for chlorpyrifos. Atrazine and chlorpyrifos in mixture displayed additive toxicity, whereas atrazine and chlorothalonil in mixture had a synergistic effect. The toxicity of atrazine and chlorothalonil combined was approximately 2 times greater than that of the individual chemicals. Therefore, decreases in phytoplankton populations resulting from pesticide exposure could occur at lower than expected concentrations in aquatic systems where atrazine and chlorothalonil are present in mixture. Detrimental effects on phytoplankton population growth rate could impact nutrient cycling rates and food availability to higher trophic levels. Characterizing the toxicity of chemical mixtures likely to be encountered in the environment may benefit the pesticide registration and regulation process.     

Pesticide levels in surface waters in an agricultural-forestry basin in Southern Chile

Residues of five pesticides in surface water were surveyed during 2001 and 2003 in the Traiguen river basin in Southern Chile. Simazine, hexazinone, 2,4-D, picloram herbicides and carbendazim fungicide were selected through a pesticide risk classification index. Six sampling stations along the river were set up based on agricultural and forestry land use. The water sampling was carried out before and after the pesticide application periods and in correspondence to some rain events. Pesticides were analyzed by HPLC with DAD detection in a multiresidue analysis. During 2001, in the first sampling campaign (March), the highest concentrations of pesticides were 3.0 microg l(-1) for simazine and hexazinone and 1.8 microg l(-1) for carbendazim. In the second sampling (September), the highest concentration were 9.7 microg l(-1) for 2,4-D, 0.3 microg l(-1) for picloram and 0.4 microg l(-1) for carbendazim. In the last sampling period (December), samples indicated contamination with carbendazim fungicide at levels of up to 1.2 microg l(-1). In sampling carried out on May 2003, no pesticides were detected. In October 2003, the highest concentrations of pesticides were 4.5 microg l(-1) for carbendazim and 2.9 microg l(-1) for 2,4-D. Data are discussed in function of land use and application periods of the products, showing a clear seasonal pattern pollution in the Traiguen river. Risk assessment for these pesticides was calculated by using a risk quotient (RQ = PNEC/PEC). For picloram the calculated RQ < was 0, which indicates that no adverse effects may occur due to the exposure to this herbicide in the Traiguen river basin. For 2,4-D, simazine, hexazinone, carbendazim RQ > 1, meaning that adverse effects could occur and it is necessary to reduce pesticide exposure in surface waters. It is recommended to continue with a pesticide monitoring program and the implementation of ecotoxicological testing with local and standardized species in order to consider the probability of effects occurrence, with less uncertainty. Thus, it will be more feasible to make some recommendations to regulatory agencies regarding the pesticide use.     

Persistence and runoff losses of 3 herbicides and chlorpyrifos from a corn field in the Lake Balaton watershed of Hungary

Corn is intensively cultivated in western Hungary in the basin of Lake Balaton, one of the most important water resources in eastern Europe. Pesticide runoff was measured in 1996 and 1997 from a typical corn field near Zalaegerszeg, Hungary, which drains into the Zala River, an important water source of Lake Balaton. Three herbicides, namely atrazine, acetochlor, and propizochlor, and the insecticide chlorpyrifos were applied to bare soil in a field with 5% slope and soil and runoff water pesticide concentrations were monitored. In 1997, a rainfall-runoff simulation experiment was conducted on a small sub-plot in order to measure pesticide runoff under reasonable worst-case conditions. Under natural rainfall almost all losses occurred in a large runoff event in 1996 one month after application in which 3% of atrazine and 1% of acetochlor was transported off the field. Propizochlor and chlorpyrifos losses in the same event were much lower: 0.2% and <0.01%, respectively, because of these chemicals' shorter persistence times in near-surface soil. The rainfall simulation produced only trace amounts of losses even though 4.1 cm was applied in 2 hours; the soil was extremely dry and only 0.2 cm runoff occurred containing less than 0.01% of all chemicals applied. The results suggest that intensive use of corn herbicides, which have been found to result in widespread contamination of water resources elsewhere, may be expected to have the same impact in the Balaton watershed depending on the amounts and intensities used in the basin.     

Runoff and leaching of atrazine and alachlor on a sandy soil as affected by application in sprinkler irrigation

Abstract

Rainfall simulation was used with small packed boxes of soil to compare runoff of herbicides applied by conventional spray and injection into sprinkler‐irrigation (chemigation), under severe rainfall conditions. It was hypothesized that the larger water volumes used in chemigation would leach some of the chemicals out of the soil surface rainfall interaction zone, and thus reduce the amounts of herbicides available for runoff. A 47‐mm rain falling in a 2‐hour event 24 hours after application of alachlor (2‐chloro‐N‐(2,6‐diethylphenyl)‐N‐(methoxymethyl)‐acetamide) and atrazine (6‐chloro‐N‐ethyl‐N‐(1‐methylethyl)‐1,3,5‐triazine‐2,4‐diamine) was simulated. The design of the boxes allowed a measurement of pesticide concentrations in splash water throughout the rainfall event. Initial atrazine concentrations exceeding its’ solubility were observed. When the herbicides were applied in 64000 L/ha of water (simulating chemigation in 6.4 mm irrigation water) to the surface of a Tifton loamy sand, subsequent herbicide losses in runoff water were decreased by 90% for atrazine and 91% for alachlor, as compared to losses from applications in typical carrier water volumes of 187 L/ha. However, this difference was not due to an herbicide leaching effect but to a 96% decrease in the amount of runoff from the chemigated plots. Only 0.3 mm of runoff occurred from the chemigated boxes while 7.4 mm runoff occurred from the conventionally‐treated boxes, even though antecedent moisture was higher in the former. Two possible explanations for this unexpected result are (a) increased aggregate stability in the more moist condition, leading to less surface sealing during subsequent rainfall, or (b) a hydrophobic effect in the drier boxes. In the majority of these pans herbicide loss was much less in runoff than in leachate water. Thus, in this soil, application of these herbicides by chemigation would decrease their potential for pollution only in situations where runoff is a greater potential threat than leaching.     

Runoff and leaching of atrazine and alachlor on a sandy soil as affected by application in sprinkler irrigation

Rainfall simulation was used with small packed boxes of soil to compare runoff of herbicides applied by conventional spray and injection into sprinkler-irrigation (chemigation), under severe rainfall conditions. It was hypothesized that the larger water volumes used in chemigation would leach some of the chemicals out of the soil surface rainfall interaction zone, and thus reduce the amounts of herbicides available for runoff. A 47-mm rain falling in a 2-hour event 24 hours after application of alachlor (2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)-acetamide) and atrazine (6-chloro-N-ethyl-N'-(1-methylethyl)-1,3,5-triazine-2, 4-diamine) was simulated. The design of the boxes allowed a measurement of pesticide concentrations in splash water throughout the rainfall event. Initial atrazine concentrations exceeding its' solubility were observed. When the herbicides were applied in 64,000 L/ha of water (simulating chemigation in 6.4 mm irrigation water) to the surface of a Tifton loamy sand, subsequent herbicide losses in runoff water were decreased by 90% for atrazine and 91% for alachlor, as compared to losses from applications in typical carrier water volumes of 187 L/ha. However, this difference was not due to an herbicide leaching effect but to a 96% decrease in the amount of runoff from the chemigated plots. Only 0.3 mm of runoff occurred from the chemigated boxes while 7.4 mm runoff occurred from the conventionally-treated boxes, even though antecedent moisture was higher in the former. Two possible explanations for this unexpected result are (a) increased aggregate stability in the more moist condition, leading to less surface sealing during subsequent rainfall, or (b) a hydrophobic effect in the drier boxes. In the majority of these pans herbicide loss was much less in runoff than in leachate water. Thus, in this soil, application of these herbicides by chemigation would decrease their potential for pollution only in situations where runoff is a greater potential threat than leaching.     

Hydroponic uptake of atrazine and lambda-cyhalothrin in Juncus effusus and Ludwigia peploides

Phytoremediation encompasses an array of plant-associated processes known to mitigate contaminants from soil, sediment, and water. Modification of pesticides associated with agricultural runoff includes processes directly associated with aquatic macrophytes in addition to changes in soil geochemistry and associated rhizospheric degradation. Remediation attributes of two vegetative species common to agricultural drainages in the Mississippi Delta, USA, were assessed using atrazine and lambda-cyhalothrin. Concentrations used in 8-d hydroponic exposures were calculated using recommended field applications and a 5% runoff model from a 0.65-cm rainfall event on a 2.02-ha field. While greater atrazine uptake was measured in Juncus effusus, greater lambda-cyhalothrin uptake occurred in Ludwigia peploides. Maximum pesticide uptake was reached within 48h for each exposure and subsequent translocation of pesticides to upper plant biomass occurred in macrophytes exposed to atrazine. Sequestration of 98.2% of lambda-cyhalothrin in roots of L. peploides was measured after 8d. Translocation of lambda-cyhalothrin in J. effusus resulted in 25.4% of pesticide uptake partitioned to upper plant biomass. These individual macrophyte remediation studies measured species- and pesticide-specific uptake rates, indicating that seasonality of pesticide applications and macrophyte emergence might interact strongly to enhance mitigation capabilities in edge-of-field conveyance structures.     

MTBE and aromatic hydrocarbons in North Carolina stormwater runoff

A total of 249 stormwater samples were collected from 46 different sampling locations in North Carolina over an approximate 1-year period and analyzed to identify land use types where fuel oxygenates and aromatic hydrocarbons may be present in higher concentrations and at greater frequency. Samples were analyzed by gas chromatography-mass spectrometry in ion selective mode to achieve a quantitation limit of 0.05 microg/l. m-,p-Xylene and toluene were detected in over half of all samples analyzed, followed by MTBE: o-xylene: 1,3,5-trimethylbenzene: ethylbenzene; and 1,2,4-trimethylbenzene. Benzene, DIPE, TAME and 1,2,3-trimethylbenzene were detected in < 10% of the samples analyzed. Median contaminant concentrations (when detected) varied from 0.07 microg/l for ethylbenzene to 0.11 microg/l for toluene. All of the locations with significantly higher contaminant concentrations were associated with direct runoff from a gas station or discharge of contaminated groundwater from a former leaking underground storage tank. For all of the aromatic hydrocarbons, the maximum observed contaminant concentrations were over an order of magnitude lower than current drinking water standards.     

Estimating pesticide runoff in small streams

Surface runoff is one of the most important pathways for pesticides to enter surface waters. Mathematical models are employed to characterize its spatio-temporal variability within landscapes, but they must be simple owing to the limited availability and low resolution of data at this scale. This study aimed to validate a simplified spatially-explicit model that is developed for the regional scale to calculate the runoff potential (RP). The RP is a generic indicator of the magnitude of pesticide inputs into streams via runoff. The underlying runoff model considers key environmental factors affecting runoff (precipitation, topography, land use, and soil characteristics), but predicts losses of a generic substance instead of any one pesticide. We predicted and evaluated RP for 20 small streams. RP input data were extracted from governmental databases. Pesticide measurements from a triennial study were used for validation. Measured pesticide concentrations were standardized by the applied mass per catchment and the water solubility of the relevant compounds. The maximum standardized concentration per site and year (runoff loss, R_Loss) provided a generalized measure of observed pesticide inputs into the streams. Average RP explained 75% (p < 0.001) of the variance in R_Loss. Our results imply that the generic indicator can give an adequate estimate of runoff inputs into small streams, wherever data of similar resolution are available. Therefore, we suggest RP for a first quick and cost-effective location of potential runoff hot spots at the landscape level.     

Responses of Hyalella azteca and phytoplankton to a simulated agricultural runoff event in a managed backwater wetland

We assessed the aqueous toxicity mitigation capacity of a hydrologically managed floodplain wetland following a synthetic runoff event amended with a mixture of sediments, nutrients (nitrogen and phosphorus), and pesticides (atrazine, S-metolachlor, and permethrin) using 48-h Hyalella azteca survival and phytoplankton pigment, chlorophyll a. The runoff event simulated a 1 h, 1.27 cm rainfall event from a 16 ha agricultural field. Water (1 L) was collected every 30 min within the first 4 h, every 4 h until 48 h, and on days 5, 7, 14, 21, and 28 post-amendment at distances of 0, 10, 40, 300 and 500 m from the amendment point for chlorophyll a, suspended sediment, nutrient, and pesticide analyses. H. azteca 48-h laboratory survival was assessed in water collected at each site at 0, 4, 24, 48 h, 5 d and 7 d. Greatest sediment, nutrient, and pesticide concentrations occurred within 3 h of amendment at 0 m, 10 m, 40 m, and 300 m downstream. Sediments and nutrients showed little variation at 500 m whereas pesticides peaked within 48 h but at <15% of upstream peak concentrations. After 28 d, all mixture components were near or below pre-amendment concentrations. H. azteca survival significantly decreased within 48 h of amendment up to 300 m in association with permethrin concentrations. Chlorophyll a decreased within the first 24 h of amendment up to 40 m primarily in conjunction with herbicide concentrations. Variations in chlorophyll a at 300 and 500 m were associated with nutrients. Managed floodplain wetlands can rapidly and effectively trap and process agricultural runoff during moderate rainfall events, mitigating impacts to aquatic invertebrates and algae in receiving aquatic systems.     

A qualitative sampling method for monitoring water quality in temporary channels or point sources and its application to pesticide contamination

A water-sampling device to monitor the quality of water periodically and temporarily flowing out of concrete tubes, sewers or channels is described. It inexpensively and easily enables a qualitative characterization of contamination via these point-source entry routes. The water sampler can be reverse engineered with different sizes and materials, once installed needs no maintenance, passively samples the first surge, and the emptying procedure is short. In an agricultural catchment area in Germany we monitored an emergency overflow of a sewage sewer, an outlet of a rainwater sewer and two small drainage channels as input sources to a small stream. Seven inflow events were analysed for 20 pesticide agents (insecticides, fungicides and herbicides). All three entry routes were remarkably contaminated. We found parathion-ethyl concentrations of 0.3 microg l(-1), diuron up to 17.3 microg l(-1), ethofumesate up to 51.1 microg l(-1), metamitron up to 92 microg l(-1) and prosulfocarb up to 130 microg l(-1).     

Bioconcentration factor of relatively low concentrations of chlorophenols in Japanese medaka

Bioconcentration factors (BCF) for pentachlorophenol (PCP) and 2,4-dichlorophenol (2,4-DCP) in Japanese medaka (Oryzias latipes) were determined at five different concentrations of the chemicals, between 0.1 and 10 microg/l (PCP), 0.3 and 30 microg/l (2,4-DCP), in the ambient water. Medaka were exposed to each chemicals in a continuous-flow system during the embryonic development period and 60 days after hatching from eggs collected in the laboratory. Both the exposure time and the aqueous concentrations are much more realistic and closer to natural aquatic environments than those used in conventional BCF studies. The BCF values of PCP were from (4.9+/-2.8)x10(3) at the aqueous concentration of 0.074+/-0.028 microg/l to (2.1+/-1.4)x10(3) at 9.70+/-0.56 microg/l. The BCF value of 2,4-DCP were from (3.4+/-3.0)x10(2) at 0.235+/-0.060 microg/l to 92+/-27 at 27.3+/-1.6 microg/l. Generally, BCF values increased as the aqueous concentrations of PCP or 2,4-DCP decreased. This finding suggests that a relatively low and realistic aqueous concentration of these compounds is necessary to more accurately determine their BCF values in natural aquatic environments. Conventional BCF experiments at higher aqueous concentrations may underestimate the BCF values.     

Pesticide concentrations in agricultural storm drainage inlets of a small Swiss catchment

Agricultural pesticides transported to surface waters pose a major risk for aquatic ecosystems. Modelling studies indicate that the inlets of agricultural storm drainage systems can considerably increase the connectivity of surface runoff and pesticides to surface waters. These model results have however not yet been validated with field measurements. In this study, we measured discharge and concentrations of 51 pesticides in four out of 158 storm drainage inlets of a small Swiss agricultural catchment (2.8 km²) and in the receiving stream. For this, we performed an event-triggered sampling during 19 rain events and collected plot-specific pesticide application data. Our results show that agricultural storm drainage inlets strongly influence surface runoff and pesticide transport in the study catchment. The concentrations of single pesticides in inlets amounted up to 62 µg/L. During some rain events, transport through single inlets caused more than 10% of the stream load of certain pesticides. An extrapolation to the entire catchment suggests that during selected events on average 30 to 70% of the load in the stream was transported through inlets. Pesticide applications on fields with surface runoff or spray drift potential to inlets led to increased concentrations in the corresponding inlets. Overall, this study corroborates the relevance of such inlets for pesticide transport by establishing a connectivity between fields and surface waters, and by their potential to deliver substantial pesticide loads to surface waters.

     

Organo-chlorine pesticide (DDT and HCH) residues in the Taihu Lake Region and its movement in soil-water system I. Field survey of DDT and HCH residues in ecosystem of the region

The use of organo-chlorine (DDT and HCH) has been banned in China for 20 years. A field survey was carried out during 1999-2000 in the Taihu Lake Region. Organo-chlorine pesticide (OCP) residues in soil, water, fish and sediment samples were investigated. DDT was detected in 5 out of 10 samples with concentration ranging from 0.3 to 5.3 microg/kg in the surface (0-15 cm) layer, 6 out of 10 with 0.5 to 4.0 microg/kg in the subsoil layer (16-30 cm), and 4 of 10 with 0 to 2.7 microg/ kg in the deep soil layer (31-50 cm). Results for HCH residues in soil samples were similar to those of DDT. These results indicate that OCP residues in 0-50 cm profile had been leached out or degraded to safe level. In river water DDT was detected in 10 out of 13 samples ranging from 0.2 to 9.3 microg/l, with an average of 1.0 microg/l. While HCH was detected in 12 out of 13 samples ranging from 0.02 to 36.1 microg/l, with an average 5.6 microg/l. DDT residues in sediment ranged from 0.1 to 8.8 microg/kg, while HCH ranged from 0.3 to 66.5 microg/kg. DDT residues in fish body ranged from 3.7 to 23.5 microg/kg and HCH ranged from 3.7 to 132 microg/kg. These results demonstrate an accumulation through food chain (from soil-water-sediment-microbes-crop-fish-... etc.), also that HCH residues are generally more persistent than DDT residues. However, all these data are well below than the state warning standard limit.     

Determination of beta-adrenergic receptor blocking pharmaceuticals in United States wastewater effluent

Beta adrenergic receptor antagonists (beta-Blockers) are frequently prescribed medications in the United States and have been identified in European municipal wastewater effluent, however no studies to date have investigated these compounds in United States wastewater effluent. Municipal wastewater effluent was collected from treatment facilities in Mississippi, Texas, and New York to investigate the occurrence of metoprolol, nadolol, and propranolol. Propranolol was identified in all wastewater samples analyzed (n = 34) at concentrations < or = 1.9 microg/l. Metoprolol and nadolol were identified in > or = 71% of the samples with concentrations of metoprolol < or = 1.2 microg/l and nadolol < or = 0.36 microg/l. Time course studies at both Mississippi plants and the Texas plant indicate that concentrations of propranolol, metoprolol, and nadolol remain relatively constant at each sampling period. This study indicates that beta-Blockers are present in United States wastewater effluent in the ng/l to microg/l range.