The potential steroid hormone contribution of farm animals to freshwaters, the United Kingdom as a case study

The combined farm animal population is considerably larger than the human one in the United Kingdom, implying a possibly important contribution to the environmental load of steroid hormones entering water. To make comparisons on the amount of steroid hormones produced by the different livestock, information was gathered on the structure of the UK farm animal populations and the amount of hormones excreted by animals at each of their life stages. An individual normalised dairy cow excretes two orders of magnitude more, and a normalised pig excretes more than one order of magnitude more steroid oestrogens than a normalised human. In terms of excretion, the combined farm animal population (including sheep and poultry) probably generates around four times more oestrogens than the human population in the UK. The biggest contributor on the animal side is the relatively small dairy cow population. If steroid oestrogens behave like herbicides, in which a worst case loss to surface waters is around 1%, then it could be argued that farm animals are responsible for 15% of all the oestrogens in UK waters. When simulations were made with the MACRO pesticide leaching model, predicted concentrations for field drains failed to exceed 1 ng/L. The rapid biodegradation rates, and high sorption rates taken from the literature and used in the model suggested less than 0.001% of oestrogens would reach the field drains. This survey suggests that direct excretion of steroid hormones by animals into water courses, or discharges from farmyard drains, are likely to be more important sources of contamination rather than via normal agricultural scenarios.     

Modelling through-soil transport of phosphorus to surface waters from livestock agriculture at the field and catchment scale

A model of phosphorus (P) losses in a small dairy farm catchment has been set up based on a linkage of weather-driven field-scale simulations using an adaptation of the MACRO model. Phosphorus deposition, both in faeces from grazing livestock in summer and in slurry spread in winter, has been represented. MACRO simulations with both forms of P deposition had been calibrated and tested at the individual field scale in previous studies. The main contaminant transport mechanism considered at both field and catchment scales is P sorbed onto mobile colloidal faeces particles, which move through the soil by macropore flow. Phosphorus moves readily through soil to field drains under wet conditions when macropores are water-filled, but in dry soil the P carrying colloids become trapped so losses remain at a low level. In the catchment study, a dairy farm is assumed to be composed of fields linked by a linear system of ditches which discharge into a single river channel. Results from linked simulations showed reasonable fits to values of catchment outflow P concentrations measured at infrequent intervals. High simulated outflow P concentrations occurred at similar times of year to high measured values, with some high loss periods during the summer grazing season and some during the winter when slurry would have been spread. However, there was a lack of information about a number parameters that would be required to carry out a more exact calibration and provide a rigorous test of the modelling procedure. It was nevertheless concluded that through soil flow of colloid sorbed P by macropore flow represents a highly plausible mechanism by which P is transported to river systems in livestock farming catchments. This represents an alternative to surface runoff transport, a mechanism to which high P losses from livestock farming areas have often been attributed. The occurrence of high simulated levels of loss under wet conditions indicates environmental benefits from avoiding slurry spreading on wet soil or during rain, and from some forms of grazing management.     

Using a linked soil model emulator and unsaturated zone leaching model to account for preferential flow when assessing the spatially distributed risk of pesticide leaching to groundwater in England and Wales

Although macropore flow is recognized as an important process for the transport of pesticides through a wide range of soils, none of the existing spatially distributed methods for assessing the risk of pesticide leaching to groundwater account for this phenomenon. The present paper presents a spatially distributed modelling system for predicting pesticide losses to groundwater through micro- and macropore flow paths. The system combines a meta version of the mechanistic, dual porosity, preferential flow pesticide leaching model MACRO (the MACRO emulator), which describes pesticide transport and attenuation in the soil zone, to an attenuation factor leaching model for the unsaturated zone. The development of the emulator was based on the results of over 4000 MACRO model simulations. Model runs describe pesticide leaching for the range of soil types, climate regimes, pesticide properties and application patterns in England and Wales. Linking the MACRO emulator to existing spatial databases of soil, climate and compound-specific loads allowed the prediction of the concentration of pesticide leaching from the base of the soil profile (at 1 m depth) for a wide range of pesticides. Attenuation and retardation of the pesticide during transit through the unsaturated zone to the watertable was simulated using the substrate attenuation factor model AQUAT. The MACRO emulator simulated pesticide loss in 10 of 12 lysimeter soil-pesticide combinations, for which pesticide leaching was shown to occur and also successfully predicted no loss from 3 soil-pesticide combinations. Although the qualitative aspect of leaching was satisfactorily predicted, actual pesticide concentrations in leachate were relatively poorly predicted. At the national scale, the linked MACRO emulator/AQUAT system was found to predict the relative order of, and realistic regional patterns of, pesticide leaching for atrazine, isoproturon, chlorotoluron and lindane. The methodology provides a first-step assessment of the potential for pesticide leaching to groundwater in England and Wales. Further research is required to improve the modelling concept proposed. The system can be used to refine regional groundwater monitoring system designs and sampling strategies and improve the cost-effectiveness of the measures needed to achieve 'good status' of groundwater quality as required by the Water Framework Directive.     

Particulate phosphorus transport by sub-surface drainage from agricultural land in the UK. Environmental significance at the catchment and national scale

Phosphorus (P) is the key limiting nutrient in most UK freshwater systems. With increased legislation controlling point source inputs, dissolved (DP) and particulate P (PP) derived from diffuse sources are making a more significant contribution to the total P loading of surface waters. Recent research has focused on pathways linking diffuse sources to the fluvial system and sub-surface field drains have been shown to transport both sediment and P rapidly to watercourses. Preliminary results are presented from an ongoing study using environmental tracers to identify the source of the drain sediment and its potential as a carrier of PP. These results suggest that the majority of sediment in drains is topsoil derived, but the significance of P loss via this pathway in a regional or UK context has yet to be evaluated. A protocol to study the potential problem at a regional/national scale is discussed and initial data presented.     

Identification and significance of sulphonamides (p-TSA, o-TSA, BSA) in an urban water cycle (Berlin, Germany)

Because of the nature of the water cycle in Berlin, a number of persistent wastewater residues are present in the surface water and may potentially reach the groundwater via bank filtration and artificial recharge. The occurrence and behaviour of the wastewater residues para-toluenesulphonamide (p-TSA), ortho-toluenesulphonamide (o-TSA) and benzenesulphonamide (BSA) through wastewater treatment, surface water, bank filtration and drinking water treatment was studied. In addition, groundwater below a former sewage farm was investigated. All three compounds are ubiquitous in the aquatic environment of Berlin. p-TSA concentrations are much higher than those of o-TSA and BSA. p-TSA was found in high concentrations in the wastewater influent (2 to 15microg/L), in the wastewater effluent (<0.15 to 2.34microg/L) and in sewage farm groundwater (<0.05 to 20microg/L) and in lower concentrations in the surface water (<0.05 to 1.15microg/L), bank filtrate (<0.05 to 0.30microg/L) and drinking water (<0.05 to 0.54microg/L). p-TSA is considerably depleted during waste- and drinking water treatment ( approximately 90% reduction each). The concentration ranges for o-TSA and BSA in wastewater influents were 0.11 to 8microg/L and <0.05 to 0.64microg/L, respectively, while the values for wastewater effluents were 0.14 to 4microg/L for o-TSA and 0.25 to 0.49microg/L for BSA. Wastewater treatment and drinking water treatment do not reduce the concentrations of o-TSA and BSA. The behaviour of o-TSA during wastewater treatment varies largely between different wastewater treatment plants where concentrations increase, remain constant or decrease. BSA forms during treatment. The concentrations measured in surface water, sewage farm groundwater, bank filtrate and drinking water were <0.05 to 1.74microg/L for o-TSA and <0.05 to 0.53microg/L for BSA.     

Runoff-related agricultural impact in relation to macroinvertebrate communities of the Lourens River, South Africa

A field study at the Lourens River, South Africa, was undertaken during the pesticide application period between November 2001 and January 2002 in order to investigate the potential relation of agricultural pollution to the aquatic macroinvertebrate fauna. The upper regions of the Lourens River were free of contamination (LR1), whereas subsequent stretches flowing through a 400-ha orchard area (LR2) received transient insecticide peaks. Continuously operating suspended-particle samplers as well as flood samplers operating during runoff events were used to measure pesticide contamination. In addition, various physicochemical and morphological parameters were examined. A survey of the macroinvertebrate communities associated with the rocky substrates was carried out every three weeks. Community indices were calculated using the South African Scoring System (SASS 5) for bioassessment of water quality in rivers. The two sites differed in pesticide pollution as well as in average turbidity levels (LR1 5.5 mg/L; LR2 64.3 mg/L), but were similar in bottom substrate composition and most other abiotic factors. At the downstream site (LR2), pesticide values of 0.05 microg/L azinphos-methyl in water as well as 49 microg/kg azinphos-methyl, 94 microg/kg chlorpyrifos and 122 microg/kg total endosulfan in suspended particles were found during runoff conditions. The macroinvertebrate communities of the two sampling sites were similar in terms of number of total individuals, but differed significantly (ANOVA) in average number of taxa (LR1 11.7, LR2 8.9). Seven out of 17 investigated taxa occurred in significantly reduced numbers or were even absent at the downstream site LR2. The community characteristics determined by SASS 5 showed a significantly less sensitive community structure at the downstream site (TS 41; ASPT 4.6), indicating continuously lower water quality compared to site LR1 (TS 80; ASPT 6.9). It is concluded that the Lourens River macroinvertebrate communities are affected by agricultural pollution, with pesticides and increased turbidity as the most important stressors.     

Phosphorus in soils and field drainage water in the Thame catchment,UK

Field drains were sampled at five farms in a catchment in south-central England. The farms were selected to include the main soil types present in the catchment, stagnogleys and pelosols. The phosphorus content of field drainage water was measured on several occasions from 1999 to 2000, under varying flow conditions. The components measured were soluble reactive phosphorus (SRP), total dissolved phosphorus (TDP) and total phosphorus (TP). SRP concentrations in drainage water were lower than in streams in the catchment which had no apparent point source. This indicated that many streams were receiving unidentified point sources of SRP. Measurements of P in field drainage water samples under high flow conditions showed concentrations of particulate phosphorus and SRP up to 1300 and 300 μg l⁻¹, respectively, these being associated with high suspended sediment concentrations. Comparison of field drain and soil phosphorus contents at the locations sampled did not provide evidence of an inter-relationship. The equilibrium phosphorus content (EPC₀) of surface soil was generally higher than the SRP content of drainage water, at one farm by 1 order of magnitude. The variability in measurements suggested a larger-scale and more focussed survey would be required to characterise catchment-scale phosphorus losses from commercial farms by land use and soil type.     

Mitigation strategies to reduce pesticide inputs into ground- and surface water and their effectiveness; a review

In this paper, the current knowledge on mitigation strategies to reduce pesticide inputs into surface water and groundwater, and their effectiveness when applied in practice is reviewed. Apart from their effectiveness in reducing pesticide inputs into ground- and surface water, the mitigation measures identified in the literature are evaluated with respect to their practicability. Those measures considered both effective and feasible are recommended for implementing at the farm and catchment scale. Finally, recommendations for modelling are provided using the identified reduction efficiencies. Roughly 180 publications directly dealing with or being somehow related to mitigation of pesticide inputs into water bodies were examined. The effectiveness of grassed buffer strips located at the lower edges of fields has been demonstrated. However, this effectiveness is very variable, and the variability cannot be explained by strip width alone. Riparian buffer strips are most probably much less effective than edge-of-field buffer strips in reducing pesticide runoff and erosion inputs into surface waters. Constructed wetlands are promising tools for mitigating pesticide inputs via runoff/erosion and drift into surface waters, but their effectiveness still has to be demonstrated for weakly and moderately sorbing compounds. Subsurface drains are an effective mitigation measure for pesticide runoff losses from slowly permeable soils with frequent waterlogging. For the pathways drainage and leaching, the only feasible mitigation measures are application rate reduction, product substitution and shift of the application date. There are many possible effective measures of spray drift reduction. While sufficient knowledge exists for suggesting default values for the efficiency of single drift mitigation measures, little information exists on the effect of the drift reduction efficiency of combinations of measures. More research on possible interactions between different drift mitigation measures and the resulting overall drift reduction efficiency is therefore indicated. Point-source inputs can be mitigated against by increasing awareness of the farmers with regard to pesticide handling and application, and encouraging them to implement loss-reducing measures of "best management practice". In catchments dominated by diffuse inputs at least in some years, mitigation of point-source inputs alone may not be sufficient to reduce pesticide loads/concentrations in water bodies to an acceptable level.     

Drainage ditch–aquifer interaction with special reference to surface water salinity in the Thurne catchment,Norfolk, UK

Open drainage ditches located in low permeability material can interact with an underlying aquifer, especially if the drains almost or totally penetrate through to the aquifer. This interaction can be represented by drain coefficients incorporated in regional groundwater models. The drain coefficients depend on both the vertical distance from the base of the drain to the aquifer and the hydraulic conductivities of the low permeability deposits and the underlying aquifer. In a case study of drained marshes in the Thurne catchment in Norfolk, UK, drains with a water level below ordnance datum (OD) draw in saline water from the coast and freshwater from recharge areas. Pathlines, derived from a regional groundwater model analysis, explain the salinities measured in drains. In addition a series of vertical section numerical model solutions are used to develop general guidance on the selection of drain coefficients.     

Dynamics of arsenic in agricultural soils irrigated with arsenic contaminated groundwater in Bangladesh

Arsenic (As) concentrations in the soil layers of 12 rice fields located in four As affected areas and two unaffected areas in Bangladesh were monitored during 2003. In the unaffected areas, where irrigation water contained little As (<1 microg/L), As concentrations of rice field soils ranged from 1.5 to 3.0 mg/kg and did not vary significantly with either depth or sampling time throughout the irrigation period. In the As affected areas where the irrigation water contained elevated As (79 to 436 microg/L), As concentrations of rice field soils were much higher compared to those in the unaffected areas and varied significantly with both depth and sampling time. For the top 0 to 150 mm of the soil, the As concentration increased significantly at the end of the irrigation season (May-June 2003). About 71% of the As that is applied to the rice field with irrigation water accumulates in the top 0 to 75 mm soil layer by the end of the irrigation season. After the wet season during which the rice fields were inundated with flood/rain water, the As concentrations in the soil layer decreased significantly and were reduced to levels comparable to those found in soil samples collected at the beginning of the irrigation period. The long-term As accumulation in agricultural soil appears to be counteracted by biogeochemical pathways leading to As removal from soil.     

Pesticides in the Rhône river delta (France): basic data for a field-based exposure assessment

The pesticide concentration levels flowing into paddy fields and surrounding lagoons of the Rh?ne river delta were investigated over a period of 6 months in 2004. Water samples were collected at the outlets of the major ditches and in the lagoons in order to study the seasonal variation in pesticide concentrations and the spatial contamination profile. Twenty four pesticides were monitored, mainly herbicides and insecticides. Rice pesticides accounted for 90% of the detection rates while the pesticides transported by the Rh?ne river water dissolved phase only accounted for 10%. Pretilachlor, oxadiazon, MCPA and bentazone herbicides were found at the highest frequencies into the effluent waters of ditches with maximum concentration levels of 1.2, 0.8, 2.5 and 1.6 microg/L, respectively. Only one insecticide, tebufenozide, was sporadically detected at a maximum concentration level of 0.12 microg/L. There were two main peaks of contamination. The first one in April corresponded to the use of pre-emergence herbicides (oxadiazon and pretilachlor) and the second one in June was related to the post-emergence herbicides (MCPA and bentazone). These concentration peaks were well correlated with the pesticide application period time and rapid pesticide transfer (1-2 weeks) from fields to lagoons were observed. Increased loads of the pre-emergence herbicides were induced by the specific management of paddy fields which includes water emptying of fields before and after rice seeding. Pesticide dissipation into the lagoons occurred very quickly and the duration of the exposure of non-target aquatic organisms to high pesticide concentrations (in total a few microg/L level) was no longer than 2 weeks. According to the physico-chemical properties of the chemicals, contrasting results were observed when studying the spatial variation in pesticide concentrations through the lagoons. The concentrations of bentazone and MCPA, two substances with high phototransformation abilities, quickly decreased between the ditches and the lagoons while the oxadiazon and pretilachlor concentrations were more homogeneous.     

成层未打穿砂井地基固结Lagrange插值解法

考虑井阻和涂抹区的影响,建立成层未打穿砂井地基固结的数值模型和算法。将未打穿砂井底面下的软土层视为虚拟排水井,同时将未打穿砂井转化为打穿的多段砂井,使得土层边界条件和数值计算过程简单化。对超孔隙水压力用Lagrange插值多项式等结点插值近似,把砂井打设区固结方程转化为结点的超孔隙水压力的简单微分方程组,砂井固结方程转化为一线性代数方程组,以4层土为例,导出详细的计算公式。如增加土层数,仅需改变边界结点系数公式。最后,把该解法与相关近似方法的计算结果进行分析比较,并给出一个多层软土路基预压加固工程案例。结果表明,将下卧层简化为一维固结与考虑其三维固结对计算结果影响很小。     

Pesticide Transport to Surface Waters within an Agricultural Catchment

This paper presents data on the distribution of seven pesticides in an agricultural catchment which is located within the Agricultural Development and Advisory Service farm at Rosemaund, 11 km north-east of Hereford, UK. Data for aldicarb, atrazine, carbofuran, dimethoate, MCPA and isoproturon, are available for both the soil and surface waters (drain and stream water), with simazine data available only for the stream. Measurements were taken before and after pesticide application, which was made following normal agricultural practice. Soil residue data showed the degradation rates of the pesticides to be within the range of literature values. Pesticide levels in the stream and drains during runoff events following rainfall ranged from below detection limits (typically 0.02-0.1 μg/1), to 264 μg/1 (for carbofuran). Over 90% of the events had detectable maximum concentrations. The percentage of pesticide applied, which was removed during individual rainfall events, was calculated. The maximum value estimated was 1.1%, again for carbofuran. Most of the events gave values several orders of magnitude below this value.
The data have been used to try to validate a range of models which could be used for screening new pesticides or for informing decisions on the use of existing pesticides. The results of the validations are summarized.     

Comparative ecological risks of pesticides used in plantation production of papaya: application of the SYNOPS indicator

Pesticides are used intensively for crop protection in tropical fruit plantations. Assessments of the relative risks posed by pesticides are needed to assist in the development of management plans that minimize ecological impacts. In this study, the risk indicator SYNOPS_2 was used to compare risks to aquatic ecosystems by pesticides commonly used in papaya plantations. Plant interception and spray drift were measured during six applications of three pesticides (chlorothalonil, chloropyrifos, and malathion) using a turbo fan driven sprayer. Plant interception was estimated to be higher (42.6+/-12.7%; p=0.04) in late (8-14 months old) than in early (4 months old) trees (20.1+/-25.3%). Chlorothalonil concentrations of up to 11.0 microg L(-1) were found in water from an adjacent ditch after field application. Concentrations of this pesticide (7.4+/-4.1 microg L(-1)) in runoff water were also significantly (p<0.01) higher than those of malathion (2.4+/-1.9 microg L(-1)) and chlorpyrifos (0.8+/-0.5 microg L(-1)). Good correlation between measured and predicted values (r2=0.56-0.85, p<0.01) showed that SYNOPS_2 is able to describe trends in runoff pollution in papaya plantations. Linear equations were obtained in order to correct numerical disagreement between measured and calculated runoff concentrations. An independent test showed a reasonable agreement between measured chlorothalonil concentrations and the predicted values using the proposed equations. Fifteen pesticides used in papaya cultivation were ranked according to their calculated chronic biological risk index. Pesticides with the highest risk index for non-target organisms were: chlorothalonil for algae, lambda cyahalotrin for Daphnia and fish, and malathion for earthworms. Chlorothalonil was the pesticide with the highest exposure level in water and therefore represents a high risk for aquatic life. Results show that SYNOPS_2 can be used as a pesticide risk indicator on papaya and possibly other tropical fruit plantations.     

Verification of effectiveness and design procedure of gravel drains for liquefaction remediation

The current design practice of using gravel drains as a liquefaction countermeasure involves the selection of the drain spacing and drain diameter to keep the peak excess pore water pressure ratio low. As it has mostly been verified through small-scale 1 g shaking tests, its validity for the field-scale prototype has yet to be well investigated. In this study, a series of centrifuge tests was conducted to gain insight into the stress-dependent behavior of loose sand deposits with a level surface improved by gravel drains. Meanwhile, the current design procedure was validated with experimental data. The results revealed that the effects of gravel drains in suppressing the excess pore pressures depend significantly on the depth of the drains. The current design procedure has failed to elucidate the depth-dependent behavior of sand deposits. One of the important features of the mechanical properties of the soil used for the design of gravel drains was revealed through laboratory tests in which the coefficient of volumetric compressibility, m_v, was found to be highly dependent on the stress level, while m_v was assumed to be fixed in the design procedure. It was also found that the water flow regime in gravel drains can be a turbulent flow. The Reynolds number in drains increases from the bottom to the top, and the permeability coefficient decreases accordingly, resulting in more significant well resistance than expected based on the current design procedure. In the present study, when stress level-dependent m_v and Reynolds number-dependent k_w were used as input soil parameters, the axisymmetric diffusion equation, with consideration given to the well resistance, satisfactorily predicted the excess pore pressures in sand with gravel drains.     

Characterization of a braided strip drain with coir and jute yarns

A simple machine has been developed at the Textile Technology Department of IIT Delhi that uses coir and jute yarns to manufacture 100% natural fibre strip drains. The machine employing braiding technology braids jute yarns to form the filter sheath and coir yarn as core. Typically the drains are about 7.5–12.5 mm thick in dry state and have a tensile strength of above 3 kN. The properties of the drain have been studied in comparison with two synthetic strip drains and another type of natural fibre strip drain. In general, the properties of this drain are found comparable with typical synthetic drains, except that for a slightly lower discharge capacity under soil confinement. An important feature of the jute yarn sheath is its swelling nature that allows it to function as filter without clogging. The present drain differs from the other natural fibre sheath drain is that it is manufactured in single machine, and has capability of varying the width, thickness and weight per linear meter to suit different soil conditions.     

The specification and use of geotextile fin drains

This paper describes the composition, construction and uses of the rather special range of geotextile composites which have generally become known as ‘fin drains’. It tries to provide a generic definition of the term ‘fin drain’ which encompasses all current commercial products, and foreseeable types. In particular, it excludes composites which are intended for, or which function as, either pressure-driven water transporters, or capillary driven systems. Pressure-driven drains include, in particular, those drains commonly known as ‘wicks’ which are used for the relief of excess pore pressure in soft ground construction work. Similarly, a number of geotextiles have the facility of passing water within their plane by virtue of internal capillary attraction generated at the interfaces of the composite fine fibres. Such products transmit only small volumes of water, and their intended functions and design principles are entirely different from those of ground fin drains in the sense included in this paper.     

Natural organic matter (NOM) and pesticides removal using a combination of ion exchange resin and powdered activated carbon (PAC)

The combination of anion exchange resins (AERs) and powdered activated carbon (PAC) was studied to remove both natural organic matter (NOM) and pesticides. Experiments were conducted with high dissolved organic carbon (DOC) surface water (about 6.0mg DOC/L) spiked with both atrazine and isoproturon. AERs, like MIEX and IRA938, showed up to 75% removal of DOC after 30min contact time. The addition of PAC after treatment with these AERs only slightly decreased the residual DOC from 1.4 to 1.2mg/L. Experiments conducted with high (200microg/L) and low (1microg/L) initial pesticide concentrations showed that simultaneous and successive combinations of AER and PAC significantly improve the removal of both pesticides compared with PAC treatment on raw water. The improvement of short-term adsorption kinetics was explained by the adsorption of pesticides on AERs (about 5%) and the removal of high molecular weight (MW) NOM structures by AERs that reduce pore blockage phenomena. For 24h contact time with PAC (adsorption isotherms), the benefit of AER treatment was lower, which indicates that the refractory DOC to AER treatment still competes through direct site competition mechanism. MIEX resin had a distinct behavior since the simultaneous treatment with PAC showed no benefit on pesticide adsorption. The presence of fine residues of MIEX was shown to interfere with PAC adsorption.     

大型污水处理厂生化池进出水暗渠施工技术

沈阳南部污水处理工程有3个大型生化池,采用暗渠配水,进出水渠道长约400m,其中出水渠道和二沉池排泥渠合建。针对暗渠路线长,防水、防渗问题大、易产生裂缝等特点,采用分区施工、基坑开挖、模板选择、加强钢筋和混凝土施工管理、伸缩缝和施工缝精细施工以及重视检查井安装等措施,有效保证了工程质量。