Drainage Water Samples Research Articles

Investigating the Effect of Three Nitrate Fertilizers on Nitrate Leaching under the Root Zone in Clay Loam Soil

Problem statements: Nitrogen fertilizer is recognized as an important factor in crop’s yield level, however more application of N fertilizers in the soil have some adverse effects on environment and especially on groundwater contamination. Perception and recognition the factors influencing nitrate transport through soil profile is helpful for fertilizer management to minimize adverse impacts on environment and nitrate leaching below the root zone. Approach: In this study, 9 large cylindrical lysimeters with 1 m height and 0.5 m diameter were filled with clay loam soil and planted with maize to investigate nitrate leaching under different types of N-fertilizer, chemical fertilizer, activated sludge and organic manure. Nitrate concentration in the soil and drainage water samples were analyzed by spectrophotometer method and the mass of nitrate was calculated in soil and drainage water. Crop productions for different treatments were compared too. Results: Results showed that cumulative mass of nitrate leaching from organic fertilizer was greater than the other treatments (229 kg ha-1). Organic manure had the greatest nitrate accumulation in soil (15.17 mg kg-1), which was significantly greater than chemical fertilizer. Conclusions/Recommendations: Experimental results showed that manure application could result in NO3--N accumulation increase in the deeper soil profiles compared with activated sludge. Results showed that maize production was significantly higher under activated sludge fertilizer. Observations made in the current study suggest activated sludge fertilizer due to a higher crop production with same level of groundwater contamination, especially in clay loam soils.

Understanding the extent of interactions between groundwater and surface water through major ion chemistry and multivariate statistical techniques

AbstractThe present work examines the possible use of major ion chemistry and multivariate statistical techniques as a rapid and relatively cost‐effective method of identifying the extent of groundwater and surface water (GW–SW) interaction in an urban setting. The original hydrogeochemical dataset consists of groundwater (n = 114), stream water (n = 42) and drain water (n = 24) samples, collected twice in a year for the pre‐ and post‐monsoon seasons, for three successive years along an 8 km reach of the Delhi segment of River Yamuna, India. The dynamic and similar seasonal changes of hydro‐geochemical facies and major ion trends of river, drain and groundwater samples indicate the existence of an empirical relationship between GW and SW. Results of both R‐ and Q‐mode factor and cluster analyses highlight multi‐scale control of the fluid exchange distributions, with distinct seasonal alteration in mode and extent of GW–SW interaction, namely, the influence of the mixing zones between urban river and groundwater and the pattern of groundwater flow through the river bed. Hierarchical cluster analysis (HCA) of sampling locations efficiently illustrates different groups that comprise samples severely influenced by contaminated surface water downstream and the upstream fresh water samples. These results substantiate the strong exchange processes between GW and SW all along the stretch. The study shows that the combination of an empirical and statistical relationship between different ionic species and sampling locations can provide greater confidence in identifying the extent of GW–SW interaction/exchange processes. Copyright © 2008 John Wiley & Sons, Ltd.

The impact of artificial drainage on water quality in two model areas in the bohemian forest foothills

This contribution arises from a broader research assignment dealing with the changes in soil properties and characteristics which have occurred following the artificial drainage of some agricultural soils in the Czech Republic. The current state is statistically compared with the state before the drainage. Thanks to the Research Institute for Soil and Water Conservation database, extensive sets of historical data are available. To enable a more detailed evaluation of the changes discovered, we chose two smaller study areas with different soil use. In the first area (Haklovy Dvory – arable land) there is intensive use of the soil, while in the other area (Železná – pastures) the use is not intensive. Historical data from about 30 years ago on the quality of surface and ground (well) water in the Železná area were taken as a starting point. The same types of water quality analyses were then made with water samples taken semi-annually in the Železná area since 2004 and once only (in 2005) in the Haklovy Dvory area. That led to the creation of an extensive body of information of water quality in the study areas. Within the framework of this information, the recent data, being still constantly supplemented, and the historical data on tile drainage, surface (stream) and underground (well) water quality are compared. In the course of the monitoring we focused on the following chemical indicators in the water: pH, alkalinity-acidity, total hardness, the concentrations of selected cations (magnesium, calcium, potassium, ammonia) and most important anions (bicarbonates, nitrates, nitrites, sulphates, phosphates, chlorides) and the electrical conductivity of the water. Individual samplings of surface and tile drainage water were, on the basis of the above mentioned analytical data, assigned appropriate quality categories according to the five-level pollution classification system defined by surface water quality standard (ČSN 75 7221). In Železná, no pronounced water pollution was found during the entire course of the monitoring, with the exception of one sampling point in the vicinity of which there was once a farmyard manure heap. By contrast, in the intensively managed Haklovy Dvory study area there was evidence of significant pollution of all tile drainage water samples. This finding supports our hypothesis about a direct impact of the type of agriculture practised in the area on the quality of tile drainage water. Both the use of fertilizers for agricultural crops and the intensive tillage of the soil have a commensurately large negative impact on the quality of tile drainage water and, subsequently, on the quality of water in surface watercourses.

Compositional relationships between organic matter in a grassland soil and its drainage waters

SummaryWe present a novel study of the compositional relationships between soil organic components extractable in aqueous extractants and those in sub‐soil drainage and surface runoff waters from the soil. The surface soil (0–20 cm) of a stagnogley in long‐term grassland was sequentially and exhaustively extracted in aqueous media at pH values of 7, 10.6 and 12.6. Extracts from the soils and their runoff and drainage waters were processed by the procedures of the International Humic Substances Society (IHSS), and fractionated into humic, fulvic, and XAD‐4 acids. Elemental, δ13C, δ15N, sugar, amino acids, and solid state CPMAS 13C NMR analyses were used to identify similarities and differences between the fractions from the different extracts. There were few differences between the compositions of drainage water samples taken 1 year apart, and these had compositional features similar to those from the more highly oxidized fractions isolated from the soil at pH 7. There were significant differences between the humic components from the drainage waters and isolated from the soil at pH 7 and those of the humic fractions isolated at the higher pH values whose compositions are more clearly related to origins in plants. The compositions of the surface runoff waters indicate origins in transformed plant and animal manures on the soil surface, whereas those of the deep drainage waters originate in more extensively transformed materials, including products of microbial metabolism. The resin technique used in the fractionation allowed the isolation of novel humic acid fractions from the soil extracts, in particular at pH 7 and 12.6. These fractions clearly originated in microbial sources, were rich in saccharides and amino acids (peptides), and low in lignin‐derived components.

Searching for Useful Bacteria on Chalcopyrite Leaching from Japanese Abandoned Mines

Bioleaching studies have been conducted to obtain bacteria having a high ability to dissolve copper from chalcopyrite. For these studies, samples of mine drainage water which contain high concentrations of copper or iron ions in several abandoned mines in Japan were used to inoculate enrichment cultures on 0.16 M ferrous iron in the absence of chalcopyrite concentrate. Afterwards, these were accumulated and supplied to shaking-flask bioleaching tests on chalcopyrite concentrate. Copper dissolution rates were measured in chalcopyrite leaching experiments and compared with those using cell-free ferrous/ferric media. The copper dissolution rate in ferrous sulphate medium was higher than that in ferric sulphate medium. Moreover, tests in the presence of bacteria showed even an higher copper dissolution rate.

Modelling the Transport of Metalaxyl in Gerbera Plants grown in a Closed-loop Hydroponic System

The transport and the kinetics of the fungicide metalaxyl were followed in various parts of gerbera plants ( Gerbera jamesonii ) grown in a closed hydroponic system. The pesticide was applied into the nutrient solution and supplied to the plants in the mode of a pulse at two concentrations, 112·5 and 225 mg l −1 . Its fate was then followed regularly for a period of 121 days, by collecting and analysing samples of irrigation solution, drainage water, roots, leaves and flowers of the plants by means of gas chromatography. The dimensionless parameter D/uL , where D is the diffusion coefficient, u is the linear velocity and L is the length of flow, for the movement of the tracer metalaxyl in the whole plant was found to be about 0·15–0·30 for both concentration treatments. These relatively high values support the statement that the plant operates as a well mixed reactor system. Next, the variation of analytical data in the solution, the roots, the leaves, and flowers were simulated using a model of four reactor vessels connected in series. From the results, it was possible to estimate the values for the apparent rate constant k app of elimination in each compartment. The values for k app appear similar for both treatments, but differ strongly in the various parts of the plants as follows: k leaves > k flowers > k roots . These variations of the apparent rate constants in the different parts of the plant are explained based on differences in the mode of long-distance transport to each of them.

Calcium(II)-selective potentiometric sensor based on α-furildioxime as neutral carrier

A highly selective poly(vinyl chloride)-based membrane sensor using α-furildioxime ( I) as neutral carrier have been prepared and explored as Ca 2+-selective electrode. Effect of various plasticizers, viz. dibutylphthalate (DBP), dioctylsebacate (DOS), acetophenone (AP), benzyl acetate (BA), tributylphosphate (TBP) and o-nitrophenyloctyl ether ( o-NPOE) with anion excluder sodium tetraphenylborate (NaTPB) and KTpClPB were studied. Best performance was exhibited by the membrane having composition as I:PVC:DBP:KTpClPB as 4:32:62:2 (wt%). This membrane worked well over a wide concentration range 2.56 × 10 −7–1.0 × 10 −1 M of Ca 2+ with a Nernstian slope of 29.5 ± 0.5 mV/decade of Ca 2+ activity. The response time of the sensor is 10 s and the membrane can be used over a period 3 months with good reproducibility. The proposed electrode works well in a wide pH range 3.5–9.0 and can be used in a non-aqueous solution containing up to 20% (v/v). The sensor has also been used as an indicator electrode in the potentiometric titration of calcium(II) ions against ethylenediaminetetraacetic acid (EDTA). The sensor has been used for the analysis of Ca 2+ ions in soil drainage water samples.

Determination of pharmaceuticals in environmental waters by liquid chromatography/electrospray ionization/tandem mass spectrometry

A high-performance liquid chromatography/electrospray ionization/tandem mass spectrometry (LC/MS-MS) method was developed, validated and used to characterize pharmaceutical inputs in the Grand River watershed, Ontario, Canada. Twenty-seven antibiotics and neutral pharmaceuticals were extracted from aqueous environmental samples in a single step using 13C6-labeled sulfamethazine phenyl as a method surrogate and analyzed by LC/MS-MS. Method detection limits were in the range of 20-1,400 ng/L for the compounds of interest with recoveries from 51 to 130%. Using this method, pharmaceutical profiles in tributaries flowing into the Grand River were investigated using samples collected from seven agricultural sites and one urban site. Quality control data collected during the 5-month field study period showed good method performance. Concentrations of pharmaceuticals in source water with heavy agricultural input and surface waters downstream with urban inputs were determined to examine the effect of agricultural and urban inputs to surface water quality. Only human prescription drugs were found from urban site samples taken at both high-flow (spring and fall) and low-flow (summer) events in 2003, indicating minimal agricultural input. We also found for the first time the presence of the ionophore monensin in the environment as well as the occurrence of the human prescription drug carbamazepine in surface waters receiving primarily agricultural inputs. Possible causes and analytical solutions for some poor recoveries are discussed with respect to extraction pH, total organic carbon and metal ions in the water samples. The ability to extract 27 pharmaceuticals in a single solid-phase extraction step from diverse environmental matrices such as agricultural tile drain, tributary and surface water samples, followed by a single LC/MS-MS analysis, enabled the effective delivery of quality data.

Fate of metalaxyl applied in nutrient solution to gerbera (Gerbera jamesonii) grown in a ‘closed’ hydroponic system

SummaryThe application of fungicides via the recycled nutrient solution in ‘closed’ hydroponic systems may restrict the leaching of residues into groundwater. To assess the possibility of applying selected fungicides via the recycled nutrient solution to flower crops grown in ‘closed’ hydroponic systems, the widely-used fungicide metalaxyl was applied to gerbera (Gerbera jamesonii) at two different doses (112.5 and 225 mg l–1) using this method. The experiment was conducted in a glasshouse using pumice (0–5 mm) as the substrate. The fate of the metalaxyl, which was added to the nutrient solution was traced in the plants and the environment by regularly collecting samples of irrigation solution, drainage water, pumice, roots, leaves, and flowers over a period of 121 d and analysing them by gas chromatography. Metalaxyl residues in leaves were also studied over a 50 d summer period, 7 months later. Metalaxyl concentrations were relatively high in both drainage and irrigation solutions over the first 5 d following its application, but dropped markedly on day 17. Thereafter, the metalaxyl level declined slowly to a mean value of 0.02 mg l–1 on day 121, without any significant difference between the two doses originally applied. The estimated half-life of the metalaxyl was 6.5 and 5.4 d at the low and high dose, respectively. Leaf concentrations of metalaxyl increased gradually during the first 5 d following application, and remained almost constant up to day 17. Thereafter, leaf concentrations declined progressively to 0.6 mg kg–1 (fresh weight) by day 121, without significant differences between treatments. This response, independent of application dose, implies that even lower doses of metalaxyl may be applied via the nutrient solution in ‘closed’ hydroponics. The concentration of metalaxyl in roots reached a peak earlier than in leaves. In the 50 d, summer experiment, the highest concentration of metalaxyl in leaves was found 6 d after application, followed by a rapid decrease. Theses results indicate that application of metalaxyl via the recycled nutrient solution in a ‘closed’ hydroponic system provides effective, high concentrations of the fungicide in roots and leaves, which are maintained for a long period after application.

Movement of suspended matter and a bromide tracer to field drains in tilled and untilled soil

Abstract. Drainage water was sampled intensively during a four‐year field experiment on a sandy loam soil subjected to four unreplicated tillage treatments: (1) harrowing with a springtine harrow, drilling; (2) direct drilling; (3) ploughing with light subsurface compaction, one pass with a PTO‐driven rotary harrow, drilling; (4) ploughing, one pass with a springtine harrow, drilling. In all years, the losses of suspended matter with drainage water (0.1–4.3 kg ha−1 yr−1) were smaller by a factor of 1.9 or more from direct drilled plots than from plots subjected to the other tillage treatments, strongly suggesting that tillage increased the losses. Annual bromide losses were governed by the amount of drainage water rather than by the tillage treatments. However, after one drainage season, more bromide was left in the soil at 0–100 cm depth with ploughless tillage than with ploughing, thus indicating more bypass flow without ploughing. The study demonstrated very changeable patterns of suspended matter and bromide concentrations in drainage water sampled from large field plots, and questions the representativeness of drainage water samples for water reaching the subsoil or shallow groundwater.

<i>Arcobacter butzlieri </i>strains from poultry abattoir effluent in Nigeria

To investigate the prevalence, species distribution and genetic diversity of zoonotic Arcobacter species. Prospective study. Drainage system of a cosmopolitan chicken abattoir in Lagos, Nigeria. One hundred and fifty drainage water samples were enriched in a minimal antibiotics-containing medium at room temperature and bacteria then isolated by use of a membrane filtration method. Twenty six (14%) of samples were positive for Arcobacter spp. Of these, 20 were examined by a comprehensive probabilistic identification scheme for Epsilobacteria and all strains identified as A. butzleri. AFLP analysis of these strains revealed considerable genetic diversity among the strains, with 12 genotypes defined at the 90% similarity level. The prevalence of A. butzleri in Nigerian poultry abattoir effluent indicates this species may constitute a public health problem in this country. AFLP profiling could be a useful tool for molecular epidemiological and population genetic studies of this organism. This is the first known report of A. butzleri in Nigeria, and first application of AFLP analysis for genotyping the species.

Campylobacter and farm dairy effluent irrigation

Campylobacter were studied at a mole‐tile drained farm over a 12‐month period. Farm dairy effluent was applied to the farm in January, October, and November. In January, herd 1 was on the farm and effluent that contained 103 campylobacter 100 ml−1 was sourced from a storage pond. In October and November herd 2 was on the farm and effluent that contained 105 and 106 campylobacter 100 ml−1 respectively was sourced from the dairy shed. In January and November, when irrigation caused preferential flow, concentrations in the drainage water were similar to those in the applied effluent, creating a potential for water contamination. C. jejuni was the predominant campylobacter species recovered. Only one subspecies type (i.e., one Penner serotype and one PFGE type) was observed in the effluent, drainage water, and soil samples collected after the January application. This recovery of a single subtype allowed tracing from effluent into drainage water and soil. In contrast, several subspecies types were observed after the October and November applications, and the study demonstrated that when there is a diversity of subtypes, typing was less effective as a means of tracking campylobacter. Penner serotyping of C. jejuni in these effluents revealed serotypes linked to the human illness, campylobacteriosis.

Phosphogypsum Amendment Effect on Radionuclide Content in Drainage Water and Marsh Soils from Southwestern Spain

Phosphogypsum (PG) is a residue of the phosphate fertilizer industry that has relatively high concentrations of 226Ra and other radionuclides. Thus, it is interesting to study the effect of PG applied as a Ca amendment on the levels and behavior of radionuclides in agricultural soils. A study involving treatments with 13 and 26 Mg ha(-1) of PG and 30 Mg ha(-1) of manure was performed, measuring 226Ra and U isotopes in drainage water, soil, and plant samples. The PG used in the treatment had 510 +/- 40 Bq kg(-1) of 226Ra. The 226Ra concentrations in drainage waters from PG-amended plots were similar (between 2.6 and 7.2 mBq L(-1)) to that reported for noncontaminated waters. Although no significant effect due to PG was observed, the U concentrations in drainage waters (200 mBq L(-1) for 238U) were one order of magnitude higher than those described in noncontaminated waters. This high content in U can be ascribed to desorption processes mainly related to the natural adsorbed pool in soil (25 Bq kg(-1) of 238U). This is supported by the 234U to 238U isotopic ratio of 1.16 in drainage waters versus secular equilibrium in PG and P fertilizers. The progressive enrichment in 226Ra concentration in soils due to PG treatment cannot be concluded from our present data. This PG treatment does not determine any significant difference in 226Ra concentration in drainage waters or in plant material [cotton (Gossipium hirsutum L.) leaves]. No significant levels of radionuclides except 40K were found in the vegetal tissues.

Leaching of Pesticides Through Normal‐Tillage and Low‐Tillage Soil—A Lysimeter Study. I. Isoproturon

Isoproturon is a herbicide, which was used in Denmark against grass weeds and broad‐leaved weeds until 1998. Isoproturon has frequently been detected in ground water monitoring studies. Leaching of isoproturon (N,N‐dimethyl‐N′‐(4‐(1‐methylethyl)phenyl)urea) and its metabolites, N′‐(4‐isopropylphenyl)‐N‐methylurea and N′‐(4‐isopropylphenyl)urea was studied in four lysimetres, two of them being replicates from a low‐tillage field (lysimeter 3 and 4), the other two being replicates from a normal tillage field (lysimeter 5 and 6). In both cases the soil was a sandy loam soil with 13–14% clay. The lysimetres had a surface area of 0.5 m2 and a depth of 110 cm. Lysimeter 3 and 4 were sprayed with unlabelled isoproturon while lysimeter 5 and 6 was sprayed with a mixture of 14C‐labelled and unlabelled isoproturon. The total amount of isoproturon sprayed onto each lysimeter was 63 mg, corresponding to 1.25 kg active ingredient per ha. The lysimeters were sprayed with isoproturon on October 26, 1997. The lysimetres were installed in an outdoor system in Research Centre Flakkebjerg and were thus exposed to normal climatic conditions of the area. A mean of 360 l drainage water were collected from lysimeter 3 and 4 and a mean of 375 litres from lysimeter 5 and 6. Only negligible amounts of isoproturon and its primary metabolites were found in the drainage water samples, and thus no significant difference between the two lysimeter sets was shown. In a total of 82 drainage water samples, evenly distributed between the four lysimetres isoproturon was found in detectable amounts in two samples and N′‐(4‐isopropylphenyl)urea was found in detectable amounts in two other samples. The detection limit for all the compounds was 0.02 μg/l. 48% and 54% of the added radioactivity were recovered from the upper 10 cm soil layer in lysimeter 5 and 6, respectively, and 17 and 14% from 10–20 cm's depth. By extraction first with an aquatic CaCl2 solution 0.49% of the added radioactivity was extracted from the upper 10 cm layer in lysimeter 5. In the subsequent extraction with acetonitril, 1.19% of the added radioactivity was ekstracted. In lysimeter 6, upper 10 cm, 0.2% were extracted with water and 0.56% were extracted with acetonitril. Below 10 cm's depth no measurable amounts could be extracted.

Simultaneous determination of inorganic and organic anions, alkali, alkaline earth and transition metal cations by capillary electrophoresis with contactless conductometric detection.

Simultaneous separation of up to 22 inorganic and organic anions, alkali, alkaline earth and transition metal cations was achieved in less than 3 min in the capillary electrophoresis system with contactless conductometric detector. The sample was injected from both capillary ends (dual opposite end injection) and anionic and cationic species were detected in the center of the separation capillary. The parameters of the separation electrolyte, such as pH, concentration of the electrolyte, concentration of complexing agents and concentration of 18-crown-6 were studied. Best results were achieved with electrolytes consisting of 8 mM L-histidine, 2.8 mM 2-hydroxyisobutyric acid, 0.32 mM 18-crown-6 at pH 4.25 or 9 mM L-histidine, 4.6 mM lactic acid, 0.38 mM 18-crown-6 at pH 4.25. Other electrolytes containing complexing agents such as malic or tartaric acid at various concentrations could also be used. The detection limits achieved for most cations and anions were 7.5 - 62 micro gL(-1) except for Ba2+ (90 micro gL(-1)), Cd 2+, Cr 3+ and F- (125 micro gL(-1)), and fumarate (250 micro gL(-1)). The repeatability of migration times and peak areas was better than 0.4% and 5.9%, respectively. The developed method was applied for analysis of real samples, such as tap, rain, drainage and surface water samples, plant exudates, plant extracts and ore leachates.

Nitrogen and phosphorus losses in mole and tile drainage from a cattle‐grazed pasture in eastern Southland

An experimental system for monitoring drainage outflows from mole‐ and tile‐drained plots is described, and nitrogen (N) and phosphorus (P) losses in drainage are reported for Year 1 of a 4‐year study examining nutrient losses in drainage from a pasture in Southland. Twelve plots (0.09 ha), grazed by non‐lactating dairy stock, were artificially drained by installing a mole and tile drainage network. A metering station was used to monitor drainage flow rate from six of these plots using a V‐notch weir and a shaft encoder system. Drainage water samples were collected on a flow proportional basis using either an automated water sampler triggered by the flow monitoring system, or by manual collection during daylight hours. The amount of nitrate‐N lost in drainage water in this first year of study was 25 kg N ha–1, resulting in a volume‐averaged nitrate‐N concentration of 6.9 mg N litre–1. Although this is a significant loss of potentially plant available N, the average nitrate‐N concentration of the drainage water was below the 11.3 mg N litre–1 standard adopted by the New Zealand Ministry of Health for acceptable nitrate levels in drinking water. Mean dissolved reactive P and total P concentrations in drainage waters were 23 and 74 μg P litre–1, respectively. Analysis of forms of P showed 61 % of the total P lost in the drainage was in the form of particulate P, which may reflect the recent introduction of mole and tile drainage to this site.

Application of a contactless conductometric detector for the simultaneous determination of small anions and cations by capillary electrophoresis with dual-opposite end injection

A contactless conductometric detection (CCD) system for capillary electrophoresis (CE) with a flexible detection cell was applied for the simultaneous determination of small anions and/or cations in rain, surface and drainage water samples. The applied frequency, the amplitude of the input signal, the electrolyte conductivity and electrode distance were found to be the most significant factors affecting the detection sensitivity. 2-( N-Morpholino)ethanesulfonic acid/histidine-based (MES/His) electrolytes were used for direct conductivity detection of anions and cations, while ammonium acetate was selected for indirect conductivity determination of alkylammonium salts. For the simultaneous separation procedure, involving dual-opposite end injection, an electrolyte consisting of 20 m M MES/His, 1.5 m M 18-crown-6 and 20 μ M cetyltrimethylammonium bromide provided baseline separation of 13 anions and cations in less than 6 min. The detection limits achieved were 7–30 μg/l for direct conductometric detection of various common inorganic cations and anions, excluding F − (62 μg/l) and H 2PO 4 − (250 μg/l), and 35–178 μg/l for indirect conductometric detection of alkyl ammonium cations. The developed electrophoretic method with conductometric detection was compared to ion chromatography.

Occurrence and determination of herbicides and their major transformation products in environmental waters

A method for the simultaneous determination of selected maize and grain herbicides (amidosulfuron, N-([{[(4,6-dimethoxy-2-pyrimidinyl)amino]carbonyl}amino)sulfonyl]- N-methylmethanesulfonamide; bentazone, 3-(1-methylethyl)-1H-2,1,3-benzothiadiazin-4(3H)-one2,2-dioxide; 2,4-D, (2,4-dichlorophenoxy)acetic acid; MCPA, (4-chloro-2-methylphenoxy)acetic acid; metosulam, N-(2,6′-dichloro-3-methylphenyl)-5,7-dimethoxy[1,2,4]triazolo[1,5- a]pyrimidine-2-sulfonamide) and their transformation products (TPs) (8-hydroxybentazone, 1H-2,1,3-benzothiadiazin-4(3H)-one,8-hydroxy-3-(1-methylethyl)-2,2-dioxide; bifenox acid, 5-(2,4-dichlorophenoxy)-2-nitrobenzoic acid; clodinafop acid; 2,4-dichlorophenol; 4-chloro-2-methylphenol) in environmental waters was developed. The procedure combines a solid-phase extraction (SPE) with column liquid chromatography–tandem mass spectrometry detection utilizing a pneumatically assisted and heat-assisted electrospray interface in negative mode. The extraction of analytes from filtered drainage or river water samples was performed using as sorbent a graphitized carbon. The recovery, for drinking water, ranged from 91 to 98%, and from 84 to 95% for river water. Excellent method precision was demonstrated with percent relative standard deviation of less than 10% for all analytes at fortification level. Detection limits were at level of few nanograms per liter, except for 2,4-dichlorophenol and 4-chloro-2-methylphenol, that was in the range of tens of nanogram per liter. The present methodology was used for searching in river and drainage waters of maize-grain fields of the Tiber valley, during a typical period of herbicides application from April to July 2001. The levels detected of four compounds were in the range of: non-detectable (ND)–6.1, ND–27, ND–1.9 and ND–0.5 μg l −1, for MCPA, bentazone, 8-hydroxybentazone and 2,4-D, respectively. Detectable amounts of bentazone-8-hydroxy at level of 0,3 μg l −1 was found to be transported into river. The highly satisfactory results for all target analytes demonstrate the potential of liquid chromatography–tandem mass spectrometry for the identification and the quantification of the polar and acidic herbicides at below 100 ng l −1 levels.

Calcium sulfate (gypsum) scaling in nanofiltration of agricultural drainage water

Reclamation and reuse of agricultural tile drainage water in the San Joaquin Valley, California, by membrane desalination has been given serious consideration for nearly 30 years. The agricultural drainage water has very high levels of calcium and sulfate ions, rendering it nearly saturated with gypsum in some locations in this region. The present paper focuses on the conditions of membrane surface gypsum scale formation during nanofiltration (NF) of agricultural drainage water. Experimental studies with drainage water samples and model solutions were conducted in laboratory glassware as well as with a small plate-and-frame cross-flow membrane re-circulation unit. NF membrane experiments consisted of two types: permeate disposal to measure the effect of increasing recovery on the onset of scaling, and feed water re-circulation at a fixed concentration factor to establish performance change over time. An expression relating NF product water recovery to feed water concentration factor enabled numerous membrane scale formation studies that have direct relevance to full-scale NF systems. Glassware experiments showed that magnesium ions decreased the amount of gypsum incipient nuclei because of MgSO 4 0 complexation, which reduces the availability of sulfate ions for nucleus formation. In membrane experiments, model solutions showed that bicarbonate, magnesium ions, and humic acid retarded the onset of gypsum scaling by tying up calcium ions that would have otherwise been used for formation of gypsum incipient nuclei. Both calcium carbonate and gypsum scales may result from particulate deposition rather than membrane surface (wall) crystallization, with the likelihood of particulate fouling increasing with supersaturation.

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 (EPC 0) 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.