Runoff Samples Research Articles

Sediment content and chemical properties of water runoff on biocrusts in drylands

In drylands, water erosion can be a process with important economic and ecological implications, and is very dependent on the soil surface cover. There is broad agreement that biocrusts protect the soil from erosion in a wide range of circumstances. However, there is little information available on the effect of rain and biocrust types on this protective capacity and there is particularly very little knowledge on the erosive effects of runoff on biocrusts, which are expected to be larger in larger drainage areas, on the resistance of biocrusts to the combined effect of raindrops plus runoff flow and on the solute mobilisation by runoff in biocrusts. To answer these questions, we performed 96 rainfall-simulation in situ factorial experiments, including two biocrust types (cyanobacteria and lichens), three rain types (42, 63 and 77 mm h−1, always 20 min rain), four plot lengths (1, 2, 3 and 4 m long) and four replicates. In each experiment, runoff volume was measured and a runoff sample was taken to determine (i) the amount of dry matter in runoff, (ii) the amount of organic matter among the dry matter, (iii) the electrical conductivity, pH and alkalinity in runoff water. The main findings were: biocrusts strongly protected soil against water erosion, even under the most erosive conditions, and the protection increased with the successional development. Biocrusts were very resistant to the impact of raindrops and also to runoff flow, although an emergent hypothesis arose: under the most erosive conditions, a threshold of erodibility could be reached at the cyanobacterial biocrust. The lichen crust also protected the soil against the removal of soil soluble substances. The development of a biocrust could change the chemical composition of the solutes in runoff.

Suitability of a Saccharomyces cerevisiae-based assay to assess the toxicity of pyrimethanil sprayed soils via surface runoff: Comparison with standard aquatic and soil toxicity assays

The present study is aimed at evaluating whether a gene expression assay with the microbial eukaryotic model Saccharomyces cerevisiae could be used as a suitable warning tool for the rapid preliminary screening of potential toxic effects on organisms due to scenarios of soil and water contamination with pyrimethanil. The assay consisted of measuring changes in the expression of the selected pyrimethanil-responsive genes ARG3 and ARG5,6 in a standardized yeast population. Evaluation was held by assessing the toxicity of surface runoff, a major route of pesticide exposure in aquatic systems due to non-point-source pollution, which was simulated with a pyrimethanil formulation at a semifield scale mimicking worst-case scenarios of soil contamination (e.g. accident or improper disposal). Yeast cells 2-h exposure to the runoff samples led to a significant 2-fold increase in the expression of both indicator genes. These results were compared with those from assays with organisms relevant for the aquatic and soil compartments, namely the nematode Caenorhabditis elegans (reproduction), the freshwater cladoceran Daphnia magna (survival and reproduction), the benthic midge Chironomus riparius (growth), and the soil invertebrates Folsomia candida and Enchytraeus crypticus (survival and reproduction). Under the experimental conditions used to simulate accidental discharges into soil, runoff waters were highly toxic to the standard test organisms, except for C. elegans. Overall, results point out the usefulness of the yeast assay to provide a rapid preview of the toxicity level in preliminary screenings of environmental samples in situations of inadvertent high pesticide contamination. Advantages and limitations of this novel method are discussed.

English

The study was conducted in two sub watersheds in the Upper Blue Nile Basin in Ethiopia to determine the quantity, quality of sediment lost and its onsite costs in terms of crop yield. Two monitoring stations at the outlets were selected. Discharges were estimated and depth integrated daily runoff samples were collected during the rainy season in 2011. The sediment concentration and nitrogen (N) and phosphorus (P) content was analyzed and related to crop yield using a nutrient response equation for maize (Zea mays). The result shows statistically significant differences in sediment concentration of the two watersheds. Suspended sediment concentration was strongly correlated with the discharge from Chekorsa River (R2 = 0.7) but it was very weak for Dapo. There was higher concentration of nutrients in the sediment than the surface soil in both watersheds. Particularly, sediment enrichment ratio of available P was 2.7 and 9 for Dapo and Chekorsa Rivers, respectively. The estimated yield reduction of maize due to N and P loss was about 950 and 1420, and 1015 and 665 kgha-1 from Dapo and Chekorsa catchments, respectively. Such results are equivalent to an onsite cost to farmers of about 190 and 285 USD ha-1 for Dapo, and 203 and 133 USDha-1 for Chekorsa catchments in that order. This monetary value can alert farmers and decision makers to take soil and water conservation measures.   Key words: Soil loss, enrichment ratio, nutrient depletion, Blue Nile Basin, sediment.

A novel approach to determine estrogenic hormones in swine lagoon wastewater using the QuEChERS method combined with solid phase extraction and LC/MS/MS analysis

A novel approach is reported to quantify estrone (E1), 17β-estradiol (βE2), 17α-estradiol (αE2), estriol (E3), and 17α-ethynylestradiol (EE2) in storm water runoff and swine lagoon wastewater samples. A considerable amount of residue was collected when lagoon wastewater samples were centrifuged therefore both resulting residues and aqueous portions were analyzed separately. A modified Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) method was utilized to efficiently extract the target analytes in the residue. Aqueous portions were pre-concentrated using solid phase extraction (SPE). A simple liquid–liquid extraction in a test tube was carried out as a sample clean-up step after SPE. This approach is inexpensive and requires only 3 mL of organic solvent per analysis. The resulting extracts were further purified using a dispersive solid phase extraction (dSPE) technique (not required in storm water analyses). βE2 and E1 glucuronide and sulfate conjugates were also analyzed in the aqueous portions of the lagoon samples as well as in the storm water runoff samples. An enzymatic hydrolysis was performed prior to SPE to deconjugate conjugated estrogens. Samples were derivatized with dansyl chloride to enhance LC/MS/MS analytical sensitivity. Insignificant matrix effects (1–12%) were determined for the analyses of aqueous samples. Thus, matrix matched calibration curves were not required. Matrix effects for residue analyses ranged from 14 to 20%, requiring that matrix matched calibration curves be used for quantification. All developed methods gave 84–106% recoveries for free estrogens and 65–86% recoveries for estrogen conjugates. The LODs for lagoon wastewater and storm water analyses ranged from 0.9–2 ng L−1 and 0.3–0.5 ng L−1, respectively. The developed methods were validated by analyzing eighteen lagoon water samples and twenty six storm water samples in three replicates.

Nutrient loads and sediment losses in sprinkler irrigation runoff affected by compost and manure

High water application rates beneath the outer spans of center pivot sprinkler systems can cause runoff, erosion, and nutrient losses, particularly from sloping fields. This field study determined runoff, sediment losses, and nutrient loads (dissolved organic carbon [C], nitrate-nitrogen [NO3-N], ammonium-nitrogen [NH4-N], total phosphorus [TP], ferric-oxide strip phosphorus [FeO P], dissolved reactive phosphorus [DRP], potassium [K], calcium [Ca], magnesium [Mg], and sodium [Na]) in sprinkler runoff for two years after a single application of either stockpiled or composted dairy manure. We studied five treatments, including a nonamended control, in each of six blocks, with each block situated under a different span of a low-pressure, moving-lateral sprinkler system. In October of 1999, we incorporated 29.1 Mg ha−1 (13 tn ac−1) or 71.7 Mg ha−1 (32 tn ac−1) of dry manure or 22.4 Mg ha−1 (10 tn ac−1) or 47 Mg ha−1 (21 tn ac−1) of dry compost into a calcareous silt loam soil on slopes from 0.8% to 4.4%. In the spring of 2000 and 2001, we collected surface soil (0 to 30 mm [0 to 1.2 in]) from furrows to determine soil test phosphorus (STP). We applied 21 to 46 mm (0.8 to 1.8 in) of water at an average application intensity of 28 mm h−1 (1.1 in hr−1; peak intensity of 40 mm h−1 [1.6 in hr−1]) to 6.4 × 36.6 m (21 × 120 ft) plots six times in 2000 and two times in 2001. Additional nonmonitored irrigations were made as needed to produce corn ( Zea mays L.) silage each year. At 15 to 30 minute intervals after runoff began, we measured runoff rates and collected runoff samples to determine sediment and constituent losses for each monitored irrigation. None of the amendment treatments significantly affected runoff, sediment losses, or loads of dissolved organic C, NO3-N, NH4-N, TP, FeO P, or Mg when averaged across irrigations. Without exception, runoff, sediment losses, and loads of every measured constituent varied among irrigations after accounting for differences in water applied. Treatments influenced DRP, K, and Ca runoff loads. Loads of Ca decreased, but Na increased with increasing manure application rates. Relative to the control, manure DRP loads were five to six times greater, whereas compost DRP loads were similar.

Effect of soil erosion on dissolved organic carbon redistribution in subtropical red soil under rainfall simulation

Water erosion governs soil carbon reserves and distribution across the watershed or ecosystem. The dynamics of dissolved organic carbon (DOC) under water erosion in red agricultural soil is not clear. To determine the effect of tillage management and water erosion on vertical and lateral transportation of soil organic carbon (SOC) and DOC production under distinct rainfall intensities in the hilly red soil region of southern China, a chisel tillage plot with low rainfall intensity (CT-L) and two no-tillage plots with high (NT-H) and low rainfall intensity (NT-L) studies were conducted. Soil samples were collected from 0–5, 5–10, 10–20, and 20–40cm soil layers from triplicate soil blocks pre- and post-rainfall for determining concentration of SOC and DOC. Runoff samples were collected at every 6min for determining concentration of DOC and sediments during rainfall simulations on runoff plots (2m×5m) with various intensities. No fertilizer was applied in any plots. Results clearly show that runoff volumes, sediments and SOC entrained with sediment, and laterally mobilized DOC were significantly larger on NT-H compared to other plots, coinciding with changes in rainfall intensity; and the extent of roughness of the plot surface (CT vs. NT) was the variation in runoff DOC concentration. During the simulated rainfall events, DOC exports average 0.76, 0.64, and 0.27gCm−2h−1; SOC exports average 3.52, 1.08, and 0.07gm−2h−1 in the NT-H, NT-L, and CT-L soils, respectively. The maximum export of DOC was obtained under a high intensity rainfall plot, which lagged behind maximum runoff volumes, sediments, and SOC losses with sediment. Export of DOC was proportional to SOC content of soil loss. The least DOC losses in surface runoff and SOC losses with sediment were observed in CT-L plots. Vertical DOC mobilization achieved its maximum with low intensity rainfall under CT treatment. The DOC did not accumulate at the soil surface and was distributed mainly in the second and third soil horizons. The distribution of DOC content down the soil profile increased compared to pre-rainfall, except for subplots E at NT-H and NT-L. Results indicate that rainfall significantly increased DOC content in experimental plots. The SOC content of sediment leaving the erosion zone was significantly correlated with overland flow volume and soil loss. These observations lead to the conclusion that soil erosion is an important factor controlling the export of dissolved organic carbon.

Runoff, erosion and sediment particle size from smooth and rough soil surfaces under steady rainfall-runoff conditions

The responses of runoff and erosion to soil surface roughness (SSR) have been extensively studied in the past decades; however, most of these studies were conducted at the early stage of rainfall, whereas few studies were specifically conducted during steady runoff conditions. In this study, runoff, soil losses and sediment particle sizes from smooth and rough surfaces were measured after surface runoff stabilisation to improve the understanding of the relationship between SSR and soil erosion. A cascade of two independent soil boxes in which the runoff samples from upslope and downslope boxes can be collected independently or together was used to perform the experiments. The upslope box supplied runoff to the downslope study box. Three rainfall intensities of 50, 75 and 100 mm/h were applied. The results suggest that SSR has a significant effect on soil erosion when runoff reaches a steady state. Although the difference in the runoff rate was small between the rough and smooth surfaces, the sediment rate and concentration of particles were significantly lower for the rough surface than for the smooth surface. Through analysing the particle size distribution (PSD) of sediment, we found that selective sediment delivery is an important reason for the soil erosion reduction by SSR. The rainfall intensity decreased the difference in the sediment rates between the smooth and rough surfaces. The extra inflow increased the runoff rates, sediment rates and concentration rates for both the smooth and rough surfaces; however, the increasing degrees of the runoff rate, sediment rate and concentration rate had significant differences between the rough and smooth surfaces. A stepwise multiple regression showed that significant linear relationships existed between one or more PSDs of 20–50, 50–100, 100–250 and 1000–2000 µm and the sediment rate.

Comparison of Indicator Bacteria Concentrations Obtained by Automated and Manual Sampling of Urban Storm-Water Runoff

A comparative study of indicator bacteria concentrations obtained by laboratory analysis of grab samples of storm water, which were collected manually or by automatic samplers, was carried out in two urban catchments. Samples were analyzed for four types of indicator bacteria, total coliforms, Escherichia coli (E. coli), enterococci, and Clostridium perfringens and further documented by measurements of total suspended solids (TSS) and turbidity. Analysis of complete data sets (N = 198) indicated no statistically significant differences in the geometric means of all the constituent samples collected automatically or manually, but there were some small differences between the results produced by the two sampling methods applied. Total coliform concentrations were positively biased in samples collected by automatic samplers, but for the three remaining indicator bacteria (E. coli, enterococci, and C. perfringens), the opposite was true. Risk of sample cross-contamination in automatic samplers was assessed in the laboratory by sampling consecutively synthetic storm water with high and low concentrations of E. coli and enterococci. The first low-concentration samples preceded by high-concentration samples were cross-contaminated and the measured concentrations were positively biased. This cross-contamination was explained by storm-water residue in the sampling line. Such a residue remained in place even after line purging by compressed air, and its mass depended on the sampling line length (tested up to 5 m), as verified by measurements in the laboratory. The study findings should be helpful for improving field protocols for indicator bacteria sampling.

Linking phosphorus export and hydrologic modeling: a case study in Central Italy.

Soil erosion is an open topic, not only because soil fertility is lost, but also because nutrients are spilled into water bodies, thereby causing pollution. Research carried out in this field has amply described this process, but the interaction between these factors is complex and experimental research is needed to understand the production of loads of nutrients for different land uses. This paper describes a long-term monitoring case study using high-resolution rainfall data and runoff samples, carried out in the Lake Vico basin (Central Italy) to determine the phosphorus (P) export during erosive rainfall events. State of the art GIS-based basin characterization and advanced rainfall-runoff models are employed in order to describe the relationship between nutrient export and rainfall or runoff time distribution. Results show that the phosphorus export is strongly related to such time distributions, and less to the cumulative amount of rainfall or runoff.

Particle size distributions in combined sewer overflows in a high-intensity urban catchment in Shanghai, China

To determine the dissolved-phase chemicals and solid-phase particulate matter (PM) in a combined sewer overflow (CSO), the event mean concentrations of typical particulate-band and dissolved-band contaminants were analyzed. Particulate-band chemical oxygen demand and total phosphorous formed the majority of particles, while only around 50% of the total nitrogen was found in the particulate-band. Particle size distributions (PSDs) for PM in 49 CSO samples collected during seven rainfall events, and 18 run-off samples collected during two rainfall events, were analyzed. Variation in PSDs in both CSO and dry weather flow samples occurred with sample storage time. Mean values of particle size in CSO samples were not significantly different from median values for particles within the size range from 0.41 to 3,080 μm, at a 95% confidence level. Values for D50 and D90 for PSDs of PM in both CSO and run-off samples were higher than for previous studies. It was caused by high flow rates during the operation of storm water lifting pumps. The first flush of particles in different size ranges was quantitatively evaluated using PSDs and total suspended solids in each sample. Given the prevalence of CSOs in China and other countries, knowledge of the PSD, and its variation with time, facilitates both the design of CSO treatment procedures and optimization of wastewater treatment plants; it also provides important input for modeling water treatment operations.

Comparing Bridge Deck Runoff and Stormwater Control Measure Quality in North Carolina

AbstractBridge deck runoff sometimes directly discharges through deck drains to water bodies. As such, the runoff is usually not treated; however, recent pressures have led Departments of Transportation to install closed pipe drainage systems beneath bridges to deliver stormwater to a stormwater control measure (SCM). This can be costly both in terms of up-front and long-term maintenance capital. This study compared bridge runoff concentrations of nutrients, sediment, and heavy metals to effluent concentrations from six commonly used SCMs. Runoff quality samples from 15 bridges in North Carolina were collected and compared to those from 41 different SCMs across North Carolina. The SCMs examined in this study were permeable friction course (PFC) overlays, wet retention ponds (WP), bioretention cells (BRC), vegetated filter strips (VFS), constructed stormwater wetlands (CSW), and grassed swales (GS). Bridge deck runoff concentrations were not statistically different from SCM effluent concentrations for tota...

Nutrient Concentrations of Runoff as Affected by the Diameter of Unconsolidated Material from Feedlot Surfaces

Abstract. Beef cattle feedlots contain unconsolidated material that accumulates on the feedlot surface during a feeding cycle. This study was conducted to measure the effects of varying diameters of unconsolidated surface material and varying flow rates on nutrient concentrations in runoff. Unconsolidated surface material with an average diameter of 4.76, 9.53, 19.1, or 47.5 mm and a composite sample with a 15.2 mm mean diameter were placed within 0.75 m wide A— 4.0 m long plot areas. Flow was then introduced at the top of the plots in successive increments, and runoff samples for water quality analyses were obtained. Particle diameter significantly influenced runoff concentrations of dissolved phosphorus (DP), particulate phosphorus (PP), total phosphorus (TP), NH 4 -N, and solids transport. Concentrations of DP, PP, TP, and NH 4 -N for the composite material were 1.90, 1.28, 3.18, and 3.81 mg L -1 , respectively, and solids transport was 19.8 g min -1 . Runoff rate significantly affected concentrations of DP, PP, TP, NH 4 -N, and solids transport for each of the particle size classes except the 4.76 mm diameter material. For the composite material, concentrations of DP, PP, TP, and NH 4 -N decreased from 4.30 to 0.34 mg L -1 , from 5.52 to 0.41 mg L -1 , from 9.82 to 0.75 mg L -1 , and from 25.8 to 0.49 mg L -1 , respectively, as runoff rate increased from 0.02 to 1.10 L s -1 . Nutrient concentrations of runoff from feedlot surfaces are affected by both varying diameters of unconsolidated surface material and varying flow rates.

Human and bovine viruses in the Milwaukee River watershed: Hydrologically relevant representation and relations with environmental variables

To examine the occurrence, hydrologic variability, and seasonal variability of human and bovine viruses in surface water, three stream locations were monitored in the Milwaukee River watershed in Wisconsin, USA, from February 2007 through June 2008. Monitoring sites included an urban subwatershed, a rural subwatershed, and the Milwaukee River at the mouth. To collect samples that characterize variability throughout changing hydrologic periods, a process control system was developed for unattended, large-volume (56–2800L) filtration over extended durations. This system provided flow-weighted mean concentrations during runoff and extended (24-h) low-flow periods. Human viruses and bovine viruses were detected by real-time qPCR in 49% and 41% of samples (n=63), respectively. All human viruses analyzed were detected at least once including adenovirus (40% of samples), GI norovirus (10%), enterovirus (8%), rotavirus (6%), GII norovirus (1.6%) and hepatitis A virus (1.6%). Three of seven bovine viruses analyzed were detected including bovine polyomavirus (32%), bovine rotavirus (19%), and bovine viral diarrhea virus type 1 (5%). Human viruses were present in 63% of runoff samples resulting from precipitation and snowmelt, and 20% of low-flow samples. Maximum human virus concentrations exceeded 300genomiccopies/L. Bovine viruses were present in 46% of runoff samples resulting from precipitation and snowmelt and 14% of low-flow samples. The maximum bovine virus concentration was 11genomiccopies/L. Statistical modeling indicated that stream flow, precipitation, and season explained the variability of human viruses in the watershed, and hydrologic condition (runoff event or low-flow) and season explained the variability of the sum of human and bovine viruses; however, no model was identified that could explain the variability of bovine viruses alone. Understanding the factors that affect virus fate and transport in rivers will aid watershed management for minimizing human exposure and disease transmission.

Impact of Variable Rate Fertilization on Nutrients Losses in Surface Runofffor Wild Blueberry Fields

Abstract. Wild blueberry producers apply agrochemicals uniformly without considering substantial variation in soil properties and topographic features that may affect fruit yield within a field and pollute environment. A wild blueberry field was selected in central Nova Scotia, Canada to evaluate the impact of variable rate (VR) fertilization on nutrient losses in surface runoff, from steep slope to low lying areas, and crop productivity. The field was divided into three subfields (Field 1, Field 2, and Field 3) under three management zones (Zone 1, Z1; Zone 2, Z2; and Zone 3, Z3). The runoff plots were installed to collect surface runoff samples from different zones of the field. Three fertilizer (NPK: 16.5 – 34.5 – 4.5, respectively) rates (200,150, and 100 kg ha -1 for Z1, Z2, Z3, respectively) were applied in runoff plots of VR treatment using fertilizer spreader. Uniform fertilizer rate of 200 kg ha -1 for comparison was applied in runoff plots of uniform application (UA) treatment. No fertilizer was applied in runoff plots of control treatment. The surface runoff samples were collected after every heavy rainfall event and analyzed for total phosphorus (TP), dissolved reactive phosphorus (DRP), particulate phosphorus (PP), and inorganic nitrogen concentrations. The VR treatment significantly (p≤0.05) decreased TP, DRP, PP, and inorganic nitrogen losses in surface runoff as compared to UA. Plant growth parameters and fruit yield were also collected from runoff plots. Plants in UA treatment were taller than VR treatment in low lying areas. Numbers of buds per stem were significantly affected by fertilizer treatments. The fruit yield in VR treatment was non-significantly different than UA treatment. The VR fertilizer application used 40% less fertilizer than standard UA of fertilizer. The VR fertilization could reduce nutrients loading in surface runoff from wild blueberry fields. The runoff plots could be used to accurately determine the surface runoff from small-scale runoff plots. However, the construction of runoff plots and data collection at field scale is laborious and time consuming.

Soil water content, runoff and soil loss prediction in a small ungauged agricultural basin in the Mediterranean region using the Soil and Water Assessment Tool

SUMMARYThe aim of the present work was to evaluate the possibilities of using sub-basin data for calibration of the Soil and Water Assessment Tool (SWAT) model in a small (46 ha) ungauged basin (i.e. where the water flow is not systematically measured) and its response. This small basin was located in the viticultural Anoia-Penedès region (North-east Spain), which suffers severe soil erosion. The data sources were: daily weather data from an observatory located close to the basin; a detailed soil map of Catalonia; a 5-m resolution digital elevation model (DEM); a crop/land use map derived from orthophotos taken in 2010 and an additional detailed soil survey (40 points) within the basin, which included properties such as texture, soil organic carbon, electrical conductivity, bulk density and water retention capacity at −33 and −1500 kPa. A sensitivity analysis was performed to identify and rank the sensitive parameters that affect the hydrological response and sediment yield to changes of model input parameters. A 1-year calibration and 1-year validation were carried out on the basis of soil moisture measured at 0·20-m intervals from depths of 0·10 to 0·90 m in two selected sub-basins, and data related to estimations of runoff and sediment concentrations in runoff collected in the same sub-basins. The present paper shows a methodological approach for calibrating SWAT in small ungauged basins using soil water content measurements and runoff samples collected within the basin. The SWAT satisfactorily predicted the average soil water content, runoff and soil loss for moderate intensity events recorded during the study periods. However, it was not satisfactory for high-intensity events which would require exploring the possibilities of using sub-daily information as an input model parameter.

Land application of poultry manure and its influence on spectrofluorometric characteristics of dissolved organic matter

Land application of manure is a common practice that is used to supplement nutrients from fertilizers as well as to reuse and recycle waste in agricultural watersheds. Excess application of manure can however result in elevated exports of organic and inorganic nutrients in runoff. We evaluated the concentration and composition of dissolved organic matter (DOM) in runoff from cropland (corn) receiving poultry manure. Manure was applied once every three years at the rate of 9Mgha−1 in early spring and was incorporated into the soil during application. Surface runoff and soil water sampling was performed for eight natural storm events with one storm event prior to manure application. Samples were collected from the field edge, upland and lowland riparian zones and a receiving stream. Concentrations of dissolved organic carbon (DOC) were highest at the field edge (mean: 94mgL−1) and then declined sharply for the riparian and stream locations. Temporally, DOC concentrations in field runoff were highest for the first storm event following manure application and then declined quickly over the next 1–3 weeks. DOM composition in runoff following manure application had low aromaticity and a microbial/tryptophan-like character. These characteristics evolved with time toward more aromatic, more humic, and a terrestrial-like DOM composition. The decrease in runoff DOM was attributed to sorption and microbial degradation. Our observations suggest that while concentrations of DOM can be low in manure runoff, a short period (1–3 weeks) following manure application could be an environmentally sensitive and vulnerable period for runoff water quality.

Spatial distribution of perchlorate, iodide and thiocyanate in the aquatic environment of Tianjin, China: Environmental source analysis

Although China is the largest producer of fireworks (perchlorate-containing products) in the world, the pathways through which perchlorate enters the environment have not been characterized completely in this country. In this study, perchlorate, iodide and thiocyanate were measured in 101 water samples, including waste water, surface water, sea water and paired samples of rain water and surface runoff collected in Tianjin, China. The concentrations of the target anions were generally on the order of rain>surface water≈waste water treatment plant (WWTP) influent>WWTP effluent. High concentrations of perchlorate, iodide and thiocyanate were detected in rain samples, ranging from 0.35 to 27.3 (median: 4.05), 0.51 to 8.33 (2.92), and 1.31 to 107 (5.62) ngmL−1, respectively. Furthermore, the concentrations of the target anions in rain samples were significantly (r=0.596–0.750, p<0.01) positively correlated with the concentrations obtained in the paired surface runoff samples. The anions tested showed a clear spatial distribution, and higher concentrations were observed in the upper reaches of rivers, sea waters near the coast, and rain-surface runoff pairs sampled in urban areas. Our results revealed that precipitation may act as an important source of perchlorate, iodide and thiocyanate in surface water. Moreover, iodide concentrations in the Haihe River and Dagu Drainage Canal showed a good correlation with an ideal marker (acesulfame) of domestic waste water, indicating that input from domestic waste water was an important source of iodide in the surface waters of Tianjin.

Characterization and first flush analysis in road and roof runoff in Shenyang, China.

As urbanization increases, urban runoff is an increasingly important component of total urban non-point source pollution. In this study, the properties of urban runoff were examined in Shenyang, in northeastern China. Runoff samples from a tiled roof, a concrete roof and a main road were analyzed for key pollutants (total suspended solids (TSS), total nitrogen (TN), total phosphorus (TP), chemical oxygen demand (COD), Pb, Cd, Cr, Cu, Ni, and Zn). The event mean concentration, site mean concentration, M(V) curves (dimensionless cumulative curve of pollutant load with runoff volume), and mass first flush ratio (MFF30) were used to analyze the characteristics of pollutant discharge and first flush (FF) effect. For all events, the pollutant concentration peaks occurred in the first half-hour after the runoff appeared and preceded the flow peaks. TN is the main pollutant in roof runoff. TSS, TN, TP, Pb, and Cr are the main pollutants in road runoff in Shenyang. There was a significant correlation between TSS and other pollutants except TN in runoff, which illustrated that TSS was an important carrier of organic matter and heavy metals. TN had strong positive correlations with total rainfall (Pearson's r = 0.927), average rainfall (Pearson's r = 0.995), and maximum rainfall intensity (Pearson's r = 0.991). TP had a strong correlation with rainfall intensity (Pearson's r = 0.940). A significant positive correlation between COD and rainfall duration (Pearson's r = 0.902, significance level = 0.05) was found. The order of FF intensity in different surfaces was concrete roof > tile roof > road. Rainfall duration and the length of the antecedent dry period were positively correlated with the FF. TN tended to exhibit strong flush for some events. Heavy metals showed a substantially stronger FF than other pollutant.

Effects of native perennial vegetation buffer strips on dissolved organic carbon in surface runoff from an agricultural landscape

Dissolved organic carbon (DOC) constitutes a small yet important part of a watershed’s carbon budget because it is mobile and biologically active. Agricultural conservation practices such as native perennial vegetation (NPV) strips will influence carbon cycling of an upland agroecosystem, and could affect how much DOC enters streams in runoff, potentially affecting aquatic ecosystems. In a study conducted in Iowa (USA), four treatments with strips of NPV varying in slope position and proportion of area were randomly assigned among 12 small agricultural watersheds in a balanced incomplete block design. Runoff samples from 2008 to 2010 were analyzed for DOC and correlated with flow data to determine flow weighted DOC concentrations and loads. Data were analyzed for the entire 3 years, annually, seasonally, monthly, by flow event size and for one extreme storm event. Overall we found few differences in DOC concentration with the exception that concentrations were greater in the 10 % NPV at the footslope watersheds than the 20 % NPV in contours watersheds over the 3 years, and the 100 % agricultural treatment had higher DOC concentrations than all NPV treatments during the one extreme event. Because the NPV treatments reduced runoff, DOC export tended to be highest in the 100 % agricultural watersheds over the 3 years and during high flows. We also compared two watersheds that were restored to 100 % NPV and found decreases in DOC concentrations and loads indicating that complete conversion to prairie leads to less watershed DOC export. Regression results also support the contention that increases in the percentage of NPV in the watershed decreases watershed export of DOC. Further analysis indicated that DOC concentrations were diluted as flow event size increased, independent of any treatment effects. It appears groundwater sources become an important component to flow as flow event size increases in these watersheds.

Developmental toxicity and DNA damage from exposure to parking lot runoff retention pond samples in the Japanese medaka (Oryzias latipes)

Parking lot runoff retention ponds (PLRRP) receive significant chemical input, but the biological effects of parking lot runoff are not well understood. We used the Japanese medaka (Oryzias latipes) as a model to study the toxicity of water and sediment samples from a PLRRP in Morehead City, NC. Medaka exposed in ovo to a dilution series of PLRRP water had increased odds of death before hatching, but not teratogenesis or delayed hatching. Next, we adapted a long-amplicon quantitative PCR (LA-QPCR) assay for DNA damage for use with the Japanese medaka. We employed LA-QPCR to test the hypotheses that PLRRP water and sediments would cause nuclear and mitochondrial DNA damage with and without full-spectrum, natural solar radiation. Fluoranthene with and without natural sunlight was a positive control for phototoxic polycyclic aromatic hydrocarbon-induced DNA damage. Fluoranthene exposure did not result in detectable DNA damage by itself, but in combination with sunlight caused significant DNA damage to both genomes. PLRRP samples caused DNA damage to both genomes, and this was not increased by sunlight exposure, suggesting the DNA damage was unlikely the result of PAH phototoxicity. We report for the first time that PLRRP-associated pollutants cause both nuclear and mitochondrial DNA damage, and that fluoranthene-mediated phototoxicity results in similar levels of damage to the nuclear and mitochondrial genomes. These effects may be especially significant in sensitive marine ecosystems.