Storm Runoff Samples Research Articles

THE FIRST FLUSH ANALYSIS OF STORMWATER RUNOFF IN A HUMID CLIMATE

This study focuses on the pollutants from urban runoff to Zarjoob River, which is one of the rivers leading to Anzali International Wetland, which was listed in the Montreux Record in 1993 as a site in need of priority conservation. Storm water runoff from a residential area in Rasht (the largest city on Iran’s Caspian Sea coast) was monitored in this study during thirteen rainfall events, with a total of 58 storm runoff samples collected from 2018 to 2019. In most rainfall events, the mean concentration of total suspended solids (TSS) and chemical oxygen demand (COD) were higher than the other pollutants. The event mean concentrations (EMC) of TSS loads ranged from 57.3 mg/L to 682.5 mg/L and from 46.7 mg/L to 590.4 mg/L for COD. The site mean concentrations (SMC) for TSS, COD, total phosphorus (Total P), nitrate-nitrogen (NO3-N), and total lead (Pb) were 219, 205, 1.91, 20.63, and 0.25 mg/L, respectively. The first flush coefficient (b) was used to evaluate the first flushing of various events. The results of the study confirmed that the first flush occurred in all events, and the average ranking of first flush strength among the pollutants was COD > NO3-N > TP > Pb > TSS. Controlling one-third of the initial runoff volume appeared to be critical for managing the quality of urban rivers in humid regions. The findings of this study can be applied to urban runoff management strategies in cities with similar climatic conditions.

The effects of surface pollution on urban river water quality under rainfall events in Wuqing district, Tianjin, China

A large quantity of pollutants is washed off by stormwater during rainfall events. Polluted storm runoff deteriorates the water quality of receiving water bodies, which is becoming a main threat to urban water environment. In this work, five rainfall events were monitored to clarify the characteristics of land surface pollution in Wuqing district, China. Four pollutant indicators of storm runoff samples, including chemical oxygen demand (COD), total phosphorus (TP), total nitrogen (TN) and ammonia nitrogen (NH3-N), were analyzed and then used to validate the parameters of a model established by Infoworks integrated catchment modeling (ICM). The land surface pollutant loads of metropolitan area for four different rainfall scenarios and the variations in pollutants concentration in urban rivers were illustrated based on the model. The simulated results showed that the volume of runoff increased from 31.8 × 104 m3 to 139.7 × 104 m3 with the increase in the return period. The EMCs (Event Mean Concentration) of pollutants, however, were negatively correlated with return periods and the maximum drop was approximately 67%. Furthermore, the increased runoff enhanced the dilution effect and reduced the residence time of pollutants in rivers, which were the main reasons for the decrease of the pollutants concentrations. The results suggested that the runoff should be taken into account when considering the effects of surface pollution on urban river water quality.

Subtype analysis of zoonotic pathogen Cryptosporidium skunk genotype

Cryptosporidium skunk genotype is a zoonotic pathogen commonly identified in surface water. Thus far, no subtyping tool exists for characterizing its transmission in humans and animals and transport in environment. In this study, a subtyping tool based on the 60kDa glycoprotein (gp60) gene previously developed for Cryptosporidium chipmunk genotype I was used in the characterization of Cryptosporidium skunk genotype in animal and storm runoff samples from a watershed in New York. Altogether, 17 positive samples from this watershed and 5 human and animal specimens from other areas were analyzed. We identified 14 subtypes of Cryptosporidium skunk genotype, 11 of which were seen in the watershed. In phylogenetic analysis, these subtypes belonged to 4 subtype families (XVIa, XVIb, XVIc, and XVId). No host-adapted subtypes were identified and the two subtypes in humans were genetically similar to some in raccoons, otters, and storm runoff samples from the watershed. The characteristics of gp60 protein sequences of the Cryptosporidium skunk genotype are similar to those of other Cryptosporidium species, but only its XVIb subtype family has a putative furin cleavage site. This subtyping tool might be useful in characterizing Cryptosporidium skunk genotype in clinical and environmental samples.

An integrated simulation-monitoring framework for nitrogen assessment: A case study in the Baixi watershed, China

Abstract As the deterioration of drinking water quality has become increasingly severe worldwide, there is a considerable need to accurately identify variable pollution sources. Currently, simulation programs have been shown to be less effective in short-term and detailed simulations. Therefore, this study advanced an integrated framework for simulation by combining the modelling and monitoring methods. A case study was conducted to identify the spatial and temporal distribution of nitrogen (N) in the upstream watershed of a typical drinking water reservoir, in the city of Ningbo, Zhejiang province, China. In this study, a watershed model, Soil and Water Assessment Tool (SWAT), was used to estimate N load for the 254 km2 upper stream watershed; while storm runoff samples were also collected to illuminate more detailed processes in the storm event. Based on the model output, the critical N source in Baixi watershed was identified as the forest. The potential nonpoint source (NPS) pollution risk areas were also illustrated as Sub-basin 21, 20 and 26. In addition, the model simulation proved that the Qingshui River contributed more N load than the other two tributaries. Conversely, the short-term and detailed trends were obtained through storm sampling. By analyzing the storm samples, it was clear that the N load into the drinking water reservoir results from a combination of land-use, agricultural activities, as well as atmospheric deposition, especially in the acid rain control region. It could be further inferred that modelling and monitoring could serve as a framework to provide information for N load prediction and protection of drinking water. Using the integrated simulation-monitoring framework, the SWAT model could be used as an effective tool to foretell the potential risk of detrimental NPS conditions, while monitoring could provide an inventory and detailed means to further study short-term trends.

Quality and first flush analysis of stormwater runoff from a tropical commercial catchment

This paper examines the storm runoff quality from a commercial area in south Johor, Malaysia. Six storm events with a total of 68 storm runoff samples were analyzed. Event Mean Concentration (EMC) for all constituents analysed showed large inter-event variation. Site mean concentrations (SMC) for total suspended solids (TSS), oil and grease (O&G), biochemical oxygen demand (BOD), chemical oxygen demand (COD), nitrate-nitrogen (NO(3)-N), nitrite-nitrogen (NO(2)-N), ammonia-nitrogen (NH(3)-N), total phosphorus (Total P) and Soluble P are 261, 4.31, 74, 192, 1.5, 0.006, 1.9, 1.12 and 0.38 mg/L, respectively. The SMCs at the studied site are higher than those reported in many urban catchments. The mean baseflow concentrations were higher than the EMCs for COD, Soluble P, NH(3)-N, NO(3)-N, Total P and NO(2)-N. However, the reverse was observed for TSS and O&G. All pollutants showed the occurrence of first flush phenomenon with the highest strength was observed for TSS, COD and NH(3)-N.

Reducing microbial contamination in storm runoff from high use areas on California coastal dairies

High use areas are a fundamental part of California coastal dairies and grazing livestock ranches as feeding areas, nurseries, and sick pens. High stocking densities and daily use in these areas lead to soil surfaces devoid of vegetation and covered in manure, with high potential for manure transport during winter rains to receiving waters regulated for shellfish harvesting and recreation. We characterized the association between California's Mediterranean climate and a series of existing and proposed management practices on fecal coliform bacteria (FCB) transport from high use areas on dairies and ranches. Results from 351 storm runoff samples collected below 35 high-use areas indicate that removal of cattle during winter, locating high use areas on level ground, application of straw and seeding, and vegetative buffer strip implementation were significantly associated with FCB concentration and load reductions. These results complement our findings for reductions of specific pathogens in runoff from these areas. These findings have practical significance because they document surface water quality benefits that the studied management practices provide in application on working farms and ranches. This direction is critical and timely for on-farm management efforts seeking to reduce microbial pollution in runoff and comply with indicator bacteria water quality criteria.

Farm Factors Associated with Reducing Cryptosporidium Loading in Storm Runoff from Dairies

A systems approach was used to evaluate environmental loading of Cryptosporidium oocysts on five coastal dairies in California. One aspect of the study was to determine Cryptosporidium oocyst concentrations and loads for 350 storm runoff samples from dairy high use areas collected over two storm seasons. Selected farm factors and beneficial management practices (BMPs) associated with reducing the Cryptosporidium load in storm runoff were assessed. Using immunomagnetic separation (IMS) with direct fluorescent antibody (DFA) analysis, Cryptosporidium oocysts were detected on four of the five farms and in 21% of storm runoff samples overall. Oocysts were detected in 59% of runoff samples collected near cattle less than 2 mo old, while 10% of runoff samples collected near cattle over 6 mo old were positive. Factors associated with environmental loading of Cryptosporidium oocysts included cattle age class, 24 h precipitation, and cumulative seasonal precipitation, but not percent slope, lot acreage, cattle stocking number, or cattle density. Vegetated buffer strips and straw mulch application significantly reduced the protozoal concentrations and loads in storm runoff, while cattle exclusion and removal of manure did not. The study findings suggest that BMPs such as vegetated buffer strips and straw mulch application, especially when placed near calf areas, will reduce environmental loading of fecal protozoa and improve stormwater quality. These findings are assisting working dairies in their efforts to improve farm and ecosystem health along the California coast.

Climate and On-Farm Risk Factors Associated with Giardia duodenalis Cysts in Storm Runoff from California Coastal Dairies

Climatic factors and on-farm management practices were evaluated for their association with the concentrations (cyst/liter) and instantaneous loads (cysts/second) of Giardia duodenalis in storm-based runoff from dairy lots and other high-cattle-use areas on five coastal California farms over two storm seasons. Direct fluorescent antibody analysis was used to quantitate cysts in 350 storm runoff samples. G. duodenalis was detected on all five dairy farms, with fluxes of 1 to 14,000 cysts/liter observed in 16% of samples. Cysts were detected in 41% of runoff samples collected near cattle less than 2 months old, compared to 10% of runoff samples collected near cattle over 6 months old. Furthermore, the concentrations and instantaneous loads of cysts were > or =65 and > or =79 times greater, respectively, in runoff from sites housing young calves than in sites housing other age classes of animals. Factors associated with environmental loading of G. duodenalis included cattle age, cattle stocking number, and precipitation but not lot area, land slope, or cattle density. Vegetated buffer strips were found to significantly reduce waterborne cysts in storm runoff: each additional meter of vegetated buffer placed below high-cattle-use areas was associated with reductions in the concentration and instantaneous load of cysts by factors of 0.86 and 0.79 (-0.07 and -0.10 log(10)/m), respectively. Straw mulch, seed application, scraping of manure, and cattle exclusion did not significantly affect the concentration or load of G. duodenalis cysts. The study findings suggest that vegetated buffer strips, especially when placed near dairy calf areas, should help reduce the environmental loading of these fecal protozoa discharging from dairy farms.

Seasonal solute behaviour of stormflow in a small agricultural catchment

Summary With reference to storm runoff samples, the importance of seasonal variation in solute behaviour in a small agricultural catchment is identified by means of simple power function models relating solute concentration to discharge. These models are applied to a seasonally subdivided data set, in an attempt to obtain quantitative information on the importance of season in controlling solute response. Specific electrical conductance and the concentrations of Chloride and Sodium, are shown not to vary seasonally in relation to discharge. Relationships between Potassium, Calcium, Magnesium and Nitrate concentrations, and discharge, are shown to exhibit seasonally dependent behaviour. An attempt is made to explain these characteristics in terms of physical processes and the likely origins of individual solute species.