Drainage Outlet Research Articles

Influence of Low Impact Development practices on urban diffuse pollutant transport process at catchment scale

Understanding the entire urban diffuse pollutant transport process in a Low Impact Development (LID) pilot catchment is critical for developing efficient and reliable LID strategies to remove stormwater pollutants. Previous studies focused on the LID performance at a system scale and modeling work. However, the influence of LID practices on the entire urban diffuse pollutant transport process at a catchment scale through field studies remains unclear. The present study analyzed particle loads, particle size distribution and heavy metal concentrations during the accumulation-release-transport process of urban diffuse pollutants. It was found that 13.11% particles can be washed-off from the road surfaces, and a vast majority (12.40%) of suspended solids (SS) in the road surface runoff was retained by LID while only a small fraction (0.71%) can overflow through the LID system and finally 0.42% SS was discharged from the drain outlet. This result implies that LID practices can significantly reduce the contribution of road deposited sediments pollution to urban receiving water. Outcomes also found that most heavy metals in stormwater are particulate, and furthermore, finer particles contain more heavy metals and are easily removed by the stormwater runoff. Therefore, it is essential to consider the influence of particle size on SS removal performance of LID and apply enhanced LID techniques which can remove the fine particles, especially the particles 10–105 μm, in the stormwater.

Subglacial water storage and drainage beneath the Fennoscandian and Barents Sea ice sheets

Subglacial hydrology modulates how ice sheets flow, respond to climate, and deliver meltwater, sediment and nutrients to proglacial and marine environments. Here, we investigate the development of subglacial lakes and drainage networks beneath the Fennoscandian and Barents Sea ice sheets over the Late Weichselian. Utilizing an established coupled climate/ice flow model, we calculate high-resolution, spatio-temporal changes in subglacial hydraulic potential from ice sheet build-up (∼37 ka BP) to complete deglaciation (∼10 ka BP). Our analysis predicts up to 3500 potential subglacial lakes, the largest of which was 658 km2, and over 70% of which had surface areas <10 km2, comparable with subglacial lake-size distributions beneath the Antarctic Ice Sheet. Asynchronous evolution of the Fennoscandian Ice Sheet into the flatter relief of northeast Europe affected patterns of subglacial drainage, with up to 100 km3 more water impounded within subglacial lakes during ice build-up compared to retreat. Furthermore, we observe frequent fill/drain cycles within clusters of subglacial lakes at the onset zones and margins of ice streams that would have affected their dynamics. Our results resonate with mapping of large subglacial channel networks indicative of high-discharge meltwater drainage through the Gulf of Bothnia and central Barents Sea. By tracking the migration of meltwater drainage outlets during deglaciation, we constrain locations most susceptible to focussed discharge, including the western continental shelf-break where subglacial sediment delivery led to the development of major trough-mouth fans. Maps of hydraulic potential minima that persist throughout the Late Weichselian reveal potential sites for preserved subglacial lake sediments, thereby defining useful targets for further field-investigation.

Occurrence of fecal and non-fecal sources bacteria during several overlap rainfall events at Fujiazhuang bathing beach in Dalian, China

With an aim to provide guidance for public health swimming in the beach, as well as provide a scientific basis for beach safety management, a continuous 16-day monitoring after the first rainfall and 6-day monitoring after the last rainfall in the swimming season in 2015 was carried out at Fujiazhuang bathing beach in Dalian to evaluate the effects of rainfall on typical fecal sources (enterococci, human specific bacteroides) and non-fecal bacteria (staphylococcus aureus) contamination. The results showed that the concentration of enterococci using culture dependent method and human bacteroides using real-time PCR always fluctuated with six overlap rainfalls, which had a severe impact on fecal bacteria indicators. During sampling period, the water quality exceeded the single sample standard for enterococci (<35 cfu/100 mL) and human specific bacteroides (<8.6 × 102 copies/100 mL) in 100% and 96% of the samples, respectively, higher concentrations were consistently distributed near the drain outlet, indicating that most of the stormwater flowed to the drainage system discharging into the marine. The fecal sources bacteria, enterococci and human specific bacteroides were significantly correlated with each other, both of them have a strong relationship with rainfall (p<0.01), while non-fecal contaminated bacterial concentration showed no correlation with rainfall (p>0.05). Swimmer density is another major factor affecting the concentration of both fecal and non-fecal sources bacteria in seawater. Considering from the public health, it is recommended to reduce the swimming frequence during continuous rainfall period, as well as to increase periodic surveying of highly frequented beaches, especially during periods of peak bather density.

Assessing Pathogen Presence in an Intensively Tile Drained, Agricultural Watershed.

Increases in swine production and concomitant manure application provide beneficial nutrients for crops but also include the potential to spread pathogenic bacteria in the environment. While manure is known to contain a variety of pathogens, little is known regarding the long-term effect of manure application on fate and transport of this diverse set of pathogens into surrounding waterways. We report on the use of 16S-rRNA gene sequencing to detect pathogen-containing genera in the agriculturally dominated South Fork Iowa River watershed, home to approximately 840,000 swine in the 76,000-ha basin. DNA was extracted from monthly grab samples collected from three surface water sites and two main artificial drainage outlets. DNA sequences from water samples were matched with sequences from genera known to contain pathogens using targeted 16S rRNA amplicon sequencing. The specific genera known to contain pathogens were quantified by combining percentage of genera sequence matches with 16S rRNA gene quantitative polymerase chain reaction results. Specifically, abundances of , , and significantly increased in surface water after typical fall manure application. Additionally, the likely transport pathways for specific genera known to contain pathogens were identified. Surface water concentrations were influenced mainly by artificial drainage, whereas was primarily transported to surface waters by runoff events. The results of this study will help us to understand environmental pathways that may be useful for mitigation of the diverse set of pathogenic genera transported in agroecosystems and the capability of manure application to alter existing microbial community structures.

GEOMORPHOLOGICAL STUDY USING GIS TECHNIQUE OF EL-BURULLUS COASTAL AREA, EGYPT

Nile Delta coastal area including El-Burullus headland has experienced to face significant erosion in some local parts. The temporal and spatial geomorphological variations due to coastal processing and establishment of shore protection structures along El-Burullus coastal area were investigated in two ways. The first way is to study the stretches surf, breaker and offshore zones as perpendicular to the shoreline and the second way is to focus on three regions of interest along the shoreline (El-Burullus lake outlet, Balteem beach, and Kitchener drain outlet). Geostatistical Analyst model was used as advanced GIS technique to interpolate the data gathered from field campaigns and laboratory work. The results of grain size analyses of the sediments indicated fine sand is the dominant size in surf (0.16 mm) and breaker (0.15 mm) zones, while very find sand is in offshore (0.11 mm) zone. The sediment sorting in the three zones is recognized as moderately well sorted. Certainly, the moderately sorted sites have a mixing between indigenous and allochthonous sands. Variation of depth during the two successive years 2015 and 2013 was used as indicator of coastal processing in this area to identify the sites of erosion and accretion. The depth indicator revealed that the majority of the coastal area of El-Burullus is in erosion status with little accretion sites. Texture characteristics of sediments were used to recognize the depositional environments in the three interested areas. The dominant finer sand can attributed to deposition at low energy condition. Sorting investigation revealed that indigenous sediments were detected.

Soluble and colloidal translocation of Al, Fe, Si and Mn in an artificially drained French Retisol

Soil evolution results from both solute and colloid/particle translocation, but their relative importance in terms of soil formation is still under debate. The genesis of albic material in Retisols represents an ideal case to quantify the relative contribution of these two forms of transport in soil evolution since it results from i) clay eluviation, ii) reductive solubilisation of Fe oxides, and possibly iii) silicate hydrolysis. This issue seems particularly challenging in cultivated Retisols in which detailed analysis of the soil solid phases has demonstrated that artificial drainage and liming alter the genetic pathway of albic material both qualitatively and quantitatively.In the present study, we characterised the chemistry (pH, Eh, Al, Si, Fe and Mn) and dynamics of soil water and its evolution with increasing distance from the drain. Rainfall water, soil solution at water saturation in the E&Bt horizon and drainage water were sampled by an open rainfall collector, piezometers located at different distances from the drain, and an automatic water collector located at the main drain outlet, respectively.An element budget at the profile level revealed that only Si was lost from the soil profile while the leaching losses of Al, Fe and Mn were overcompensated by deposition from the atmosphere. The constant Fe/Al concentration ratios in piezometers and drain waters as well as the breakthrough curves at the drain outlet for individual rainfall events suggested that Fe and Al were exported together and mainly in colloidal form. While this was also partly true for Si, a longer tailing of the Si than the Fe and Al breakthrough curves indicated that Si was additionally transported in soluble form. Lastly, the temporal variation of the Mn concentrations was unrelated to that of the other elements, pointing to the predominance of translocation in soluble form. All these results demonstrated that: i) particle/colloidal translocation is more important than translocation in soluble form in a drained Retisol; ii) reductive solubilisation of Fe and Mn oxides still occurred, in spite of the artificial drainage; iii) processes such as wet and dry deposition, dissolution of quartz or ferrolysis also contribute to element budgets in Retisols, at least at some microsites and in some years.

Water quality assessment of an urban river receiving tail water using the single-factor index and principal component analysis

Abstract Tail water from wastewater treatment plants (WWTP) serves as a major supplementary water source for scenic water bodies, whose water quality is one of the major focuses of public and scientific inquiries. This study investigated the temporal and spatial variations in water quality of Tangxihe River, a eutrophic urban river receiving tail water from a nearby WWTP in Hefei City, using the single-factor index (SFI) and principal component analysis (PCA). The results of SFI indicated that the most important parameters responsible for low water quality were total nitrogen (TN) and ammonia (NH4+-N). PCA showed that tail water from the WWTP greatly reduced water quality, as demonstrated by the significantly increased SFIs and integrated principal component values (F values) of the sampling points around the drain outlet of the WWTP (T3, T4 and T5). The sampling points located at the upstream of the river (T1) and up the water-gate of Chaohu Lake (T6) had negative F values, indicating relatively higher water quality. In addition, the season had a significant effect on the water quality of the river. Moreover, we discuss measures to improve the water quality of urban rivers in order to maintain their ecological functions.

Adoption of sawah eco-technology in rice production by farm households in Kebbi State, Nigeria

AbstractThis study examined factors influencing the adoption of sawah technology in Kebbi State, Nigeria. Sawah refers to levelled rice field surrounded by banks with inlet and outlet for irrigation and drainage. Using pre-tested interview guide, data were collected from 300 sawah farmers in the study area. Data collected were analysed with both descriptive and inferential statistics using STATA package. The results showed that respondents were predominantly male, married and had no formal education. The mean age of was 48.13 years with mean household size of 14 persons; farm sizes ranged from 1–50 hectares with average of 4.70 ha, the mean yield was 6.88 tꞏha−1. The results further showed that bond construction had 100% adoption, nursery 99%, puddling 98%, flooding 95%, leveling and smoothening 94% and power tiller use 88% adoption. Adoption of sawah technology was influenced by socio economic characteristics which include sex, age, educational level, farm size, yield and income of the farmers. The study also showed that the attributes of sawah, production factors, information and extension and perception of respondent toward sawah technology influenced adoption. It is concluded that the sawah eco-technology is widely adopted by rice farmers in Kebbi State. The study therefore recommended that dissemination of sawah to other states in Nigeria need to consider factors that promote its adoption. Improvement of those factors that significantly affect adoption of sawah technology is also recommended.

Nitrate and phosphorus transport through subsurface drains under free and controlled drainage

Controlled drainage (CD) is a structural conservation practice in which the drainage outlet is managed in order to reduce drain flow volume and nutrient loads to water bodies. The goal of this study was to evaluate the potential of CD to improve water quality for two different seasons and levels of outlet control, using ten years of data collected from an agricultural drained field in eastern Indiana with two sets of paired plots. The Rank Sum test was used to quantify the impact of CD on cumulative annual drain flow and nitrate-N and phosphorus loads. CD plots had a statistically significant (at 5% level) lower annual drain flow (eastern pair: 39%; western pair: 25%) and nitrate load (eastern pair: 43%; western pair: 26%) compared to free draining (FD) plots, while annual soluble reactive phosphorus (SRP) and total phosphorus (TP) loads were not significantly different. An ANCOVA model was used to evaluate the impact of CD on daily drain flow, nitrate-N, SRP and TP concentrations and loads during the two different periods of control. The average percent reduction of daily drain flow was 68% in the eastern pair and 58% in the western pair during controlled drainage at the higher outlet level (winter) and 64% and 58% at the lower outlet level (summer) in the eastern and western pairs, respectively. Nitrate load reduction was similar to drain flow reduction, while the effect of CD on SRP and TP loads was not significant except for the increase in SRP in one pair.These results from a decade-long field monitoring and two different statistical methods enhance our knowledge about water quality impacts of CD system and support this management practice as a reliable system for reducing nitrate loss through subsurface drains, mainly caused by flow reduction.

Posterior osteotomy for thoracolumbar stress fracture in ankylosing spondylitis through the gap of a pathological fracture

To evaluate the effectivity and safety of posterior osteotomy for thoracolumbar stress fracture in ankylosing spondylitis (AS) through the gap of a pathological fracture. Between April 2012 and August 2015, 8 patients with AS combined with thoracolumbar stress fracture were treated with posterior osteotomy through the gap of a pathological fracture to correct the kyphosis. There were 7 males and 1 female, with an average age of 51 years (range, 37-74 years). The history of AS was 1-40 years (mean, 21.7 years) and disease duration of stress fracture was 2-60 months (mean, 18.5 months). The segmental lesions included T 8, 9 in 1 case, T 10, 11 in 2 cases, T 11 in 2 cases, T 12, L 1 in 1 case, L 1, 2 in 1 case, and L 2, 3 in 1 case. The nerve function before operation according to Frankel grading was grade D in 3 cases and grade E in 5 cases. The pre- and post-operative X-ray films, CT three-dimensional reconstruction, and MRI were collected to measure the global kyphosis (GK), local kyphosis (LK), angle of the fusion levels (AFL), pelvic incidence (PI), pelvic tilt (PT), and sagittal vertical axis (SVA). Visual analogue scale (VAS) score was used to assess the back pain intensity. The operation time was 210-320 minutes (mean, 267 minutes), and the intraoperative blood loss was 400-2 000 mL (mean, 963 mL). Cerebrospinal fluid leakage was found in 3 patients, and the wound healed by removal of drainage tube and suturing drainage outlet after 5-7 days of operation. The wounds of the rest patients healed by first intention. Lower extremity numbness occurred in 1 case and recovered after 1 month of postoperative administration of oral mecobalamin. All the patients were followed up 20-43 months (mean, 28.4 months). No internal fixator loosening, fracture, and other complications occurred. All the fractures healed with the healing time of 3-12 months (mean, 6.8 months). At 3 months after operation, 3 cases with spinal cord injury of preoperative Frankel grade D recovered to grade E. The GK, LK, AFL, PI, PT, SVA, and VAS scores at 1 week after operation and at last follow-up were significantly improved when compared with preoperative ones ( P<0.05). Except for VAS score at last follow-up was significantly improved when compared with that at 1 week after operation ( P<0.05), there was no significant difference in the other indexes between at 1 week after operation and at last follow-up ( P>0.05). Posterior osteotomy through the gap of a pathological fracture is a safe and effective surgical procedure for kyphosis correction and relief of back pain in AS patients combined with thoracolumbar stress fracture. Successful bony fusion and good clinical outcomes can also be achieved by this surgical procedure.

The Pros and Cons of Encouraging Shallow Groundwater Use through Controlled Drainage in a Salt-Impacted Irrigation Area

Encouraging shallow groundwater use through water table management or controlled drainage in irrigated areas can relief crop water stress under water shortage condition. But substituting fresh irrigation water with saline groundwater may speed up salinity buildup in the crop root zone, and consequently increase water use for salt leaching. With a proposed analytical model, this paper presents a case study demonstrating the effect of encouraging shallow groundwater use through controlled drainage on salt and water management in a semi-arid irrigation area in northwestern China. Based on the average rainfall condition, the model assumes that salt accumulates in the crop root zone due to irrigation and shallow groundwater use; till the average soil salinity reaches the crop tolerance level, leaching irrigation is performed and the drainage outlet is lowered to discharge the salt-laden leaching water. For the relatively salt tolerant crop–cotton in the study area, the predicted leaching cycle was as long as 751 days using the fresh water (with salinity of 0.5 g/L) irrigation only; it was shortened to 268 days when the water table depth was controlled at 2 m and 23% of the crop water requirement was contributed from the saline groundwater (with salinity of 4.43 g/L). The predicted leaching cycle was 140 days when the water table depth was controlled at 1.5 m and groundwater contribution was 41% of the crop water requirement; it was shortened to 119 days when the water table depth was controlled at 1.2 m and the groundwater contribution was 67% of the crop water requirements. So the benefit from encouraged shallow groundwater use through controlled drainage is obtained at the expense of shortened leaching cycle; but the shallow groundwater use by crops consists of a significant portion of crop water requirements, and the leaching cycle remains long enough to provide a time window for scheduled leaching in the off season of irrigation. Weighing the pros and cons of the encouraged shallow groundwater use may help plan irrigation and drainage practices to achieve higher water use efficiency in saline agricultural areas.

Minimizing microbial contamination risk simultaneously from multiple hospital washbasins by automated cleaning and disinfection of U-bends with electrochemically activated solutions

Outbreaks of infection associated with microbial biofilm in hospital hand washbasin U-bends are being reported increasingly. In a previous study, the efficacy of a prototype automated U-bend decontamination method was demonstrated for a single non-hospital pattern washbasin. It used two electrochemically activated solutions (ECA) generated from brine: catholyte with detergent properties and anolyte with disinfectant properties. To develop and test a large-scale automated ECA treatment system to decontaminate 10 hospital pattern washbasin U-bends simultaneously in a busy hospital clinic. A programmable system was developed whereby the washbasin drain outlets, U-bends and proximal wastewater pipework automatically underwent 10-min treatments with catholyte followed by anolyte, three times weekly, over five months. Six untreated washbasins served as controls. Quantitative bacterial counts from U-bends were determined on Columbia blood agar, Reasoner's 2A agar and Pseudomonas aeruginosa selective agar following treatment and 24h later. The average bacterial densities in colony-forming units/swab from treated U-bends showed a >3 log reduction compared with controls, and reductions were highly significant (P<0.0001) on all media. There was no significant increase in average bacterial counts from treated U-bends 24h later on all media (P>0.1). P.aeruginosa was the most prevalent organism recovered throughout the study. Internal examination of untreated U-bends using electron microscopy showed dense biofilm extending to the washbasin drain outlet junction, whereas treated U-bends were free from biofilm. Simultaneous automated treatment of multiple hospital washbasin U-bends with ECA consistently minimizes microbial contamination and thus the associated risk of infection.

Characterization and Laboratory-Scale Treatment of Municipal Drainage Wastewater of Khulna, Bangladesh

The study was conducted to characterize and perform laboratory-scale treatment of municipal drainage wastewater of Khulna, Bangladesh. Wastewater samples were collected from three different points of existing urban drain outlets into the Mayur River around Khulna. Laboratory testing shows the BOD5 and COD concentration of wastewater samples varied from 57 - 226 mg/l and 320 - 435 mg/l, respectively, and the total dissolved solids ranged from 1800 - 2525 mg/l. Therefore, a laboratory-scale treatment technology was developed to treat this wastewater. Treatment technologies adopted were primary sedimentation, followed by aeration, chemical precipitation and filtration. In treated wastewater, BOD5, COD and TDS were found to be in the range of 40 - 115 mg/l, 160 - 256 mg/l and 1356 - 1500 mg/l, respectively. These test results suggest that the performance of laboratory-scale treatment plant was not adequate to fulfil the acceptable limit (ECR’97) for safe disposal into surface water bodies. Due to poor quality of effluents, modification of laboratory-scale treatment plant was made by an activated sludge process followed by granular media filtration. The final BOD5, COD TDS and TSS concentration of effluents was found to be 1.38 - 9.8 mg/l, 32 - 192 mg/l, 590 - 1667 mg/l, and 35 - 95 mg/l respectively, which satisfy ECR’97 standard limits for safe disposal into inland water bodies.

Weather, Landscape, and Management Effects on Nitrate and Soluble Phosphorus Concentrations in Subsurface Drainage in the Western Lake Erie Basin

Abstract. Subsurface drainage, while an important and necessary agricultural production practice in the Midwest, contributes nitrate (NO3-N) and soluble phosphorus (P) to surface waters. Eutrophication (i.e., excessive enrichment of surface water by NO3-N and soluble P) supports harmful algal blooms in receiving waters. The magnitude of NO3-N and soluble P loss in subsurface drainage varies greatly by landscape, weather, and field management factors. This study evaluated both the relative and combined impacts of these factors on observed NO3-N and soluble P concentrations in subsurface drainage water in the Western Lake Erie Basin watershed. Water quality data from multiple drainage outlet sites in northwest Ohio provided evidence that the primary management factors affecting NO3-N and soluble P loss were the amount and time of fertilizer application. Results strongly support following Tri-State fertilizer recommendations and 4R nutrient stewardship principles to reduce the risk of NO3-N and soluble P loss. Results also provided evidence of NO3-N and soluble P transport to subsurface drains via different pathways. Due to differences in NO3-N and soluble P transport through the soil profile (via baseflow and preferential flow, respectively), management approaches taken to reduce one nutrient may exacerbate losses of the other. Further research is needed to address potential changes in field hydrology (and consequently the in-field transport of soluble nutrients) from different types of agricultural best management practices (BMPs) and to evaluate optimal stacking of BMPs to achieve reductions in both NO3-N and soluble P loss. Controlled drainage has a high potential for stacking with other BMPs because it is primarily a physical discharge and load reduction practice. Keywords: Agriculture, Eutrophication, Nutrient transport, Regression analysis, Water quality.

Hydro‐sedimentary Dynamics of a Drained Agricultural Headwater Catchment: A Nested Monitoring Approach

Core Ideas Discharge and sediment concentrations were measured in a drained catchment. The impact of tile drainage at the catchment scale was analyzed with a nested approach. The major part of sediment fluxes occurred during winter floods. Sediment transfer in the tile drain was episodic although significant. Soil erosion and sediment transfer are extensive in lowland agricultural catchments. In these environments, high‐frequency datasets of both water discharge and suspended sediment concentrations are often lacking. In particular, the impact of tile drainage networks on sediment fluxes in these catchments is poorly understood. Our research quantified sediment fluxes between 2013 and 2016 at five nested stations including a tile drain outlet across a small (25‐km2) agricultural catchment (located in the Loire River basin, France) representative of lowland cultivated environments of the middle part of this basin. Sediment fluxes varied from 1 to 38 t km−2 yr−1 across the monitored subcatchments. Most of sediment fluxes (79 ± 9%) were measured during flood events (n = 44), mostly occurring in winter (75%) and spring (20%). Seasonality controlled most of the variations of sediment fluxes. Sediment transfers in tile drains occurred episodically. Flows were measured during 11.4% of the monitoring time. A mean time lag of 80 min was recorded between the peak discharge at the drain outlet and the downstream river station. At the event scale, sediment fluxes exported from the tile drain varied between 1.1 × 10−4 and 2.5 t km−2 and remained of the same order of magnitude as those measured at the downstream river station, although the latter were on average 53% lower. Results suggest significant storage of sediment material in the river channel and its export during the most intense flood events. Our research emphasizes the need for continuous monitoring of water and sediment transfers in agricultural catchments equipped with tile drains.

Pesticide fate on catchment scale: conceptual modelling of stream CSIA data

Abstract. Compound-specific stable isotope analysis (CSIA) has proven beneficial in the characterization of contaminant degradation in groundwater, but it has never been used to assess pesticide transformation on catchment scale. This study presents concentration and carbon CSIA data of the herbicides S-metolachlor and acetochlor from three locations (plot, drain, and catchment outlets) in a 47 ha agricultural catchment (Bas-Rhin, France). Herbicide concentrations at the catchment outlet were highest (62 µg L−1) in response to an intense rainfall event following herbicide application. Increasing δ13C values of S-metolachlor and acetochlor by more than 2 ‰ during the study period indicated herbicide degradation. To assist the interpretation of these data, discharge, concentrations, and δ13C values of S-metolachlor were modelled with a conceptual mathematical model using the transport formulation by travel-time distributions. Testing of different model setups supported the assumption that degradation half-lives (DT50) increase with increasing soil depth, which can be straightforwardly implemented in conceptual models using travel-time distributions. Moreover, model calibration yielded an estimate of a field-integrated isotopic enrichment factor as opposed to laboratory-based assessments of enrichment factors in closed systems. Thirdly, the Rayleigh equation commonly applied in groundwater studies was tested by our model for its potential to quantify degradation on catchment scale. It provided conservative estimates on the extent of degradation as occurred in stream samples. However, largely exceeding the simulated degradation within the entire catchment, these estimates were not representative of overall degradation on catchment scale. The conceptual modelling approach thus enabled us to upscale sample-based CSIA information on degradation to the catchment scale. Overall, this study demonstrates the benefit of combining monitoring and conceptual modelling of concentration and CSIA data and advocates the use of travel-time distributions for assessing pesticide fate and transport on catchment scale.

Occurrence and seasonal variations of per- and polyfluoroalkyl substances (PFASs) including fluorinated alternatives in rivers, drain outlets and the receiving Bohai Sea of China

A simultaneous sampling campaign was undertaken to study the pollution by 21 per- and polyfluoroalkyl substances (PFASs) in rivers, drain outlets and their receiving Bohai Sea of China. Chlorinated polyfluoroalkyl ether sulfonic acids (Cl-PFESAs) are being used as fluorinated alternatives and they were included in this study. In comparison with other regions and countries, high concentrations of ∑21PFASs in seawater samples from the Bohai Sea, ranging from 5.03 to 41 700 ng/L (median: 64.8 ng/L), were observed. The spatial distribution of PFAS levels in this sea area was in the ranking of Laizhou Bay > Liaodong Bay > Bohai Bay > other sea areas. By comparing the levels and composition profiles of PFASs in the seawater and their sources (rivers and drain outlets), it was concluded that rivers and drain outlets are the primary sources of PFAS contamination to the Bohai Sea. These PFAS levels varied seasonally among the rivers and drain outlets, but statistically significant changes were not observed. Levels of 6:2 and 8:2 Cl-PFESAs in rivers, drain outlets and receiving sea were firstly reported in the present study. Relatively high concentrations of 6:2 Cl-PFESA were found in drain outlets, ranging from below method limits of quantification (MLQ) to 7600 ng/L, but 8:2 Cl-PFAES detection was infrequent and all median concentration below MLQ. Mass discharges to the sea of 6:2 Cl-PFESA from rivers and drain outlets to the sea were estimated to be 37 and 17 kg/y, respectively.

Seasonal variation of macrolide resistance gene abundances in the South Fork Iowa River Watershed

The Midwestern United States is dominated by agricultural production with high concentrations of swine, leading to application of swine manure onto lands with artificial subsurface drainage. Previous reports have indicated elevated levels of antibiotic resistance genes (ARGs) in surface water and groundwater around confined animal feeding operations which administer antimicrobials. While previous studies have examined the occurrence of ARGs around confined swine feeding operations, little information is known how their transport from tile-drained fields receiving swine manure application impacts downstream environments. To further our knowledge in this area, water samples were collected from five locations in the agriculturally dominated South Fork Iowa River Watershed with approximately 840,000 swine present in the 76,000ha basin. Samples were collected monthly from three stream sites and two main artificial subsurface drainage outlets. Samples were analyzed for macrolide resistance genes ermB, ermF and 16S rRNAgene abundance using qPCR. Abundance of erm genes ranged from below limits of quantification to >107 copies 100mL−1 water. Eighty-nine percent of stream water samples contained one of these two ARGs. Results indicate significantly more ermB and ermF in main drainage outlets than stream samples when normalized by 16S rRNA abundance (p<0.0001). Both artificial drainage locations revealed temporal trends for ermB and ermF abundance when normalized to 16S rRNA abundance. The higher resistance gene concentrations identified in artificial drainage samples occurring mid-Spring and late-Fall are likely due to manure application.

Field assessment of surface runoff, sediment yield and soil erosion in the opencast mines in Chirimiri area, Chhattisgarh, India

Chirimiri Coal field is located in the Koriya district of Chhattisgarh state of India. It lies in the valley of the Hasdeo River and is spread over 125 km2 area. Ever increasing problem of declining forest resources and water quality is a cause of concern particularly due to excessive soil erosion resulting in soil sediment deposition from the overburdened dump. Dwindling resources has compelled the policy makers to search for alternatives such as waste lands and mined areas to improve soil and water resources for use in agriculture and allied sectors while maintaining the local ecology and hydrology. Most Opencast mines release huge amount of mining wastes in the form of overburden dump (OBD) materials that are prone to soil erosion and also create problems of sedimentation and deteriorating water quality, affecting agriculture. Historical daily rainfall data for 21 years and daily surface runoff as estimated by SCS-Curve Number method were analysed. Sediment yield was estimated at lower end of erosion face of OBD and near drainage outlet of opencast mine. Assessment of soil erosion from OBD materials was made byRevised Universal Soil Loss Equation (RUSLE) method and was compared with direct field measurements by placing plastic sheets in downstream portion of OBD. As a result monsoon rainfall constitutes 91.6 percent of the annual rainfall and surface runoff constitutes 31.7 percent of monsoon rainfall. The surface runoff was found to be 4133 m3/ha while the sediment yield of drainage effluent was negligible. The soil loss from OBD as estimated by the RUSLE method (62.7 t ha−1 yr−1) was quite close (+13.2 percent) to the direct field measurement 54.44 t ha−1. The sediment samples from OBD were found acidic in nature and exhibited low values of Electrical Conductivity (EC), Organic Content (OC), Water Holding Capacities (WHC), and Available Nitrogen (N), Phosphorus (P) and Potassium (K). For controlling soil erosion of OBD, mechanical and vegetative measures have been suggested along with installation of sediment traps inside and outside the mines. There is good scope to backfill the mines with the OBD in the form of well laid out terraces to support plantation. This can be eventually used for leguminous fodder/grass production.

Alternative alert system for Ganga river eutrophication using alkaline phosphatase as a level determinant

Short-term variations in phosphorus (P) concentrations must be considered while assessing the long-term changes in trophic status and estimating the P load and export. Furthermore, given the challenges of conventional monitoring of river systems, a sediment-specific biomonitoring tool may be more successful inferring P related human controls. In this study, conducted along a 37km river channel representing up-and downstream urban control, and through a trajectory from a major point source (Assi drain), we tested the patterns of concordance between alkaline phosphatase (AP) activity and soluble reactive-P (SRP) and between AP activity and trophic status in the Ganga River. To validate data comparison, we selected a reference site at Dev Prayag, situated ∼1130km upstream to the main study stretch. Samples were collected for three consecutive year (March 2013 to February 2016) with respect to atmospheric deposition, surface runoff, point source loading, river water and sediment analysis. For trajectory analysis, samples were collected from 15 locations starting from the drain outlet (zero distance) upto 1.5km downstream with sampling location 100m away from the preceding one. We found marked spatial and temporal variations in P concentrations which could be traced by quantifying the AP activity. The AP activity, recorded highest at reference site, declined with increases in P; and at drain mouth it was close to zero reflecting strong influence of P level on alkaline phosphatase activity in the river. We used canonical correlation analysis (CCorA) to test the degrees of concordance and similarity in different variables. Most of the environmental variables and indicators of eutrophy appear largely clustered at one side of the coordinate separating AP activity and dissolved oxygen towards opposite side of the axis. The dynamic fit function relating AP activity with different variables showed significant positive correlation with DO (R2=0.67; p<0.001) and negative correlations with BOD (R2=0.82; p<0.001), Chl a biomass (R2=0.52; p<0.001) and trophic status index (R2=0.54 (Chl a), 0.96 (DRP); p<0.001). Furthermore, the enzyme activity did not show significant negative correlation with heavy metals in sediment. Because anthropogenic activities continue to enhance P loads; AP is inhibited directly by P availability; and eutrophy feedbacks sediment P release, our observations on P-AP activity relationship provide a valuable alternative means for detecting P related controls on water quality, trophic status and biogeochemical feedbacks in human impacted rivers.