Modeling Nonpoint Source Pollutant Losses from a Small Watershed Using HSPF Model

Hydrologic models play an important role in the assessment of nonpoint source (NPS) pollution, which is essential for the environmental management of water resources. The present study has been undertaken to evaluate the applicability of a physically based continuous time scale, hydrological, and water quality computer model—Hydrologic Simulation Program-Fortran (HSPF)—in simulating runoff and sediment associated NPS pollutant losses from a small mixed type (land under agriculture, shrubs and forest, rocks, grasses) watershed of the Damodar Valley Corporation, Hazaribagh, India. Water soluble NO3–N, NH4–N, and P were considered as pollutants and their concentrations in the runoff were measured at the outlet of the watershed, randomly for 15 dates during the monsoon season (June–October) of 2000 and 2001. The model calibration and validation results reveal that the seasonal trend of HSPF simulated runoff, sediment yield, and NPS pollutants compared reasonably with their measured counterparts. Although the concentrations of pollutants were generally overpredicted for NO3–N and underpredicted for NH4–N and water-soluble P in the month of June when fertilizers releasing NH4–N and P are applied in rice fields, the differences in the mean concentration were not significantly different at a 95% level of confidence. Variation in the simulated losses of water soluble N and P species between the years occurred largely due to differences in the amount and distribution of rainfall. These results indicate that the HSPF model can be used as a tool for simulating runoff and sediment associated NPS pollution losses from the study area.     

Volumetric Filtration of Rainfall Runoff. II: Event-Based and Interevent Nutrient Fate

This study examines in situ phosphorus treatment using a combined unit operation and process, a volumetric clarifying filter (VCF). Urban rainfall-runoff transports phosphorus in dissolved and particulate phases with the latter phase distributed across the particulate matter (PM) gradation. From a clean initial condition, the VCF was monitored across 19 events without maintenance, to examine partitioning and phosphorus distribution on PM. For the monitoring period, site influent total phosphorus (TP) is 0.342 mg/L of which 0.081 mg/L is dissolved; and subsequently reduced to 0.095 and 0.031 mg/L, respectively, by the VCF. PM-bound phosphorus is categorized as suspended, settleable and sediment fractions based on PM size and separation behavior. Site influent PM-based concentrations (mg/g) are 0.22 for sediment, 0.42 for settleable and 3.27 for the suspended fraction with each fraction further enriched in the VCF, based on effluent monitoring. A categorical analysis and odds ratio testing of PM-based phosphorus specific capacities (mg/g) indicate that a significant fraction of phosphorus can bind to suspended PM preferentially over settleable and sediment PM as a PM-based concentration. At the end of the event-based monitoring the inter-event change in phosphorus and nitrogen, chemistry is examined as a function of runoff storage time. Runoff retention generates nitrate reduction and ammonia (NH3+NH4+) production; predominately as ammonium. Phosphorus partitioning is stable during runoff storage with a dissolved fraction between one fourth to one-third of TP. Predominant species are H2PO4? for a pH<7 and HPO42? for a pH>7.     

HSPF Simulation of Runoff and Sediment Loads in the Upper Changjiang River Basin, China

To evaluate the performance of a computer model simulating runoff and sediment load in the upper region of the Changjiang (Yangtze River) basin over a relatively short time interval, including examining the applicability of the input precipitation data generated from global circulation models and satellite data, we used a spatially distributed model, HSPF with the International Satellite Land Surface Climatology Project (ISLSCP) precipitation data for 1987 and 1988 as input data. The Nash–Sutcliffe coefficient (R2) for 5-day average streamflow was 0.94 in the calibration period and 0.95 in the verification period for the whole upper region. Moreover, the model simulated the 5-day average streamflow well in each main tributary, as shown by R2 values of 0.46–0.96, except that it underestimated the peak flow rates during the flood season over 2 years by up to 71% in Tuojiang and 61% in Jialingjiang. The model simulated the 5-day concentrations of suspended solids (SS) fairly well in the headwaters and upper regions of the Jinshajiang, Yalongjiang, and Minjiang watersheds, as shown by R2 values of 0.31–0.65. In the other regions, however, the model underestimated the SS load by up to 72%, and rarely simulated the fluctuation of SS concentration in each river channel during the flood season. These errors led to the underestimation of sediment runoff volume from the whole upper region during the flood season, as shown by the ratio of the simulated sediment load to the observed data at Yichang: 0.69 in the calibration period and 0.68 in the verification period. The ISLSCP precipitation tended to be more frequent and less intense than the measured precipitation. This was probably the main reason why the HSPF did not perform well in all regions at all times.     

Hydrologic and Water Quality Aspects of Using a Compost/Mulch Blend for Erosion Control

Construction projects often expose large amounts of soil to erosive forces of wind and rain. These areas must be stabilized and vegetated before a Notice of Termination can be submitted to regulators. The objectives of this project were to compare the stabilization performance of two types of compost wood mulch blend top dressing (low and high organic matter), a wood based hydromulch, and seeded bare soil and to determine the amount of sediment and nutrients exported from each type of treatment. Ten test plots (12.2×2.4?m2) were constructed at a quarry in Parker County, Texas and outfitted with runoff capture systems. Runoff quality and quantity was evaluated for 2 years after installation. Sediment discharge was reduced by 98% on the compost/mulch blend plots and about 75% with hydromulch treatment compared to bare plots. Treatments reduced nutrient loads, although runoff concentrations of nitrate and dissolved P from compost treated plots were often higher than from bare soil or hydromulch plots.     

Economics of Nitrate Losses from Drained Agricultural Land

Some of the highest losses of nitrate to surface waters come from drained agricultural land. This research studied, for Belgian farming conditions, (i) the effect of subsurface drainage density on nitrate losses and (ii) the economics of nitrate losses, using the nitrogen version of the program DRAINMOD-N. DRAINMOD was used to simulate the performance of the drainage system of the Hooibeekhoeve experiment, situated in the sandy region of the Kempen (Belgium) for a 14-year (1985–1998) period. A continuous cropping with maize was assumed. Daily NO3-N losses were predicted for a range of drain spacings and depths, two drainage strategies (conventional and controlled), and three fertilizer application rates (225, 275, and 325 kg?N?ha?1). Losses of N in subsurface drainage were assumed to occur almost entirely in the NO3-N form. Losses of organic and inorganic N in the form of NO3-N in surface runoff are small and were neglected. Hydrologic results indicated that increasing drain spacing or decreasing drain depth reduces drainage discharge while it increases runoff. The use of controlled drainage reduces subsurface drainage and increases runoff. Results also revealed that increasing the drain spacing or decreasing the drain depth reduces nitrate-nitrogen (NO3-N) drainage losses and net mineralization, while increasing denitrification and runoff losses. Controlled drainage caused a predicted reduction in drainage losses and an increase in denitrification and runoff losses. The optimal combination of drain density and management is one that maximizes profits and minimizes environmental impacts. Simulated results indicated that NO3-N losses to the environment could be substantially reduced by reducing the drainage density below the level required for maximum profits based on grain sales. The study concluded that, if the environmental objective is of importance equal to or greater than profits, drainage systems can be designed and managed to reduce NO3-N losses while still providing an acceptable profit.     

Upland Erosion Modeling in a Semihumid Environment via the Water Erosion Prediction Project Model

The major water quality impairment in the midwest United States is sediment eroded from agricultural lands. Yet, few understand the spatial and temporal variability of erosion, or soil erosion dynamics, in relation to precipitation, topography, land management, and severe events. The objectives of this paper are to (1) develop a methodology for estimating long-term spatial soil erosion and water runoff losses and (2) explore issues in applying an established physical-based process model, Water Erosion Prediction Project (WEPP), to a large area by establishing a prototype system for the state of Iowa. This study for the first time provides a comparison of the model predictions against long-term measurements of the sediment delivery ratio (SDR) in the South Amana Catchment of the Clear Creek Watershed (CCW), a heavily instrumented watershed that is roughly 10 times the maximum WEPP fold size. To further examine the performance of WEPP in a semihumid environment, such as the CCW, where runoff and raindrop impact to erosion may be significant, the SDR was plotted as a function of the runoff coefficient, defined as the runoff/rainfall ratio. In addition, the WEPP predictions are compared against the statistical relation of SDR vs. runoff coefficient developed by Piest et al. in 1975) for watersheds in Iowa. It is shown that WEPP follows the trend shown by Piest et al. quite closely and performs well for continuous simulations extended up to 300?years.     

Transport and Distribution of Particulate Matter Phosphorus Fractions in Rainfall-Runoff from Roadway Source Areas

During runoff transport, phosphorus (P) partitions between dissolved and particulate matter (PM) phases. PM-based P distributes across the particle-size distribution (PSD). This study investigates the transport and distribution for P and PM in runoff from a fully paved highway watershed in Baton Rouge, La. Eight events with discrete manual runoff sampling are studied. PSDs are modeled with a cumulative gamma distribution and PM-based P distributions are modeled with a Freundlich-type power law. P and PM fractions examined are dissolved, suspended, settleable, and sediment. Measured mass transport of these fractions is modeled based on flow-limited (zero-order) or mass-limited (first-order) delivery. Results demonstrate that transport of each fraction can be represented by these limiting categories, but fractions illustrate differing elution rates during the same event. Event-based signatures for PM or P are controlled by the fraction that dominates the transported mass. Even for small source area catchments such as roadways without complex flow patterns, where first-order transport should dominate, transport of P and PM fractions is not consistently first-order; exceptions are mainly dissolved and suspended fractions. A water quality volume (WQV) for 25 mm of runoff resulted in 100% capture for all fractions of seven events and significant bypass for all fractions of a single event with a 1-year return frequency. By contrast, a WQV of 5 mm of runoff resulted in significant bypass for most fractions for seven events and 100% capture for the single event of the lowest runoff volume.     

Nitrification∕Denitrification in Intermittent Aeration Process for Swine Wastewater Treatment

A continuous-flow intermittent aeration (IA) process has been studied for nitrogen removal from anaerobically digested swine wastewater with high ammonium content. High nitrogen removal efficiency of average 91% total Kjeldahl nitrogen and 92% NH4-N was achieved in an IA system with an alteration of 1-h aeration and 1-h nonaeration. Nitrification and denitrification were found to be responsible for the nitrogen removal in the system. Nitrite and nitrate in the effluent were less than 1.0 mg∕L and 8.0 mg∕L, respectively. The specific nitrification and denitrification rates of the single-sludge IA culture were determined through batch experiments as 2.79–3.70 mgNO3-N∕g volatile suspended solids-h and 0.59–1.03 mgNO3-N∕g volatile suspended solids-h, respectively. In the IA process, the aeration period created favorable conditions for nitrifying bacteria (dissolved oxygen = 4–6 mg∕L and oxidation-reduction potential = 80–100 mV), while the nonaeration period provided good environment for denitrifying bacteria (dissolved oxygen < 1 mg∕L and oxidation-reduction potential as low as 0 mV). Ammonia volatilization in the IA process was negligible (<0.008%). Denitrification activity in the IA process prevented nitrate from accumulation and significant pH change in the system, which is critical for nitrogen removal from swine wastewater with high ammonium content.     

Plasmid DNA in a groundwater aquifer microcosm--adsorption, DNAase resistance and natural genetic transformation of Bacillus subtilis

Prokaryotes can exchange chromosomal and plasmid genes via extracellular DNA in a process termed genetic transformation. This process has been observed in the test tube for several bacterial species living in the environment but it is not clear whether transformation occurs in natural bacterial habitats. A major constituent of terrestrial environments are solid particles such as quartz, silt and clay, which have considerable surface areas and which make up the solid-liquid interfaces of the habitat. In previous experiments the adsorption of DNA to chemically purified quartz and clay minerals was shown and the partial protection of adsorbed DNA against DNAase I. In a microcosm consisting of natural groundwater aquifer material (GWA) sampled directly from the environment and groundwater (GW) both linear duplex and supercoiled plasmid DNA molecules bound rapidly and quantitatively to the minerals. The divalent cations required to form the association were those present in the GWA/GW microcosm. The association was stable to extended elution over one week at 23 degrees C. Upon adsorption, the DNA became highly resistant against enzymatic degradation. About 1000 times higher DNAase I concentrations were needed to degrade bound DNA to the same extent as DNA dissolved in GW. Furthermore, chromosomal and plasmid DNA bound on GWA transformed competent cells of Bacillus subtilis. However, in contrast to DNA in solution, on GWA the chromosomal DNA was more active in transformation than the plasmid DNA. The studies also revealed that in the transformation of B. subtilis Mg2+ can be replaced by Na+, K+ or NH4+. The observations suggest that in soil and sediment environments, mineral material with inorganic precipitates and organic matter can harbour extracellular DNA leaving it available for genetic transformation.     

Hydrology and Nitrogen Components of a Simple Rye Growth Model

Cover cropping practices are being researched to reduce artificial subsurface drainage nitrate-nitrogen (nitrate-N) losses from agricultural lands in the upper Mississippi watershed. A soil-plant-atmosphere simulation model, RyeGro, was developed to quantify the influence of a winter cereal rye cover crop on nitrate-N losses given climatic variability in the region. This paper describes the hydrology and nitrogen cycle submodels of RyeGro, which was developed with a low level of complexity and conceptualizes the soil profile as three soil layers. The model was calibrated with data from a three-year rye cover crop field study conducted at Lamberton, Minnesota, and validated with data from a previous study. During model calibration, field subsurface drainage nitrate-N loadings were predicted within 0.2, 0, and 1.6?kg?N?ha?1 (1, 0, and ?3%) of measured loadings for the corn-soybean treatment and within 1.2, 0, and 1.6?kg?N?ha?1 (11, 0, and 3%) of measured loadings for the corn-rye-soybean treatment. The model validation showed nitrate-N loading differences of 7 and 1?kg?N?ha?1 (?22 and 4%) for the two years tested.     

Friedreich's ataxia: point mutations and clinical presentation of compound heterozygotes

The effects of ammonium nitrate, ammonium chloride, ammonium sulfate, and sodium nitrate on survival and growth of Pacific treefrog (Pseudacris regilla) and African clawed frog (Xenopus laevis) embryos were determined in static-renewal tests. The 10-day LC50s for the three ammonium compounds for P. regilla ranged from 25.0-32. 4 mg/L NH4 -N. The 10-day sodium nitrate LC50 for P. regilla was 578. 0 mg/L NO3-N. LC50s for X. laevis exposed for 4 or 5 days to the three ammonium compounds ranged from 27.5-60.2 mg/L NH4-N. The sodium nitrate LC50 for X. laevis ranged from 438.4-871.6 mg/L NO3-N. The lowest LOAEL based on length or weight was 6.1 mg/L NH4-N for the two species. The lowest LOAELs for NO3-N were 111.1 mg/L for P. regilla and 56.7 mg/L for X. laevis. Calculated unionized NH3 comprised 0.5-1.8% of measured NH4-N concentrations. Potential harm to amphibian populations could occur if NH4-N and NO3-N in agricultural runoff or drainage impacts sensitive life stages for a sufficiently long period.     

三价锰容量法测定锰碳合金球中的锰

采用三价锰容量法测定锰碳合金球中锰含量,因合金中碳含量高（30%以上）,磷酸溶样后加入高氯酸溶解难溶碳化物,同时加入硝酸铵定量氧化锰。温度控制在200℃左右,高氯酸用量以5～9mL为宜,分析结果稳定准确,相对标准偏差在0.1842%～0.2234%,加标回收率在96%～103%。     

Removal of Dissolved Organic Carbon in Sanitary Gravity Sewer

Utilization of dissolved organic matter in a 1.5 km section of a sanitary gravity concrete sewer with an inner diameter of 450 mm constructed on a slope of 0.0075 was studied. Continuous measurements of dissolved organic carbon (DOC), suspended solids, dissolved oxygen, and flow rate were performed along the sewer. About 14% of the DOC was removed in an 18-min retention time. A slower flow rate in the sewer would favor higher DOC removal efficiency because it offers a longer retention time. Oxygen was not a limiting factor as the dissolved oxygen level was at least 1 mg∕L. Batch tests using raw sewage and either suspended solids or settled sediments yielded specific DOC rates of 1.3 mg and 2.6 mg DOC∕mg dry wt/day for the sewage phase and sediment phase, respectively. Adenosine triphosphate content analysis of the suspended solids and sediment samples confirmed that both contained substantial amounts of active biomass. In the 1.5-km sewer system, it is estimated that 39.13 kg of DOC can be stabilized∕day; the sewage phase contributes 40% while the sediment phase contributes 60%.     

Watershed-Scale Impacts of Nitrogen from On-Site Wastewater Systems: Parameter Sensitivity and Model Calibration

A numerical watershed model was used to evaluate the potential influence of various point and nonpoint sources including on-site wastewater systems (OWS) on stream nitrate concentration in Turkey Creek Watershed, Colorado. A watershed analysis risk management framework model was used for this study, and was calibrated to observed stream nitrate concentrations using an automatic calibration tool. Parameter sensitivity analysis was done to select critical parameters for calibration and to reduce uncertainty in the simulated results. Sensitivity analysis of nitrate transport and transformation parameters showed that stream nitrate concentration is highly sensitive to cation exchange capacity, nitrification rate, base saturation of ammonium, initial concentration of ammonium in the soil, and some of the crop growth related parameters. The calibrated model was used to evaluate scenarios related to OWS including the impacts of population growth and new development and impacts of conversion of OWS to conventional sewers. The results showed that there would be a significant increase in stream nitrate concentration with increasing population. Conversion of OWS to sewers increased stream nitrate concentration but decreased nitrate concentration in the bottom soil layer indicating that OWS are beneficial with respect to stream nitrate concentration but may increase nitrate concentrations in groundwater.     

Pollutant Mass Flushing Characterization of Highway Stormwater Runoff from an Ultra-Urban Area

Water quality of highway stormwater runoff from an ultra-urban area was characterized by determining the event mean concentration (EMC) for several pollutants and by evaluating pollutant flushing. Thirty-two storm events were monitored between June 2002 and October 2003. Mean EMCs in mg/L were 0.035, 0.11, 0.22, 1.18, 420, 3.4, 0.14, 1.0, and 0.56 for Cd, Cu, Pb, Zn, total suspended solids (TSS), total Kjeldahl nitrogen (TKN), NO2–N, NO3–N, and TP. First flush as defined by flushing of 50% of the total pollutant mass load in the first 25% of the event runoff volume occurred in 33% of the storm events for NO2?, 27% for TP, 22% for NO3? and TKN, 21% for Cu, 17% for TSS, 14% for Zn, and 13% for Pb. Median values for the mass flushed in the first 25% of runoff volume were greater than the mass flushed in any 25% portion beyond the first for all pollutants. The mass in later 25% volume portions were greater than in the first 25% volume in at least 17% of the events for all pollutants, indicating that a significant amount of the pollutant load can be contained in later portions of the runoff volume. Nonetheless, management of the first 1.3?mm (1/2?in.) of runoff was able to capture 81–86% of the total pollutant mass.     

砂岩铀矿围岩中性条件下对铀的吸附试验

砂岩型铀矿地浸采铀体系中,溶解铀在水岩界面发生的吸附作用对铀的浸出造成一定影响。为研究CO_2+O_2中性地浸条件下含矿层砂岩介质对溶解铀的吸附特征,采用取自新疆蒙其古尔铀矿床围岩和含铀浸出液,在实验室开展了不同粒径介质和不同固液比的吸附试验。结果表明,不同粒径介质对铀的平衡吸附量介于11.62～20.28mg/g,铀的平衡吸附量以及吸附率与粒径负相关;不同液固比试验条件的平衡吸附量介于10.07～18.23mg/g,铀的平衡吸附量与液固比正相关,铀的吸附率则与液固比负相关。围岩对铀的吸附动力学特征符合粒内扩散模型。试验结果可以为地浸采铀溶质运移模拟过程中吸附模型及其参数的确定提供依据。     

Cu（II）、Ni（II）离子在蛇纹石表面的吸附及对其浮选的影响

通过吸附量测试、纯矿物浮选和红外光谱分析,研究Cu2+和Ni2+离子在蛇纹石表面的吸附过程及对蛇纹石浮选的活化机理.Cu2+和Ni2+离子在蛇纹石表面的吸附符合二级动力学模型,等温吸附过程符合Langmuir等温吸附模型,吸附能够自发进行,为物理吸附和化学吸附的共同作用,Cu2+和Ni2+离子在蛇纹石表面的吸附量随p H值升高而增大.Cu2+和Ni2+离子在弱碱性条件下对蛇纹石具有活化作用,活化机理为铜镍的氢氧化物沉淀和羟基络合物作用于蛇纹石表面,形成活性位点,黄药在活性位点上吸附生成黄原酸铜或黄原酸镍,从而使蛇纹石表面疏水性增大,浮选受到活化.      

The anaerobic oxidation of ammonium

From recent research it has become clear that at least two different possibilities for anaerobic ammonium oxidation exist in nature. 'Aerobic' ammonium oxidizers like Nitrosomonas eutropha were observed to reduce nitrite or nitrogen dioxide with hydroxylamine or ammonium as electron donor under anoxic conditions. The maximum rate for anaerobic ammonium oxidation was about 2 nmol NH4+ min-1 (mg protein)-1 using nitrogen dioxide as electron acceptor. This reaction, which may involve NO as an intermediate, is thought to generate energy sufficient for survival under anoxic conditions, but not for growth. A novel obligately anaerobic ammonium oxidation (Anammox) process was recently discovered in a denitrifying pilot plant reactor. From this system, a highly enriched microbial community with one dominating peculiar autotrophic organism was obtained. With nitrite as electron acceptor a maximum specific oxidation rate of 55 nmol NH4+ min-1 (mg protein)-1 was determined. Although this reaction is 25-fold faster than in Nitrosomonas, it allowed growth at a rate of only 0.003 h-1 (doubling time 11 days). 15N labeling studies showed that hydroxylamine and hydrazine were important intermediates in this new process. A novel type of hydroxylamine oxidoreductase containing an unusual P468 cytochrome has been purified from the Anammox culture. Microsensor studies have shown that at the oxic/anoxic interface of many ecosystems nitrite and ammonia occur in the absence of oxygen. In addition, the number of reports on unaccounted high nitrogen losses in wastewater treatment is gradually increasing, indicating that anaerobic ammonium oxidation may be more widespread than previously assumed. The recently developed nitrification systems in which oxidation of nitrite to nitrate is prevented form an ideal partner for the Anammox process. The combination of these partial nitrification and Anammox processes remains a challenge for future application in the removal of ammonium from wastewater with high ammonium concentrations.     

Quality of Runoff Leachate Collected from Biosolids and Dairy-Manure Compost-Amended Topsoils

Compost amendment of pavement shoulder subgrades was attempted to mitigate shrinkage cracking, which otherwise would result in severe distress to adjacent pavement infrastructure systems. Two types of composts, biosolids and dairy-manure composts, were evaluated. As a part of this application, the runoff leachate emanating from the compost soils needs to be environmentally assessed as this leachate potentially ends up in storm sewer collection systems. As a part of the research, runoff collection systems were placed in both dairy-manure and biosolids compost-amended soil sections and a control untreated soil section. The collected water samples at various time intervals were then subjected to various chemical and environmental tests, including total suspended and dissolved solids, biochemical and chemical oxygen demand, total Kjeldahl nitrogen (TKN), and phosphorous measurements. This paper presents a summary of these test results from both sections and their comparisons with similar results from another leachate collected from a control or untreated section. These test results are also compared with a few local studies conducted on highway runoff samples and EPA benchmark values. Possible causes for chemical contaminant concentration differences in the leachate samples from both composts are also explained.     

电感耦合等离子体原子发射光谱法测定钢中铌钨锆

采用硫酸和硝酸溶解样品,加入草酸铵溶液以溶解试样处理中形成的盐类和防止试液中铌、钨和锆水解,在优化仪器工作参数条件下用电感耦合等离子体原子发射光谱法(ICP-AES)测定试液中铌、钨、锆含量,从而建立了钢中铌、钨和锆的测定方法。研究表明:通过加热,0.1 g钢样能溶解于15 mL硫酸(1+4)和几滴硝酸中,且冒硫酸烟后出现的盐类,加入10 mL 4.0 g/L草酸铵溶液可将其溶解完全。以Nb 316.340 nm,Zr 343.823 nm,W 207.011 nm为分析谱线,采用基体匹配方法克服基体干扰。待测元素校准曲线相关系数大于0.999 5,铌、钨和锆的检出限分别为 1.9、9.9 和 3.2 ng/mL。方法应用于YSBC11217-94低合金钢标准样品中铌、钨和锆的测定,结果与认定值相符,相对标准偏差(n=10)分别为1.7%,1.1%和2.1%,加标回收率在97%～104%之间。对其他标准样品(合金钢、合金结构钢、低合金钢)及合成钢样品中铌、钨、锆进行测定,测定值与认定值或参考值相符。