Characterization and optimization of physical and chemical properties of drilling fluids are critical for the efficiency and success of drilling operations.In particular,maintaining the optimal levels of solids conten...Characterization and optimization of physical and chemical properties of drilling fluids are critical for the efficiency and success of drilling operations.In particular,maintaining the optimal levels of solids content is essential for achieving the most effective fluid performance.Proper management of solids content also reduces the risk of tool failures.Traditional solids content analysis methods,such as retort analysis,require substantial human intervention and time,which can lead to inaccuracies,time-management issues,and increased operational risks.In contrast to human-intensive methods,machine learning may offer a viable alternative for solids content estimation due to its pattern-recognition capability.In this study,a large set of laboratory reports of drilling-fluid analyses from 130 oil wells around the world were compiled to construct a comprehensive data set.The relationships among various rheological parameters were analyzed using statistical methods and machine learning algorithms.Several machine learning algorithms of diverse classes,namely linear(linear regression,ridge regression,and ElasticNet regression),kernel-based(support vector machine)and ensemble tree-based(gradient boosting,XGBoost,and random forests)algorithms,were trained and tuned to estimate solids content from other readily available drilling fluid properties.Input variables were kept consistent across all models for interpretation and comparison purposes.In the final stage,different evaluation metrics were employed to evaluate and compare the performance of different classes of machine learning models.Among all algorithms tested,random forests algorithm was found to be the best predictive model resulting in consistently high accuracy.Further optimization of the random forests model resulted in a mean absolute percentage error(MAPE)of 3.9%and 9.6%and R^(2) of 0.99 and 0.93 for the training and testing sets,respectively.Analysis of residuals,their histograms and Q-Q normality plots showed Gaussian distributions with residuals that are scattered around a mean of zero within error ranges of±1%and±4%,for training and testing,respectively.The selected model was further validated by applying the rheological measurements from mud samples taken from an offshore well from the Gulf of Mexico.The model was able to estimate total solids content in those four mud samples with an average absolute error of 1.08% of total solids content.The model was then used to develop a web-based graphical-user-interface(GUI)application,which can be practically used at the rig site by engineers to optimize drilling fluid programs.The proposed model can complement automation workflows that are designed to measure fundamental rheological properties in real time during drilling operations.While a standard retort test can take approximately 2 h at the rig site,such kind of real-time estimations can help the rig personnel to timely optimize drilling fluids,with a potential of saving 2920 man-hours in a given year for a single drilling rig.展开更多
Background:In recent years,there has been an increasing interest in using high quantities of milk or milk replacer(MR)in heat-stressed calves to alleviate the negative effects of high environmental temperatures on the...Background:In recent years,there has been an increasing interest in using high quantities of milk or milk replacer(MR)in heat-stressed calves to alleviate the negative effects of high environmental temperatures on their performance.However,observations have indicated a decline in growth performance in the weaning and postweaning period,which might be optimized with increasing total solids(TS)in milk and weaning age.This study aims to optimize the effects of higher quantities of milk on late weaned calves'performance by increasing TS concentration or delivery route in summer conditions.Method:Forty-eight newborn Holstein calves were used in a 2×2 factorial arrangement with the factors of preweaning total plane of milk(PM)intake(low vs.high)and milk TS content(12%vs.17%).The treatments were(1)low PM(LPM)intake with 12%TS(TS intake=45.9 kg),(2)LPM intake with 17%TS(TS intake=65.1 kg),(3)high PM(HPM)intake with 12%TS(TS intake=63.7 kg);and(4)HPM intake with 17%TS(TS intake=90.3 kg).Calves were weaned at d 83,and the study was terminated at d 103 of age.Performance data(every 10 day),skeletal growth(d 80 and 100),ruminal fermentation parameters(d 48 and 91),and behavioral measurements(d 69,70,93 and 94)were analyzed as repeated measurements with PROC MIXED of SAS 9.4(SAS Institute Inc.,Cary,NC).Results:Calves receiving HPM consumed less PMR from d 44 to 83 of age,but they had higher ADG from d 24 to 53 of age compared to those fed LPM(PM×age,P<0.001).In addition,calves receiving milk with 17%TS had lower PMR intake from d 14 to 83 of age,but greater ADG from d 34 to 53 compared to those receiving milk with 12%TS(TS×age,P<0.001).Calves that received HPM had greater skeletal growth parameters compared to LPMfed calves,with a similar effect evident for calves fed milk with 17%TS compared with those fed milk with 12%TS.Calves receiving milk with 17%TS had greater fecal scores and diarrhea occurrence than those fed milk with 12%TS in HPM,but not LPM.Conclusions:Increasing PM and milk TS concentration improved growth in summer-exposed calves as demonstrated by increased pre-weaning ADG,pre-and post-weaning BW,and structural growth.展开更多
High total dissolved solids （TDS） content is one of the most important pollution contributors in lakes in arid and semiarid areas. Ulansuhai Lake, located in Urad Qianqi, Inner Mongolia, China, was selected as the o...High total dissolved solids （TDS） content is one of the most important pollution contributors in lakes in arid and semiarid areas. Ulansuhai Lake, located in Urad Qianqi, Inner Mongolia, China, was selected as the object of study. Temperatures and TDS contents of both ice and under-ice water were collected together with corresponding ice thickness. TDS profiles were drawn to show the distribution of TDS and to describe TDS migration. The results showed that about 80% （that is 3.602x108 kg） of TDS migrated from ice to water during the whole growth period of ice. Within ice layer, TDS migration only occurred during initial ice-on period, and then perished. The TDS in ice decreased with increasing ice thickness, following a negative exponential-like trend. Within un- der-ice water, the TDS migrated from ice-water interface to the entire water column under the effect of concentra- tion gradient until the water TDS content was uniform. In winter, 6.044x 107 kg （16.78% of total TDS） TDS migrated from water to sedirnent, which indicated that winter is the best time for dredging sediment. The migration effect gives rise to TDS concentration in under-ice water and sediment that is likely to affect ecosystem and water quality of the Yellow River. The trend of transfer flux of ice-water and water-sediment interfaces is similar to that of ice growth rate, which reveals that ice growth rate is one of the determinants of TDS migration. The process and mechanism of TDS migration can be referenced by research on other lakes with similar TDS content in cold and arid areas.展开更多
In recirculating aquaculture systems(RASs),the effective treatment of aquaculture tailwater is essential to maintain the health of the RAS.This study investigated the optimal time and method for tailwater treatment du...In recirculating aquaculture systems(RASs),the effective treatment of aquaculture tailwater is essential to maintain the health of the RAS.This study investigated the optimal time and method for tailwater treatment during three periods of the aquaculture of the Litopenaeus vannamei:nursery(0–26 d),middle(27–57 d),and later(57–104 d).The variation of several water parameters during the dissolution of total suspended solid(TSS)in tailwater,applied with the effects of ozone on the microorganism and water quality parameters were investigated.Results showed that the TSS concentrations in tailwater decreased with time,although not significantly(P>0.05),whereas total ammonia nitrogen(TAN),nitrite(NO-2-N),and nitrate(NO_(3)^(-)-N)increased significantly(P<0.05).Therefore,TSS should be removed from the tailwater as early as possible,being most optimal within 4 h.Ozone removed 38.24%–48.95%of TSS,17.78%–90.14%of TAN,and 87.50%–98.90%of NO-2-N after 4 h of treatment.However,it resulted in the significant accumulation of NO_(3)^(-)-N.Moreover,the total number of Vibrio and bacterial counts in aquaculture tailwater was reduced completely by ozone within 4 h.Thus,these results provided technical details and data support for the effective treatment of tailwater from shrimp RAS.展开更多
This article examines the influence of seawater temperature and total dissolved solids (TDS) on reverse osmosis (RO) desalination in the Arabian Gulf region, with a focus on the impact of climate change. The study hig...This article examines the influence of seawater temperature and total dissolved solids (TDS) on reverse osmosis (RO) desalination in the Arabian Gulf region, with a focus on the impact of climate change. The study highlights the changes in seawater temperature and TDS levels over the years and discusses their effects on the efficiency and productivity of RO desalination plants. It emphasizes the importance of monitoring TDS levels and controlling seawater temperature to optimize water production. The article also suggests various solutions, including intensive pre-treatment, development of high-performance membranes, exploration of alternative water sources, and regulation of discharges into the Gulf, to ensure sustainable water supply in the face of rising TDS levels and seawater temperature. Further research and comprehensive monitoring are recommended to understand the implications of these findings and develop effective strategies for the management of marine resources in the Arabian Gulf.展开更多
This study presents a significant contribution to the field of water quality assessment and sustainable water management practices. By evaluating the levels of total dissolved solids (TDS) in seawater intakes within A...This study presents a significant contribution to the field of water quality assessment and sustainable water management practices. By evaluating the levels of total dissolved solids (TDS) in seawater intakes within Al-Khobar desalination production system, the study addresses a crucial aspect of water treatment and environmental impact assessment. The findings provide valuable insights into the variations and trends of TDS levels across different phases of the system, highlighting the importance of monitoring and management strategies. The study provided both gravimetric total dissolved solids (TDS) and electrical conductivity (EC) measurements to analyze TDS calculation factor and evaluate measurement accuracy. Results revealed significant variations in TDS levels across the sampling locations, with phase-2 exhibiting higher levels and greater fluctuations. Phase-3 displayed similar trends but with lower TDS levels, while phase-4 showed slightly different behavior with higher average TDS levels. EC measurements demonstrated a strong correlation with TDS, providing a reliable estimation. However, additional methods such as gravimetric analysis should be employed to confirm TDS measurements. The findings contribute to understanding water quality in the Al-Khobar desalination system, aiding in monitoring, management, and decision-making processes for water treatment and environmental impact assessment. The study enhances the credibility of water quality assessments and supports sustainable water management practices.展开更多
A relationship between electrical conductivity (EC) and total dissolved solids (TDS) was tested for solutions of same salinity levels with respect to different artificial salts with their combinations. Results showed ...A relationship between electrical conductivity (EC) and total dissolved solids (TDS) was tested for solutions of same salinity levels with respect to different artificial salts with their combinations. Results showed remarkable jumping at the order of the artificial salt sequence specially that of the magnesium type. A computer model is designed with an input of EC and TDS. The output will be the possible prevailing artificial salts. The accuracy of the model was tested by using the groundwater data of Safwan-Zubair area south of Iraq and it proved to be significant at 95% matching. The 5% unmatched results are due to the possibility of having more than one type of prevailing salt.展开更多
Winter irrigation is a crucial measure for preventing farmland salinity in arid inland regions.However,given the relatively complex process of salt leaching under the influence of freezing and thawing,present salinity...Winter irrigation is a crucial measure for preventing farmland salinity in arid inland regions.However,given the relatively complex process of salt leaching under the influence of freezing and thawing,present salinity management has led to soil quality deterioration in the irrigation areas in Northwest China.To better understand this process,a field experiment was conducted in Huangyang Town,Wuwei City,Gansu Province,China to simulate the evolution of soil profile salinity and alkalinity in a typical oasis farmland under 3-year regular barley planting,using a local prevailing water-salt management mode of drip irrigation for the growing period and winter irrigation for the fallow period.This study investigated the impact of freezing on salt leaching by comparing the soil profile water,heat,and salt movements under different winter irrigation quotas.Compared to no winter irrigation,a reduction in the winter irrigation quota from the standard one to a halved one led to a transition from a sink of 11.05% by salt leaching to a source of 13.75% by salt addition.This means that overwintering soil freezing,especially in oases with deep groundwater tables,can worsen root zone salinization caused by a deficit winter irrigation,through freezing-induced root zone soil water and salt return.Furthermore,dry saline soil dominated by sulfate is at the risk of soil alkalization when freezing-induced oversaturation of solute concentration leads to significant salt precipitation.These findings are crucial for understanding the mechanisms behind the increasing secondary salinization caused by unsustainable winter irrigation in oasis irrigation areas.展开更多
The application of single nanofiltration （NF） and sequential filtration of microfiltration （MF） and NF for the concentration of vinasse were studied. Filtration experiments were performed at 60 ℃, 500 rpm and dif...The application of single nanofiltration （NF） and sequential filtration of microfiltration （MF） and NF for the concentration of vinasse were studied. Filtration experiments were performed at 60 ℃, 500 rpm and different transmembrane pressures using four commercial membranes： MF, PVDF 0.2 μm; NF, PES 300, 500 and 1000 Da. The process effectiveness was evaluated through the permeate flux and the total solids （TS） concentration in the retentate. Because the retention of TS and permeate fluxes were very similar for MF, PVDF-0.2 membrane at 0.10 MPa was selected because of its lower power consumption. The best conditions tested for NF were the following： PES-1000 at 3.50 MPa with a flux of 183.2 kg/m^2 h at a volume reduction factor （VRF） of 2, under which 68% of solids were retained. For the MF ＋ NF, a PES-1000 at 3.50 MPa was selected because a higher permeate flux was achieved at a VRF of 4, and PES-500 at 3.50 MPa because a higher retention of TS was achieved compared to the other experiments. A single NF resulted in a retentate concentration that was almost twice as high as the hybrid MF and NF process, allowing reduced costs in its transportation from distilleries to distant areas.展开更多
High-pressure homogenization （HPH） technology was applied as a pretreatment to disintegrate sewage sludge. The effects of homogenization pressure, homogenization cycle number, and total solid content on sludge disin...High-pressure homogenization （HPH） technology was applied as a pretreatment to disintegrate sewage sludge. The effects of homogenization pressure, homogenization cycle number, and total solid content on sludge disintegration were investigated. The sludge disintegration degree （DDCOD）, protein concentration, and polysaccharide concentration increased with the increase of homogenization pressure and homogenization cycle number, and decreased with the increase of sludge total solid （TS） content. The maximum DDCOD of 43.94% was achieved at 80 MPa with four homogenization cycles for a 9.58 g/L TS sludge sample. A HPH sludge disintegration model of DDCOD= kNaPb was established by multivariable linear regression to quantify the effects of homogenization parameters. The homogenization cycle exponent a and homogenization pressure exponent b were 0.4763 and 0.7324 respectively, showing that the effect of homogenization pressure （P） was more significant than that of homogenization cycle number （N）. The value of the rate constant k decreased with the increase of sludge total solid content. The specific energy consumption increased with the increment of sludge disintegration efficiency. Lower specific energy consumption was required for higher total solid content sludge.展开更多
Irrigation with various dilutions of seawater can act as an alternate water resource and thus plays an important role in saving freshwater resources as well as promoting agriculture in the coastal semi-arid areas of t...Irrigation with various dilutions of seawater can act as an alternate water resource and thus plays an important role in saving freshwater resources as well as promoting agriculture in the coastal semi-arid areas of the North China Plain. Jerusalem artichoke （Helianthus tuberosus L.） grown in a field experiment was irrigated with seawater diluted with freshwater from 2001 to 2003 to determine the feasibility of seawater irrigation in the Laizhou area. For treatments of CK （non-irrigation） along with seawater concentrations of 25%, 50%, and 75%, total dissolved solid （TDS） in the non-irrigated soil significantly increased （P ≤ 0.05） in both 2002 and 2003 and was 1.3 times higher in 2003 than in 2001. In the 25% and 50% seawater concentration treatments, TDS in 2001 was significantly greater （P ≤ 0.05） than CK; however, TDS in these two treatments decreased by 34.9% and 40.1%, respectively, in 2003 compared with 2001. The sodium adsorption ratio （SAR） remained below 10 mmol^1/2 L^-1/2, indicating that alkalization was low with seawater irrigation. In 2001 and 2002, compared to CK and the irrigation treatment with 75% seawater, irrigation with 25% and 50% seawater increased the yields of Jerusalem .artichoke. This meant that Jerusalem artichoke could be safely grown in salt-affected land of Laizhou area with 25% and 50% seawater irrigation.展开更多
Located in the inland arid area of central Asia, salt-affected farmlands take up one third of the total irrigated land area in Xinjiang of Northwest China. Spatio-temporal variability of soil salinity and the underlyi...Located in the inland arid area of central Asia, salt-affected farmlands take up one third of the total irrigated land area in Xinjiang of Northwest China. Spatio-temporal variability of soil salinity and the underlying mechanism are fundamental problems challenging the sustainability of oasis agriculture in China. In this study, the data of total dissolved solids(TDS) measured for soil samples collected from 27 representative study areas in the oasis areas of Xinjiang were analyzed and the coefficient of variation(CV) and stratification ratio(SR) of TDS were used to describe the lateral and vertical soil salinity variations, respectively. Weekly, monthly,and annual changes in soil salinity were also summarized. Results showed that the top(0–20 cm) soil salinity was highly variable(CV> 75%) for most studied areas. Lateral variation of soil salinity was significantly correlated with the sampling interval; as a result, a maximum sampling interval of 0.9 m was found for reducing evaluation uncertainty. The top 0–20 cm soil salt accounted for about25.2% of the total salt in the 0–100 cm soil profile. The stratification ratio values(the ratio of TDS at the 20–40 cm depth to that at the 0–20 cm depth) were mostly smaller than 1 and on average 0.92, illustrating that the top 0–20 cm soil contained slightly more salt and a considerable amount of salt still existed in subsurface and deep horizons. Irrigation reduced top soil salinity by 0.52 g kg-1, or14.6%, within the first week. On average, the relative range of soil salinity, calculated to indicate monthly changes in soil salinity, was58.2% from May to September. A 27-year experiment indicated that cultivation increased soil salinity by 44.4% at a rate of 0.14 g kg-1year-1. At small spatio-temporal scales, soil salinity variation was mainly affected by anthropogenic factors, such as irrigation and land use. However, natural factors, including groundwater, topography, and climate conditions, mainly influenced soil salinity variation at large spatio-temporal scales. This study displayed the highly variable nature of soil salinity in space and time. Those driving factors identified in this study could provide guidelines for developing sustainable agriculture in the oasis areas and combating salinization in arid regions of China.展开更多
Allelopathic effects of submerged macrophytes against algae are affected by many environmental factors which can only be measured one by one by traditional methods. Box-Behnken design of response surface methodology w...Allelopathic effects of submerged macrophytes against algae are affected by many environmental factors which can only be measured one by one by traditional methods. Box-Behnken design of response surface methodology was used to optimize three environmental factors （temperature, light intensity and total dissolved solids） of allelopathic effects of Potarnogeton pectinatus against Microcystis aeruginosa at the same time. By solving the regression equation and analyzing the response surface contour plots, the optimal conditions of the relatively inhibitory rate of Microcystis aeruginosa were that the temperature was 23℃, the light intensity was 2 700 lx and the total dissolved solids were 4 415 mg/L. Under these conditions, the optimal value of relatively inhibitory rate of Microcystis aeruginosa was 81.9%. According to validation experiments, the results of analysis indicated that the experimental values fitted well with the predicted ones.展开更多
This paper presents an assessment of the hydrochemical characteristics of groundwater in Northern Gezira State, Central Sudan. The approaches followed here include the chemical analyses for major ions chemistry and co...This paper presents an assessment of the hydrochemical characteristics of groundwater in Northern Gezira State, Central Sudan. The approaches followed here include the chemical analyses for major ions chemistry and construction of hydrochemical maps of total dissolved solids (TDS), sodium (Na +), bicarbonate (HCO 3 -), and chloride (Cl -) ions. The hydrochemical characteristics of the groundwater in each aquifer and management consideration are discussed. Sources of major ions in groundwater are analyzed. The hydrochemical maps of important species are constructed. The relationship of groundwater to use is elaborated. High concentrations of the chemical and hydrochemical constituents and the occurrence of calcretes (CaCO 3) in upper zones suggest a long history of evaporation and increasing leachates.展开更多
To accurately evaluate ecological risks trigged by groundwater exploitation,it must be clarified the relationship between vegetation and groundwater.Based on remote sensing data sets MOD13Q1,groundwater table depth(WT...To accurately evaluate ecological risks trigged by groundwater exploitation,it must be clarified the relationship between vegetation and groundwater.Based on remote sensing data sets MOD13Q1,groundwater table depth(WTD)and total dissolved solids(TDS),the relationship between groundwater and natural vegetation was analyzed statistically in the main plain areas of Qaidam Basin.The results indicate that natural vegetation is groundwater-dependent in areas where WTD is less than 5.5 m and TDS is less than 7.5 g/L.Aquatic vegetation,hygrophytic vegetation and hygrophytic saline-alkali tolerant vegetation are mainly distributed in areas with WTD<1.1 m.Salt-tolerant and mesophytic vegetation mainly occur in areas with WTD of 1.4-3.5 m,while the xerophytic vegetation isprimarily present in areas where WTD ranges from 1.4 m to 5.5 m.Natural vegetation does not necessarily depend on groundwater in areas with WTD>5.5 m.For natural vegetation,the most suitable water TDS is less than 1.5 g/L,the moderately suitable TDS is 1.5-5.0 g/L,the basically suitable TDS is 5.0-7.5 g/L,and the unsuitable TDS is more than 7.5 g/L.展开更多
Hourly mapping by a Geostationary Ocean Color Imager was used to reveal the spatial pattern and tidal variation of total suspended solids(TSS)over the Yangtze Bank in the Yellow and East China Seas during the winter.T...Hourly mapping by a Geostationary Ocean Color Imager was used to reveal the spatial pattern and tidal variation of total suspended solids(TSS)over the Yangtze Bank in the Yellow and East China Seas during the winter.The TSS form a tongueshaped structure,which decreases further offshore in a stepwise manner.The stepwise change is separated by two fronts of TSS,which are located near the 20-m and 50-m isobaths.The tidal variation of TSS concentration during the study period is evident and can be divided into three stages:decay,maintenance,and growth.Compared with the relatively stationary TSS during the maintenance stage,drastic changes exist during the decay and growth stages.In terms of tide-induced mixing,the dynamic analysis shows that both the topography and the tidal currents play an important role in the spatio-temporal variation of TSS during the tidal period.In particular,spatial distribution is primarily determined by the topography,whereas the temporal variations in tidal scale are determined by the tidal currents.展开更多
Rheological tests for raw and conditioned activated sludge （AS） or anaerobic digested sludge （ADS） show that power-law relationships can be used to describe the evolution of several rheological parameters, i.e., l...Rheological tests for raw and conditioned activated sludge （AS） or anaerobic digested sludge （ADS） show that power-law relationships can be used to describe the evolution of several rheological parameters, i.e., limiting viscosity （η∞）, yield stress （τy）, cohesion energy of the sludge network （Ec）, and storage modulus （G＇）, with total suspended solid （TSS） content in raw and conditioned sludge. A gel-like structure that behaves similar to weak-link flocs/aggregates was observed in AS and ADS. As derived from the double-logarithmic plots of G＇-TSS content, the mass fractal dimensions of the raw and conditioned AS or ADS flocs/aggregates were 2.70 and 2.53 or 2.85 and 2.79, respectively. The theological tests also indicate that both polymer conditioning and increased TSS content led to improved elastic behavior, cohesion energy, and yield stress of the sludge network, as well as expanded the corresponding linear viscoelastic range. The porosity of AS or ADS flocs/aggregates will be improved by polymer conditioning.展开更多
Mandarin (Citrus reticulata Blanco) is a premier fruit crop which ranks in first position of the total fruit industry in Nepal. Studies were conducted to assess the maturity indices and quality parameters of mandarin ...Mandarin (Citrus reticulata Blanco) is a premier fruit crop which ranks in first position of the total fruit industry in Nepal. Studies were conducted to assess the maturity indices and quality parameters of mandarin at three altitudes i.e. 1300 m·asl, 1000 m·asl, and 700 m·asl with six maturity stages i.e. 11 Oct, 21 Oct, 31 Oct, 10 Nov, 20 Nov, and 30 Nov. The most important and reliable judging criteria of fruit maturity in mandarin i.e. fruit weight, external fruit colour, firmness, TSS, acidity, and TSS/Acid ratio, and vitamin C were experimented. The experiment results revealed that 1000 m·asl location was showed the highest fruit weight (104.9 g) and juice percentage (55.23) followed by 1300 m·asl altitude (99.5 g and 53.75% respectively) at 20<sup>th</sup> of November. The maturity advanced at lower altitude with 50 percent yellow orange rind colour, 10.98 TSS/acid ratio and 4 kg/cm<sup>2</sup> firmness from 10<sup>th</sup> November at lower altitudes whereas it was appeared in 20<sup>th</sup> November at higher altitudes. The TSS/acid ratio was significantly higher (10.98) in the fruits of 700 m·asl as compared to 1300 m·asl (9.76) on 10<sup>th</sup> November, however, on 20<sup>th</sup> November 1300 m·asl showed the highest ratio (17.76). The fruit weight, juice content, TSS was found in increasing trends up to 20 November and then showed constant and decreasing trend. However, TA, firmness and vitamin C were showed in decreasing trends with time. The 1000 - 1300 m·asl was the best location for the mandarin production and 10-20 November was the best period for the mandarin harvesting for optimum maturity.展开更多
Stormwater runoff has been identified as a source of pollution for the environment, especially for receiving waters. In order to quantify and manage the impacts of stormwater runoff on the environment, predictive mode...Stormwater runoff has been identified as a source of pollution for the environment, especially for receiving waters. In order to quantify and manage the impacts of stormwater runoff on the environment, predictive models and mathematical models have been developed. Predictive tools such as regression models have been widely used to predict stormwater discharge characteristics. Storm event characteristics, such as antecedent dry days （ADD）, have been related to response variables, such as pollutant loads and concentrations. However it has been a controversial issue among many studies to consider ADD as an important variable in predicting stormwater discharge characteristics. In this study, we examined the accuracy of general linear regression models in predicting discharge characteristics of roadway runoff. A total of 17 storm events were monitored in two highway segments, located in Gwangju, Korea. Data from the monitoring were used to calibrate United States Environmental Protection Agency＇s Storm Water Management Model （SWMM）. The calibrated SWMM was simulated for 55 storm events, and the results of total suspended solid （TSS） discharge loads and event mean concentrations （EMC） were extracted. From these data, linear regression models were developed. R2 and p-values of the regression of ADD for both TSS loads and EMCs were investigated. Results showed that pollutant loads were better predicted than pollutant EMC in the multiple regression models. Regression may not provide the true effect of site-specific characteristics, due to uncertainty in the data.展开更多
A study was conducted to investigate the status of the water and sediment quality in the Chalan Beel——a major fresh water fish reservoir of the country for a period of one year from July 2007 to June 2008. The mean ...A study was conducted to investigate the status of the water and sediment quality in the Chalan Beel——a major fresh water fish reservoir of the country for a period of one year from July 2007 to June 2008. The mean values of water quality parameters(depth: 214.73±152.22 cm, temperature 27.68±4.26℃, transparency 123±82 cm, p H 9.7±0.47, total alkalinity 137±42 mg/L, conductivity 307±147 μs/cm, total dissolved solids 183±89 mg/L, ammonia-N 0.27±0.39 mg/L, nitrate-N 0.09±0.07 mg/L, phosphate-P 2.01±2.53 mg/L) and sediment quality parameters(p H 7.21±0.35, organic matter 2.59±0.52%, total nitrogen 0.09±0.04%, available phosphorus 5.4±3.6 Meq./100 g and exchangeable potassium 0.43±0.14 Meq./100 g) were within the range recommended for most of the inland fishes of Bangladesh. Although the water and sediment quality parameters except ammonia and phosphate are in the suitable range, the overall results suggest that better management techniques should be practiced in order to overcome the declining trend of associated aquatic life(fauna and flora) of this important fresh water body of Bangladesh.展开更多
文摘Characterization and optimization of physical and chemical properties of drilling fluids are critical for the efficiency and success of drilling operations.In particular,maintaining the optimal levels of solids content is essential for achieving the most effective fluid performance.Proper management of solids content also reduces the risk of tool failures.Traditional solids content analysis methods,such as retort analysis,require substantial human intervention and time,which can lead to inaccuracies,time-management issues,and increased operational risks.In contrast to human-intensive methods,machine learning may offer a viable alternative for solids content estimation due to its pattern-recognition capability.In this study,a large set of laboratory reports of drilling-fluid analyses from 130 oil wells around the world were compiled to construct a comprehensive data set.The relationships among various rheological parameters were analyzed using statistical methods and machine learning algorithms.Several machine learning algorithms of diverse classes,namely linear(linear regression,ridge regression,and ElasticNet regression),kernel-based(support vector machine)and ensemble tree-based(gradient boosting,XGBoost,and random forests)algorithms,were trained and tuned to estimate solids content from other readily available drilling fluid properties.Input variables were kept consistent across all models for interpretation and comparison purposes.In the final stage,different evaluation metrics were employed to evaluate and compare the performance of different classes of machine learning models.Among all algorithms tested,random forests algorithm was found to be the best predictive model resulting in consistently high accuracy.Further optimization of the random forests model resulted in a mean absolute percentage error(MAPE)of 3.9%and 9.6%and R^(2) of 0.99 and 0.93 for the training and testing sets,respectively.Analysis of residuals,their histograms and Q-Q normality plots showed Gaussian distributions with residuals that are scattered around a mean of zero within error ranges of±1%and±4%,for training and testing,respectively.The selected model was further validated by applying the rheological measurements from mud samples taken from an offshore well from the Gulf of Mexico.The model was able to estimate total solids content in those four mud samples with an average absolute error of 1.08% of total solids content.The model was then used to develop a web-based graphical-user-interface(GUI)application,which can be practically used at the rig site by engineers to optimize drilling fluid programs.The proposed model can complement automation workflows that are designed to measure fundamental rheological properties in real time during drilling operations.While a standard retort test can take approximately 2 h at the rig site,such kind of real-time estimations can help the rig personnel to timely optimize drilling fluids,with a potential of saving 2920 man-hours in a given year for a single drilling rig.
基金The authors acknowledge Isfahan University of Technology,Isfahan,Iran(IUT)for their support with financial resources and research facilitiesFurther acknowledgment goes to Mahdi Mohsenian and Soha Agreen Tech Company(Tehran,Iran)for donating milk powder and funding this project.
文摘Background:In recent years,there has been an increasing interest in using high quantities of milk or milk replacer(MR)in heat-stressed calves to alleviate the negative effects of high environmental temperatures on their performance.However,observations have indicated a decline in growth performance in the weaning and postweaning period,which might be optimized with increasing total solids(TS)in milk and weaning age.This study aims to optimize the effects of higher quantities of milk on late weaned calves'performance by increasing TS concentration or delivery route in summer conditions.Method:Forty-eight newborn Holstein calves were used in a 2×2 factorial arrangement with the factors of preweaning total plane of milk(PM)intake(low vs.high)and milk TS content(12%vs.17%).The treatments were(1)low PM(LPM)intake with 12%TS(TS intake=45.9 kg),(2)LPM intake with 17%TS(TS intake=65.1 kg),(3)high PM(HPM)intake with 12%TS(TS intake=63.7 kg);and(4)HPM intake with 17%TS(TS intake=90.3 kg).Calves were weaned at d 83,and the study was terminated at d 103 of age.Performance data(every 10 day),skeletal growth(d 80 and 100),ruminal fermentation parameters(d 48 and 91),and behavioral measurements(d 69,70,93 and 94)were analyzed as repeated measurements with PROC MIXED of SAS 9.4(SAS Institute Inc.,Cary,NC).Results:Calves receiving HPM consumed less PMR from d 44 to 83 of age,but they had higher ADG from d 24 to 53 of age compared to those fed LPM(PM×age,P<0.001).In addition,calves receiving milk with 17%TS had lower PMR intake from d 14 to 83 of age,but greater ADG from d 34 to 53 compared to those receiving milk with 12%TS(TS×age,P<0.001).Calves that received HPM had greater skeletal growth parameters compared to LPMfed calves,with a similar effect evident for calves fed milk with 17%TS compared with those fed milk with 12%TS.Calves receiving milk with 17%TS had greater fecal scores and diarrhea occurrence than those fed milk with 12%TS in HPM,but not LPM.Conclusions:Increasing PM and milk TS concentration improved growth in summer-exposed calves as demonstrated by increased pre-weaning ADG,pre-and post-weaning BW,and structural growth.
基金Financial support was provided by the National Natural Science Foundation of China (50569002,50669004 and 51069007)Natural Science Foundation of Inner Mongolia (200711020604)Key Project from Department of Water Resources of Inner Mongolia (20080105)
文摘High total dissolved solids （TDS） content is one of the most important pollution contributors in lakes in arid and semiarid areas. Ulansuhai Lake, located in Urad Qianqi, Inner Mongolia, China, was selected as the object of study. Temperatures and TDS contents of both ice and under-ice water were collected together with corresponding ice thickness. TDS profiles were drawn to show the distribution of TDS and to describe TDS migration. The results showed that about 80% （that is 3.602x108 kg） of TDS migrated from ice to water during the whole growth period of ice. Within ice layer, TDS migration only occurred during initial ice-on period, and then perished. The TDS in ice decreased with increasing ice thickness, following a negative exponential-like trend. Within un- der-ice water, the TDS migrated from ice-water interface to the entire water column under the effect of concentra- tion gradient until the water TDS content was uniform. In winter, 6.044x 107 kg （16.78% of total TDS） TDS migrated from water to sedirnent, which indicated that winter is the best time for dredging sediment. The migration effect gives rise to TDS concentration in under-ice water and sediment that is likely to affect ecosystem and water quality of the Yellow River. The trend of transfer flux of ice-water and water-sediment interfaces is similar to that of ice growth rate, which reveals that ice growth rate is one of the determinants of TDS migration. The process and mechanism of TDS migration can be referenced by research on other lakes with similar TDS content in cold and arid areas.
基金Supported by the National Key R&D Program of China(No.2019YFD0900502)。
文摘In recirculating aquaculture systems(RASs),the effective treatment of aquaculture tailwater is essential to maintain the health of the RAS.This study investigated the optimal time and method for tailwater treatment during three periods of the aquaculture of the Litopenaeus vannamei:nursery(0–26 d),middle(27–57 d),and later(57–104 d).The variation of several water parameters during the dissolution of total suspended solid(TSS)in tailwater,applied with the effects of ozone on the microorganism and water quality parameters were investigated.Results showed that the TSS concentrations in tailwater decreased with time,although not significantly(P>0.05),whereas total ammonia nitrogen(TAN),nitrite(NO-2-N),and nitrate(NO_(3)^(-)-N)increased significantly(P<0.05).Therefore,TSS should be removed from the tailwater as early as possible,being most optimal within 4 h.Ozone removed 38.24%–48.95%of TSS,17.78%–90.14%of TAN,and 87.50%–98.90%of NO-2-N after 4 h of treatment.However,it resulted in the significant accumulation of NO_(3)^(-)-N.Moreover,the total number of Vibrio and bacterial counts in aquaculture tailwater was reduced completely by ozone within 4 h.Thus,these results provided technical details and data support for the effective treatment of tailwater from shrimp RAS.
文摘This article examines the influence of seawater temperature and total dissolved solids (TDS) on reverse osmosis (RO) desalination in the Arabian Gulf region, with a focus on the impact of climate change. The study highlights the changes in seawater temperature and TDS levels over the years and discusses their effects on the efficiency and productivity of RO desalination plants. It emphasizes the importance of monitoring TDS levels and controlling seawater temperature to optimize water production. The article also suggests various solutions, including intensive pre-treatment, development of high-performance membranes, exploration of alternative water sources, and regulation of discharges into the Gulf, to ensure sustainable water supply in the face of rising TDS levels and seawater temperature. Further research and comprehensive monitoring are recommended to understand the implications of these findings and develop effective strategies for the management of marine resources in the Arabian Gulf.
文摘This study presents a significant contribution to the field of water quality assessment and sustainable water management practices. By evaluating the levels of total dissolved solids (TDS) in seawater intakes within Al-Khobar desalination production system, the study addresses a crucial aspect of water treatment and environmental impact assessment. The findings provide valuable insights into the variations and trends of TDS levels across different phases of the system, highlighting the importance of monitoring and management strategies. The study provided both gravimetric total dissolved solids (TDS) and electrical conductivity (EC) measurements to analyze TDS calculation factor and evaluate measurement accuracy. Results revealed significant variations in TDS levels across the sampling locations, with phase-2 exhibiting higher levels and greater fluctuations. Phase-3 displayed similar trends but with lower TDS levels, while phase-4 showed slightly different behavior with higher average TDS levels. EC measurements demonstrated a strong correlation with TDS, providing a reliable estimation. However, additional methods such as gravimetric analysis should be employed to confirm TDS measurements. The findings contribute to understanding water quality in the Al-Khobar desalination system, aiding in monitoring, management, and decision-making processes for water treatment and environmental impact assessment. The study enhances the credibility of water quality assessments and supports sustainable water management practices.
文摘A relationship between electrical conductivity (EC) and total dissolved solids (TDS) was tested for solutions of same salinity levels with respect to different artificial salts with their combinations. Results showed remarkable jumping at the order of the artificial salt sequence specially that of the magnesium type. A computer model is designed with an input of EC and TDS. The output will be the possible prevailing artificial salts. The accuracy of the model was tested by using the groundwater data of Safwan-Zubair area south of Iraq and it proved to be significant at 95% matching. The 5% unmatched results are due to the possibility of having more than one type of prevailing salt.
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA24040203)the Inner Mongolia Key R&D Program,China(No.NMKJXM202107)+1 种基金the Key R&D Program of Gansu Province of China(No.21CX6QA026)the Natural Science Foundation of Gansu Province of China(No.20JR5RA074)。
文摘Winter irrigation is a crucial measure for preventing farmland salinity in arid inland regions.However,given the relatively complex process of salt leaching under the influence of freezing and thawing,present salinity management has led to soil quality deterioration in the irrigation areas in Northwest China.To better understand this process,a field experiment was conducted in Huangyang Town,Wuwei City,Gansu Province,China to simulate the evolution of soil profile salinity and alkalinity in a typical oasis farmland under 3-year regular barley planting,using a local prevailing water-salt management mode of drip irrigation for the growing period and winter irrigation for the fallow period.This study investigated the impact of freezing on salt leaching by comparing the soil profile water,heat,and salt movements under different winter irrigation quotas.Compared to no winter irrigation,a reduction in the winter irrigation quota from the standard one to a halved one led to a transition from a sink of 11.05% by salt leaching to a source of 13.75% by salt addition.This means that overwintering soil freezing,especially in oases with deep groundwater tables,can worsen root zone salinization caused by a deficit winter irrigation,through freezing-induced root zone soil water and salt return.Furthermore,dry saline soil dominated by sulfate is at the risk of soil alkalization when freezing-induced oversaturation of solute concentration leads to significant salt precipitation.These findings are crucial for understanding the mechanisms behind the increasing secondary salinization caused by unsustainable winter irrigation in oasis irrigation areas.
文摘The application of single nanofiltration （NF） and sequential filtration of microfiltration （MF） and NF for the concentration of vinasse were studied. Filtration experiments were performed at 60 ℃, 500 rpm and different transmembrane pressures using four commercial membranes： MF, PVDF 0.2 μm; NF, PES 300, 500 and 1000 Da. The process effectiveness was evaluated through the permeate flux and the total solids （TS） concentration in the retentate. Because the retention of TS and permeate fluxes were very similar for MF, PVDF-0.2 membrane at 0.10 MPa was selected because of its lower power consumption. The best conditions tested for NF were the following： PES-1000 at 3.50 MPa with a flux of 183.2 kg/m^2 h at a volume reduction factor （VRF） of 2, under which 68% of solids were retained. For the MF ＋ NF, a PES-1000 at 3.50 MPa was selected because a higher permeate flux was achieved at a VRF of 4, and PES-500 at 3.50 MPa because a higher retention of TS was achieved compared to the other experiments. A single NF resulted in a retentate concentration that was almost twice as high as the hybrid MF and NF process, allowing reduced costs in its transportation from distilleries to distant areas.
基金supported by the China-Israel Joint Research Program, MOST of Chinathe National Natural Science Foundation of China (No. 51178047)the Foundation of Key Laboratory for Solid Waste Management and Environment Safety,Ministry of Education of China (No. SWMES 2010-2)
文摘High-pressure homogenization （HPH） technology was applied as a pretreatment to disintegrate sewage sludge. The effects of homogenization pressure, homogenization cycle number, and total solid content on sludge disintegration were investigated. The sludge disintegration degree （DDCOD）, protein concentration, and polysaccharide concentration increased with the increase of homogenization pressure and homogenization cycle number, and decreased with the increase of sludge total solid （TS） content. The maximum DDCOD of 43.94% was achieved at 80 MPa with four homogenization cycles for a 9.58 g/L TS sludge sample. A HPH sludge disintegration model of DDCOD= kNaPb was established by multivariable linear regression to quantify the effects of homogenization parameters. The homogenization cycle exponent a and homogenization pressure exponent b were 0.4763 and 0.7324 respectively, showing that the effect of homogenization pressure （P） was more significant than that of homogenization cycle number （N）. The value of the rate constant k decreased with the increase of sludge total solid content. The specific energy consumption increased with the increment of sludge disintegration efficiency. Lower specific energy consumption was required for higher total solid content sludge.
基金the National Natural Science Foundation of China(No.30600086)
文摘Irrigation with various dilutions of seawater can act as an alternate water resource and thus plays an important role in saving freshwater resources as well as promoting agriculture in the coastal semi-arid areas of the North China Plain. Jerusalem artichoke （Helianthus tuberosus L.） grown in a field experiment was irrigated with seawater diluted with freshwater from 2001 to 2003 to determine the feasibility of seawater irrigation in the Laizhou area. For treatments of CK （non-irrigation） along with seawater concentrations of 25%, 50%, and 75%, total dissolved solid （TDS） in the non-irrigated soil significantly increased （P ≤ 0.05） in both 2002 and 2003 and was 1.3 times higher in 2003 than in 2001. In the 25% and 50% seawater concentration treatments, TDS in 2001 was significantly greater （P ≤ 0.05） than CK; however, TDS in these two treatments decreased by 34.9% and 40.1%, respectively, in 2003 compared with 2001. The sodium adsorption ratio （SAR） remained below 10 mmol^1/2 L^-1/2, indicating that alkalization was low with seawater irrigation. In 2001 and 2002, compared to CK and the irrigation treatment with 75% seawater, irrigation with 25% and 50% seawater increased the yields of Jerusalem .artichoke. This meant that Jerusalem artichoke could be safely grown in salt-affected land of Laizhou area with 25% and 50% seawater irrigation.
基金Supported by the Special Fund for Agro-scientific Research in the Public Interest of China(No.200903001-3)the National Natural Science Foundation of China(No.41301231)the Recruitment Program of High-Level Talents of Xinjiang,China
文摘Located in the inland arid area of central Asia, salt-affected farmlands take up one third of the total irrigated land area in Xinjiang of Northwest China. Spatio-temporal variability of soil salinity and the underlying mechanism are fundamental problems challenging the sustainability of oasis agriculture in China. In this study, the data of total dissolved solids(TDS) measured for soil samples collected from 27 representative study areas in the oasis areas of Xinjiang were analyzed and the coefficient of variation(CV) and stratification ratio(SR) of TDS were used to describe the lateral and vertical soil salinity variations, respectively. Weekly, monthly,and annual changes in soil salinity were also summarized. Results showed that the top(0–20 cm) soil salinity was highly variable(CV> 75%) for most studied areas. Lateral variation of soil salinity was significantly correlated with the sampling interval; as a result, a maximum sampling interval of 0.9 m was found for reducing evaluation uncertainty. The top 0–20 cm soil salt accounted for about25.2% of the total salt in the 0–100 cm soil profile. The stratification ratio values(the ratio of TDS at the 20–40 cm depth to that at the 0–20 cm depth) were mostly smaller than 1 and on average 0.92, illustrating that the top 0–20 cm soil contained slightly more salt and a considerable amount of salt still existed in subsurface and deep horizons. Irrigation reduced top soil salinity by 0.52 g kg-1, or14.6%, within the first week. On average, the relative range of soil salinity, calculated to indicate monthly changes in soil salinity, was58.2% from May to September. A 27-year experiment indicated that cultivation increased soil salinity by 44.4% at a rate of 0.14 g kg-1year-1. At small spatio-temporal scales, soil salinity variation was mainly affected by anthropogenic factors, such as irrigation and land use. However, natural factors, including groundwater, topography, and climate conditions, mainly influenced soil salinity variation at large spatio-temporal scales. This study displayed the highly variable nature of soil salinity in space and time. Those driving factors identified in this study could provide guidelines for developing sustainable agriculture in the oasis areas and combating salinization in arid regions of China.
基金Supported by the National Key Technology Research and Development Program of the Ministry of Science and Technology of China(No.2012BAC13B05)Science and Technology Foundation of Beijing Municipal Research Institute of Environmental Protection(No.2013B05)
文摘Allelopathic effects of submerged macrophytes against algae are affected by many environmental factors which can only be measured one by one by traditional methods. Box-Behnken design of response surface methodology was used to optimize three environmental factors （temperature, light intensity and total dissolved solids） of allelopathic effects of Potarnogeton pectinatus against Microcystis aeruginosa at the same time. By solving the regression equation and analyzing the response surface contour plots, the optimal conditions of the relatively inhibitory rate of Microcystis aeruginosa were that the temperature was 23℃, the light intensity was 2 700 lx and the total dissolved solids were 4 415 mg/L. Under these conditions, the optimal value of relatively inhibitory rate of Microcystis aeruginosa was 81.9%. According to validation experiments, the results of analysis indicated that the experimental values fitted well with the predicted ones.
文摘This paper presents an assessment of the hydrochemical characteristics of groundwater in Northern Gezira State, Central Sudan. The approaches followed here include the chemical analyses for major ions chemistry and construction of hydrochemical maps of total dissolved solids (TDS), sodium (Na +), bicarbonate (HCO 3 -), and chloride (Cl -) ions. The hydrochemical characteristics of the groundwater in each aquifer and management consideration are discussed. Sources of major ions in groundwater are analyzed. The hydrochemical maps of important species are constructed. The relationship of groundwater to use is elaborated. High concentrations of the chemical and hydrochemical constituents and the occurrence of calcretes (CaCO 3) in upper zones suggest a long history of evaporation and increasing leachates.
基金Thanks to Dr.Yin Lihe of Xi'an Center of China Geology Survey for his hard workon the English translation of this paper.This study was supported by Geological Survey Project of China Geological Survey(DD20160291).
文摘To accurately evaluate ecological risks trigged by groundwater exploitation,it must be clarified the relationship between vegetation and groundwater.Based on remote sensing data sets MOD13Q1,groundwater table depth(WTD)and total dissolved solids(TDS),the relationship between groundwater and natural vegetation was analyzed statistically in the main plain areas of Qaidam Basin.The results indicate that natural vegetation is groundwater-dependent in areas where WTD is less than 5.5 m and TDS is less than 7.5 g/L.Aquatic vegetation,hygrophytic vegetation and hygrophytic saline-alkali tolerant vegetation are mainly distributed in areas with WTD<1.1 m.Salt-tolerant and mesophytic vegetation mainly occur in areas with WTD of 1.4-3.5 m,while the xerophytic vegetation isprimarily present in areas where WTD ranges from 1.4 m to 5.5 m.Natural vegetation does not necessarily depend on groundwater in areas with WTD>5.5 m.For natural vegetation,the most suitable water TDS is less than 1.5 g/L,the moderately suitable TDS is 1.5-5.0 g/L,the basically suitable TDS is 5.0-7.5 g/L,and the unsuitable TDS is more than 7.5 g/L.
基金supported by the National Key Research&Development Program of China(Grant No.2016YFC1401603)the NSFC-Zhejiang Joint Fund for the Integration of Industrialization and Informatization(Grant No.U1609201)the National Natural Science Foundation of China(Grant No.41621064)。
文摘Hourly mapping by a Geostationary Ocean Color Imager was used to reveal the spatial pattern and tidal variation of total suspended solids(TSS)over the Yangtze Bank in the Yellow and East China Seas during the winter.The TSS form a tongueshaped structure,which decreases further offshore in a stepwise manner.The stepwise change is separated by two fronts of TSS,which are located near the 20-m and 50-m isobaths.The tidal variation of TSS concentration during the study period is evident and can be divided into three stages:decay,maintenance,and growth.Compared with the relatively stationary TSS during the maintenance stage,drastic changes exist during the decay and growth stages.In terms of tide-induced mixing,the dynamic analysis shows that both the topography and the tidal currents play an important role in the spatio-temporal variation of TSS during the tidal period.In particular,spatial distribution is primarily determined by the topography,whereas the temporal variations in tidal scale are determined by the tidal currents.
基金supported by the Fundamental Research Funds for the Central Universities (No. JC2011-1,TD2010-5)the National Natural Science Foundation of China (No. 51078035,21177010)+2 种基金the Ph.D. Programs Foundation of the Ministry of Education of China (No.20100014110004)the High-Tech Research and Development Program (863) of China (No. 2007AA06Z301)the Major Projects on the Control and Rectificationof Water Body Pollution (No. 2008ZX07422-002-004,2008ZX07314-006)
文摘Rheological tests for raw and conditioned activated sludge （AS） or anaerobic digested sludge （ADS） show that power-law relationships can be used to describe the evolution of several rheological parameters, i.e., limiting viscosity （η∞）, yield stress （τy）, cohesion energy of the sludge network （Ec）, and storage modulus （G＇）, with total suspended solid （TSS） content in raw and conditioned sludge. A gel-like structure that behaves similar to weak-link flocs/aggregates was observed in AS and ADS. As derived from the double-logarithmic plots of G＇-TSS content, the mass fractal dimensions of the raw and conditioned AS or ADS flocs/aggregates were 2.70 and 2.53 or 2.85 and 2.79, respectively. The theological tests also indicate that both polymer conditioning and increased TSS content led to improved elastic behavior, cohesion energy, and yield stress of the sludge network, as well as expanded the corresponding linear viscoelastic range. The porosity of AS or ADS flocs/aggregates will be improved by polymer conditioning.
文摘Mandarin (Citrus reticulata Blanco) is a premier fruit crop which ranks in first position of the total fruit industry in Nepal. Studies were conducted to assess the maturity indices and quality parameters of mandarin at three altitudes i.e. 1300 m·asl, 1000 m·asl, and 700 m·asl with six maturity stages i.e. 11 Oct, 21 Oct, 31 Oct, 10 Nov, 20 Nov, and 30 Nov. The most important and reliable judging criteria of fruit maturity in mandarin i.e. fruit weight, external fruit colour, firmness, TSS, acidity, and TSS/Acid ratio, and vitamin C were experimented. The experiment results revealed that 1000 m·asl location was showed the highest fruit weight (104.9 g) and juice percentage (55.23) followed by 1300 m·asl altitude (99.5 g and 53.75% respectively) at 20<sup>th</sup> of November. The maturity advanced at lower altitude with 50 percent yellow orange rind colour, 10.98 TSS/acid ratio and 4 kg/cm<sup>2</sup> firmness from 10<sup>th</sup> November at lower altitudes whereas it was appeared in 20<sup>th</sup> November at higher altitudes. The TSS/acid ratio was significantly higher (10.98) in the fruits of 700 m·asl as compared to 1300 m·asl (9.76) on 10<sup>th</sup> November, however, on 20<sup>th</sup> November 1300 m·asl showed the highest ratio (17.76). The fruit weight, juice content, TSS was found in increasing trends up to 20 November and then showed constant and decreasing trend. However, TA, firmness and vitamin C were showed in decreasing trends with time. The 1000 - 1300 m·asl was the best location for the mandarin production and 10-20 November was the best period for the mandarin harvesting for optimum maturity.
基金supported by the Korea Ministry of Environment, as "The Eco-innovation Project" (No. 413111-003)
文摘Stormwater runoff has been identified as a source of pollution for the environment, especially for receiving waters. In order to quantify and manage the impacts of stormwater runoff on the environment, predictive models and mathematical models have been developed. Predictive tools such as regression models have been widely used to predict stormwater discharge characteristics. Storm event characteristics, such as antecedent dry days （ADD）, have been related to response variables, such as pollutant loads and concentrations. However it has been a controversial issue among many studies to consider ADD as an important variable in predicting stormwater discharge characteristics. In this study, we examined the accuracy of general linear regression models in predicting discharge characteristics of roadway runoff. A total of 17 storm events were monitored in two highway segments, located in Gwangju, Korea. Data from the monitoring were used to calibrate United States Environmental Protection Agency＇s Storm Water Management Model （SWMM）. The calibrated SWMM was simulated for 55 storm events, and the results of total suspended solid （TSS） discharge loads and event mean concentrations （EMC） were extracted. From these data, linear regression models were developed. R2 and p-values of the regression of ADD for both TSS loads and EMCs were investigated. Results showed that pollutant loads were better predicted than pollutant EMC in the multiple regression models. Regression may not provide the true effect of site-specific characteristics, due to uncertainty in the data.
基金Supported by the United States Department of Agriculture(USDA) through the Project ‘‘Ex situ conservation of some indigenous fishes of Bangladesh by selecting the best stock through DNA markers’’(BGARS-120)
文摘A study was conducted to investigate the status of the water and sediment quality in the Chalan Beel——a major fresh water fish reservoir of the country for a period of one year from July 2007 to June 2008. The mean values of water quality parameters(depth: 214.73±152.22 cm, temperature 27.68±4.26℃, transparency 123±82 cm, p H 9.7±0.47, total alkalinity 137±42 mg/L, conductivity 307±147 μs/cm, total dissolved solids 183±89 mg/L, ammonia-N 0.27±0.39 mg/L, nitrate-N 0.09±0.07 mg/L, phosphate-P 2.01±2.53 mg/L) and sediment quality parameters(p H 7.21±0.35, organic matter 2.59±0.52%, total nitrogen 0.09±0.04%, available phosphorus 5.4±3.6 Meq./100 g and exchangeable potassium 0.43±0.14 Meq./100 g) were within the range recommended for most of the inland fishes of Bangladesh. Although the water and sediment quality parameters except ammonia and phosphate are in the suitable range, the overall results suggest that better management techniques should be practiced in order to overcome the declining trend of associated aquatic life(fauna and flora) of this important fresh water body of Bangladesh.
