Using doubly-labeled water measurements of human energy expenditure to estimate inhalation rates

Doubly-labeled water (DLW) data is recognized as an improvement over alternative methods to quantify human energy expenditure. Previously, energy expenditure has been estimated indirectly using heart-rate monitoring, calorimetry, or accelerometer measurements. Inhalation rate estimates can benefit from improved energy expenditure estimates using equations developed by Layton. DLW methods are advantageous for several reasons: the database is robust, they are direct measures, subjects are free-living, and the observation period is longer than what is possible from staged activity measures. DLW energy data is an improvement over previous inhalation estimates based on dietary recall survey data. Mean long-term inhalation rates of 16 m3/day and 13 m3/day, for physically active adult men and women, respectively, were derived based on DLW estimates of energy expended. The range of human energy expenditure is narrow with the maximum energy expenditure not likely greater than twice the minimum.     

New inhibitors of corrosion and depositions of sediments for water circulation systems

New efficient inhibitors of steel corrosion and scale formation have been developed for water circulation cooling systems. They include sodium dimethylenesulfophosphonate and sodium methylenedisulphonate. The processes of scale formation and steel corrosion in water in the presence of these inhibitors were studied. It was shown that the synthesized inhibitors in terms of the efficiency were not inferior to the most effective of well-known reagents: nitryltrimethylphosphonic acid and oxyethylidendiphosphonic acid. Compositions for preventing the scale formation in waters with high hardness (carbonate index > 70 (mg-eq/dm³)²) at < 100°C were also developed.     

An optimization model for water quantity and quality integrated management of an urban lake in a water deficient city

This paper presents an optimization model for water quantity and quality integrated management of an urban lake in a water deficient city. A representative water quantity and quality safeguard system served urban lake, including multi-source water supply facilities, recirculating water purification facilities and surplus water discharge facilities, is widely used in Chinese water deficient cities. Because it is complicated, any mismanagement will result in water quality deterioration, water waste and high operation cost. The presented model attempts to achieve the objectives of controlling water pollution, reducing economic cost and improving water utilization efficiency through an optimized operating water safeguard system. The model is applied to Qingjing Lake in Tianjin, China. Results show that the model plays a more positive role for water quantity and quality integrated management.     

A water quality index for lake beaches

Discriminant analysis of ten years of data from seven beaches located on three lakes in Gatineau Park (Québec) leads to a canonical vector accounting for most of the variability of the three microbial count variables recorded. This discriminant axis orders the beaches along a cline of increasing pollution. It is then transformed into a microbial water quality index calibrated for the given set of beaches, which is in turn used to study the medium-term variability and the long-term evolution of water quality of the beaches.     

Factors affecting phosphate adsorption to aluminum in lake water: implications for lake restoration

Treatment of lake inlets or lake sediments with aluminum (Al) is being increasingly used for lake restoration but only few studies exist concerning competitive substances that might influence phosphate (PO(4)(3-)) removal from lake water. Therefore, chemical interferences of several ions (magnesium, silicate, chloride and humic acid) on PO(4)(3-) adsorption to Al(OH)(3) were studied. Interference of each ion was studied in artificial lake water, and the complex interactions occurring in natural water were studied in water from 30 Danish lakes at pH 7 in both cases. In the artificial lake water Al:P ratio was high as sediment P-pools were the targets while in the natural lake water Al addition was generally lower as only P present in the water was targeted (i.e. inlet water). The single-ion experiments evidenced that silicate (>200 microM) and humic acids significantly decreased the effectiveness of PO(4)(3-) adsorption to Al(OH)(3) by 10-13% at 450 microM Si and 17% at 1 mM C, respectively. NaCl did not influence adsorption of PO(4)(3-) to Al(OH)(3), however, PO(4)(3-) removal was slightly reduced in seawater, mainly due to the presence of Mg(2+). The studies on interferences in natural lake water showed that as long as the PO(4)(3-) concentration was low (<5 microM), silicate competed with PO(4)(3-) for adsorption sites on Al(OH)(3) but at higher PO(4)(3-) concentrations, color and DOC (as indicators of HA) were the main variables decreasing PO(4)(3-) removal from lake water. Inhibition of PO(4)(3-) precipitation in natural lake water appeared complex and did not allow for a simple calculation of Al dose from the concentration of potentially competitive ions. Recommendation for lake management is therefore still that precipitation assays should be carried out for any type of inlet or lake water prior to Al application.     

Factors controlling mobility of 127I and 129I species in an acidic groundwater plume at the Savannah River Site

In order to quantify changes in iodine speciation and to assess factors controlling the distribution and mobility of iodine at an iodine-129 (¹²⁹I) contaminated site located at the U.S. Department of Energy's Savannah River Site (SRS), spatial distributions and transformation of ¹²⁹I and stable iodine (¹²⁷I) species in groundwater were investigated along a gradient in redox potential (654 to 360 mV), organic carbon concentration (5 to 60 μmol L^− 1), and pH (pH 3.2 to 6.8). Total ¹²⁹I concentration in groundwater was 8.6 ± 2.8 Bq L^− 1 immediately downstream of a former waste seepage basin (well FSB-95DR), and decreased with distance from the seepage basin. ¹²⁷I concentration decreased similarly to that of ¹²⁹I. Elevated concentrations of ¹²⁷I or ¹²⁹I were not detected in groundwater collected from wells located outside of the mixed waste plume of this area. At FSB-95DR, the majority (55-86%) of iodine existed as iodide for both ¹²⁷I and ¹²⁹I. Then, as the iodide move down gradient, some of it transformed into iodate and organo-iodine. Considering that iodate has a higher K_d value than iodide, we hypothesize that the production of iodate in groundwater resulted in the removal of iodine from the groundwater and consequently decreased concentrations of ¹²⁷I and ¹²⁹I in downstream areas. Significant amounts of organo-iodine species (30-82% of the total iodine) were also observed at upstream wells, including those outside the mixed waste plume. Concentrations of groundwater iodide decreased at a faster rate than organo-iodine along the transect from the seepage basin. We concluded that removal of iodine from the groundwater through the formation of high molecular weight organo-iodine species is complicated by the release of other more mobile organo-iodine species in the groundwater.     

129I in Swedish rivers: distribution and sources

We analyzed the concentration of 129I in the water of 26 rivers covering most of the runoff from Sweden, with the aim of assessing current contamination levels, distribution patterns and potential sources in freshwater systems of northern Europe. The results show relatively high values (up to 1.4 x 10(9) atoms l(-1)), steeply decreasing levels with increasing latitude and a positive correlation with Cl concentration and other chemical parameters. The 129I concentrations observed in south Sweden are probably the highest ever recorded in rivers without any direct discharge from a nuclear installation. The strong latitudinal dependence suggests a northward dilution and possibly depletion of the isotope and a transport from a source located to the south. The most plausible source of the 129I in the studied rivers is atmospheric fallout of 129I emitted either by atmospheric discharges from the nuclear reprocessing facilities at Sellafield (England) and La Hague (France) or by volatilization from seawater contaminated by the same sources. The question is now whether and at what rate the 129I concentration in Nordic watersheds will increase further if discharges from nuclear reprocessing continue.     

Black water and two peculiar types of stratification in an organically loaded strip-mine lake

During summer stratification a strip-mine lake in which fish were cultured in floating cages developed black water in its anoxic zone. The blackness was evidently produced by ferrous sulfide. Two types of black water stratification were observed. In one the blackness occurred throughout the anoxic zone but was more intense in the upper part, while iron and alkalinity were high throughout this zone. In the second the black water was confined to a meter-thick stratum within the anoxic zone, and iron and alkalinity were remarkably low except in two strata: the one with black water, and the one at the top of the anoxic zone.It is suggested that both types of stratification were caused by a high rate of sulfide production in the metalimnion. The relatively high temperature there (as compared to the hypolimnion) and the presumably higher concentrations of organic matter and ammonia, resulting from fish food and fish wastes, would account for this high rate of sulfide production. Because of sharp oxygen stratification two carbonate-forming processes, photosynthesis and sulfate reduction, occurred in close proximity to each other. In especially calm weather vertical density currents could be initiated by the calcium carbonate crystals and produce the second type of stratification. If the second type of stratification could be produced at will it might be used to improve the quality of strip-mine lake water.     

Application of an efficient search technique for solving optimal regional water quality management problems

This article presents a simple yet effective search algorithmic method for solving regional water quality management problems. Essentially, the algorithm assigns the amount of wastewater flow to be treated at each treatment plant together with the associated level of treatment. When necessary this set of assigned values is adjusted appropriately (by raising the treatment efficiency of. and/or reduction of wastewater quantity to be treated by the treatment plant concerned), so that all the physical and water quality constraints are satisfied. Optimization is achieved by the use of a Random Polyhedron Search (RPS) algorithm which identifies progressively superior solutions. The paper comprises two parts: the first, in which feasibility is confined to treatment plant/transfer capacities, and the second, in which constraints relating to the in-stream quality of the receiving water are incorporated.     

人工湿地在湖水净化和中水回用中的应用

介绍了高效垂直流人工湿地处理系统在公园湖水水质净化和小区生活污水处理及回用中的应用,综合分析了系统运行后对污染物的去除效果.结果表明,人工湿地技术对富营养化水体的处理效果较好,其中对BOD5和TN的去除率高于55%,TP去除率为80%～90%,叶绿素a去除率高于63%,湿地出水水质达到了国家地表水标准中Ⅲ～Ⅳ类水体水质.该系统用于小区生活污水处理及回用时,运行稳定,出水水质可以满足绿化用水水质要求,且达到了良好的景观效果,具有良好的经济效益和应用前景.     

Phosphate removal in acidified and limed lake water

Biotic and abiotic removal of phosphate from lake water from the acidified Lake Gårdsjön as well as immediate changes in these processes upon liming were tested in laboratory experiments. Phosphate was added and analyses of particulate material from both sterilized and nonsterilized series permitted determinations of biotic uptake as the difference between the series. In the original lake water (pH 4.7) biotic uptake largely dominated phosphate removal and abiotic precipitation was of minor importance.In the limed series at pH 7.2 the results had changed and abiotic precipitation dominated the phosphate removal and biotic uptake was strongly reduced. Of the analysed metals, Ca, Mn, Fe and Al, only Fe and Al occurred in the particulate material. The coprecipitation of phosphate and iron was probably due to adsorption on iron hydroxide at both pH values. The nature of phosphorus-aluminium precipitates is largely unknown but different possible complexes are discussed as well as the relative importance of iron and aluminium precipitates.Application of the results in relation to the ongoing lake liming and phosphorus fertilization are discussed.     

Laboratory studies of dissolved radiolabelled microcystin-LR in lake water

The fate of dissolved microcystin-LR was studied in laboratory experiments using surface water taken from a eutrophic lake. Based on initial range finding, a concentration of 50 microg l(-1) dissolved 14C-microcystin-LR was selected for subsequent time-course experiments. The first was performed in May before the cyanobacterial bloom season and low increases in the radioactivity of particulate fractions occurred with an approx. halving of the cyano-toxin during 4 days. The radioactivity of the dissolved fraction remained stable and there was no significant formation of radiolabelled inorganic carbon. A second time-course experiment was performed in September during the cyanobacterial bloom season. At the end of the four-day incubation period, the microcystin-LR concentration had decreased to an undetectable level and 24% of the added radiolabelled substance was found in different particulate fractions. The study demonstrated that biodegradation of dissolved microcystin-LR occurred in water collected at a lake surface with carbon dioxide as a major end-product.     

Phosphorus partitioning in a shallow lake: implications for water quality management

This paper describes the seasonal partitioning of phosphorus (P) across the sediment–water interface in Loch Leven, Scotland, and discusses the implications for future lake management strategy with respect to recovery from eutrophication. In a 10‐month survey, surface water total phosphorus (TP) concentrations were highest in late summer and lowest in early spring. In contrast, sediment TP concentrations were highest in mid‐winter and lowest in late summer. Water discharge at the main outflow of the loch was highest when water‐column TP was low and sediment TP high, and vice versa. Monthly sediment P uptake/release values showed significant cycling between the water‐column and the sediment and showed seasonal variation in four release‐sensitive P pools. Regulating the water level to increase flushing during sediment release periods and decrease flushing during uptake periods has the potential to significantly enhance the recovery of shallow lakes and reservoirs following historic nutrient loading.     

PIV measurements of water mist transport in a homogeneous turbulent flow past an obstacle

To obtain a better understanding of the physical processes involved in liquid suppressant transport in cluttered spaces, particle image velocimetry (PIV) measurements were carried out in the droplet-laden, grid-generated, homogeneous turbulent flow over both an unheated and heated cylinder, and a body-centered cube (BCC) arrangement of spheres. Transport of both water droplets and aerosol particles was characterized upstream and downstream of these obstacles. Data were recorded for the cylinder at ambient and elevated temperatures (at 423 K) to estimate the effects of the hot cylinder surface on droplet transport. The results indicated that smaller droplets are entrained into the recirculation region behind the cylinder while the larger droplets impact the cylinder surface, accumulate and drip off, and/or rebound off the surface and disperse into the free stream. The flow over the heated cylinder resulted in the formation of a vapor layer on the downstream side of the cylinder in the shear region between the recirculation zone and free stream. Thus, vaporization of larger droplets impinging on the heated cylinder surface suggests an increased probability of vapor. For the BCC (with a blockage ratio of about 64%), there was both transport of droplets and seed particles around and through the BCC, as well as significantly more liquid accumulation and dripping than for the cylinder.     

Removal of viable bacteria in lake water by denim filtration

A series of experiments were performed to investigate the removal of viable bacteria [Escherichia coli, total coliforms and standard plate count (SPC) bacteria] in lake water by denim filtration. Filtration with indigo reagent‐dyed denim physically removed E. coli (up to 95%) and total coliforms (up to 92%) from lake water. The removal efficiencies of SPC bacteria (up to 85%) were generally lower than those of E. coli and total coliforms. The adsorption of bacteria to particulate matter larger than the effective pore size of the denim (ca. 48 μm) and the subsequent physical sieving of the large particulate matter seemed to be the dominant disinfection mechanism.     

Determination of labile and strongly bound metals in lake water

Differential pulse anodic stripping voltammetry is applied to differentiate and determine the labile and strongly bound forms of Zn, Cd, Pb and Cu in lake water without preconcentration of the sample. The sensitivities as established for an oxidation peak current of 0·020 μA are: 0·2 ppb for Zn. 0·4 ppb Cd. 0·7 ppb Pb and 0·5 ppb for Cu. For the analysis of a lake water containing 5·0–24·5 ppb of the four metals, the relative S.D. ranged from 1·6 to 10 per cent. Interferences of cations and anions and the choice of a buffer system have been discussed. The method has been applied to study a number of small lakes in the Sudbury area. Ontario.     

Spring bloom in a hypereutrophic lake, lake Kasumigaura, Japan—III Phytoplankton abundance in standing stock of organic matter in lake water

The rapid increase of phytoplankton biomass was the major process for the increase of particulate organic matter in Lake Kasumigaura in 1980. During the first phytoplankton pulse in the bloom relative abundance of each component of organic matter in the lake water was: dissolved organic matter 100, phytoplankton 28, bacteria 27, and detrital particle 27. This relative abundance was maintained as a steady-state oscillation throughout the spring bloom similar to that usually observed in moderately eutrophic waters. Thus phytoplankton abundance in the standing stock of organic matter of the hypereutrophic water during the spring bloom does not show any marked difference from that of moderately eutrophic waters.     

Level and source of 129I of environmental samples in Xi'an region, China

Iodine-129 is widely used as a tracer in various environmental practices such as monitoring of nuclear environmental safety, seawater exchange and transport, geochemical cycle of stable iodine and dating of geological events. The spatial distribution of ¹²⁹I concentration varies significantly on global scale because of anthropogenic input from nuclear activities coupled with scarcity of data on environmental ¹²⁹I variability in many parts of the world including Asia. Here we report new data on ¹²⁹I and ¹²⁷I concentrations in soil, vegetation, river water and precipitation collected from Xi'an area, China. The results indicate values for environmental ¹²⁹I/¹²⁷I ratios in the investigated area range from 1.1 × 10^− 10 to 43.5 × 10^− 10 with a mean of 20.6 × 10^− 10, which is 1-3 orders of magnitude lower than the ratios observed in Europe, but comparable with those observed in the locations far from direct effect of point release sources and at similar latitude. The main source of ¹²⁹I in the investigated area is attributed to the global fallout of both atmospheric nuclear weapons testing and long distance dispersion of fuel reprocessing releases.     

Retracted: Study of the change of water quality for a lake in Central China

Water environment has undergone several state changes, and the factors responsible for causing these water state changes are different. In this paper, a fuzzy comprehensive-quantifying assessment (FCQA) is proposed to evaluate the water quality changes for a representative lake in central China in recent decades. The innovation assessment method develops an index, S_mid, by applying a quantifying method to the fuzzy comprehensive assessment (FCA). The water quality of the lake is evaluated, and the temporal and spatial variations are analysed based on the data of 1991–2006. The Gray Filling Model [GM (1,1)] was used to predict the water quality trends in the subsequent 5 years, and the possible factors responsible for causing water environmental changes were analysed. The temporal and spatial variations of water quality show that there is a strong relationship between human activities and the water quality, and that excessive pen fish farming is the key internal pollution source threatening the lake at present.     

Relative influence of 129I sources in a sediment core from the Kattegat area

The depth profiles of the (129)I concentration and the (129)I/(127)I ratio in a surface sediment core from the Kattegat area have been analyzed in order to obtain information about the different sources of (129)I in that core. Therefore, a mathematical model that relates the measured values to the available emission data from the nuclear fuel reprocessing plants and nuclear weapons tests has been applied. Results show that the reprocessing plants at La Hague and Sellafield are the main sources of (129)I in the sediment. Results about the transfer from the release points at the reprocessing plants to the sampling zone agree with other literature data. The model calculates quite fast the sedimentation of (129)I in the sampling place, probably attached to organic matter. Finally, an estimation of approximately 89 kg of (129)I released by Sellafield between 1952 and 1968 has been obtained from the model.