Lake Water Source Research Articles

Size, number and chemical composition of nanosized particles in drinking water determined by analytical microscopy and LIBD

In this paper we comprehensively characterized particles in drinking water originating from a lake water source. We focused on particles smaller than a few hundred nm. Several analytical techniques were applied to obtain information on number concentration, size distribution, morphology and chemical composition of the particles. Morphological information was obtained by atomic force microscopy (AFM) analysis. Two types of particles, spherical aggregates up to a few tens of nm and elongated fibers were identified. Similar structures were also observed in transmission electron microscope (TEM) images. A size distribution of the particles was obtained by applying image analysis (IA) tools on the TEM images. IA results showed an exponential increase of the particle number concentration down to 40nm, which is the lower detection limit of our setup. The total number of particles down to 10nm and the average particle diameter were determined with the laser-induced breakdown detection (LIBD) method. The results were in good agreement with the TEM-IA data and showed a total number concentration of roughly 108particles/mL in the purified water. The carbon of the particles was investigated with scanning transmission X-ray microscopy (STXM), which revealed that most particles were organic matter; the C-1s spectra were typical for dissolved organic matter.The methods were applied to characterize the particles from two different drinking waters treated with different methods (conventional vs. ultrafiltration (cut-off 100kDa)). The results showed that the particle number density following ultrafiltration was lower by a factor of 5–10, compared to conventional treatment. However, the average particle diameter in the finished water of both treatment trains was roughly the same.

Occurrence of microcystins in 33 US water supplies

Microcystin levels in 33 lake and reservoir raw water sources were monitored biweekly during summer 2003. Hydrophobic C18 chromatography was used for sample concentration and microcystin purification. Total toxin levels were expressed as microcystin‐LR equivalent concentrations using a commercial enzyme‐linked immunosorbent assay. Results showed that microcystins were detectable in most raw water samples, but concentrations exceeded 1 μg/L in only 14 of 206 samples (7%). Stagnant water conditions were associated with the two raw water sources in which average toxin levels exceeded 1 μg/L. When aggregate results were considered, plant effluent samples showed toxin levels nearly 10‐fold lower, suggesting that existing water treatment processes were effective for toxin removal.

Effect of combined floating bed ecosystem on water quality improvement in lake water source area

A new type of ecological floating bed is developed that combined hydmphyte,aquatic animal and biofilm together.The purification effect of the floating bed for eutrophic lake water under static condition was tested.Result shows that the removal efficiency of TN and TP is 83.7% and 90.7% respectively during 20 days,and the trans- parency is also heightened sharply.Additionally,the floating bed shows better removal effect on non-degradative organic matters.During 25 days,the removal efficiency of r-BHC,HE,DDE,DDD,DDT can reach 25.2%, 63.8%,42.1%,71.6% and 27.6% separately.Furthermore,for benzene chloride and atraizine,up to 55.9% and 72.1% respectively.The biodegradability of non-degradative organic matters and availability of N P for hy- drophyte are all enhanced by aquatic animal's metabolism.The new type of ecological floating bed may be used to drinking water source quality improvement,ecological engineering for wastewater purification,and ecological resto- ration of eutrophic lakes.

On the Water-Salt Change of Bosten Lake in Xinjiang

在博斯腾湖水文和水化学实测资料的基础上,研究了博斯腾湖水盐的年际和年内变化.近 40年来,水质年际变化经历了好→中→差→中的过程;年内变化与区内最大补给源开都河不同季节河流来水量变化以及湖周农田排盐水等因素直接相关,而湖水的矿化度与水位变化呈负相关.对湖水主要离子含量变化特点和湖区矿化度变化规律的研究表明,湖水补给源及湖水循环状况是影响湖水水质变化的主要因素.;Bosten Lake isone of the biggest freshwater lakes in China.On the basis of in situ hy drological and hy dro-chemical data of Bosten Lake, this paper discusses the annual and seasonal change of water saltof Bosten Lake in detail.During the past 40 years or so, The lake water has undergone an annual changing process and the seasonal change is closely related to the water discharge coming from Kaidu River thatis the largest water source supplying for the Bosten Lake.The farmland drainage contains salt around the Lake.The change of mineralized deg ree in the lake is negatively correlated with the water levelin the pasr 40 years, i.e.when the water levelis lower, the lake mineralized deg ree is higher.With the increase of ion content, Ca²⁺ and Mg²⁺ increase slow ly, while the contents of SO₄^2-, Cl^-and K⁺+Na⁺ show markable increase.The descending ion contentorder is SO₄^2->Cl^->HCO₃->K⁺+Na⁺ >Mg²⁺ > Ca²⁺ >CO₃^2-, and its proportion may differ with the sampling positions in the lake.The hydro-chemical ty pe is SO₄^Na.The lake water sources and lake water circulation are the main factors that have impacts on the change of lake water quality.The measurement for improving Bosten lake water eco-environment are suggested as follows:farmland irrigation quota should be reduced, river water amount flowing into Bosten Lake be promised, the groundwater resources utilization in the Yanji Basin be sped-up, and the lake water circulation intensity streng thened.

Location and sampling of aqueous and hydrothermal deposits in martian impact craters.

Do large craters on Mars represent sites that contain aqueous and hydrothermal deposits that provide clues to astrobiological processes? Are these materials available for sampling in large craters? Several lines of evidence strongly support the exploration of large impact craters to study deposits important for astrobiology. The great depth of impact craters, up to several kilometers relative to the surrounding terrain, can allow the breaching of local aquifers, providing a source of water for lakes and hydrothermal systems. Craters can also be filled with water from outflow channels and valley networks to form large lakes with accompanying sedimentation. Impact melt and uplifted basement heat sources in craters > 50 km in diameter should be sufficient to drive substantial hydrothermal activity and keep crater lakes from freezing for thousands of years, even under cold climatic conditions. Fluid flow in hydrothermal systems is focused at the edges of large planar impact melt sheets, suggesting that the edge of the melt sheets will have experienced substantial hydrothermal alteration and mineral deposition. Hydrothermal deposits, fine-grained lacustrine sediments, and playa evaporite deposits may preserve evidence for biogeochemical processes that occurred in the aquifers and craters. Therefore, large craters may represent giant Petri dishes for culturing preexisting life on Mars and promoting biogeochemical processes. Landing sites must be identified in craters where access to the buried lacustrine sediments and impact melt deposits is provided by processes such as erosion from outflow channels, faulting, aeolian erosion, or excavation by later superimposed cratering events. Very recent gully formation and small impacts within craters may allow surface sampling of organic materials exposed only recently to the harsh oxidizing surface environment.

Iodine speciation in the Nile River estuary

Abstract During high- and low-flood periods, surface and bottom water samples were collected along the Nile River estuary for the voltammetric determination of dissolved iodine species. Iodine occurs in the estuary as iodate, iodide and organic iodine. Total iodine increases with salinity, showing a source feature in surface and bottom waters during high-flow indicating iodine input. During low-flow, total iodine showed both addition and removal throughout the course of mixing. Maximum input was associated with turbidity and chlorophyll maxima originating from the agricultural anthropogenic input from Lake Burullus. At the bottom, total iodine enrichment in water matches sulphide production in the anoxic zone. The annual total dissolved iodine flux from the Nile to the S.E. Mediterranean is about 100×106 g yr−1 during 1993. Iodate was not measured below salinity 19, nor in the anoxic waters. It is derived mainly from marine waters that contribute between 38–65% and 44–90% of total dissolved iodine during high- and low-flow periods, respectively. Iodate in the surface layer behaves almost conservatively. Iodate behavior during the low-flow period showed three end members: seawater, river, lake water (source) and/or anoxic bottom waters (sink). Iodide, of riverine, marine and sedimentary origins, is almost without exception the dominant iodine fraction in the surface and bottom waters of the Nile estuary. At high- and low-flow periods, iodide showed an increase with salinity in the upper estuary followed by a dramatical decrease seawards beyond salinities 17–23 and 16–28 at surface and bottom layers, respectively. During low-flow, iodine invades the estuary from seawater as iodate which is converted at the bottom layer to iodide by sulphide ion present during anoxic conditions. Organic iodine is a river-derived species, appearing at the surface and bottom waters, coexisting with iodate and iodide in the river side and contributing between 9–40% and 23–29% of total iodine. A flux of 6±2.3 μM I− m−2 day−1 is estimated to be released from the bottom oxic sediments, increasing to 13.4 μM I− m−2 day−1 at the anoxic zone, and is sufficient to raise the iodide concentration to near 500 nM in the bottom waters.

Coliforms, fecal coliforms, and fecal streptococci as indicators of water pollution

The presence and survival of coliforms, fecal coliforms, and fecal streptococci were studied in sewage treatment plants, heavily polluted rivers, a lake, and other drinking water sources. In all cases the fecal streptococci were generally more resistant to the natural water environment and to purification processes than the other indicator organisms and, at points distant from the original source of pollution were often the only indicators of the fecal nature of the pollution. In two of the systems studied the survival of the fecal streptococci paralleled the survival of enteric viruses better than the coliforms. The fecal streptococci may thus in certain cases provide a better estimate of the probable virus content in lightly contaminated water than the other two indicators.