Stream Discharge and Riparian Land Use Influence In-Stream Concentrations and Loads of Phosphorus from Central Plains Watersheds

Total annual nutrient loads are a function of both watershed characteristics and the magnitude of nutrient mobilizing events. We investigated linkages among land cover, discharge and total phosphorus (TP) concentrations, and loads in 25 Kansas streams. Stream monitoring locations were selected from the Kansas Department of Health and Environment stream chemistry long-term monitoring network sites at or near U.S. Geological Survey stream gauges. We linked each sample with concurrent discharge data to improve our ability to estimate TP concentrations and loads across the full range of possible flow conditions. Median TP concentration was strongly linked (R ² = 76%) to the presence of cropland in the riparian zones of the mostly perennial streams. At baseflow, discharge data did not improve prediction of TP, but at high flows discharge was strongly linked to concentration (a threshold response occurred). Our data suggest that on average 88% of the total load occurred during the 10% of the time with the greatest discharge. Modeled reductions in peak discharges, representing increased hydrologic retention, predicted greater decreases in total annual loads than reductions of ambient concentrations because high discharge and elevated phosphorus concentrations had multiplicative effects. No measure of land use provided significant predictive power for concentrations when discharge was elevated or for concentration rise rates under increasing discharge. These results suggest that reductions of baseflow concentrations of TP in streams without wastewater dischargers may be managed by reductions of cropland uses in the riparian corridor. Additional measures may be needed to manage TP annual loads, due to the large percentage of the TP load occurring during a few high-flow events each year.     

营养物质对细菌质粒pEA9∷Km在土壤中接合转移频率的影响

用成团肠杆菌(Enterobacter agglomerans) T7(pEA9∷Km)为供体菌,以E.a.339(pEA9-)为受体菌在天然土壤中进行接合实验,测定各种营养物质对重组质粒pEA9∷Km同源接合转移频率的影响.实验发现,如果在土壤中只加入生理盐水或无机盐培养基,就观察不到细菌数量的增加和质粒的转移;只有加入碳源物质后才检测到细菌数量的增加和质粒的接合转移,接合转移频率的大小位于1.2×10-4～4.4×10-4之间,与所加碳源物质的种类关系不大.图2 表1 参13     

Snapping Turtles (Chelydra serpentina) As Monitors for Mercury Contamination of Aquatic Environments

We assessed the distribution of mercury in snapping turtles(Chelydra serpentina) by analyzing front shoulder muscle,back leg muscle, tail muscle, blood, liver, and marginalcarapacial scute (shell) of 26 adult turtles from five smalllakes. Total mercury concentration in muscle ranged from 50 to500 ng g^–1 wet weight and was highly correlated among the threetissue locations. There was no relationship between musclemercury concentration and body size. Mercury concentration inblood was similar to muscle; the correlation with muscle mercuryconcentration was significant but there was some variability. Mercury concentration in shell was much higher than in muscle orblood, ranging from 500 to 3300 ng g^–1, and was highly correlatedwith muscle mercury concentration. Liver mercury concentrationwas similar to shell, but was highly variable and uncorrelatedwith any other tissue. We conclude that snapping turtlesaccumulate mercury from their environment and may be usefulmonitors of mercury contamination.     

Survey on fluoride, bromide and chloride contents in public drinking water supplies in Sicily (Italy)

Six hundred and sixty-seven water samples were collected from public drinking water supplies in Sicily and analysed for electric conductivity and for their Cl(-), Br(-) and F(-) contents. The samples were, as far as possible, collected evenly over the entire territory with an average sampling density of about one sample for every 7,600 inhabitants. The contents of Cl(-) and Br(-), ranging between 5.53 and 1,302 mg/l and between <0.025 and 4.76 mg/l respectively, correlated well with the electric conductivity, a parameter used as a proxy for water salinity. The highest values were found both along the NW and SE coasts, which we attributed to seawater contamination, and in the central part of Sicily, which we attributed to evaporitic rock dissolution. The fluoride concentrations ranged from 0.023 to 3.28 mg/l, while the highest values (only three exceeding the maximum admissible concentration of 1.5 mg/l) generally correlated either with the presence in the area of crystalline (volcanic or metamorphic) or evaporitic rocks or with contamination from hydrothermal activity. Apart from these limited cases of exceeding F(-) levels, the waters of public drinking water supplies in Sicily can be considered safe for human consumption for the analysed parameters. Some limited concern could arise from the intake of bromide-rich waters (about 3% exceeding 1 mg/l) because of the potential formation of dangerous disinfection by-products.     

An ultracompact photo-ionization time-of-flight mass spectrometer with a novel vacuum ultraviolet light source for on-line detection of organic trace compounds and as a detector for gas chromatography

A recently developed novel intense rare-gas excimer vacuum ultraviolet (VUV) light source, the electron beam-pumped excimer lamp (EBEL), has been applied to the soft single-photon ionization (SPI) of organic molecules in a compact orthogonal acceleration time-of-flight mass spectrometer (oaTOFMS). The SPI-oaTOFMS system was applied to the on-line monitoring of tobacco smoke. With this setup, it was possible to analyze the composition of individual puffs of cigarette smoke. Furthermore, a gas chromatograph (GC) was coupled to the EBEL SPIoaTOFMS system. Soft photo-ionization represents an additional separation dimension. By combination of the gas chromatographic and the soft-ionization mass spectroscopic separation dimensions, a truly multidimensional comprehensive analytical method could be derived.     

The Potential Use of Synthetic Aperture Radar for Estimating Methane Ebullition From Arctic Lakes1

Abstract: Arctic lakes are significant emitters of methane (CH₄), a potent greenhouse gas, to the atmosphere; yet no rigorous quantification of the magnitude and variability of pan‐Arctic lake emissions exists. In this study, we demonstrate the potential for a new method using synthetic aperture radar (SAR) imagery to detect methane bubbles in lake ice to scale up whole‐lake measurements of CH₄ ebullition (bubbling) to regional scales. We estimated ebullition from lakes, which is often the dominant mode of lake emissions, by mapping the distribution of bubble clusters frozen in early winter ice across surfaces of seven tundra lakes and one boreal forest lake in Alaska. Applying previously measured ebullition rates associated with four distinct classes of bubble clusters found in lake ice, we estimated whole‐lake emissions from individual lakes. The percent surface area of lake ice covered with bubbles (R² = 0.68) and CH₄ ebullition rates from lakes (R² = 0.59) and were correlated with radar return values from RADARSAT‐1 Standard Beam mode 3 for the tundra lakes, suggesting that with appropriate scaling and consideration for variability in lake‐ice conditions, this technique has the potential to be used for estimating broader‐scale regional and pan‐Arctic lake methane emissions.     

Structure and origin of the natural halogenated monoterpene MHC-1 and its concentrations in marine mammals and fish

The halogenated natural product previously named mixed-halogenated compound 1 (MHC-1) was isolated from the red seaweed Plocamium cartilagineum harvested in Helgoland, Germany. A total of 1.9mg of pure MHC-1 was obtained from 1g air-dried seaweed. The (1)H and (13)C NMR data matched those reported for a natural monoterpene isolated from this species. Thus, the structure of MHC-1 was established to be (1R,2S,4R,5R,1'E)-2-bromo-1-bromomethyl-1,4-dichloro-5-(2'-chloroethenyl)-5-methylcyclohexane. Moreover, the isolated monoterpene proved to be identical with the compound previously detected in marine mammals and fish from different locations. In addition we examined two samples of P. cartilagineum from Ireland and from the Antarctic; however MHC-1 was only present at low levels. Not only the concentrations were lower but also the pattern of polybrominated compounds differed from MHC-1. A calibrated solution of MHC-1 was used to determine correct concentrations from samples where previously only estimates existed relative to the gas chromatography-electron capture detector (GC/ECD) response of trans-chlordane, which underrated the MHC-1 concentrations by more than factor 2. The highest MHC-1 concentration determined to date in marine mammals is 0.14mgkg(-1) blubber. Significantly higher MHC-1 concentrations were determined in farmed fish with up to 2.2mgkg(-1) lipids. The samples with high concentrations of MHC-1 have in common that they were collected in proximity of the natural habitats of P. cartilagineum.     

Occurrence of platinum and additional traffic related heavy metals in sediments and biota

Non-point sources play an important role in metal emissions into surface waters. One of the most important non-point sources is automobile traffic. Recent studies determining traffic related heavy metals in surface waters have concentrated mainly on worst case scenarios by analyzing heavy metal loads in waters and sediments close to storm-water overflow inlets. The present study aims at identifying traffic related heavy metals in moderately polluted sites, as they occur in highly urbanized regions. Therefore, the concentrations of eight traffic related metals (Pt, Sb, Mo, Cd, Pb, Cu, Cr and Zn) were determined in sediment and crustacean samples from eight different aquatic habitats in the Ruhr district, Germany. Traffic related heavy metals could be identified in sediment and biota samples as a combination of heavy metals (Pt, Sb, Cd, Pb for sediments and Pt and Sb for crustacean samples). Pt concentrations received special attention due to the relatively recent occurrence of anthropogenically emitted Pt in the environment. At six sampling sites, Pt was detected in sediment and/or biota samples. The uptake of Pt compared to other traffic related heavy metals by Asellus aquaticus and Gammarus pulex is relatively high and can be compared with the uptake rates of essential metals like Zn.     

Persistence revisited

We are happy and proud to announce that our book ‘Atmospheric Degradation of Organic Substances — Data for Persistence and Long-range Transport’ (see pp. 143–144) has recently been published by Wiley-VCH [1]. It contains a critical compilation of photo degradation rate constants and quantum efficiencies relevant for calculating the atmospheric persistence of volatile and a few semi-volatile organic compounds. In addition to the data of nearly 1100 substances, the importance of persistence in air and long-range transport potential is presented in two chapters from the point of view of chemicals legislation and of atmospheric photochemistry.     

The opposing effects of bacterial activity and gas production on anaerobic TCE degradation in soil columns

This laboratory study explores the effect of growth substrate concentration on the anaerobic degradation of trichloroethylene (TCE) in sand packed columns. In all columns the growth substrate rapidly degraded to gas, that formed a separate phase. Biomass accumulated in the 0–4.8 cm section of the columns in proportion to the influent growth substrate concentration and biomass concentrations in the remaining sections of all columns were similar to the column receiving the lowest substrate concentration. Increases in growth substrate concentration up to 3030 mg-COD l⁻¹ promoted TCE degradation, but a further increase to 14 300 mg-COD l⁻¹ reduced the amount of TCE completely dechlorinated but did not affect the production of chlorinated TCE intermediates. The mathematical model developed here satisfactorily described the enhancement in TCE dehalogenation for substrate concentration up to 3030 mg-COD l⁻¹; reproducing TCE dehalogenation for 14 300 mg-COD l⁻¹ required that the moisture content used in simulation be lowered to 0.1. The study shows that volatilization of TCE can be significant and volatilization losses should be taken into account when anaerobic activity in in-situ bioremediation applications is stimulated via addition of growth substrates. An implication of the modeling simulations is that maintaining a lower, but uniform, substrate concentration over the contaminated region may lead to faster contaminant degradation.