Source partitioning of anthropogenic groundwater nitrogen in a mixed-use landscape,Tutuila, American Samoa

This study presents a modeling framework for quantifying human impacts and for partitioning the sources of contamination related to water quality in the mixed-use landscape of a small tropical volcanic island. On Tutuila, the main island of American Samoa, production wells in the most populated region (the Tafuna-Leone Plain) produce most of the island’s drinking water. However, much of this water has been deemed unsafe to drink since 2009. Tutuila has three predominant anthropogenic non-point-groundwater-pollution sources of concern: on-site disposal systems (OSDS), agricultural chemicals, and pig manure. These sources are broadly distributed throughout the landscape and are located near many drinking-water wells. Water quality analyses show a link between elevated levels of total dissolved groundwater nitrogen (TN) and areas with high non-point-source pollution density, suggesting that TN can be used as a tracer of groundwater contamination from these sources. The modeling framework used in this study integrates land-use information, hydrological data, and water quality analyses with nitrogen loading and transport models. The approach utilizes a numerical groundwater flow model, a nitrogen-loading model, and a multi-species contaminant transport model. Nitrogen from each source is modeled as an independent component in order to trace the impact from individual land-use activities. Model results are calibrated and validated with dissolved groundwater TN concentrations and inorganic δ¹⁵N values, respectively. Results indicate that OSDS contribute significantly more TN to Tutuila’s aquifers than other sources, and thus should be prioritized in future water-quality management efforts.     

Kritische Bemerkung zur Frage der Temperatur-abhängigkeit der Ozonverteilung

Zusammenfassung A. undE. Vassy haben in der Frage der Temperatur-abhängigkeit des Ozongehalts der Atmosphäre aus der Gleichung loge _n –logJ _n logK(T _n ) geschlossen, daß auch die Gleichung loge _n logJ _n +logK(T _n ) gültig sei. Es wird hier nun gezeigt, daß die bei der ersten Gleichung erlaubten Vernachlässigungen bei der zweiten zu großen Fehlern führen können und daß daher von A. undE. Vassy kein Beweis für die Richtigkeit der Beziehunge=J.K(T) erbracht ist.

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Summary In the question of temperature dependence of ozone content of the atmosphere A. andE. Vassy have concluded from the equation loge _n –logJ _n logK(T _n ) that also the formula loge _n logJ _n +logK(T _n ) must be valid. In this paper it is proved that the neglections which may be admitted for the first equation, can conduct to great errors. Therefore A. andE. Vassy have not produced a proof for the correctness of the equatione=J.K(T).

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Résumé A. etE. Vassy en étuidant le problème de la teneur de l'ozone atmosphérique en relation avec la température ont admis que l'équation loge _n –logJ _n logK(T _n ) entraînait aussi la relation loge _n logJ _n +logK(T _n ). On montre ici que les simplifications admises pour la première équation conduisent pour l'application de la seconde à de fortes erreurs, et que par conséquent ces auteurs n'ont pas fourni de preuve de la justesse de la relatione=J.K(T).

     

Temporal features in thunder days in the United States

1901–80 data for the contiguous U.S. show that secular variability of thunder days was very much less than that of precipitation or of frequency of extra tropical cyclones. Overall, there may have been a slight decline, but more evident was an increase to the thirties followed by a falling off, broken only by a peak in the seventies. These up-and-down movements were evident in most months of the year and regions of the U.S. The general decrease, however, was clear only in the South East and replaced by an increase in the Upper Great Lakes region. Secular variation in thunder day frequency was slightly correlated positively with that of extra tropical cyclone frequency and negatively with sea level pressure. The analysis also confirmed well known seasonal and regional patterns of thunder activity.     

A framework for sourcing of evaporation between saturated and unsaturated zone in bare soil condition

ABSTRACT

Sourcing subsurface evaporation (E_ss) into groundwater (E_g) and unsaturated zone (E_u) components has received little scientific attention so far, despite its importance in water management and agriculture. We propose a novel sourcing framework, with its implementation in dedicated post-processing software called SOURCE (used along with the HYDRUS1D model), to study evaporation sourcing dynamics, define quantitatively “shallow” and “deep” water table conditions and test the applicability of water table fluctuation (WTF) and “bucket” methods for estimation of E_g and E_u separately.

For the “shallow” and “deep” water table we propose E_g?>?0.95E_ss and E_g = 0 criteria, respectively. Assessment of the WTF method allowed sourcing of very small fluxes otherwise neglected by standard hydrological methods. Sourcing with SOURCE software was more accurate than the standard “bucket” method mainly because of greater flexibility in spatio-temporal discretization. This study emphasized the dry condition relevance of groundwater evaporation which should be analysed by applying coupled flow of heat, vapour and liquid water.

Editor D. Koutsoyiannis; Associate editor S. Kanae     

A deep seismic profile of 800 km length recorded in southern Queensland, Australia

Summary. In 1984, the Australian Bureau of Mineral Resources and the Geological Survey of Queensland recorded a regional seismic reflection profile of over 800 km length from the eastern part of the Eromanga Basin to the Beenleigh Block east of the Clarence Moreton Basin. A relatively transparent upper crustal basement with an underlying, more reflective lower crust is characteristic of much of the region. Prominent westerly dipping reflectors occur well below the sediments of the eastern margin of the Clarence Moreton Basin and the adjacent Beenleigh Block, and provide some of the most interesting features of the entire survey. A wide angle reflection/refraction survey of 192 km length and an expanding reflection spread of 25 km length were recorded across the Nebine Ridge. The only clear deep reflectors are interpreted as P-to-SV or SV-to-P converted reflections from a mid-crustal boundary at a depth of about 17 km. The combined Nebine Ridge data provide well-constrained P and S wave velocity models of the upper crust, and suggest a crustal structure quite different from that beneath the adjacent Mesozoic basins.     

Enzymatic and cellular responses in relation to body burden of PAHs in bivalve molluscs: A case study with chronic levels of North Sea and Barents Sea dispersed oil

Mytilus edulis and Chlamys islandica were exposed to nominal dispersed crude oil concentrations in the range 0.015–0.25 mg/l for one month. Five biomarkers (enzymatic and cellular responses) were analysed together with bioaccumulation of PAHs at the end of exposure. In both species, PAH tissue residues reflected the exposure concentration measured in the water and lipophylicity determined the bioaccumulation levels. Oil caused biomarker responses in both species but more significant alterations in exposed C. islandica were observed. The relationships between exposure levels and enzymatic responses were apparently complex. The integrated biomarker response related against the exposure levels was U-shaped in both species and no correlation with total PAH body burden was found. For the monitoring of chronic offshore discharges, dose- and time-related events should be evaluated in the selection of biomarkers to apply. From this study, cellular damages appear more fitted than enzymatic responses, transient and more complex to interpret.     

Cotton yield prediction through spectral parameters

To predict the crop yield from spectral parameters, a field experiment was conducted on cotton crop during 1997-98 Kharif season on a sandy loam soil at the Punjab Agricultural Unjversity, Ludhiana. India. Spectral reflectance and agronomic measurements were made for cotton species (American and Desi cotton), sown on two dates (May 1 and May 29) under five nitrogen levels (0, 40, 80, 120 and 160 kg/ha). Regression analysis showed that growth variables had poor correlation with seed cotton yield for all three models, however, yield attributes were significantly and highly correlated for second degree model with seed cotton yield. The integrated Radiance Ratio (RR) and Normalized Difference Vegetation Index (NDVI) measured over time were significantly correlated quadratically with seed cotton yield on three time segment periods viz., 81–110, 111–140 and 141–200 DAS, but highest correlation values were obtained during 81–110 DAS, In American cotton, the highest correlation coefficient for RR and NDVI were 0.91 and 0.81, respectively; whereas for Desi cotton these values were 0.88 and 0.84, respectively.     

Check dam positioning by prioritization of micro-watersheds using SYI model and morphometric analysis — Remote sensing and GIS perspective

Sediment Yield Index (SYI) model and results of morphometric analysis have been used to prioritize watersheds and to locate sites for checkdam positioning in Tarafeni watershed in Midnapur district. West Bengal. Various thematic maps such as land use/land cover, slope, drainage, soil etc. were prepared from 1RS ID LISS III digital data, SOI toposheets of 1:50,000 scale and other reference maps. Morphometric parameters such as bifurcation ratio (R_b). drainage density (D_d), texture ratio (T), length of overland flow (L_o), stream frequency (F_u), compactness coefficient (C_c), circularity ratio (R_c), elongation ratio (E_r), shape factor (B_s) and form factor (R_f) were computed. Automated demarcation of prioritization of micro-watersheds was done by using GIS overlaying technique by assigning weight factors to all the identified features in each thematic map and ranks were assigned to the morphometric parameters. Five categories of priority viz., very high, high, medium, low and very low, were given to all the watersheds in both the methods. Sixty-two micro-watersheds using SYI method and twenty-three micro-watersheds using morphometric have been prioritized as very high priority. Final priority map was prepared by considering the commonly occurred very high-prioritized micro-watersheds in both SYI model and morphometric analysis. Twenty-four suitable sites were identified for check dam construction in 21 highly prioritized watersheds. It is proved that integrated study of SYI model and morphometric analysis yield good result in prioritization of watersheds.     

Organic contaminants and characteristics of sediments from Oso Bay,south Texas,USA

The Oso Bay, Texas, sediments from nine sites were analyzed by GC-MS for organics to measure contamination in the bay. In most of the sites sediments contained tetrachloroethene (87–1433 g/kg), bis (2-ethylhexyl)phthalate (40–193 g/kg), and aliphatic hydrocarbons, C₈-C₁₃ (720–2491 g/kg). Sources of these contaminants include a landfill, military facilities, and municipal and industrial discharges. Size analysis of the sediments indicates they contain a high percentage of muddy sand (50–75 percent), which suggests that Oso Bay consists of common bay margin sediments.