Allochthonous and autochthonous organic matter in surface waters in Karelia

A relationship between indirect chemical indices of organic matter content of surface waters and light absorption in the visible and ultraviolet ranges is discussed. The allochthonous and autochthonous types of organic matter are found to essentially differ in the rate of light absorption. Techniques are proposed for the calculation of the concentrations of allochthonous and autochthonous organic matter by the integral rate of light consumption in the visible region and the bichromate oxidability of water, as well as by three indirect indices: chemical oxygen demand, permanganate oxidability, and water color index. The mean concentrations of allochthonous and autochthonous organic matter in large lakes (Ladoga, Onega, and Baikal) and in rivers and smaller water bodies in Karelia (>300 water objects) are analyzed. Allochthonous organic matter was found to predominate in most surface waters of Karelia (>80%), while allochthonous organic matter predominates only in lakes with a small specific catchment area (supposedly, <5) and in highly eutrophic lakes.     

Biofacies analysis of Upper Cretaceous deposits in the Ust-Yenisei region: Implications of palynomorphs

The results of palynomorph biofacies analysis in the Upper Cretaceous deposits of the Ust-Yenisei region are presented. The established facies confinement and indicative features of separate palynomorph groups are used, along with identified dinocyst morphotypes and taxa, in paleogeographic reconstructions. Seven palynomorph associations characterizing continental, coastal-marine, shallow-and deep-water facies are distinguished based on quantitative proportions between morphological groupings and individual taxa. As boundaries between distinguishable biostratigraphic and facies subdivisions do not coincide, dinocysts were likely insignificantly dependent in distribution on facies in the West Siberian epicontinental basin at least. On the other hand, distribution trends of particular dinocyst morphotypes and other microphytofossils are correlative with transgressive-regressive cycles and can be used for reconstruction of paleoenvironments.     

Stable isotope composition of subfossil Cerastoderma glaucum shells from the Szczecin Bay brackish deposits and its palaeogeographical implications (South Baltic Coast,Poland)

The environmental conditions of the Szczecin Bay, which existed prior to Szczecin Lagoon, have been reconstructed on the basis of the stable carbon and oxygen isotope (¹⁸O and ¹³C) analysis and radiocarbon dates obtained for subfossil shells of Cerastoderma (Cardium) glaucum. The shells in the collected core were well preserved in their life positions, representing a geochemical record of past temperature variation over the middle Holocene. Three major periods with different thermal conditions have been distinguished in the interval ~ 6000–4300 cal yr BP, when the important Littorina regional transgression took place. During the first period, 6000–5250 cal yr BP, water temperature decreased by 1.4°C, and then remained constant over the second period (5250–4750 cal yr BP). In contrast, during the third period (4750–4300 cal yr BP) both δ-values were highly variable and the mean summer temperature (March–November) increased by about 3.5°C. During first two periods, δ¹⁸O and δ¹³C were significantly correlated, indicating stability of the environmental conditions.     

Buried paleo-channels on the New Jersey continental margin: channel porosity structures from electromagnetic surveying

We report on a marine electromagnetic (EM) survey across two portions of the New Jersey continental margin that have been previously shown to contain buried paleo-channels. The EM method used provides bulk porosity estimates to depths of around 20 m below the seafloor and is thus able to place porosity constraints on the nature of the channel infill and the contrast in physical properties across the channel boundaries. Our data show that a key condition for the channels to have an electrical signature is that they incise an underlying regional unconformity, R, thought to represent a subaerially eroded surface, exposed during the late Wisconsinan glaciation. Channels that cut R are seen through increases in apparent porosity. Another seismically imaged channel sequence, which lies within the outer-shelf sediment wedge sequence above R, does not have an electrical signature, indicating that the sediments above and below the channel boundaries have similar physical properties.     

Qualitätsanforderungen an Oberflächengewässer: Zielvorgaben,Qualitätsziele und chemische Gewässergüteklassifizierung

Quality Requirements for Fresh Waters: Water Quality Targets, Water Quality Objectives, and Chemical Water Quality Classification In the Federal Republic of Germany, water quality requirements for the protection of inland surface waters against hazardous substances are formulated on the basis of a quality targets derivation concept developed jointly by the Federal Government and the Federal States. The quality requirements were termed “water quality targets” in order to make it clear that the values derived are orientational values rather than legally binding limit values. The international comparison of quality requirements for surface waters shows that, on the whole, the national quality targets ensure a high level of protection. According to present scientific knowledge, impairments of uses, such as supply of drinking water, or risks to aquatic communities need not to be expected if the quality targets are complied with. A comparison of water quality data with the water quality targets makes it possible, on the one hand, to identify those substances whose inputs must be further reduced; on the other hand, it also shows that, for a number of substances, there is no need at present for concern over their adversely water quality. A further differentiation of the aquatic hazard potential of pollutants allows a water quality classification system to be developed on the basis of the quality targets derivation concept. The basic elements of this water quality classification system are presented, and its application is explained by way of examples.     

Nonstationary pearl pulsations as a signature of magnetospheric disturbances

We analyse long-lasting (several hours) Pc1 pearl pulsations with decreasing, increasing or constant central frequencies. We show that nonstationary pearl events (those with either decreasing or increasing central frequency) are observed simultaneously with increasing auroral magnetic activity at the nightside magnetosphere while the stationary events (constant central frequency) correspond to quiet magnetic conditions. Events with decreasing central frequency are observed mostly in the late morning and daytime whereas events with increasing central frequency appear either early in the morning or in the afternoon. We explain the diurnal distribution of the nonstationary pearl pulsations in terms of proton drifts depending on magnetic activity, and evaluate the magnetospheric electric field based on the variation of the central frequency of pearl pulsations.     

Groundwater-level prediction using multiple linear regression and artificial neural network techniques: a comparative assessment

The potential of multiple linear regression (MLR) and artificial neural network (ANN) techniques in predicting transient water levels over a groundwater basin were compared. MLR and ANN modeling was carried out at 17 sites in Japan, considering all significant inputs: rainfall, ambient temperature, river stage, 11 seasonal dummy variables, and influential lags of rainfall, ambient temperature, river stage and groundwater level. Seventeen site-specific ANN models were developed, using multi-layer feed-forward neural networks trained with Levenberg-Marquardt backpropagation algorithms. The performance of the models was evaluated using statistical and graphical indicators. Comparison of the goodness-of-fit statistics of the MLR models with those of the ANN models indicated that there is better agreement between the ANN-predicted groundwater levels and the observed groundwater levels at all the sites, compared to the MLR. This finding was supported by the graphical indicators and the residual analysis. Thus, it is concluded that the ANN technique is superior to the MLR technique in predicting spatio-temporal distribution of groundwater levels in a basin. However, considering the practical advantages of the MLR technique, it is recommended as an alternative and cost-effective groundwater modeling tool.     

Non-point source pollution in Indian agriculture: Estimation of nitrogen losses from rice crop using remote sensing and GIS

The paper presents a detailed understanding of nitrogenous fertilizer use in Indian agriculture and estimation of seasonal nitrogen loosses from rice crop in Indo-Gangetic plain region, the ‘food bowl’ of the Indian sub-continent. An integrated methodology was developed for quantification of different forms of nitrogen losses from rice crop using remote sensing derived inputs, field data of fertilizer application, collateral data of soil and rainfall and nitrogen loss coefficients derived from published nitrogen dynamics studies. The spatial patterns of nitrogen losses in autumn or ‘kharif’ and spring or ‘rabi’ season rice at 1 × 1 km grid were generated using image processing and GIS. The nitrogen losses through leaching in form of urea-N, ammonium-N (NH₄-N) and nitrate-N (NO₃-N) are dominant over ammonia volatilization loss. The study results indicate that nitrogen loss through leaching in kharif and rabi rice is of the order of 34.9% and 39.8% of the applied nitrogenous fertilizer in the Indo-Gangetic plain region. This study provides a significant insight to the role of nitrogenous fertilizer as a major non-point source pollutant from agriculture.     

Evaluation of significant sources influencing the variation of physico-chemical parameters in Port Blair Bay,South Andaman,India by using multivariate statistics

Port Blair is the capital city of Andaman & Nicobar Islands, the union territory of India. More than 50% of the population of these islands lives around Port Blair Bay. Therefore the anthropogenic effects in the bay water were studied for monitoring purpose from seven stations. Physico-chemical parameters of seawater were analyzed in samples collected once in every 3 months for 2 years from seven sampling stations located in Port Blair Bay, South Andaman Island to evaluate the spatial and tidal variation. Cluster analysis and factor analysis were applied to the experimental data in an attempt to understand the sources of variation of physico-chemical parameters. In cluster analysis, the stations Junglighat Bay and Phoenix Bay having high anthropogenic influence formed a separate group. The factors obtained from factor analysis indicated that the parameters responsible for physico-chemical variations are mainly related to land run-off, sewage outfall and tidal flow.