Przemysław Wachniew

Carbon budget of a mid-latitude, groundwater-controlled lake: Isotopic evidence for the importance of dissolved inorganic carbon recycling

Abstract The carbon cycle of the groundwater-controlled Lake Gościaz, Poland, was investigated. The study covered a period of intensive primary production from April to November 1993. Physiochemical and isotope characteristics of the lake system (depth profiles of temperature, pH, alkalinity, concentrations of Ca 2+ , dissolved inorganic carbon (DIC), and δ 13 C of DIC) monitored on a monthly basis. Carbon isotope compositions of calcite samples collected in the sediment traps were determined. The carbon cycle of the lake was simulated using a numerical model which accounts for all basic processes controlling concentration and carbon isotope composition of DIC. The model allowed researchers to quantify the relative importance of sources and sinks of carbon influencing the δ 13 C DIC in the epilimnion and, consequently, of the authigenic calcite deposited in the sediments. Inorganic carbon dissolved in groundwaters feeding the lake appeared to be insufficient to maintain the concentration and δ 13 C of DIC in the epilimnion in the observed range. DIC originating from decomposition of organic matter is a crucial element of the carbon budget of the lake. For the entire studied period, it accounted for about two-thirds of the total DIC supplied to the epilimnion; its average δ 13 C was −25.5%c. Decomposition of organic matter within the lake appeared to be at least one-third higher than its production. Of the external sources of carbon, groundwater inflow contributes 50%, terrestial biomass, 30%, and atmospheric CO 2 , 20% of the total carbon input to the lake. Evasion of CO 2 and CH 4 drives the average δ 13 C DIC in the epilimnion to the values which are considerably higher than δ 13 C of the external sources of carbon.

Natural radioactivity in groundwater – a review

The issue of natural radioactivity in groundwater is reviewed, with emphasis on those radioisotopes which contribute in a significant way to the overall effective dose received by members of the public due to the intake of drinking water originating from groundwater systems. The term ‘natural radioactivity’ is used in this context to cover all radioactivity present in the environment, including man-made (anthropogenic) radioactivity. Comprehensive discussion of radiological aspects of the presence of natural radionuclides in groundwater, including an overview of current regulations dealing with radioactivity in drinking water, is provided. The presented data indicate that thorough assessments of the committed doses resulting from the presence of natural radioactivity in groundwater are needed, particularly when such water is envisaged for regular intake by infants. They should be based on a precise determination of radioactivity concentration levels of the whole suite of radionuclides, including characterisation of their temporal variability. Equally important is a realistic assessment of water intake values for specific age groups. Only such an evaluation may provide the basis for possible remedial actions.

Groundwater Pollution and Quality Monitoring Approaches at the European Level

The authors investigate the sources and processes of groundwater contamination and their assessment within the Drivers-Pressures-State-Impact-Response (DPSIR) framework. Naturally occurring substances, trace elements, radionuclides, nutrients, and salt (sodium chloride) are reviewed with emphasis on the assessment of the natural background load. Some synthetic substances are also considered, these being petroleum hydrocarbons, chlorinated aliphatics, pesticides and organic-waste contaminants. Newly emerging contaminants cannot be described within the DPSIR; therefore monitoring approaches and indicators of contamination are discussed in order to propose improved monitoring plans that combine physical, chemical and biological indicators and combine science with policy.

Toward operational methods for the assessment of intrinsic groundwater vulnerability: A review

ABSTRACT Assessing the vulnerability of groundwater to adverse effects of human impacts is one of the most important problems in applied hydrogeology. At the same time, many of the widespread vulnerability assessment methods do not provide physically meaningful and operational indicators of vulnerability. Therefore, this review summarizes (i) different methods used for intrinsic vulnerability assessment and (ii) methods for different groundwater systems. It particularly focuses on (iii) timescale methods of water flow as an appropriate tool and (iv) provides a discussion on the challenges in applying these methods. The use of such physically meaningful indices based on timescales is indispensable for groundwater resources management.

Monte Carlo validation of the self-attenuation correction determination with the Cutshall transmission method in 210Pb measurements by gamma-spectrometry

The accuracy of estimation of the self-attenuation correction Cs with the Cutshall transmission method in (210)Pb measurements by gamma-spectrometry was assessed using the Monte Carlo method. The Cutshall method overestimates the correction for samples with linear attenuation coefficient at 46.5 keV higher than that of the standard and underestimates it in the opposite case. The highest bias was found for thick samples. C(s,Cuts)/C(s) ratio grows linearly with sample linear attenuation coefficient.

Does groundwater protection in Europe require new EU-wide environmental quality standards?

The European Groundwater Directive could be improved by limiting the scopes of the Annexes I and II to the manmade and natural substances, respectively, and by defining a common monitoring protocol. The changes in the European landuse patterns, in particular the urban sprawl phenomena, obscure the distinction between the point and diffuse sources of contamination. In the future more importance will be given to the household contamination. Moreover, the agricultural environment could be used for developing new conceptual models related to the pharmaceuticals.

A decision tree tool supporting the assessment of groundwater vulnerability

The Water Framework Directive and Groundwater Directive aim at preserving and improving the groundwater status. Groundwater bodies are classified as being or not being at risk of failing to meet these objectives. Those at risk are subject to more precise risk assessment where the concept of vulnerability is considered in the pathway part of the source–pathway–receptor scheme. However, no further details on implementation strategies are provided. In order to support groundwater managers and decision-makers in implementation of programs protecting groundwater, a systematic operational approach based on a decision tree is proposed, which leads the user through the stages of vulnerability assessment. First, a problem has to be formulated related to a threatening of the quantitative and/or qualitative status of a groundwater body. Next, the stated problem needs to be related to the intrinsic or specific vulnerability. Methods used for the intrinsic vulnerability assessment belong to two categories: subjective rating and objective methods. Method selection depends primarily on: data availability, knowledge and available resources. A key issue is the lag time associated with transport between a source/event of contamination and the water body. This lag time is primarily controlled by the temporal scale of water flow. It provides information about flow processes and at the same time also about timescales required for the implementation of strategies. Effects of any measures taken cannot be observed immediately but at the earliest after these estimated lag times emphasizing the need to also proactively safeguard groundwater resources and preserve their good status.