Uptake and bioavailability of persistent organic pollutants by plants grown in contaminated soil

This paper assesses the uptake of persistent organic pollutants (POP's) into plants. In particular, uptake of alpha-endosulfan, beta-endosulfan and endosulfan sulfate from lettuce. The lettuce plants were grown on compost that had previously been contaminated at 10 and 50 microg g(-1) per POP. The soil was slurry spiked by adding the appropriate amount of POP in acetone in an approximate ratio of 1 ratio 2, w/v soil ratio solvent. The solvent was left to evaporate at ambient temperature for 24 hours. Lettuce plants were grown under artificial daylight for 12 hours a day. The influence of soil ageing on the recovery of POP's from spiked soil samples was also assessed. The average recovery of endosulfan compounds from slurry spiked soil (10, 20 and 40 microg g(-1)) was consistent (92.9 +/- 4.4% for n= 9). However, ageing of endosulfan compounds on the slurry spiked soil resulted in lower recoveries (average losses were 12.5% after 14 days ageing of slurry spiked soil). The uptake of POP's was assessed by measuring the amount of endosulfan compounds in roots and leaves from lettuce plants after 10, 20 and 33 days. In addition, control plants grown in uncontaminated soil were monitored and analysed. It was found that endosulfan compounds were present in the roots of all lettuce plants irrespective of soil spike level or age of plant. In the 33 day lettuce plants where the soil was spiked at the highest level (50 microg g(-1)) endosulfan compounds were determined in the leaves. The root to leaf ratio was found to be 3.1 for alpha-endosulfan, 46.0 for beta-endosulfan, and 24.3 for endosulfan sulfate. Spiked lettuce samples were subjected to in vitro gastrointestinal extraction to assess the bioavailability of endosulfan compounds. No detectable endosulfan compounds were determined in the gastric extracts while small quantities (range 0.06-0.12 microg g(-1)) were found in the intestinal extraction. All samples (soil and lettuce) were extracted using pressurised fluid extraction and analysed using gas chromatography with mass selective detection.     

Assessment of phenanthrene bioavailability in aged and unaged soils by mild extraction

It has become apparent that the threat of an organic pollutant in soil is directly related to its bioavailable fraction and that the use of total contaminant concentrations as a measure of potential contaminant exposure to plants or soil organisms is inappropriate. In light of this, non-exhaustive extraction techniques are being investigated to assess their appropriateness in determining bioavailability. To find a suitable and rapid extraction method to predict phenanthrene bioavailability, multiple extraction techniques (i.e., mild hydroxypropyl-β-cyclodextrin (HPCD) and organic solvents extraction) were investigated in soil spiked to a range of phenanthrene levels (i.e., 1.12, 8.52, 73, 136, and 335 μg g^− 1 dry soil). The bioaccumulation of phenanthrene in earthworm (Eisenia fetida) was used as the reference system for bioavailability. Correlation results for phenanthrene suggested that mild HPCD extraction was a better method to predict bioavailability of phenanthrene in soil compared with organic solvents extraction. Aged (i.e., 150 days) and fresh (i.e., 0 day) soil samples were used to evaluate the extraction efficiency and the effect of soil contact time on the availability of phenanthrene. The percentage of phenanthrene accumulated by earthworms and percent recoveries by mild extractants changed significantly with aging time. Thus, aging significantly reduced the earthworm uptake and chemical extractability of phenanthrene. In general, among organic extractants, methanol showed recoveries comparable to those of mild HPCD for both aged and unaged soil matrices. Hence, this extractant can be suitable after HPCD to evaluate risk of contaminated soils.     

High throughput analysis of solid-bound endocrine disruptors by LDTD-APCI-MS/MS

The development of a high-throughput method for the analysis of 14 endocrine-disrupting substances in environmental solid matrices has been investigated. Selected compounds were: hormones (estrogens and progestogens), parabens and triclocarban. The ultrafast method (15 s per sample) is based on the laser diode thermal desorption-atmospheric pressure chemical ionization (LDTD-APCI) coupled to tandem mass spectrometry (MS/MS). This novel approach was tested and validated in three different solid matrices (municipal sludge cakes, aquatic sediments and agricultural soils) and its performance was evaluated by estimation of extraction recovery, linearity, precision, and detection limits. In contrast to other methods based on LC-MS/MS, a cleanup step is not necessary or minimal for the municipal sludge cake matrix. Extraction recoveries ranged from 80 to 109% for all compounds in all matrix types except for estriol which was 60-75%. The intra- and inter-day precisions, as indicated by % RSD, were ≤ 14% and ≤ 16%, respectively. The method detection limits ranged from 0.7 to 4.0 ng g?1 in sediments and soil matrices and 2.8 to 16.8 ng g?1 for municipal sludge cake samples. The results for real environmental samples collected in different areas of Quebec (Canada) are illustrated.     

Trends in background levels of persistent organic pollutants at Kosetice observatory, Czech Republic.2) Part II. Aquatic and terrestrial environments 1996-2005

A multimedia sampling of ambient air, wet deposition, surface water, sediment, soil and biota has been performed at Kosetice background observatory in the southern Czech Republic since 1988. An integrated monitoring approach was applied to assess the current state, anthropogenic impacts, and possible future changes of terrestrial and freshwater environments. Average PCB concentrations in the individual matrices calculated from ten years of sampling on multiple sites varied between 2 ng g(-1) in sediment and 7 ng g(-1) in soil or moss. DDT concentrations were lower in moss and needles (2 ng g(-1) and 4 ng g(-1), respectively) than in sediment (11 ng g(-1)) and soil (20 ng g(-1)), while the HCH level was higher in moss and needles (5 ng g(-1) and 6 ng g(-1), respectively) than in soil or sediment (1 ng g(-1) and 2 ng g(-1), respectively). The highest average level of PAHs was found in soil (600 ng g(-1)), while it was lower in needles (230 ng g(-1)), moss (210 ng g(-1)) or sediment (210 ng g(-1)). Time related trends of concentration levels of persistent organic pollutants in all matrices were investigated. Moss and needle trend patterns resembled those of the ambient air, showing a slight concentration decrease of all compounds, except for hexachlorobenzene. The soil, water and sediment concentrations showed a similar decrease of PAHs, PCBs, and HCHs, but there was no clear trend for DDTs and HCB.     

Concentration and Distribution of Persistent Organic Pollutants (POPs) in Harbour Dredging Sediments: A Pilot Study Using a Statistical Approach for a More Efficient Characterisation and Management

The Italian guidelines concerning the dumping of dredgingmaterials implies chemical, physical and microbiologicalcharacterisation of dumping sediments collected through aspecific sampling strategy.POP's such as PCB's and organochlorine pesticides, areconsidered as priority pollutants in all the InternationalConventions for the protection of the marine environment, inconsequence of their persistence, toxicity and bioaccumulation capacity.In the present article the concentrations and distribution ofPCB's and organochlorine pesticides in dredging sediments ofPiombino harbour (northern Thyrrenian sea) were investigates.The results showed high POP's concentrations in all the studiedareas. The maximum values were: 3.94 mg kg^-1 dry weight for PCB's(IUPAC Nos. 28; 52; 101, 118; 137; 153; 180; 209); 2.04 mg kg^-1 d.w.for HCH's (-, -, - and -hexachlorocyclohexane isomers); 0.28 mg kg^-1 d.w. for DD's (DDT + DDE + DDD).Subsequently, the data related to each pollutant were treatedwith statistical tests, in order to verify how well the samplingstrategy is able to represent the distribution of contaminantsin the dredging area. Finally, management strategies werederived for the studied dredging sediments.     

New procedures for simultaneous determination of mesotrione and atrazine in water and soil. Comparison of the degradation processes of mesotrione and atrazine

A method for the determination of residues of mesotrione, atrazine and its degradation products: deethylatrazine, hydroxyatrazine, deisopropylatrazine, desethyldesisopropylatrazine in a variety of water and soil matrices has been developed. Mesotrione is a new selective herbicide for use in corn, which has been substituted for atrazine, which has been banned in European Union countries since 2007. Although atrazine has not been used for three vegetative periods, it is still detected in the environment. The analysis was conducted by means of ultra-high-pressure liquid chromatography with ultraviolet detection and liquid chromatography with diode array detection. The procedures for analyte separation from water and soil matrices were also established. The optimal conditions for solid-phase extraction (SPE) were determined. The recoveries were compared with that obtained by means of SPE. Method fortification recoveries from water samples averaged 78–97% and for soil 80–97% depending on the analyte and type of sample. The limits of detection were 0.04–0.61 μg/L for water samples and for soil samples 0.02–0.88 μg/g. The soil samples were collected in spring 2009 from three different fields with water samples being made from effluents from these fields. Samples collection was conducted in the day of mesotrione (Callisto 100SC) application and then done weekly, until the mesotrione concentration was below the limit of quantification. The results enabled the monitoring of mesotrione degradation in soil and its permeability into surface waters; simultaneously, the same studies were conducted for atrazine.     

Influence of solvent and soil type on the pressurised fluid extraction of PAHs

Pressurised fluid extraction (PFE) of polycyclic aromatic hydrocarbons (PAHs) from a certified reference material (CRM) 524 has been firstly optimised following a central composite design. The instrumental parameters of the PFE (pressure, temperature, extraction time and number of solvent cycles) were studied in order to obtain maximum extraction yields. Neither pressure nor extraction time or temperature seemed to have any significant effect on the extraction yield, therefore one extraction cycle was enough to exhaustively extract all the PAHs from CRM 524. Once the instrumental conditions were established, the extraction yields obtained with eight different solvents or solvent mixtures [acetone, dichloromethane, acetonitrile, acetone-dichloromethane (1 + 1 v/v), acetone-isohexane (1 + 1 v/v), isohexane, methanol and toluene] from the CRM 524 were compared and showed that the best recoveries were obtained with acetone-isohexane (1 + 1 v/v). Finally, the effect of sand, silt, clay and the organic matter content of soil was investigated with respect to recovery of PAHs by PFE with different solvents or solvent mixtures for aged soil samples. In this case, eight soils with different sand, silt, clay and organic matter contents were slurry spiked with PAHs and aged for 19 days. Three aliquots of each slurry spiked soil were extracted with the previously mentioned solvents and the results were studied by means of principal component analysis (PCA) of the whole data set (soil composition, solubility parameter of the solvent and recoveries of all PAHs) and partial least squares (PLS). Clay and organic matter content and the squared solubility parameter have the highest correlation with the recovery of PAHs from soil samples.     

An assessment of the bioavailability of persistent organic pollutants from contaminated soil

A procedure to assess the bioavailability of persistent organic pollutants (POPs) from soil samples has been developed. The procedure is based on the use of simulated in vitro gastrointestinal extraction to remove POPs from soil matrices. The level of recovery, using this approach, is assessed following liquid-liquid extraction (LLE) and analysis by gas chromatography-mass selective detection (GC-MSD). The remaining soil residue is then extracted using pressurised fluid extraction (PFE) followed by GC-MSD analysis to assess the residual fraction. The residual fraction is monitored to determine the unavailable fraction i.e. not available for absorption in the gastrointestinal tract of humans. The procedure was applied to four soil samples i.e. an aged, spiked soil and three certified reference materials (CRMs) contaminated with POPs. Recoveries of pesticides (lindane, endosulfan I, endrin, DDE, DDD and endosulfan II), phenols (cresol, TCP and PCP), and base neutral compounds (hexachloroethane, acenaphthene, dibenzofuran, fluorene and hexachlorobenzene) from aged, spiked soil following extraction with gastric fluid ranged from 0.8 to 8.3% while following intestinal extraction ranged from 5.5 to 13.5%, irrespective of POP. Recoveries of pesticides (lindane, endosulfan I, endrin, DDE, DDD and endosulfan II) from CRM 805-050 following extraction with gastric fluid were below the limit of detection while following intestinal extraction ranged from 5.3 to 12.8%. Recoveries of phenols (cresol, TCP and PCP) from CRM 401-225 following extraction with gastric fluid ranged from 1.6 to 2.0% while following intestinal extraction ranged from 4.1 to 5.4%. Recoveries of base neutral acid analytes (hexachloroethane, acenaphthene, dibenzofuran, fluorene and hexachlorobenzene) from CRM 107-100 following extraction with gastric fluid ranged from 1.4 to 4.0% while following intestinal extraction ranged from 6.6 to 12.7%. It has been found that the majority of POPs present i.e. >75%, would be excreted if consumed and not be absorbed in the gastrointestinal tract of humans.     

Colloidal mercury (Hg) distribution in soil samples by sedimentation field-flow fractionation coupled to mercury cold vapour generation atomic absorption spectroscopy

Diverse analytical techniques are available to determine the particle size distribution of potentially toxic elements in matrices of environmental interest such as soil, sediments, freshwater and groundwater. However, a single technique is often not exhaustive enough to determine both particle size distribution and element concentration. In the present work, the investigation of mercury in soil samples collected from a polluted industrial site was performed by using a new analytical approach which makes use of sedimentation field-flow fractionation (SdFFF) coupled to cold vapour generation electrothermal atomic absorption spectroscopy (CV-ETAAS). The Hg concentration in the SdFFF fractions revealed a broad distribution from about 0.1 to 1 μm, roughly following the particle size distributions, presenting a maximum at about 400-700 nm in diameter. A correlation between the concentration of Hg in the colloidal fraction and organic matter (O.M.) content in the soil samples was also found. However, this correlation is less likely to be related to Hg sorption to soil O.M. but rather to the presence of colloidal mercuric sulfide particles whose size is probably controlled by the occurrence of dissolved O.M. The presence of O.M. could have prevented the aggregation of smaller particles, leading to an accumulation of mercuric sulfides in the colloidal fraction. In this respect, particle size distribution of soil samples can help to understand the role played by colloidal particles in mobilising mercury (also as insoluble compounds) and provide a significant contribution in determining the environmental impact of this toxic element.     

Addressing the challenges of tetracycline analysis in soil: extraction, clean-up, and matrix effects in LC-MS

An optimized extraction and clean-up method for the analysis of chlortetracycline, doxycycline, oxytetracycline, and tetracycline antibiotics in soil is presented in this work. Soil extraction using different solvents was performed, but the use of a 50 : 50 (v/v) methanol : acetate buffer (pH 8) solvent mixture in a pressurized liquid extraction (PLE) system proved to give the best extraction efficiency and reproducibility. The effect of soil composition on the PLE extraction efficiency was also examined, and results indicated that recovery data for one soil is not necessarily consistent with other soil types containing different compositions of clay and organic matter content. The percent recoveries of the optimized PLE method varied between the soils and ranged from 22-99%, depending on soil type, and more specifically clay content. In addition, the extent of ionization suppression caused by co-extracted humic acids was examined in an ion trap mass spectrometer (MS), and a single quadrupole MS. It was found that under positive electrospray ionization, the single quadrupole MS was less susceptible to ionization suppression than the ion trap MS. Therefore, various sample clean-up procedures were evaluated to selectively reduce the amount of co-extracted humic acids in the soil extracts. The most effective clean-up was obtained from the use of StrataX sorbent in combination with a strong anion exchange cartridge.     

Predicting Pesticide Volatility Through Coupled Above- and Belowground Multiphysics Modeling

Pesticides are applied to agricultural fields to control unwanted pests but can volatilize and be transported downwind by wind currents to create the potential for non-target organism exposure. Volatilization rates change through the growing season due to pesticide application timing, meteorological differences, and the differential flux rates from soil and vegetation matrices. Field studies quantifying pesticide volatility are expensive and cannot capture the semi-infinite parameter combinations of soil, crop, management, and meteorological conditions encountered under regional agronomic practices. A numerical approach was used to simulate pesticide dissipation above- and belowground to augment field and laboratory experimental observations. Above- and belowground physics are coupled into a single numerical tool using the COMSOL Multiphysics® software package with the current emphasis on pesticide volatility into air from soil and vegetation and resulting near field neighboring air concentrations. Comparison of simulation results against experimental observations for an insecticide (chlorpyrifos) applied to potato and alfalfa fields shows good agreement (R² 0.68–0.98). Chlorpyrifos volatility from plant surfaces drives the overall volatility within the first several days post application. The maximum volatility flux rate simulated and observed were 0.79 and 0.66 μg m^?2 s^?1 for the alfalfa trial and 2.72 and 2.17 μg m^?2 s^?1 for the potato field, respectively. This coupled multiphysics tool [computational fluid dynamics (CFD), mass transfer coefficients, and variably saturated flow in soil] can be used to estimate volatility flux rates of pesticides when little or no prior knowledge is available and for extrapolating field study observations to different and diverse scenarios.     

Mutagenicity assessment of contaminated soil in the vicinity of industrial area

In the industrial area of Chinhat, Lucknow (India) wastewater coming from pesticide manufacturing and other industries is used to irrigate the agricultural crops. This practice has been polluting the soil and pollutants might reach the food chain. Gas chromatographic analysis revealed the presence of certain organochlorine pesticides in soil samples. Samples were extracted using different solvents, i.e., hexane, acetonitrile, methanol, chloroform, and acetone (all were HPLC-grade, SRL, India). Soil extracts were assayed for mutagenicity using Ames Salmonella/mammalian microsome test. Mutagenicity was observed in the test samples and TA98 was the most responsive strain for all the soil extracts (irrigated with wastewater) in terms of mutagenic index in the presence (+S9) and absence (−S9) of metabolic activation. In terms of slope (m) of linear dose–response curve for the most responsive strain TA98 exhibited highest sensitivity against the soil extracts in the presence and absence of S9 fraction. Hexane-extracted soil sample (wastewater) exhibited maximum mutagenicity in terms of net revertants per gram of soil in the presence and absence of S9 mix as compared to the other soil extracts. Groundwater-irrigated soil extracts displayed low level of mutagenicity as compared to wastewater-irrigated soil. The soil is accumulating a large number of pollutants due to wastewater irrigation and this practice of accumulation has an adverse impact on soil health.     

石墨炉原子吸收法测定环境空气中的锡

研究了硝酸-双氧水体系消解、石墨炉原子吸收法测定环境空气中锡的方法.采用抗坏血酸和磷酸二氢铵作混合基体改进剂,热解涂层石墨管,塞曼扣背景.方法的检测限为3.56 μg/L,实际样品回收率为90.6％～102％.     

A novel sensor for monitoring leakage of petroleum and other liquid hydrocarbons into soil environments

This paper describes the use of a potentially implantable infrared reflectometer for the qualitative detection of petroleum and a number of other hydrocarbon solvents. A rugged, low-power, re-useable sensor was evaluated in the laboratory for its ability to detect petrol in soil. A hydrophobic fluoropolymer was used as the sensing surface due to its high selectivity for petroleum hydrocarbons. The photocurrent reflected by this surface from a near IR source was measured to test for petroleum saturation within the membrane, which in turn was an indicator of petroleum in the surrounding soil. The simplicity in the sensor design enabled a stable, low cost detection method for petroleum and other hydrocarbons, ideal for use in sub-surface applications.     

An evaluation of grid size uncertainty in empirical soil loss modeling with digital elevation models

This paper presents a study on the effect of topographic variability on grid-based empirical estimation of soil erosion and sediment transport with raster geographic information systems (GIS). An original digital elevation model (DEM) of 10 m resolution for a case watershed is resampled to six realizations of greater grid sizes for a comparative examination. The Universal Soil Loss Equation (USLE) and a distance-based sediment delivery equation are applied to the watershed to calculate soil loss from each cell and total sediment transport to streams, respectively. The results suggest that the selection of the DEM gird size has considerable influence on the soil loss estimation with the empirical models. The estimate of total soil loss from the watershed decreases significantly with the increasing DEM cell size as the spatial variability is reduced by the cell aggregation. The empirical modeling approach is a useful tool for qualitative assessment of soil erosion, provided that spatial variability can be adequately represented by applied DEMs. However, discretion is suggested for its applications to quantitative estimation of soil loss concerning the sensitivity to the grid size selection.     

Recommendations for Monitoring of Polybrominated Diphenyl Ethers in the Canadian Environment

Polybrominated diphenyl ethers (PBDEs) have been reported in air, surface waters, suspended sediments, soil, sediment, fish, marine mammals, and bird eggs throughout Canada, from the St. Lawrence Estuary to the Strait of Georgia and the northernmost reaches of the Canadian Arctic. Canadian scientists have detected the presence of PBDEs in breast milk in every Canadian province. In fact, recent data on temporal trends strongly suggests that the concentrations of PBDEs are on the rise in the Canadian environment. These findings are similar to those reported in other nordic countries, and have prompted several countries to implement environmental monitoring programs. Among the key challenges currently facing Canada and other countries concerns how best to measure these chemicals in different matrices. In this paper, several analytical methods cited in the scientific literature for determining PBDE concentrations in different abiotic and biological matrices are reviewed. The critical criteria required for accurate determination of PBDEs in complex environmental matrices are discussed, including instrument sensitivity, reliability, potential interference's and the need for specialized instrumentation for the determination of compounds up to 975 Daltons. While a single analytical method that meets these and other criteria has not yet been perfected by scientists, GC/HRMS-based methods amenable to isotope dilution techniques warrant further refinement, and likely represent the best tools for future environmental monitoring programs.     

Application of laser-based ion mobility (IM) spectrometry for the analysis of polycyclic aromatic compounds (PAC) and petroleum products in soils

The capability of laser-based IM spectrometry to detect PAC and petroleum products (oils) in model matrices, laboratory reference (LR) materials and in real-world contaminated soil samples was demonstrated. Quantitative IM investigations of PAC-doped PVC films yielded detection limits in the ppm range for single PAC. The potential of IM spectrometry for in situ analysis was demonstrated by the analysis of PAC-containing certified reference (CR) material, and of petroleum product-containing LR materials and real-world soil samples. The calibration of IM signals obtained from oil-doped LR materials was also possible, and detection of oils with concentrations below 100 mg kg(-1) was achieved. The in situ analysis of real-world contaminated soils with the IM and LIF techniques was in good accordance with ex situ reference investigations.     

Solid-phase extraction using hierarchical organosilicates for enhanced detection of nitroenergetic targets

A novel porous organosilicate material was evaluated for application as a solid phase extraction sorbent for preconcentration of nitroenergetic targets from aqueous solution prior to HPLC analysis. The performance of the sorbent in spiked deionized water, groundwater, and surface water was evaluated. Targets considered included 2,4,6-trinitrotoluene, 2,4-dinitrotoluene, RDX, HMX, and nitroglycerin. The sorbent was shown to provide improved performance over Sep-Pak RDX. The impact of complex matrices on target preconcentration by the sorbent was also found to be less dramatic than that observed for LiChrolut EN. The impact of changes in pH on target preconcentration was considered. Aqueous soil extracts generated from samples collected at sites of ordnance testing were also used to evaluate the materials. The results presented here demonstrate the potential of this novel sorbent for application as a solid phase extraction material for the preconcentration of nitroenergetic targets from aqueous solutions.     

Risk-Based Prioritization of Air Pollution Monitoring Using Fuzzy Synthetic Evaluation Technique

Air pollution monitoring programs aim to monitor pollutants and their probable adverse effects at various locations over concerned area. Either sensitivity of receptors/location or concentration of pollutants is used for prioritizing the monitoring locations. The exposure-based approach prioritizes the monitoring locations based on population density and/or location sensitivity. The hazard-based approach prioritizes the monitoring locations using intensity (concentrations) of air pollutants at various locations. Exposure and hazard-based approaches focus on frequency (probability of occurrence) and potential hazard (consequence of damage), respectively. Adverse effects should be measured only if receptors are exposed to these air pollutants. The existing methods of monitoring location prioritization do not consider both factors (hazard and exposure) at a time. Towards this, a risk-based approach has been proposed which combines both factors: exposure frequency (probability of occurrence/exposure) and potential hazard (consequence).This paper discusses the use of fuzzy synthetic evaluation technique in risk computation and prioritization of air pollution monitoring locations. To demonstrate the application, common air pollutants like CO, NO_x, PM₁₀ and SO_x are used as hazard parameters. Fuzzy evaluation matrices for hazard parameters are established for different locations in the area. Similarly, fuzzy evaluation matrices for exposure parameters: population density, location and population sensitivity are also developed. Subsequently, fuzzy risk is determined at these locations using fuzzy compositional rules. Finally, these locations are prioritized based on defuzzified risk (crisp value of risk, defined as risk score) and the five most important monitoring locations are identified (out of 35 potential locations). These locations differ from the existing monitoring locations.     

Problems in characterizing the ecological quality of soil in relation to human activities

The soil ecosystem is composed of various groups of organisms which have complex relations. The physical structure and chemical characteristics of the soil provide the boundary conditions. In view of various deteriorating human activities, it is important to find soil quality characteristics with respect to its most important function: the ecological function. An enumeration has been given of chemical, physical and biological soil parameters which are more or less important for soil quality. Several of these parameters are discussed. For use as indicators of deterioration, for a given site, the optimum values of the soil parameters have to be established, as well as acceptable deviations from the optimum, taking into account natural fluctuation. It is concluded that, due to lack of data, such an approach is not possible at this moment. However, it might be possible to identify those soil parameters which should be taken into consideration when evaluating human activities.Paper presented at a Symposium held on 14 and 15 October 1982, in Utrecht, The Netherlands.