River Clay Research Articles

Sustaining Family Business: Unveiling the Resilience of Majuli Potters in Assam, India

The Kumars of Salmora village in the south-eastern part of Majuli, Assam, India, are an example of a family managed business of handcrafting river clay pots. Salmora became the Kumhar village as a result of clay, which became the primary reason for the settlement of potters in the area. The hand-beaten pottery is a cottage industry of Majuli and has been passed down through generations. Currently, the policy restrictions and the dying art form have made people think about how to sustain the handicraft, their livelihoods woven around this art form, and continue their passion/skill in the given challenging situation. This makes it interesting to adopt the case research method to examine the struggle of small businesses to sustain their livelihoods, on the one hand, and the limited alternative sources of livelihood, on the other hand, thus making the survival and sustenance of the family business a challenge, where pottery was their family business for generations. The case discussion revolves around the problems, concerns and causes for the deterioration of the art forms and highlights the issues and challenges. It contributes to the resources in the emerging family business management literature and also the family businesses to strategise in similar contexts.

Synthesis of Modified River Clay Catalyst for Valuable BTE Production via Catalytic Pyrolysis of Hazardous Plastic Waste

AbstractIn the present study, silica‐alumina rich river clay calcined at different temperatures are used as low cost natural green catalyst for the production of valuable aromatics benzene, toluene and ethylbenzene (BTE) via multiphase/Mp‐type catalytic pyrolysis of waste expanded polystyrene (WEPS). The calcined river clay catalysts are designated as RHC‐600, RHC‐700, RHC‐800 and RHC‐900 after calcination at the temperature of 600 °C, 700 °C, 800 °C, and 900 °C, respectively. Whereas, the natural river harvested clay is designated as RHC. The RHC‐800 catalyst is found to be the best catalyst for the WEPS pyrolysis due to its highest surface area of 18.83 m2/g and high silica to alumina (Si/Al) ratio of 2.23 among all other river harvested clay catalysts. The styrene content get reduced from 84.74 wt.% to 65.30 wt.% and BTE content increased from 11.38 wt.% to 23.51 wt.% when the process is switched over from thermal to Mp‐type catalytic pyrolysis using RHC‐800 catalyst. The promising results of RHC‐800 indicate that it can be an alternative to commercial catalyst for pyrolysis applications.

Avulsion of the Yellow River into the South Yellow Sea during the early to middle Holocene: Evidence from Clay Provenance of the Yangtze Paleovalley

The location of the Yellow River estuary controls the pattern of mud dispersal and therefore influences the ecology of China's marginal seas. However, little is known regarding the Holocene history of Yellow River avulsion. The Yangtze estuary, south of the Yellow River estuary, may provide some clues, as a large amount of Holocene sediments has accumulated in a major paleovalley in this area, incised during the Last Glacial Maximum (LGM). In this paper, we identify clay contributions from the Yellow River in the three Holocene cores (TZ, DY, and HM) of the Yangtze estuary using provenance analogues of clay geochemistry associated with the modern rivers, and reveal the history of Yellow River avulsion into the South Yellow Sea. The results show that clay geochemistry in the Holocene cores is similar to that of the Yangtze River, except for the period of ∼9.5–7.0 cal. kyr B.P. when it is represented by lower element contents more closely similar to those of Yellow River clays. Provenance end-member analysis shows 40%–60% clays of the Yangtze paleovalley was derived from the Yellow River during this period. These findings indicate that, at least, one channel of the Yellow River avulsed southward into the South Yellow Sea during the early to middle Holocene (∼9.5–7.0 cal. kyr B.P.). Fine-grained sediments from the Yellow River paleoestuary could be transported southward to the Yangtze paleovalley by enhanced marine energy during the early to middle Holocene. This study, not only, provides new evidence for Yellow River avulsion in the Holocene, but also sheds light on the impact of the Yellow River sediments on the depositional system along the coast of China, especially in the Yangtze delta.

Determination of Silt and Clay soil particle distribution using new Silt-Clay Separation Quick method

Hydrometer method is the standard method that normally used to determine fine particle size distributions for soil classification purposes. This study aims to develop new method that enable quick determination of silt-clay particle distribution compared to the hydrometer method that requires procedure of pretreatment and additional 24 hours required for the complete procedure of the test. The various soil samples were collected from seven different locations including Sunway Carnival (Marine Clay), Suling Hills (Residual Clay), Jawi Quarry (Residual Clay), Kelantan River (River Clay), Batu Kawan (Marine Clay), Kaolin Clay and Sungai Petani (Residual Clay). Three soil samples from each site were prepared for the hydrometer method and additional three samples for the new method silt-clay separation. Sample preparation and testing is repeated for all samples from seven site locations. The results of silt clay particle distribution obtained from both experimental works were compared to analyze the compatibility of data. The data analysis shows that there are no significant differences (P > 0.05) between the two methods in all examined soil samples. This indicates strong evidence to support this research that the silt-clay separation new method is comparable to the standard hydrometer method. Regression analysis between the two methods produced a coefficient of determination (R-square) values of 0.9912 respectively. The straight-line equation generated for all data produced the gradient equal to 0.8465, which is close to 1 indicates stronger evidence to supports the accuracy of the new method. In conclusion, the preliminary results of new method silt-clay separation confirmed its reliability to analyze the particle soil distribution in silt-clay fraction with 99.12% data accuracy compared to the standard hydrometer method.

Chemistry-driven Enchytraeidae assemblages acting as soil and ecosystem engineers in edaphic communities

Smaller body-sized invertebrate groups are known to be highly sensitive to environmental pollution. Like soil nematodes, enchytraeids have very permeable cuticles and come into direct contact with heavy metals; therefore they can be adversely affected by soil pollution. However, in contrast to nematodes, fewer data on enchytraeids are at our disposal to assess their functional responses to heavy metals. Such an assessment would be of greatest value, as in any edaphic community, enchytraeids are the only functional group bridging the detrital energy flux across the bacterial-driven and the fungal-driven pathways. For this purpose we investigated and evaluated the effect of heavy metals on the occurrence and biomass of enchytraeids in different soils in The Netherlands. Samplings of topsoils were carried out in 297 sites with Pleistocene sandy soils, river clay and sea clay under different environmental stress and all recovered enchytraeid species have been included in three existing phylogenetical clades (hereafter: A, B, and C). Our results show that the biomass of the enchytraeid species belonging to the Clade C is highly correlated with Cr, Cu and Zn in sandy soils (all 2-tails significance values share p < 0.005, n = 186) but is correlated with Cu and Hg in loamy soils (p < 0.05, n = 111), whilst the biomass of the enchytraeid species belonging to the Clade B is highly correlated with either Cd + Cu + Pb in sandy soils (p < 0.025, n = 186) or Hg + Pb in loamy soils (p < 0.05, n = 111). The entire enchytraeid community actively contributes to promote the rapid turnover of soil organic matter. Given that clay-rich soils retain a much higher amount of heavy metals in contrast to sandy soils, most enchytraeids share different values as bioindicators according to the soil type, even comparing river clay with sea clay. Hence, elemental availabilities have disproportionately strong effects on enchytraeids and on the entire edaphic community according to the soil types.

Phosphorus Removal in Vertical Flow Reed Beds using Baked Clay Balls as an Alternative Media

Phosphorous (P) entering into the water bodies through point and non-point sources is a causal agent for eutrophication. Nature Based Solutions (NBS) like Constructed Wetlands (CW) are cost effective methods for treating the grey waters in order to protect the water bodies form risk of eutrophication. The P removal efficiency of Constructed Wetlands (CW) can be improved by adding new substrate having potential P removal efficiency.The study was conducted to determine the phosphorus removal from wastewater using Baked Clay Ball (BCB) media in Vertical Flow Reed Beds (VFRB). The BCB was prepared with a mixture of river clay and saw dust. The field and lab-scale experimentation were set and operated in batch feeding mode using institutional wastewater for four months. The VFRBs were filled with BCB and planted with locally available reed grass (Phragmites karka). The hydraulic retention period in VFRB was 48 hours. Prime goal of the experiment was to investigate the Phosphorus (P) removal efficiency of the VRFBs apart from other conventional wastewater quality parameters. The concentration of phosphorus of the institutional wastewater was in the range of 27.3 mg/l to 16.3 mg/l. The average phosphorus removal efficiency of the VFRB 1 and 2 filled with BCB was 93.47%, while the average P removal efficiency of gravel filled VFRB 2 and 3 was 68.20%. Thus the experiment reflected that the BCB is a better media than the gravel for P removal. Therefore, the BCB may be used at a field scale to remove P from wastewater in constructed wetlands.Further, there is scope to develop new substrate materials focusing on its P retention capacity, long lasting performance and cost of the substrate to be applied in real treatment situations.

Evaluation of phytoremediation capability of French marigold (Tagetes patula) and African marigold (Tagetes erecta) under heavy metals contaminated soils

The pot experiment was conducted to explore the phytoremediation potential of two different marigold species grown in heavy metals contaminated red, black, alluvial, recent river clay, sewage irrigated, sewage sludge, and garden soil. Different soil types were treated uniformly with lead (20 mg Pb kg−1 soil), cadmium (5 mg Cd kg−1 soil), chromium (30 mg Cr kg−1 soil) and nickel (10 mg Ni kg−1 soil). Completely randomized design (CRD) was used with three replications. African marigold (Tagetes erecta) recorded ∼89.4% more dry matter yield over French marigold (Tagetes patula) when grown under metals treated soils. Both the marigold species were highly effective for removing Cd and Ni from contaminated soils (TF >1) however, Ni (TF ∼14.9) was more efficiently accumulated by T. patula and Cd (TF ∼12.1) by T. erecta. Higher biomass yield in T. erecta resulted higher accumulation of heavy metals (except Cr) compared to T. patula. Assessment of contamination factor (CF) and geo-accumulation index (Igeo) of heavy metals indicates that post-harvest soils had moderate to high degree of contamination by different metals, Cr being the highest. It may be concluded that T. erecta was more efficient in extracting heavy metals from different heavy metals contaminated soils. Novelty statement Contamination of land with heavy metals poses severe environmental threats. Physical and chemical remediation techniques are generally used for remediating metals contaminated sites. These methods are cost-intensive and therefore, commercially non-viable, besides being disruptive in nature and causing deterioration of soil. Alternatively, bio-remediation techniques are cost-effective and environment friendly. Among the various phytoremediation techniques, hyperaccumulator plants are most commonly used for the remediation of the contaminated sites. It has been found that different species of the same plant (marigold) differ in their ability to accumulate metals under various contaminated soils having different properties. Thus, this experiment provided an unique opportunity to investigate the effect of various soil properties on metal accumulation efficacy of marigold under metal-spiked soils. Marigold plants can grow rapidly by developing a robust root system which helps them to survive under contaminated soil environment. Thus, marigold being ornamental plant could be used to decontaminate polluted sites while providing ornamental value and may serve as a source of commercially valuable products extracting metals from biomass by way of incineration. However, meager information is available about the usage of various marigold species for phytoremediation of heavy metals under different metal-polluted soils. In the current experiment, we intend to evaluate the potential use of two different marigold species (Tagetes patula and Tagetes erecta) in remediating heavy metals under nine soils of different nature spiked with metals and assessing heavy metals pollution load indexes in these polluted soils.

Triple oxygen isotope investigation of fine-grained sediments from major world's rivers: Insights into weathering processes and global fluxes into the hydrosphere

Continental weathering is accompanied by formation of clays and other secondary minerals and their δ18O and Δ17O values should hence reflect to some extent signatures of meteoric water (δ18OMW) and mean annual temperatures (MAT). Our ability to extract climate information from weathered products across the geologic history relies on analytical methods tested and calibrated against modern climate conditions. We here present triple-oxygen isotope analyses of clay-size sediments from 45 rivers worldwide, as well as δ18O analyses of corresponding silt- and sand-rich detrital fractions, which altogether cover about 25% of the continental area that drained into the oceans, extending from the tropics to polar regions. The majority of studied clays closely approximate weathering products, always having high-δ18O signatures regardless of the bedrock type, and in equilibrium with local meteoric waters. Silts are only ∼1.9‰ lighter on average due to greater detrital dilution. Overall, bulk clays from across different climatic regions do not vary much isotopically; an observation which we attribute to opposing effects of temperature on clay-water fractionation and hydrologic relationship between temperature and δ18OMW. Mathematical inversion of measured clay δ18O and Δ17O values (corrected for detrital contribution) into MAT and δ18OMW, compiled for each studied watershed, returns satisfactory estimates. Globally, triple O isotopes in clays appear to be water-dominated, being controlled almost exclusively by δ18OMW at respective temperature of weathering, with minor effects related to evaporation. Using sand from rivers, correlation of δ18O silts with detrital proportions, and estimated surface outcrop of different rock types, we additionally arrive at a +11.5‰ estimate for the exposed silicate crust undergoing weathering.Globally-averaged, sediment-flux weighted clay δ18O and Δ17O values are +14.80‰ and −0.164‰, respectively. These values are significantly skewed toward O isotope signatures for the southeast Asia and western Pacific regions, characterized by very high sediment fluxes to the ocean. Using both clay- and silt-size fractions, the total weighted silicate weathering δ18O signature exported to the world's ocean is −2.59‰, almost 50% higher the previous estimate, yielding an ice-free world hydrosphere estimate of −0.78‰.Overall, the modern river clays represent a snapshot of modern weathering conditions on continents, and associated first-order climatic signatures related to MAT and δ18O of the hydrosphere. This implies that measured increase in δ18O and stepwise decrease in Δ17O in shales in the geologic record capture: evolving global hydrologic cycle upon continental emergence, decrease in global MAT or diagenetic conditions, and decreasing ocean mass via rehydrating of the mantle by subduction of hydrated low-δ18O, high-Δ17O slabs.

Natural radioactivity measurement of bricks used in the building materials of Egypt

Percentage and radionuclides content in the brick material used in construction depends on the origin and the geological condition got from it. They makes manufacture and preparation of bricks used as building materials in Egypt of clay and rocks extracted from deposited sediments of Nile River. Aim of the study was to determine the radiation activity resulting from a different bricks kind, which manufactured from raw materials from the Nile River clay, used in the construction process in Egypt. In the present work, we have selected 20 samples of three types of bricks, clay brick (CB), making facade brick (MFB) and firebrick (FB), it has selected from different regions and plant in Egypt. It measured the activity concentration of 226Ra, 232Th and 40K in many brick under investigation using gamma ray spectroscopy system. Results showed that, the radium equivalent concentration (Raeq) calculated and compared well with the world reported values. As shown in the results, the mean values of radioactivity concentrations of 226Ra, 232Th and 40K for CB bricks, which represent the highest in many bricks in the present study with values (39, 38 and 199 Bq/kg), respectively.

Spatial distribution of soil nematodes relates to soil organic matter and life strategy

Soils are among the most biodiverse and densely inhabited environments on our planet. However, there is little understanding of spatial distribution patterns of belowground biota, and this hampers progress in understanding species interactions in belowground communities. We investigated the spatial distribution of nematodes, which are highly abundant and diverse metazoans in most soil ecosystems. To gain insight into nematode patchiness, we mapped distribution patterns in twelve apparently homogeneous agricultural fields (100 m × 100 m each) with equal representation of three soil textures (marine clay, river clay and sandy soil). Quantitative PCRs were used to measure the abundances of 48 distinct nematode taxa in ≈1200 plots. Multivariate analysis showed that within this selection of sites, soil texture more strongly affected soil nematode communities than land management. Geostatistical analysis of nematode distributions revealed both taxon-specific and field-specific patchiness. The average geostatistical range (indicating patch diameter) of 48 nematode taxa in these fields was 36 m, and related to soil organic matter. Soil organic matter content affected the spatial variance (indicating within-field variation of densities) in a life-strategy dependent manner. The r-strategists (fast-growing bacterivores and fungivores) showed a positive correlation between organic matter content and spatial variance, whereas most K-strategists (slow-growing omnivores and carnivores) showed a negative correlation. Hence, the combination of two parameters, soil organic matter content and a general life-strategy characterisation, can be used to explain the spatial distribution of nematodes at field scale.

Mechanical Behaviour of Layered Silicate Composites from Nagavali River Clay

Abstract In the present study, clay is segregated, from both banks of Nagavali River flowing through the Srikakulam India at coordinates of 18.3°N 83.9°E. Effect of incorporation of clay into the epoxy polymer was investigated experimentally. Composites were manufactured by the conventional hand-layup process with the accumulation of the different weight ratio (10%, 20%, 30%, 40%, 50%, 60% and 80%) of clay to the Epoxy polymer. Clay obtained from both bank composites were compared. Various test was performed to analyse the mechanical behaviour of the composites. Manufacturing and testing of composites are done according to the ASTM standards.

The silicon isotopic composition of fine-grained river sediments and its relation to climate and lithology

The δ30Si stable isotopic composition of silicon in soils and fine-grained sediments can provide insights into weathering processes on continents, with important implications on the Si budget of modern and past oceans. To further constrain the factors controlling the distribution of Si isotopes in sediments, we have analysed a large number (n = 50) of separate size-fractions of sediments and suspended particulate materials collected near the mouth of rivers worldwide. This includes some of the world’s largest rivers (e.g. Amazon, Congo, Mackenzie, Mississippi, Murray-Darling, Nile, Yangtze) and rivers from the case study areas of the Congo River Basin and Northern Ireland. Silt-size fractions exhibit a mean Si isotopic composition (δ30Si = −0.21 ± 0.19‰; 2 s.d.) similar to that previously inferred for the upper continental crust. In contrast, clay-size fractions display a much larger range of δ30Si values from −0.11‰ to −2.16‰, which yield a global δ30Siclay of −0.57 ± 0.60‰ (2 s.d.) representative of the mean composition of the average weathered continental crust. Overall, these new data show that the Si isotopic signature transported by river clays is controlled by the degree of chemical weathering, as inferred from strong relationships with Al/Si ratios. At a global scale, the clay-bound Si isotopic composition of the world’s largest river systems demonstrates a link with climate, defining a general correlation with mean annual temperature (MAT) in corresponding drainage basins. While the distribution of Si isotopes in river sediments also appears to be influenced by the tectonic setting, lithological effects and sediment recycling from former sedimentary cycles, our results pave the way for their use as paleo-weathering and paleo-climate proxies in the sedimentary record.

Small-scale evaporation tests on clay: influence of drying rate on clayey soil layer

Cracks in drying soils have detrimental effects on the integrity of geotechnical structures. The evaporation rate is recognized to play an important role in fracture generation, having a direct impact on the amount of cracks produced. This investigation examined the drying behaviour of a clay with different initial water contents and under different evaporative conditions. Small-scale evaporation experiments were carried out using a river clay and commercially available suction-measuring equipment. The results showed that the initial conditions have great influence on the drying performance of a soil, which can be partly attributed to the influence of the surface texture and the pore structure. It was observed that under certain circumstances, the evaporation of a soil surface can be higher than that of open water. The different evaporation rates had a marked effect on the water distributions with depth within the soil. The evaporation rate also produced a dynamic response of the soil-water retention curve.

European badger habitat requirements in the Netherlands – combining ecological niche models with neighbourhood analysis

European badger populations in the Netherlands suffered strong declines in the 1900s, becoming endangered in the 1980s. Despite mitigation actions, recovery of the population has been slow. Here, we use ecological niche modelling, relating 1515 badger sett (burrow) localities to data on topographic, groundwater table, soil type and land‐cover variables, to investigate the factors defining badger habitat suitability. Niche modelling of mobile animals such as badgers is challenging, as relevant features that determine habitat suitability surrounding animal sightings or burrow locations are often unaccounted for. In this study, habitat properties of the entire home range of individuals were incorporated via neighbourhood analysis on land‐cover variables. The neighbourhood analysis was applied at different spatial scales, to assess maximum model fit at the scale most representative of badger home‐range area in the Netherlands, which was approximately 3.6 km2. Our results showed that marine and river clay render highly unsuitable habitat for badgers. Grassland and maize crops presence, typically reported as driving factors, had little effect on badger distribution in the Netherlands. Instead, moderate vegetation cover, remoteness from urban infrastructures and low groundwater tables resulted in optimal conditions. We conclude that food availability is not a limiting factor for badgers in the Netherlands, but rather appropriate soil conditions for sett digging and non‐urban landscapes with sufficient cover for hideout determine their distribution. Our predictions indicate suitable areas that are not currently colonized. The results presented have important implications for management and conservation strategies in the Netherlands. Furthermore, we provide a useful general approach for niche modelling of mobile animals.

Effect of lignin-rich crop residues on the viability of Verticillium in organic greenhouse soils

Healthy soils are of vital importance for organic greenhouse cultivation. Due to the intensity of the cropping system, soil-borne diseases are of great concern. To achieve a more resilient system, growers use multiple strategies, including resistant rootstocks, organic soil amendments, biological soil disinfestation and plant stimulants. Soil-borne pathogens that form (micro) sclerotia are particularly difficult to manage due to their persistence in soil. Previous studies have shown that incorporation of lignin-rich crop residues can decrease the viability of microsclerotia of Verticillium longisporum in cauliflower fields. The purpose of this study was to evaluate the effect of lignin-rich amendments on the microsclerotia of V. dahliae in soils from organic greenhouses with a history of Verticillium wilt in solanaceous crops. In the laboratory, two greenhouse soils (river and sea clay) were mixed with 10% (w/w) broccoli (stem), bristle oat (whole plant), reed (stalks or leaves), Ethiopian mustard (whole plant) and corn (stalks or leaves). In the river clay soil, corn stalks, broccoli stem, reed and bristle oat significantly decreased the amount of viable microsclerotia. In the sea clay soil, only reed leaves and stalks had a significant effect. Only in the sea clay soil, a significant negative correlation was found between the amount of lignin added and the amount of viable microsclerotia detected. These results indicate that in the river clay soil, mechanisms other than lignin may be involved in Verticillium control. Surprisingly, real-time PCR analysis showed that the amount of Verticillium tricorpus was much higher than that of V. dahliae in both soils. Sequencing of a Verticillium strain isolated from the sea clay soil showed that it should be re-classified as Verticillium isaacii (formerly V. tricorpus). It is necessary to investigate the role of these different Verticillium species, before new control measures against Verticillium are further developed.

Feeding preference as a main determinant of microscale patchiness among terrestrial nematodes.

Soil biota are responsible for essential ecosystem services such as carbon storage, nutrient cycling and water retention. However, assessment of the condition of soil biota is hampered by an overwhelming level of diversity. With representatives in all trophic levels of the food web, nematode communities can be used as bioindicators. Accurate assessment of nematode assemblages requires insight into the distribution of specimens with distinct food preferences. With the availability of taxon-specific quantitative PCR assays, distribution patterns of multiple nematode groups can be investigated simultaneously. Here, microscale patchiness of 45 nematode taxa was studied on 12 sampling sites (each with four adjacent microplots) located on arable fields or semi-natural grasslands ('system'), and on marine, river clay or sandy soils ('soil type'). From each microplot, five composite samples were collected. Contrary to our expectations, an increase in the number of cores per composite sample did not result in more accurate measurements, and apparently the levels of microscale patchiness of the taxa are low compared to what has been reported for oligophagous plant-parasites. System and soil type did not affect microscale distribution. To investigate the level of patchiness in more detail, detection probability (DP) and variability of abundances were calculated. Common and widespread bacterivorous and fungivorous taxa had DP≥90%, confirming low level of microscale patchiness. With DPs of 40%-70%, predators and most omnivores showed degrees of local clustering. An overview of mean variabilities of abundances is presented that offers insight into how feeding preferences impact the microscale distribution both between and within trophic groups.

Characterizations of Pergau River Clay as Comparison to Mambong and Sayong

Clay as pottery’s raw material is a major factor that is affecting the quality and reliability of any pottery product. The clay source areas need to be well determined their geochemical properties in order to control the end properties of clay product. Pergau river is located in the northwest of Kelantan, a state in Malaysia. In this study, elemental and phase analysis of Pergau river clay was carried out. The baked clay products were characterized their density and toughness. X-ray fluorescence showed the clay is rich with Fe and X-ray diffraction showed low concentration of feldspar compared to other known clay source areas, which are Sayong and Mambong. Fewer feldspar content decrease toughness of the pottery product. However, some location showed the comparable result with the Sayong and Mambong. The clay is high in density, low in shrinkage percentage and excellent in mechanical strength compare to other clays collected from Pergau River.

Stability Analysis of River Dyke in Estuarine Environment

River dyke stability in estuarine environment is greatly influenced by the river stage fluctuations due to spring and neap tide variation in the zone of influence. The proposed river dyke will be located along the Nayachara island at the Rangafalla and Haldia end for protection of the proposed navigational channel across Nayachara, West Bengal, India. The navigational channel will connect the shipping route from Rangafalla to Haldia dock which the Kolkata Port Trust (KoPT) proposes as a long term solution for the shipping route to Haldia bypassing the existing troublesome route via Auckland and Jellingham, in order to reduce annual maintenance dredging burden to KoPT. The river dyke will be constructed artificially using sand as main core material. The soil profile of the site consists of mixture of river borne sand, silt and clay. The present site is located in a complex estuarine environment and the island has been formed due to siltation of very recent origin in geologic scale (about 70 years old). In this paper, stability analysis of proposed dyke for protection of the channel across Nayachara Island has been carried out using conventional limit equilibrium method and finite element method, considering the fluctuation of water level due to tidal effect. The factor of safety has been found out considering both drained and undrained conditions, simulating long term and short term stability of the dyke, respectively.

Inferring &amp;lt;sup&amp;gt;222&amp;lt;/sup&amp;gt;Rn soil fluxes from ambient &amp;lt;sup&amp;gt;222&amp;lt;/sup&amp;gt;Rn activity and eddy covariance measurements of CO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;

Abstract. We present a new methodology, which we call Single Pair of Observations Technique with Eddy Covariance (SPOT-EC), to estimate regional-scale surface fluxes of 222Rn from tower-based observations of 222Rn activity concentration, CO2 mole fractions and direct CO2 flux measurements from eddy covariance. For specific events, the regional (222Rn) surface flux is calculated from short-term changes in ambient (222Rn) activity concentration scaled by the ratio of the mean CO2 surface flux for the specific event to the change in its observed mole fraction. The resulting 222Rn surface emissions are integrated in time (between the moment of observation and the last prior background levels) and space (i.e. over the footprint of the observations). The measurement uncertainty obtained is about ±15 % for diurnal events and about ±10 % for longer-term (e.g. seasonal or annual) means. The method does not provide continuous observations, but reliable daily averages can be obtained. We applied our method to in situ observations from two sites in the Netherlands: Cabauw station (CBW) and Lutjewad station (LUT). For LUT, which is an intensive agricultural site, we estimated a mean 222Rn surface flux of (0.29 ± 0.02) atoms cm−2 s−1 with values &gt; 0.5 atoms cm−2 s−1 to the south and south-east. For CBW we estimated a mean 222Rn surface flux of (0.63 ± 0.04) atoms cm−2 s−1. The highest values were observed to the south-west, where the soil type is mainly river clay. For both stations good agreement was found between our results and those from measurements with soil chambers and two recently published 222Rn soil flux maps for Europe. At both sites, large spatial and temporal variability of 222Rn surface fluxes were observed which would be impractical to measure with a soil chamber. SPOT-EC, therefore, offers an important new tool for estimating regional-scale 222Rn surface fluxes. Practical applications furthermore include calibration of process-based 222Rn soil flux models, validation of atmospheric transport models and performing regional-scale inversions, e.g. of greenhouse gases via the SPOT 222Rn-tracer method.

Magnetic studies at Starunia paleontological and hydrocarbon bearing site (Carpathians, Ukraine)

The Starunia oil-ozokerite deposit occurs in the Boryslav-Pokuttya Unit of the Carpathian Foredeep, which is the main oil- and gas-bearing part of the Ukrainian Carpathians. Starunia is of great interest in studying the relationship between the magnetic properties of rocks, soils and hydrocarbons due to extensive surface microseeps yielding oil and gas, mineral water, and clay pulp containing hydrocarbons. We identified a local negative magnetic anomaly (30–35 nT) with a width of about 700 m within the MAG1 profile. The magnetic high is associated with the area of the largest mud volcanoes in the Starunia structure. Magnetic susceptibility of the soil was measured on a site with three distinct landscape features: a patch of forest with phaeozem and mass-specific susceptibility (χ) of 20–45 × 10−8 m3/kg for the surface topsoil; an area near the volcano and Nadia-1 well with visible hydrocarbon microseepage at the surface and the topsoil showing no visible evidence of hydrocarbon presence with χ = 20–50 × 10−8 m3/kg; and a patch of lowland with gleysols and χ = 10–20 × 10−8 m3/kg. Hydrocarbon-containing clays and soils from the alluvial sediments of the Velyky Lukavets River and bedrock clays near the Nadia-1 well demonstrated high χ values (up to 250–440 × 10−8 m3/kg).