14C and 210Pb in NE atlantic sediments: Evidence of biological reworking in the context of radioactive waste disposal

Scavenging by the seabed and by sedimentary particles in the deep ocean may have a significant effect on the removal of artificial radionuclides released to the water column as a result of radioactive waste disposal operations. Biological activity in the upper layers of the sediment column will enhance the rate of removal for those particle-reactive radionuclides with a short half-life relative to the turnover time of the upper mixed layer. For longer-lived radionuclides the rate of sediment accumulation will determine the ultimate rate of removal.The rate of sediment accumulation and extent of biological mixing of deep-sea sediment from three areas of the NE Atlantic Ocean have been investigated using ¹⁴C and ²¹⁰Pb data. Treatment of the radiocarbon with a simple box model provided estimates of sedimentation rate (ω), mixed layer depth (L), mixed layer age (T_ML) and the age of material arriving at the surface (T₀), which were broadly similar to previously published values from other ocean basins. Box cores from the Iberia Abyssal Plain, Madeira Abyssal Plain and from the NEA low-level radioactive waste dumpsite yielded sedimentation rates in the range 0.8 to 2.2 cm ky^?1 over the upper 16–25 cm. Continuous particle mixing appears to be taking place to a depth of 4 to 6 cm below the present sediment-water interface. Closely spaced vertical sampling of core 161-2 for ²¹⁰Pb allowed a biodiffusion coefficient (D_B) to be calculated (4 × 10^?9cm²s^?1), treating bioturbations as a diffusive term and sedimentations as an advective term in a simple mathematical model. In general, values of D_B in deep ocean sediments fall within the range 1–10 × 10^?9cm²s^?1, two orders of magnitude lower than nearshore values. From a review of published data it is concluded that biological mixing takes place extensively in the deep ocean; it appears to be fairly constant on a basin-wide scale and amenable to incorporation in mathematical models of radionuclide behaviour in the water column.     

Greenhouse gas emissions from a semi-arid tropical reservoir in northeastern Brazil

We estimated carbon dioxide (CO₂) and methane (CH₄) emissions by diffusion, ebullition, and degassing in turbines from a semi-arid hydropower reservoir in northeastern Brazil. Sampling sites were allocated within the littoral and deeper waters of one embayment, the main-stream, and at turbines. Annual carbon emissions were estimated at 2.3?×?10⁵?±?7.45?×?10⁴ t C year^?1, or in CO₂-equivalents (CO₂-eq) at 1.33?×?10⁶?±?4.5?×?10⁵ t CO₂-eq year^?1. Diffusion across the water surface was the main pathway accounting for 96% of total carbon emissions. Ebullition was limited to littoral areas. A slight accumulation of CO₂, but not of CH₄, in bottom waters close to the turbines inlet led to degassing emissions about 8?×?10³ t C year^?1. Emissions in littoral areas were higher than in main-stream and contribute to 40% of the total carbon. Carbon (C) emissions per electricity generated, at 60% of installed capacity, is 0.05 t C-CO₂-eq MWh^?1. The ratio increases to 0.09 t C-CO₂ MWh^?1, equating 80% of the emissions from natural gas and 40% of diesel or coal power plants. Retention time and benthic metabolism were identified as main drivers for carbon emissions in littoral areas, while water column mixing and rapid water flow are important factors preventing CH₄ accumulation and loss by degassing. Our results indicate that Itaparica Reservoir, located in the semi-arid region of Northeastern Brazil, acts as a source of GHGs. Management measurements are needed to prevent emissions to raise in the future.     

Cleaning the river Damodar (India): impact of COVID-19 lockdown on water quality and future rejuvenation strategies

Globally, it is established that the partial lockdown system assists to improve the health of the total environment due to inadequate anthropogenic actions in different economic sectors. The ample research on fitness of environment has been proved that the strict imposition of lockdown was the blessings of environment. The river Damodar has historical significance and lifeline for huge population of Jharkhand and West Bengal state of India but in the recent years the water quality has been deteriorated due to untreated industrial effluents and urban sewage. The main objective of this study is to examine the water quality of river Damodar during and prelockdown phase for domestic use and restoration of river ecosystem. A total of eleven (11) effluent discharge sites were selected in prelockdown and during lockdown phase. A new approach of water quality assessment, i.e., water pollution index (WPI) has been applied in this study. WPI is weightage free, unbiased method to analysis of water quality. The result shows that the physical, chemical and heavy elements were found beyond the standard limit in prelockdown period. The cation and anion were arranged in an order of Na²⁺ ?>?K⁺ ?>?Ca²⁺ ?>?Mg²⁺ and Cl^??>?So₄^??>?No₃^??>?F^? in both the sessions. WPI of prelockdown showed that about 100% water samples are of highly polluted. WPI of lockdown period showed that around 90.90% samples improved to ‘good quality’ and 9.10% of samples are of ‘moderately polluted.’ Hypothesis testing by ‘t’ test proved that there was a significant difference (ρ?=?0.05%) in values of each parameter between two periods. Null hypothesis was rejected and indicated the improvement of river water quality statistically. Spatial mapping using Arc GIS 10.4 interpolation (IDW) helps to understand spatial intensity of pollution load in two periods. This research study should be helpful for further management and spatial diagnosis of water resource of river Damodar.

     

Vertical distributions of (99)Tc and the (99)Tc/(137)Cs activity ratio in the coastal water off Aomori, Japan

Using a sector-field ICP-MS the vertical distributions of the ⁹⁹Tc concentration and ⁹⁹Tc/¹³⁷Cs activity ratio were measured in the coastal waters off Aomori Prefecture, Japan, where a spent-nuclear-fuel reprocessing plant has begun test operation. The ⁹⁹Tc concentrations in surface water ranged from 1.8 to 2.4 mBq/m³, no greater than the estimated background level. Relatively high ⁹⁹Tc/¹³⁷Cs activity ratios (10-12 × 10⁻⁴) would be caused by the inflow of the high-⁹⁹Tc/¹³⁷Cs water mass from the Japan Sea. There is no observable contamination from the reprocessing plant in the investigated area. The ⁹⁹Tc concentration and the ⁹⁹Tc/¹³⁷Cs activity ratio in water column showed gradual decreases with depth. Our results implied that ⁹⁹Tc behaves in a more conservative manner than ¹³⁷Cs in marine environments.     

Chemical and microbiological examination of well and Nile water

The chemical composition and microbiological contamination of well water and Nile River water used for drinking were investigated in localities around Khartoum, Sudan, to present baseline data. The chemical analyses results obtained indicated that public health hazards due to pH, Ca⁺⁺, CO₃^??, HCO₃^?, and NO₃^? are unlikely in all the samples studied, while Na⁺ and Cl^? ions concentrations in well water warrant some attention. Contamination from organic matter and suspended material is also negligible. Microbial contamination with coliform and fecal coliform is high in surface wells and in the Nile River, but negligible in deep bores, tap water, and mineral water. The logarithm of the colony count ranges from zero for mineral water to 6.8 for water from the White Nile. In addition to drawing further attention to the well water and Nile water used for drinking by a wide sector of the population, the microbial count data for water from the Nile disagreed with the generally held belief that the Nile, being one of the largest rivers of the world, carries no detectable fecal contamination. Our data also did not support the belief that the White Nile is more contaminated than the Blue Nile.     

Soil migration and plant uptake of technetium from a fluctuating water table

Soil columns (50x15 cm) were used to determine the potential for 95mTc (as a surrogate for 99Tc which is an important component of some radioactive waste) to migrate from a contaminated, fluctuating water table, through sandy loam soil and into perennial ryegrass. Upward migration was significantly retarded with, generally, only the bottom few centimetres of soil becoming contaminated over the 6 months of the experiment. This is thought to have been due to the presence of anoxic conditions within the water table leading to the reduction of pertechnetate to Tc(IV) species which are relatively insoluble. However, some evidence of very slow upward migration over time was found. Only a small and inconsistent transfer of activity into the perennial ryegrass was observed. Whilst these observations would suggest that 99Tc is less important than radionuclides such as 129I and 36Cl in terms of the risk associated with radioactive waste disposal, the potential for a slow upward migration, and/or a pulse-release following the re-oxidation of reduced soil in which 99Tc has accumulated should not be overlooked.     

Diffusive gradient in thin FILMS (DGT) compared with soil solution and labile uranium fraction for predicting uranium bioavailability to ryegrass

The usefulness of uranium concentration in soil solution or recovered by selective extraction as unequivocal bioavailability indices for uranium uptake by plants is still unclear. The aim of the present study was to test if the uranium concentration measured by the diffusive gradient in thin films (DGT) technique is a relevant substitute for plant uranium availability in comparison to uranium concentration in the soil solution or uranium recovered by ammonium acetate. Ryegrass (Lolium perenne L. var. Melvina) is grown in greenhouse on a range of uranium spiked soils. The DGT-recovered uranium concentration (C_DGT) was correlated with uranium concentration in the soil solution or with uranium recovered by ammonium acetate extraction. Plant uptake was better predicted by the summed soil solution concentrations of UO₂²⁺, uranyl carbonate complexes and UO₂PO₄⁻. The DGT technique did not provide significant advantages over conventional methods to predict uranium uptake by plants.     

Assessing the fate of radioactive nickel in cultivated soil cores

Parameters regarding fate of ⁶³Ni in the soil–plant system (soil: solution distribution coefficient, K_d and soil plant concentration ratio, CR) are mostly determined in controlled pot experiments or from simple models involving a limited set of soil parameters. However, as migration of pollutants in soil is strongly linked to the water migration, variation of soil structure in the field and seasonal variation of evapotranspiration will affect these two parameters. The aim of this work was to explore to what extent the downward transfer of ⁶³Ni and its uptake by plants from surface-contaminated undisturbed soil cores under cultivation can be explained by isotopic dilution of this radionuclide in the pool of stable Ni of soils. Undisturbed soil cores (50 cm × 50 cm) were sampled from a brown rendzina (Rendzic Leptosol), a colluvial brown soil (Fluvic Cambisol) and an acidic brown soil (Dystric Cambisol) using PVC lysimeter tubes (three lysimeters sampled per soil type). Each core was equipped with a leachate collector. Cores were placed in a greenhouse and maize (DEA, Pioneer^®) was sown. After 44 days, an irrigation was simulated at the core surfaces to supply 10 000 Bq ⁶³NiCl₂. Maize was harvested 135 days after ⁶³Ni input and radioactivity determined in both vegetal and water samples. Effective uptake of ⁶³Ni by maize was calculated for leaves and kernels. Water drainage and leaching of ⁶³Ni were monitored over the course of the experiment. Values of K_d in surface soil samples were calculated from measured parameters of isotopic exchange kinetics. Results confirmed that ⁶³Ni was strongly retained at the soil surface. Prediction of the ⁶³Ni downward transfer could not be reliably assessed using the K_d values, since the soil structure, which controls local water fluxes, also affected both water and Ni transport. In terms of ⁶³Ni plant uptake, the effective uptake in undisturbed soil cores is controlled by isotope dilution as previously shown at the pot experiment scale.     

Sorption of selenate on soils and pure phases: kinetic parameters and stabilisation

This study was conducted to identify the principle selenate carrier phases for two selected soils, by comparing their reactivity with selenate to that of pure phases of the solids. Silica, calcium carbonate, aluminium hydroxide, goethite, bentonite and humic acid were selected as the main soil carrier phases. Comparisons were made first on the parameter values obtained with the best fit of a kinetic sorption model which can discriminate instantaneous sorption from kinetically limited sorption. Then comparisons were made of the ability for each solid to stabilise selenate by measuring the ratio of the partition coefficient for sorption (Kd_sorption) over that of the desorption (Kd_desorption). Kinetics and stabilisation were used to help elucidate the nature of interactions with the test solid phases for a large range of selenate concentrations. The experiments were conducted over 165 h in batch reactors, the solid being isolated from the solution by dialysis tubing, at two pH (5.4 and 8) and three selenate concentrations (1 × 10⁻³, 1 × 10⁻⁶ and 1 × 10⁻⁸ mol L⁻¹). The results obtained showed that only aluminium hydroxide can sorb selenate throughout the studied pH range (pH 5.4 to 8.0). The sorption capacity on this mineral was high (Kd_sorption > 100 to 1 × 10⁴ L kg⁻¹) and the selenate was mainly stabilized by the formation of inner sphere complexes. The sorption on goethite occurred at pH 5.4 (Kd_sorption 52 L kg⁻¹), mainly as outer sphere complexes, and was null at pH 8. On silica, a weak sorption was observed only at pH 5.4 and at 165 h (Kd_sorption 4 L kg⁻¹). On bentonite, calcium carbonate and humic acid no significant sorption was observed. Concerning the two soils studied, different behaviours were observed for selenate. For soil Ro (pH 5.4), Kd_sorption was low (8 L kg⁻¹) compared to soil Bu (pH 8) (70 L kg⁻¹). The sorption behaviour of selenate on soil Ro was mainly due to outer sphere complexes, as for goethite, whereas for soil Bu the sorption was mainly attributed to inner sphere complexes followed by reduction mechanisms, probably initiated by microorganisms, in which no steady state was reached at the end of the 165 h experiments. The sorption of selenate decreased when concentrations reached 1 × 10⁻³ mol L⁻¹, due to solid saturation, except for aluminium hydroxide. Reduction of selenate seemed also to occur on goethite and soil Ro, for the same concentration, but without preventing a decrease in sorption. Thus, this work shows that the comparison of selenate behaviour between soil and pure phases helps to elucidate the main carrier phases and sorption mechanisms in soil.     

Citric and Oxalic Acids Effect on Pb and Zn Uptake by Maize and Winter Wheat

Abstract

A pot experiment was conducted to investigate the influence of citric and oxalic acids effect on Pb and Zn uptake by corn and winter wheat. The experiment was employed with citric acid (CA) applied at 3 rates (0, 1.5 and 3.0 mmol kg^?1 soil), oxalic acid (OA) at 3 rates (0, 1.5 and 3.0mmol kg^?1 soil) and citric acid combined with oxalic acid (1.5 mmol citric acid combined with 1.5 mmol oxalic acid kg^?1). Two types of soil were chose in the experiment. One was collected from the agricultural soil near a battery-recycling factory in Anhui province, China (site A) and the other was collected from a Pb-Zn mine residues in Hunan province, China (site B). The results showed that soil pH varied with the different treatment of citric and oxalic acids. However, there were no differences in all the treatments. 3.0mmol CA kg^?1 soil addition significantly increased the concentrations of the CaCl₂-extractable Pb and Zn and other treatments have no significantly increased. The highest shoot concentrations of Pb and Zn in both species occurred in application of 3.0 mmol CA/kg^?1 soil and shoot concentrations of Pb and Zn in both species were significantly higher than the controls in this treatment. Shoot yields declined with application of citric and oxalic acids, indicating that the plants were sensitive to the toxicity of the metals or the amendments. The highest Pb uptake values by maize and wheat werell2.3 and 77.2 μg pot1 in soil of site A, and occurred with the control and 3.0 mmol CA/kg^?1 soil respectively.     

Effect of sewage sludge amendment on soil microbial activity and nutrient mineralization

An incubation experiment was performed to study the effect of sewage sludge on microbial respiration and nutrient mineralization in a sandy soil as an indication of its effects on soil biological properties and nutrient transformation. Sewage sludge was amended with a sandy soil at 0, 25, 50, 150 and 350 g kg⁻¹ fresh weight. An increase in the sludge amendment rate caused an increase in both pH and electrical conductivity (EC). However, pH decreased while EC increased and then decreased along the incubation time. Nevertheless salinity and heavy metal contents of the soil sludge mixture were all within the safety guidelines. Soluble NH₄⁺, NO₃²⁻ and PO₃²⁻ increased after amending the soil with sewage sludge, but increasing the application rate to 350 g kg⁻¹ of sludge decreased the N and P mineralization efficiency and created an adverse effect on nitrification. The daily CO₂ evolution pattern was the same in all treatments that CO₂ evolution increased initially and then decreased till the end of the incubation period. All the treatments had peak CO₂ evolution at day 7, except for the soil amended with 350 g kg⁻¹ of sludge which had peak CO₂ evolution at day 2. Similarly, the percentage of C-mineralization decreased with an increase in sludge amendment rate. The present experiment indicated that an application rate of 50–150 g kg⁻¹ sludge for sandy soil would have the optimal beneficial effect on the soil in terms of microbial activity and nutrient transformation.     

Cs uptake by four plant species and Cs-K relations in the soil-plant system as affected by Ca(OH)2 application to an acid soil

Three rates of Ca(OH)₂ were applied to an acid soil and the ¹³⁴Cs uptake by radish, cucumber, soybean and sunflower plants was studied. The ¹³⁴Cs concentration in all plant species was reduced from 1.6-fold in the sunflower seeds to 6-fold in the soybean vegetative parts at the higher Ca(OH)₂ rate. Potassium (K) concentration in plants was also reduced, but less effectively. The significantly decreased ¹³⁴Cs-K soil to plant distribution factors (D.F.) clearly suggest a stronger effect of soil liming on ¹³⁴Cs than on K plant uptake. This observation was discussed in terms of ionic interactions in the soil matrix and within the plants. The results also indicated that the increased Ca²⁺ concentration in the exchange phase and in the soil solution along with the improved root activity, due to the soil liming, enhanced the immobilization of ¹³⁴Cs in the soil matrix and consequently lowered the ¹³⁴Cs availability for plant uptake.     

Towards green membranes: preparation of cellulose acetate ultrafiltration membranes using methyl lactate as a biosolvent

Ultrafiltration membranes were prepared using cellulose acetate (CA) as a polymer, LiCl and CaCl₂ as porogens and methyl-(S)-lactate as a solvent. CA, methyl lactate and the porogens used in this work are obtained from renewable resources; they are biodegradable, non-toxic and non-volatile organic compounds. Flat sheet ultrafiltration membranes were prepared by the phase inversion technique. A molecular weight cut-off between 15 and 35 kDa (polyethylene glycol) and pure water permeability between 13 and 177 litres h^? 1m^? 2 bar^? 1 were obtained. These parameters are in the ideal range for water treatment industry. Improvement of pollutant degree and ecotoxicity of the process was evaluated by ‘green’ metrics by the P (pollutants, persistent and bioaccumulative) and E (ecotoxicity) parameters. Both of these variables were recorded as zero using our method. This study represents a step ahead towards the production of ultrafiltration polymeric membranes by a ‘greener’ process than current methods.     

Partitioning coefficients of polycyclic aromatic hydrocarbons in stack gas from a municipal incinerator

In this study, solid-gas partitioning coefficients of PAHs on fly ash in stack gas from a municipal incinerator were determined according to elution analysis with gas-solid chromatography. The fly ash from the electrostatic precipitator was sieved and packed into a 1/4 inch (6.3 mm) pyrex column. Elution analysis with gas-solid chromatography was conducted for three PAHs, Napthalene, Anthracene, and Pyrene. The temperature for elution analysis was in the range of 100°C to 300°C. V_g, specific retention volume obtained from elution analysis, and S, specific surface area of fly ash measured by a surface area measurement instrument, were used to estimate the solid-gas partitioning coefficient, K_R. In addition, the relationships between K_R and temperature and K_R and PAH concentrations were investigated.     

Greenhouse gases emissions from a closed old landfill cultivated with biomass crops

Closed landfills need after-closure rehabilitation. The chosen option should ensure greenhouse gases release, from the landfill, is not promoted once settled. The objective of this study was to estimate and confront, during different seasons, CH₄, CO₂ and N₂O emissions under three vegetation covers in a closed landfill in Buenos Aires, Argentina. CH₄ (methane), CO₂ (carbon dioxide) and N₂O (nitrous oxide) emissions from landfill’s technosol under spontaneous vegetation (control), Pennisetum purpureum and Miscanthus giganteus (biomass crops), were quantified with non-steady-state non-flow-through chambers, in July 2014 and from February to July 2015. A linear regression analysis was performed to relate the variables “flux of a gas” and “concentration of that gas” from the 3 treatments and 6 dates, separating the 5 sampling times. A high correlation between concentrations and fluxes of CO₂ and N₂O was found, but no correlation was established for CH₄. Mean emissions (2014–2015) varied from: ?2.3 to 639.41 mgCH₄ m^?2 day^?1, 3884 to 46,365 mgCO₂ m^?2 day^?1 and 0.40 to 14.59 mgN₂O m^?2 day^?1. Vegetation covers had no significant effect on CH₄ and N₂O concentration in time, but they had on CO₂ concentration. Season of the year had a significant effect on concentration of the three gases. This is the first study on CH₄, CO₂ and N₂O emissions from a landfill closed 27 years ago covered with biomass crops.     

Availability of 99Tc in undisturbed soil cores

Models for safety assessment of radioactive waste repositories need accurate values of the soil-to-plant transfer of radionuclides. In oxidizing environments, (99)Tc is expected to occur as pertechnetate ((99)TcO(4)(-)). Due to its high mobility, leaching of this element in the field might be important, potentially affecting the reliability of estimated transfer parameters of (99)Tc as measured in closed experimental systems such as hydroponics or pot experiments. The aim of this experiment was to measure the leaching of (99)Tc in undisturbed irrigated soil cores under cultivation as well as plant uptake and to study the possible competition between the two transfer pathways. Undisturbed soil cores (50 x 50 cm) were sampled from a Rendzic Leptosol (R), a colluvial Fluvic Cambisol (F) and a Dystric Cambisol (D) using PVC tubes (three cores sampled per soil type). Each core was equipped with a leachate collector at the bottom, allowing the monitoring of (99)Tc leaching through the cores. Cores were placed in a greenhouse and maize (Zea mays L., cv. DEA, Pioneer) was sown. After 135 d, maize was harvested and radioactivity determined in both plant and water samples. Results showed that during the growing period, leaching of (99)Tc was limited, due to the high evapotranspiration rate of maize. After harvest, leaching of (99)Tc went on because of the absence of evapotranspiration. Effective uptake (EU) of (99)Tc in leaves and grains was calculated. EU reached 70% of the input in the leaves and was not significantly different among soils. These results confirmed those obtained from pot experiments, even though leaching was allowed to occur in close-to-reality hydraulical conditions. As a consequence, it was concluded that pot experiments are an adequate surrogate for more complex "close-to-reality" experimental systems for measuring transfer factors.     

Contrasting cesium dynamics in neighboring deep and shallow warm-water reservoirs

To measure the long term retention and seasonal dynamics of an initial 4 kg addition of ¹³³Cs into an 11.4-ha, 157,000 m³ reservoir (Pond 4, near Aiken, South Carolina, USA), the concentrations and inventories of ¹³³Cs in the water column were measured at periodical intervals for 522 days following the 1 August, 1999 release. After rapid declines in concentrations and inventories during the first 90 days, the ¹³³Cs concentrations in the water column declined at an average proportional rate of 0.004 d⁻¹. However, there were periods of less rapid and more rapid rates of declines, and these were correlated with periods of increasing and decreasing K concentrations in the water column. The decline rates were less and the K concentrations greater in the winter than in the summer. In the deeper, neighboring monomictic reservoirs of Par Pond and Pond B, a yearly cycle of increasing and decreasing ¹³⁷Cs concentrations in the water column is driven by anoxic remobilization of Cs from the sediments into a persistent summer hypolimnion. In Pond 4, whose mean depth of 1.6 m is too shallow to support a persistent anoxic hypolimnion, the pattern of yearly dynamics for K and Cs appear to be related to the accumulation and release of these elements from the extensive, seasonal macrophyte communities. The contrasting results between Pond 4 and Pond B suggest that a full appreciation of the relative importance of 1) anoxic remobilization and 2) accumulation and release by macrophytes in these systems remains to be established.     

Mitigation of greenhouse gas emissions from an abandoned Baltic peat extraction area by growing reed canary grass: life-cycle assessment

Abandoned peat extraction areas are continuous emitters of GHGs; hence, abandonment of peat extraction areas should immediately be followed by conversion to an appropriate after-use. Our primary aim was to clarify the atmospheric impact of reed canary grass (RCG, Phalaris arundinacea L.) cultivation on an abandoned peat extraction area and to compare it to other after-treatment alternatives. We performed a life-cycle assessment for five different after-use options for a drained organic soil withdrawn from peat extraction: (I) bare peat soil (no management), (II) non-fertilised Phalaris cultivation, (III) fertilised Phalaris cultivation, (IV) afforestation, and (V) rewetting. Our results showed that on average the non-fertilised and fertilised Phalaris alternatives had a cooling effect on the atmosphere (?10,837 and ?477 kg CO₂-eq ha^?1 year^?1, respectively), whereas afforestation, rewetting, and no-management alternatives contributed to global warming (9,511, 8,195, and 2,529 kg CO₂-eq ha^?1 year^?1, respectively). The main components influencing the global warming potential of different after-use alternatives were site GHG emissions, carbon assimilation by plants, and emissions from combustion, while management-related emissions played a relatively minor role. The results of this study indicate that, from the perspective of atmospheric impact, the most suitable after-use option for an abandoned peat extraction area is cultivation of RCG.     

Taxonomy of groundwater quality using multivariate and spatial analyses in the Tuticorin District,Tamil Nadu,India

A holistic appraisal of the quality of groundwater from the Tuticorin District has been conducted using multivariate statistical and spatial analyses. The objectives of the study were to delineate the spatial and temporal variabilities in groundwater quality and to understand its suitability for human uses. A total of 100 groundwater samples were collected and analyzed for major cations and anions during pre-monsoon and post-monsoon. Water quality index rating was calculated to quantify overall water quality for human consumption. The PRM samples exhibit poor quality in greater percentage when compared with POM due to the dilution after rainfall. Correlation, factor analysis, and plot of the factor scores reflect the seawater intrusion and weathering process. The mineral stability diagrams indicated that the groundwater is in equilibrium with kaolinite and Ca-montmorillonite, whereas Gibbs plot showed that the chemical composition of groundwater in both districts is controlled by the natural weathering processes irrespective of seasons. The major water type identified in this study is the Ca²⁺–Mg²⁺–HCO₃ ^? type, which degrades into predominantly Na⁺–Cl^?–SO₄ ^2? more saline groundwater toward the coast.     

Long-term simulation of effects of energy crop cultivation on nitrogen leaching and surface water quality in Saxony/Germany

The production of energy crops in Germany is a growing agronomic sector and is expected to occupy a substantial share of farmland in the near future. At the same time, there are concerns that energy crops might cause increased nitrogen pollution of soil water, surface water and groundwater. Therefore, the Federal State of Saxony, Germany, funded a study on potential effects of an intensified cultivation of energy crops. In frame of this study, we used the Web GIS-based model STOFFBILANZ to simulate N leaching from the rooting zone and N loads of surface water for a reference scenario and an energy crop scenario. For the reference scenario, we used data representing the crop cultivation for the year 2005 at municipality level. We found that the total loads for N leaching from the rooting zone of cropland are highest for the loess region (8,067 t year^?1), followed by mountainous region (6,797 t year^?1) and lowland (5,443 t year^?1). However, highest N fluxes in the leachate from rooting zones have been simulated for lowland (40.6 kg ha^?1 year^?1) and mountainous region (37.1 kg ha^?1 year^?1), while nitrate concentrations of leachate were highest for the lowland (101.8 mg l^?1). In terms of diffuse N input into surface water, the mountainous region is the most important source area (total N load 6,380 t year^?1, flux 34.6 kg ha^?1 year^?1). Retention by in-stream processes accounts for 15 % (3,784 t year^?1) of the total N load leaving the study area (25,136 t year^?1). In the 2020 energy crop scenario, shares of rape and silage maize (id., ensiled corn) were limited for each municipality to a maximum of 25 and 33 %, respectively. The conversion of grasslands to crop farming was not allowed. Under these conditions, we found slight to substantial reductions of nitrogen loads for leachate from the rooting zone and for surface waters. The simulated reduction depends strongly on local conditions. Only small reductions (ca. 4–8 %) were found for the lowlands and mountainous regions of Saxony, while reductions for the loess region were substantial (ca. 22 %). A major outcome of our study is that the cultivation of energy crops might reduce N loss if certain preconditions are assumed, for example, without conversion of grasslands to crop farming. However, effects might vary widely depending on local conditions.