Using Modified Tessier Scheme to Metal Speciation in a Former Sewage Farm and interpretation of the sequential extraction by FTIR

<p>We present a study conducted on a former sewage farm near Berlin, where long term sewage disposal onto agricultural land resulted in a high accumulation of potentially toxic metals. Based on a previous study, 30 samples collected within an area of a former sedimentation basin were selected (at the depth of 15-20 cm and one borehole up to 100 cm deep). The modified Tessier sequential extraction was applied in order to determine the partitioning of particulate potentially toxic metals (Cr, Cu, Ni, Pb, and Zn) into following fractions: 1) Exchangeable, 2) Bound to carbonate, 3) Bound to Fe/Mn oxides, 4) Bound to organic matter, and 5) Residual fraction. As a complementary analysis, diffuse reflectance infrared fourier transform spectroscopy (DRIFTS) technique was used for the interpretation purposes.</p><p>The obtained results demonstrated different metal speciation in the studied soil; Pb was mostly discovered in the residual fraction (77%) followed by Cr (53%), Cu (8%), and Zn (5%), while Ni was not extracted in this fraction. The organic matter-bound is the dominant species of Cu (77%). However, Zn and Ni exhibit the highest affinity for Fe/Mn oxides fraction (55% and 39%, respectively). The average mobility factor followed the order Ni > Zn > Cu whereas Cr and Pb were not found as exchangeable nor in carbonate forms. Study also revealed that DRIFTS is applicable to interpret the sequential metal extraction, especially for the carbonates-bound, organic matter-bound, and residual fractions. The spectral changes in organic and inorganic regions can indicate the soil components’ dissociation is proportional to the extraction.</p>

Spatial and vertical determination of chosen potentially toxic metals and soil properties on a former sewage farm near Berlin

<p>In the past 150 years, sewage disposal onto agricultural land was a common practice around the world that resulted in accumulation of organic matter, salts, nutrients and heavy metals in the soils and the subsequent percolation into the groundwater. We present a study conducted on a former sewage farm in Germany, state of Brandenburg, were wastewater coming from Berlin was used for more than one century to irrigate the surrounding fields. In the area of a sewage sedimentation basin, 110 soil samples at the depth of 15-20 cm (waste layer) and 4 boreholes (10 samples up to 100 cm depth) were collected in order to determine pH, LOI and concentration of chosen metals. For the elemental analysis, two methods: X-ray fluorescence (XRF) and Atomic Emission Spectroscopy (MP-AES) were used. The analysis confirmed the presence of relatively homogenous sewage waste layer at the 20 cm depth, characterized by slightly acidic to neutral pH (6.3-7.5), high OM accumulation (up to 49%) and elevated concentrations of potentially toxic chosen metals (Cu, Ni, Pb, Cr and Zn). The correlation analysis performed by R software revealed strong between metal distribution and OM content. The XRF elemental analysis performed prior and after LOI, revealed metal concentration increase in mineral samples (up to 50% of the original value). An empirical correlation using a linear regression was found between OM content loss and metal concentration increase. Comparison of the AES and XRF elemental analysis of the mineral samples revealed significantly higher results for the X-ray fluorescence method, except for Cr. A correction factor, based on OM reduction, applied to the values, resulted in better correlation of XRF and AES results, questioning feasibility of this method for samples highly affected by sewage influence.</p>

HUMAN POPULATION EFFECTS ON THE ULSOOR LAKE FISH SURVIVAL

In this paper, we introduce a model to study the effects of human populations on fish survival in aquatic media. Directly, this occurs by fishing. Indirectly instead this is related to other human actions that lead to organic pollution and consequently low dissolved oxygen(DO) levels, thereby harming the aquatic fauna. Mathematically, we consider various nonlinear processes involving human population, organic pollutants, bacteria, DO and fish population. In the present study, our aim is to investigate the effect of depleted level of DO on the survival of fish populations in such an aquatic system. The case study in consideration is represented by the Ulsoor lake, Bengaluru, India. Into it, huge amounts of sewage were discharged and resulted in reduction of DO level and massive fish mortality. Equilibria are analyzed for feasibility and stability, substantiated via numerical simulations. Global sensitivity analysis identifies the important parameters having a significant impact on the fish population. The Partial Rank Correlation Coefficients (PRCCs) values of fish population in the lake with respect to input parameters of the system show that the growth rate of humans in the lake watershed has maximum negative correlation while the growth in the fish population due to DO has maximum positive correlation with the density of fish population in the lake. The results show that increase in human population may decrease fish population in the system to very low values. However, by controlling additional dissolved organic loads coming from domestic sewage, farm waste and many other sources, the level of DO can be brought back to values that allow fish survival. Maintaining it at these levels would preserve the ecosystem.

Existence and Decontamination of HVC, Infectious Enteric Bacteria and Parasites in Sewaged Soils

A surface sample representing a high contaminated loamy sand soil irrigated with sewage effluent since 30 years and was cultivated with artichoke was collected from Abu-Rawash sewage farm. The existence of HVC, enteric infectious bacteria and parasites in sewaged soil found to be negative for the forward and positive for the latter's. Out of the 30 samples separated from the sewaged soil sample, only 3 samples contained parasitic fauna of developed and undeveloped Ascaris (10%) and five samples contained Entamoeba coli. Results showed that the number of Ascaris eggs/gm soil was 0.017 and the number of E. coli/gm was 0.26. Decontamination of soil parasites was effective using either calcium hypochlorite or potassium permanganate. Salmonella, Vibrio and Campelobacter were detected in the high contaminated sewaged soil and survived for 120 days in the sewaged soil under all control and bioremediated treatments irrigated with either sewage effluent or water.

Evaluation of physico-chemical quality of groundwater in the surroundings of Valiathura sewage farm in Thiruvananthapuram District, Kerala, South India

The present study was conducted to determine the changes in the physico-chemical characteristics of the groundwater in the surroundings of the sewage farm in Valiathura, Thiruvananthpuram district, Kerala. For this, 42 groundwater samples (29 dug wells and 13 bore wells) were collected bimonthly from the study area during the period January to December 2010 covering pre-monsoon, monsoon and post-monsoon seasons and the major physico-chemical parameters were analysed. The values recorded for parameters such as total alkalinity (330 mg/l), potassium (63.40 mg/l), magnesium (52.39 mg/l) and phosphates (4.71 mg/l in dug wells at some stations exceeded the desirable limits for drinking water quality prescribed by WHO and BIS standards. The Sodium Adsorption Ratio (0.20 - 6.33), Percent sodium (8.54 - 71.83) and Permeability Index values (48.07 - 119.35) showed that all the groundwater samples in the study area were suitable for irrigation purposes. The study revealed that about 31% of the dug wells adjacent to the sewage farm and Parvathy Puthen Ar canal were moderately contaminated and consumption of water from these wells may lead to various health problems in residents. As nutrients like phosphates, sodium, potassium, magnesium were high in well water samples and prolonged consumption of nutrients enriched well water may cause health problems such as high blood pressure, bowel cancer (due to phosphates), cardiovascular diseases (due to sodium and magnesium), renal diseases (due to sodium and potassium).Therefore effective management measures should be taken to protect the groundwater sources in Valiathura area.