Mercury mobility, colloid formation and methylation in a polluted Fluvisol as affected by manure application and flooding–draining cycle

Floodplain soils polluted with high levels of mercury (Hg) are potential point sources to downstream ecosystems. Repeated flooding (e.g., redox cycling) and agricultural activities (e.g., organic matter addition) may influence the fate and speciation of Hg in these soil systems. The formation and aggregation of colloids and particles influence both Hg mobility and its bioavailability to microbes that form methylmercury (MeHg). In this study, we conducted a microcosm flooding–draining experiment on Hg-polluted floodplain soils originating from an agriculturally used area situated in the Rhone Valley (Valais, Switzerland). The experiment comprised two 14 d flooding periods separated by one 14 d draining period. The effect of freshly added natural organic matter on Hg dynamics was assessed by adding liquid cow manure (+MNR) to two soils characterized by different Hg (47.3±0.5 or 2.38±0.01 mg kg−1) and organic carbon (OC: 1.92 wt % or 3.45 wt %) contents. During the experiment, the release, colloid formation of Hg in soil solution and net MeHg production in the soil were monitored. Upon manure addition in the highly polluted soil (lower OC), an accelerated release of Hg to the soil solution could be linked to a fast reductive dissolution of Mn oxides. The manure treatments showed a fast sequestration of Hg and a higher percentage of Hg bound by particulate (0.02–10 µm). Also, analyses of soil solutions by asymmetrical flow field-flow fractionation coupled with inductively coupled plasma mass spectrometry (AF4–ICP–MS) revealed a relative increase in colloidal Hg bound to dissolved organic matter (Hg–DOM) and inorganic colloidal Hg (70 %–100 %) upon manure addition. Our experiment shows a net MeHg production the first flooding and draining period and a subsequent decrease in absolute MeHg concentrations after the second flooding period. Manure addition did not change net MeHg production significantly in the incubated soils. The results of this study suggest that manure addition may promote Hg sequestration by Hg complexation on large organic matter components and the formation and aggregation of inorganic HgS(s) colloids in Hg-polluted Fluvisols with low levels of natural organic matter.

Analysis Sulphur (S) Content of SP-36 Fertilizer PT Petrokimia Using In-House and Innovation Method

Fertilizer is an essential component in increasing food self-sufficiency in Indonesia. PT Petrokimia Gresik is one of the fourth-largest fertilizer producers in Indonesia and produces various kinds of fertilizers. One of the fertilizer is SP-36, contains sulphur and phosphate. This study investigated the sulphur (S) content in SP-36 fertilizer using the in-house and innovation method. The difference between the two methods is BaCl2; the in house method used BaCl2 powder, while the Innovation method used liquid BaCl2. Different used of BaCl2 were based on their colloid formation. This study used a UV-Vis spectrophotometer instrument to calculate the sulphur content of SP-36 fertilizer. The results obtained from the research show that the two methods tested can be used to measure the sulphur content in SP-36 fertilizer. The most accurate result was In house method. The average value of sulphur content in SP-36 fertilizer using the in house method is 4,83%, while the average value of sulphur content in SP-36 fertilizer using the innovation method is 5,22%.

Histological Studies on Foetal Thyroid Gland of Developing Human Foetuses

Introduction: Thyroid gland is the first endocrine gland to develop. It is one of the organs of interest for researchers since a long time. Though, detailed study about adult thyroid is there in the literature but histological study of thyroid gland at different stages in the foetal period is far and few. The present study aims to assess the histogenesis of thyroid gland and also to correlate the functional activity with structural changes in thyroid gland. Methods: The study was carried out on 30 foetal thyroid gland of known gestational age ranging from 10 to 38 weeks foetuses. The midline dissection of neck was done to expose the thyroid gland. After tissue processing, paraffin blocks were prepared. All sections were stained with Haematoxylin-Eosin stain. Results: In the foetuses, below 12th gestational week no colloid was detected in thyroid gland. First appearance of colloid was observed at 14th gestational week. Parafollicular cells were found after 17th gestational week. Capsule thickness and gland vascularity increased with advancement of gestational age. The size of the peripheral follicles is larger than the central follicles. Conclusions: The study concluded the developmental stage of foetal thyroid as Precolloidal stage, Colloid formation stage, Follicular stage and Maturation stage in different gestational weeks. The knowledge on the growth and differentiation of foetal thyroid will be helpful to the clinicians to judge the thyroid structure in preterm babies.

Mercury mobility, colloid formation and methylation in a polluted fluvisol as affected by manure application and flooding-draining cycle

Floodplain soils polluted with high levels of mercury (Hg) are potential point sources to downstream eco-systems. Repeated flooding (e.g. redox cycling) and agricultural activities (e.g. organic matter addition) may influence the fate and speciation of Hg in these soil systems. The formation and aggregation of colloids and particles influences both Hg mobility and its bioavailability to methylmercury (MeHg) forming microbes. In this study, we conducted a microcosm flooding-draining experiment on Hg polluted floodplain soils originating from an agriculturally used area situated in the Rhone Valley (Valais, Switzerland). The experiment comprised two 14 days flooding periods separated by one 14 days draining period. The effect of freshly added natural organic matter on Hg dynamics was assessed by adding liquid cow manure (+MNR) to two control soils characterized by different Hg (47.3 ± 0.6 mg kg−1 or 2.38 ± 0.01 mg kg−1) and organic carbon (OC: 1.92 wt. % or 3.45 wt. %) contents. During the experiment, the release, colloid formation and methylation of Hg in the soil solution were monitored. Upon manure addition in the highly polluted soil (lowest OC), an accelerated release of Hg to the soil solution could be linked to a fast reductive dissolution of Mn oxides. The manure treatments showed a fast sequestration of Hg and a higher percentage of particulate (0.02–10 µm) bound Hg. As well, analyses of soil solutions by asymmetrical flow field-flow fractionation coupled with inductively coupled plasma mass spectrometry (AF4–ICP–MS) revealed a proportional increase of colloidal DOM-Hg and inorganic colloidal Hg (+MNR: 70–100 %; control: 32–70 %) upon manure addition. Our experiment shows that net Hg methylation (MeHg/Hg) was highest after the first draining period and decreased again after the second flooding period. No significant effects on methylation upon manure addition was found. The results of this study suggest that manure addition may promote sequestration by Hg complexation on large organic matter components and the formation/aggregation of inorganic HgS(s) colloids in Hg polluted fluvisols with low levels of natural organic matter.

Biological activity of colloidal solutions of silver, obtained by means of sálix cáprea extract

The presented publication is devoted to the study of the biological activity of silver colloids synthesized based on extracts obtained from various parts of the goat willow plant (Sálix cáprea). The ability of colloidal silver solutions of various concentrations to stimulate growth processes in wheat seeds at the germination stage is analyzed. The effect of colloidal solutions on the catalytic effect of amylase was studied. The fungicidal activity of synthesized silver particles was studied. For the study, colloidal silver particles were obtained by the "green synthesis" method. Extracts of goat willow bark, leaves and buds of varying degrees of dilution were used as a reducing agent. The analysis of sugar content and pH of solutions of plant extracts before and after colloid formation was carried out in order to establish the participation of sugars and acids in the process of silver recovery. The biological activity of colloids was analyzed on the seeds of winter wheat cultivar "Moskovskaya-39". The germination energy of wheat seeds was determined on the 3rd day after sowing by counting the germinated seeds. Amylase activity was measured in the roots and shoots of wheat plants by the amount of undecomposed starch by spectrophotometry. Fungicidal activity was studied with respect to fungi: F. moniliforme, F. oxysporum, S. sclerotiorum, V. inaequalis, R. solani, B. sorokiniana, P. ostreatus. The data obtained show that the sugars that make up the initial extracts of various parts of goat willow are completely consumed in the process of silver recovery and the formation of colloidal particles. A change in the acid content at the stage of colloid formation does not allow us to draw an unambiguous conclusion about the mechanism of participation of these compounds in the process of colloid formation. A study of the biological activity of synthesized silver colloids showed their high ability to stimulate growth processes in wheat seeds. A study of enzymatic catalysis also shows, in general, the positive effect of silver colloids on amylase activity within 1 minute of the starch hydrolysis reaction. An analysis of the data obtained in the study of fungistaticity suggests that silver colloids obtained in extracts from leaves, bark and willow inflorescences exhibit high fungicidal activity against F. moniliforme, S. sclerotiorum, P. ostreatus and B. sorokiniana.