Lignin and its effects on litter decomposition in forest ecosystems

Lignin is a major component of plant litter. In this review, we found lignin comprises a complex class of organic compounds whose concentration differs greatly both between and within plant species. There are many analytical methods for detecting the composition and structure of lignins. As lignins are enormously complex compounds, chemical assay is difficult and different methods vary with the results. Lignin plays a significant role in the carbon cycle, sequestering atmospheric carbon into the living tissues of woody perennial vegetation. It has also great effects on nitrogen dynamics of forest ecosystems as well as other ecological processes. Lignin is one of the most slowly decomposing components of dead vegetation, contributing a major fraction of the material that becomes humus as it decomposes. Lignin is highly correlated with decomposition of litter. Thus, there is evidence that the lignin concentration is a more influential factor than the other chemical concentrations, in determining the rate of leaf litter decomposition of different forest ecosystems. Although a great number of researchers have addressed lignin's role in litter decomposition, still there are many aspects of lignin biogeochemistry that are not known. This lack of information hinders complete amalgam of lignin effects on litter decomposition processes and dynamics of nutrient cycling.     

Fixed-bed adsorption of Malachite Green onto binary solid mixture of adsorbents: seashells and eggshells

In this work, continuous removal of Malachite Green from aqueous solution by adsorption was investigated using a laboratory scale fixed-bed column packed with binary solid mixture of seashell powder (SSP) and eggshell powder (ESP). The effects of initial dye concentration, feed flow rate, bed height, and the SSP?:?ESP ratio in the binary solid mixture on the breakthrough characteristics were studied. The breakthrough time decreased with increase in the flow rate and the initial dye concentration. The breakthrough time also varied greatly with change in bed height. The breakthrough time increased from 17.2?h to 34.5?h with increase in bed height from 6?cm to 12?cm. The breakthrough time was significantly affected by the change in the SSP?:?ESP ratio in the binary mixture. The breakthrough time decreased with increase in the SSP ratio in the binary mixture. In order to determine the column kinetic parameters, three different column kinetic models, namely Adams–Bohart, Bed Depth Service Time (BDST), and Yoon–Nelson models were fitted to the dynamic flow experimental data. The BDST model showed good agreement with the experimental results at all the process parameters studied. Results suggest that this novel approach of simultaneous utilization of adsorbents can be adopted for the treatment of dye-bearing effluents.     

Hydro-chemical characterization of groundwater and evaluation of health risk assessment for fluoride contamination areas in the eastern blocks of Purulia district,India

Environment, Development and Sustainability - Purulia is a hard rock terrain where water scarcity as well as water quality degradation has been a major threat for the past few decades. The prolong...     

Evaluation of chlordimeform and degradation products for mutagenic and DNA‐damaging activity in salmonella typhimurium and escherichia coli

Abstract

The mutagenic activity of chlordimeform and two of its breakdown products, 4‐chloro‐o‐toludine and 4‐chloro‐N‐formyl‐o‐toluidine were determined with five histidine dependent strains of Salmonella typhimurium (TA1535, TA1537, TA1538, TA98, TA100) and five tryptophan dependent strains of E. coli WP₂. (WP₂, WP₂uvrA, WP67, CM611, CM571) with and without rat liver microsomal enzymes. 4‐chloro‐o‐toluidine increased the number of the reversions of the S. typhimurium strain TA1535 more than two fold over spontaneous at the concentration of 400 μg/plate.

The results of the DNA repair tests in the Salmonella TA1538/TA1978 and E. coli multirepair deficient systems showed that both breakdown products were active in inducing damage not repaired in at least one repair deficient strain while chlordimeform itself was inactive.     

Research trends in biodiversity loss: a bibliometric analysis

Environmental Science and Pollution Research - Although increased attempts to preserve biodiversity ecosystems have been widely publicized, bibliometric research of biodiversity loss remains...     

Water quality change in dam reservoir and shallow aquifer: analysis on trend,seasonal variability and data reduction

Change of water quality in dam reservoir and aquifer complicates safe drinking water supply. Few parameters are monitored to control water quality in these sources. Adequate knowledge on the correlation structure, interaction effect, trends and seasonal variability of these parameters is essential to control water quality. This study applied time series and multivariate analyses on 15 water quality parameters, collected from the King Fahd dam reservoir (L1) and aquifer (L2) in Saudi Arabia during April 2010 to February 2012. Moderate to strong correlations were observed between sulfate, hardness, fluoride, chloride, magnesium, conductivity, turbidity and total dissolved solids (TDS), while separate clusters were visible for TDS-chloride-magnesium-conductivity; fluoride-turbidity; chloride-hardness; ammonia-nitrate; and calcium-magnesium-hardness. Four major principal components explained 81.1 % and 83.2 % of the overall variances in L1 and L2, respectively. The factor analysis showed that 53 % and 67 % of the data were necessary to explain 81.3 % and 83.2 % of total variances for L1 and L2, respectively, indicating the possibility of data reduction. Possible degradation of water quality in these sources was highlighted, while such degradation may require enhanced treatment for producing drinking water in future.     

Levels of heavy metals in tissues of shingi fish (Heteropneustes fossilis) from Buriganga River, Bangladesh

Heavy metal pollution was reported in commercially valuable freshwater edible fish in the Buriganga River, Bangladesh. The concentrations of As, Pb, Cd, Cr, Zn, and Cu were investigated in the muscle, gill, stomach, intestine, and liver of Heteropneustes fossilis caught at three stations to assess the degree of fish pollution by heavy metals. Significant differences in concentrations of analyzed elements were observed among different tissues, but not among the stations. The ranges of the measured concentrations (μg/g dry weight) in the tissues of H. fossilis were as follows: arsenic concentration was (0.2–0.4), (0.82–0.90), (3.29–3.99), (2.20–2.80), and (2.41–2.90), that of lead was (1.79–2.20), (4.95–6.55), (10.36–13.38), (5.74–9.70), and (18.20–18.79), that of cadmium was (0.3–0.4), (2.87–4.27), (1.03–1.63), (1.55–4.59), and (2.25–5.50), that of chromium was (1.40–1.70), (3.52–3.72), (2.28–5.29), (2.77–3.79), and (4.25–8.65), that of zinc was (24.47–28.82), (16.82–18.80), (20.22–22.20), (22.86–26.68), and (60.82–67.80), and that of copper was (7.80–8.50), (6.22–6.81), (38.21–44.25), (17.07–21.03), and (43.24–47.30) in the muscle, gill, stomach, intestine, and liver, respectively. This research showed that the liver appeared to be the main heavy metal storage tissue, while the muscle had the lowest levels of analyzed metals. The concentrations of metal in the muscles not exceeded the acceptable levels for a food source for human consumption.     

Magnitude of anthropogenic phosphorus storage in the agricultural production and the waste management systems at the regional and country scales

Based on a systematic review of 17 recent substance flow analyses of phosphorus (P) at the regional and country scales, this study presents an assessment of the magnitude of anthropogenic P storage in the agricultural production and the waste management systems to identify the potential for minimizing unnecessary P storage to reduce the input of P as mineral fertilizer and the loss of P. The assessment indicates that in case of all (6) P flow analyses at the regional scale, the combined mass of annual P storage in the agricultural production and the waste management systems is greater than 50 % of the mass of annual P inflow as mineral fertilizer in the agricultural production system, while this is close to or more than 100 % in case of half of these analyses. At the country scale, in case of the majority (7 out of 11) of analyses, the combined mass of annual P storage in the agricultural production and the waste management systems has been found to be roughly equivalent or greater than 100 % of the mass of annual P inflow as mineral fertilizer in the agricultural production system, while it ranged from 30 to 60 % in the remaining analyses. A simple scenario analysis has revealed that the annual storage of P in this manner over 100 years could result in the accumulation of a massive amount of P in the agricultural production and the waste management systems at both the regional and country scales. This study suggests that sustainable P management initiatives at the regional and country scales should put more emphasis on minimizing unwanted P storage in the agricultural production and the waste management systems.     

Social constraints before sanitation improvement in tea gardens of Sylhet, Bangladesh

Sylhet, the northeastern divisional city of Bangladesh, is the major tea-producing region of the country where a large number of low-income workers completely depending on extremely labor-intensive economic activity for their bread and butter, live in and around the tea gardens. The living conditions of these communities are remarkably meager due to the lack of proper utility facilities, especially in water supply and sanitation sectors. A study was conducted at Lakkatura and Ali Bahar Tea Estates to assess the deteriorated sanitation condition of the tea garden workers community and to determine the constraints before the improvement of the condition. It was found that the existing sanitary condition of both of the tea garden slums is very poor because of the same topographical condition and socioeconomic and cultural status of the dwellers. About 50% to 60% tea garden workers still are used to open defecation causing various excreta related diseases and not practiced with washing hand after defecation. Lack of knowledge and awareness about health and hygiene, unwillingness, poverty, superstitions, etc. are responsible for the deteriorated condition of the sanitation system. Based on the analysis, providing latrines free of costs, undertaking extensive motivational and awareness programs and publicity, regular consultation of tea garden workers with the health specialists, and vector control staff of concerned utilities as well as an integrated water supply, sanitation, and hygiene promotion programs should be considered as the priority in order to improve the deteriorated sanitary conditions in two tea gardens.