Functional Diversity and Microbial Activity of For

Authors: Marek Pająk Ewa Błońska Magdalena Frąc Karolina Oszust

Publish Date: 2016/08/29

Volume: 227, Issue: 9, Pages: 348-

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Abstract

The objective of this study was to assess the impact of metal contamination on microbial functional diversity and enzyme activity in forest soils This study involved the evaluation of the influence of the texture carbon content and distance to the source of contamination on the change in soil microbial activity which did not investigate in previous studies The study area is located in southern Poland near the city of Olkusz around the flotation sedimentation pond of lead and zinc at the Mining and Metallurgical Company “ZGH Bolesław Inc” The central point of the study area was selected as the middle part of the sedimentation pond The experiment was conducted over a regular 500 × 500m grid where 33 sampling points were established Contents of organic carbon and trace elements Zn Pb and Cd pH and soil texture were investigated The study included the determination of dehydrogenase and urease activities and microbial functional diversity evaluation based on the communitylevel physiological profiling approach by Biolog EcoPlate The greatest reduction in the dehydrogenase and urease activities was observed in light sandy soils with Zn content 220 mg · kg−1 and a Pb content 100 mg · kg−1 Soils with a higher concentration of fine fraction despite having the greatest concentrations of metals were characterized by high rates of Biolog®derived parameters and a lower reduction of enzyme activityHigh heavy metal contamination negatively affects the circulation of nutrients which reduces the amount of soil microorganisms potentially changing their metabolic activity Bååth 1989 Kandeler et al 1996 Wyszkowska and Wyszkowski 2003 Guo et al 2012 The studies of Kuperman and Carreiro 1997 Šmejkalová et al 2003 and Sardar et al 2007 showed that microbial activity was inhibited by heavy metals such as Zn Cd and Pb According to Sardar et al 2010 high concentrations of heavy metals Cd and Pb change soil microbial community structure and activities The soil enzymatic activities decreased significantly with the increasing contamination of heavy metals Pb Zn Ag Cu and Cd especially dehydrogenase and urease activities Chen et al 2005 Microbial parameters may be affected not only by heavy metals but also by soil properties such as pH and carbonates organic carbon and total nitrogen content Moreno et al 2001 Chodak et al 2013 Renella et al 2003 reported that the inhibition of enzyme activity by heavy metals was greater in sandy rather than in finer textured soils Soil organic matter is the most important parameter controlling heavy metal behaviour in soils Heavy metals bound on insoluble humic substances are relatively immobile Borůvka and Drábek 2004 The most important factor which affects heavy metals mobility is clay content Clay minerals play a role as carriers of associated oxides and humic substances forming organomineral complexes which present different sorption capacities Violante et al 2010Soil enzymatic activities are sensitive bioindicators of any natural and anthropogenic disturbance Hinojosa et al 2004 Kumar et al 2013 Soil enzymes are important for catalysing several vital reactions that are necessary for microorganisms in soils as well as the stabilization of soil structure organic waste decomposition organic matter formation and nutrient cycling Dick et al 1996 Dick 1997 Siczek and Frąc 2012 Wolińska et al 2015 Wolińska and Stępniewska 2012 and Veres et al 2013 showed that soil enzyme activities are “sensors” of soil organic matter SOM decomposition Decomposition of organic matter in soil depends on substance properties and accessibility of microorganisms and their enzymes According to Brookes 1995 dehydrogenase activity can be used as an indicator of heavy metal contamination of soil The results of Shen et al 2005 indicated that urease activity may be an effective preliminary mechanism to estimate Cd Zn Pb and PAH pollution in the soil of zinc mines The inhibition of urease is especially strong in the presence of certain heavy metals due to the changes in the molecular structure of the enzyme caused by the inhibitors Metal pollution has been shown to affect microbial functional diversity Stefanowicz et al 2008 These authors found that bacterial functional diversity significantly decreased whereas fungal functional diversity slightly increased with increasing metal concentrationsThe study area is the area with the heaviest contamination of Zn and Pb in Poland Previous studies did not investigate the effect of texture variability carbon content and distance from the contamination source on the microbial activity in forest ecosystems No information is available regarding the content of Zn and Pb which clearly inhibit microbial activity Niklińska et al 2006 Stefanowicz et al 2008The objective of this study was to assess the impact of metal contamination on the microbial functional diversity and enzyme activity in forest soils This study involved evaluation of the influence of the texture carbon content and distance to the source of contamination on the change in soil microbial activity The following hypotheses were tested in this paper 1 an increase in the clay and organic carbon content in soil causes a less negative impact of Zn and Pb on microbial activity compared to that in soil with high sand content 2 decreasing distance from the source of contamination caused a decrease in the soil microbial activityThe study area is located in southern Poland near the city of Olkusz N50° 17′ 367″ E19° 29′ 4743″ and characterized by the following conditions of climate the average precipitation in the months IV–X amounts to 515 mm the average temperature is 125 °C This area includes forests around a flotation sedimentation pond of lead and zinc at the Mining and Metallurgical Company “ZGH Bolesław Inc” The pine forest was predominant in the study area the pine was 20–50 years old The central point of the study area was selected as the middle part of the sedimentation pond The sampling was designed over a regular 500 × 500m grid where 33 sampling points were designated The samples for laboratory analysis were collected in August 2014For each sampling point the coordinates x y were determined Soil samples from the depth of 0–15 cm were taken below the organic horizon from the sampling points From each sampling point five subsamples were taken to form a composite sample In addition the distances from each sampling point to the sedimentation pond Dist 1 and the steelworks of ZGH Boleslaw Dist 2 were specified

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