Effect of Heavy Metals and Storage Time on Two Types of Forest Litter: Basal Respiration Rate and Exchangeable Metals

Although the toxic effect of heavy metals on soil microorganism activity is well known, little is known about the effects on different organism groups. The influence of heavy metal addition on total, bacterial, and fungal activities was therefore studied for up to 60 days in a laboratory experiment using forest soil contaminated with different concentrations of Zn or Cu. The effects of the metals differed between the different activity measurements. During the first week after metal addition, the total activity (respiration rate) decreased by 30% at the highest level of contamination and then remained stable during the 60 days of incubation. The bacterial activity (thymidine incorporation rate) decreased during the first days with the level of metal contamination, resulting in a 90% decrease at the highest level of contamination. Bacterial activity then slowly recovered to values similar to those of the control soil. The recovery was faster when soil pH, which had decreased due to metal addition, was restored to control values by liming. Fungal activity (acetate-in-ergosterol incorporation rate) initially increased with the level of metal contamination, being up to 3 and 7 times higher than that in the control samples during the first week at the highest levels of Zn and Cu addition, respectively. The positive effect of metal addition on fungal activity then decreased, but fungal activity was still higher in contaminated than in control soil after 35 days. This is the first direct evidence that fungal and bacterial activities in soil are differently affected by heavy metals. The different responses of bacteria and fungi to heavy metals were reflected in an increase in the relative fungal/bacterial ratio (estimated using phospholipid fatty acid analysis) with increased metal load.

show abstract

“…1A). This was found earlier in different types of soils (17,33,38). In general, respiration should reflect both bacterial and fungal activities.…”

Section: Discussionsupporting

confidence: 65%

Metal Toxicity Affects Fungal and Bacterial Activities in Soil Differently

Ranil

Tobor-Kaplon

Bååth

2004

Appl Environ Microbiol

379

204

View full text Add to dashboard Cite

show abstract

“…Such differences were probably due to a variety of factors, such as adsorption on soil colloids, precipitation or interaction with organic ligands, pH, or soil clay content (Prokop et al 2003). However, it should be taken into account that the metals used in this experiment were soluble salts, so that the effective concentration of available heavy metal would be higher than in environmental levels with the same total metal concentration (Niklinska et al 1998). The higher amount of available Cd found in soil contaminated at high levels with respect to the low level suggests that the damage derived from Cd contamination increases with the pollutant rate, probably due to the saturation of Cd adsorption or linking sites of the soil colloids.…”

Section: Discussionmentioning

confidence: 98%

Evaluation of Microbial Community Activity, Abundance and Structure in a Semiarid Soil Under Cadmium Pollution at Laboratory Level

Ros

Pascual

Moreno

et al. 2009

Water Air Soil Pollut

View full text Add to dashboard Cite

Cadmium (Cd) pollution can alter soil flora and fauna, as well as the microbial community associated with the main biogeochemical cycles of a soil. The present study was conducted to investigate the effect of two different concentrations of Cd pollutant, 6.5 mg kg −1 (low level) and 12.5 mg kg −1 (high level) on microbial community activity, abundance, and structure in a semiarid soil after a 60-day incubation period at laboratory level. Available Cd, water soluble carbon (WSC), microbial biomass carbon (C mic ), adenosine triphosphate (ATP) content, and real-time polymerase chain reaction were used to measure the influence of Cd on the abundance and activity of the microbial community. Bacteria and fungi community structure and diversity based on denaturing gradient gel electrophoresis (DGGE) analysis were also analyzed. The percentage of Cd extracted by diethylenetriamine pentaacetic acid increased with the higher total concentration of Cd added to the soil, being 16.9% at low level and 77.9% at the high level. WSC, C mic , and ATP content decreased significantly as soil Cd concentration increased (WSC 29% and 34%, C mic 27% and 35%, and ATP 32% and 47%, at low and high levels, respectively). While fungal diversity already decreased with low levels of Cd concentration, and was even more negatively affected by the higher pollution levels, bacterial (acidobacteria, α-proteobacteria, and β proteobacteria) diversity only showed a decline with the higher Cd concentration. The fungi-to-bacteria ratio showed by the different treatments could imply that fungi abundance is less influenced by increased Cd pollution, although fungi diversity as revealed by DGGE analysis diminished as soil Cd concentration increased.

show abstract

“…Changes in the energy budgets of soil organisms may lead to changes in ecosystem functioning, e.g. in terms of organic matter decomposition and respiration (Nordgren et al 1988, Niklinska et al 1998, Barajas Aceves et al 1999). The effects are however ambiguous, as soil pollution has been found to increase as well as decrease respiration rate (Bååth 1989).…”

mentioning

confidence: 99%

Functional stability of microbial communities in contaminated soils

Tobor-Kaplon¹,

Bloem²,

Römkens³

et al. 2005

Oikos

View full text Add to dashboard Cite

Tobor-Kapl on, M. A., Bloem, J., Rö mkens, P. F. A. M. and de Ruiter, P. C. 2005. Functional stability of microbial communities in contaminated soils. Á/ Oikos 111: 119 Á/129.Functional stability, measured in terms of resistance and resilience of respiration and growth rate of bacteria and fungi, was studied in soils that have been exposed to copper and low pH for more than twenty years. We used treatments, consisting of soil with no or high copper load (0 or 750 kg ha (1 ) and low or neutral pH (4.0 or 6.1). Stability was examined by applying an additional stress in the form of lead or salt. After addition of lead, respiration (decomposition of freshly added lucerne meal) showed lower resistance at low than at neutral pH and at high copper than at low copper. The most acid and contaminated soil was the least resistant. Respiration showed no resilience after addition of lead. Bacterial growth rate (thymidine incorporation) also showed resistance at low pH but only in soils that were not contaminated with copper.After addition of salt, respiration showed no differences in resistance but the soils without copper contamination showed higher resilience. Bacterial growth rate showed lower resistance at low pH than at neutral pH, the latter in which the growth rate increased by on average 123%. This increase at high pH was faster in soil without copper than in soil with copper contamination in which the growth rate initially decreased and then increased. The effects of secondary stress depended on the nature of the stress (lead or salt) and on the parameter measured (respiration or bacterial growth rate). In general the highest resistance and/or resilience were found in the least contaminated soils with neutral pH and/or no copper contamination. Thus, the microbial communities in the cleaner soils showed the highest functional stability. The results seem to confirm the notion that environmental stress alters ecosystems such that supplementary stress will have stronger impacts than in an unstressed system. The results may also confirm the insurance-hypothesis that reduced biodiversity due to the first stress negatively affected community stability. As an alternative, we discuss the observed effects in terms of altered energy budget.

show abstract

Effect of Heavy Metals and Storage Time on Two Types of Forest Litter: Basal Respiration Rate and Exchangeable Metals

Cited by 20 publications

References 22 publications

Metal Toxicity Affects Fungal and Bacterial Activities in Soil Differently

Metal Toxicity Affects Fungal and Bacterial Activities in Soil Differently

Evaluation of Microbial Community Activity, Abundance and Structure in a Semiarid Soil Under Cadmium Pollution at Laboratory Level

Functional stability of microbial communities in contaminated soils

Contact Info

Product

Resources

About