Location‐specific ecotoxicological risk assessment of metal‐polluted soils

Abstract

When chemical analysis indicates metal pollution, a second-tier method is needed to evaluate whether toxic effects occur at the polluted sites. A method based on pollution-induced community tolerance (PICT) was developed using samples taken from locations polluted with sewage more than 20 years ago. Microorganisms extracted from soil samples were exposed to a concentration range of zinc, nickel, copper, chromium (III), or chromium (VI) salts in a buffer suspension. The remaining activity of the intoxicated microorganisms was determined by color formation with 31 different organic substrates in microtiter plates. Microorganisms from moderately Zn-polluted sites (>45 mg/kg) showed an increased tolerance for zinc. Nickel tolerance was observed at 51 mg Ni/kg soil, chromium (VI) tolerance at 923 mg Cr/kg. In most cases, tolerance also was observed at higher concentrations. High concentrations of 1,494 mg Cu/kg or 3,935 mg Cr/kg did not show PICT, indicating a limited bioavailability of Cu and Cr at these sites. The benefits of our method are its greater sensitivity compared to other tests used at these sites, and its specificity for those metals that exceed allowable levels.

Repeated application of composted tannery sludge affects differently soil microbial biomass, enzymes activity, and ammonia-oxidizing organisms

“…On the other hand, contrary to others studies (He et al 2007;O'Sullivan et al 2013;Rousk et al 2010), our results showed a negative correlation between pH and AOA abundance. Also, there was a negative correlation between AOA and Cr, similar to the results reported previously by Van Beelen et al (2004), who showed that AOA were more affected by contamination from Cu and Cr in a sludgeamended soil, suggesting that AOB have a higher heavy metal tolerance than AOA (Mertens et al 2009). …”

“…Previous studies have been reported that AOA and AOB are affected by metal pollution, but AOA were more strongly reduced in Cu- (Van Beelen et al 2004;Liu et al 2014), and Zn- (Kelly et al 2011) polluted soils.…”

Can Transgenic Maize Affect Soil Microbial Communities?

“…Bacteria incubation. Bacteria were extracted from soil immediately before each titration: 15 g of soil sample, based on dry weight, was blended with 150 ml sterile buffer (10 mM bis[2-Hydroxyethyl]iminotris[hydroxymethyl]methane (BisTris, Sigma, http://sigmaaldrich.com) at pH ¼ 7.0) for 1 min at maximum speed and then centrifuged for 10 min at 500 g. According to the method of Van Beelen et al [38], the supernatant was transferred to 2-ml sterile Eppendorf vials, rapidly frozen in liquid nitrogen, and stored at À70 8C until analysis of the community level physiological profiles (CLPP). This final freezing step differs from the original method of Rutgers et al [39], but the CLPP of replicates made at different time points during one year were not significantly different from each other ( p ¼ 0.12), as most fresh suspensions of soil bacteria had very similar BIOLOG profiles and CFU plate counts compared with frozen suspensions [40,41].…”

Effects of different concentrations and application frequencies of oxytetracycline on soil enzyme activities and microbial community diversity

“…The Biolog test has often been used to detect pollution-induced soil community tolerance at sites where sewage sludge has been applied [19]. The present study is based on an agricultural soil historically contaminated with long-term wastewater irrigation.…”