Effects of Pb, Cd, Zn, and Cu on Soil Enzyme Activity and Soil Properties Related to Agricultural Land-Use Practices in Karst Area Contaminated by Pb-Zn Tailings

Abstract

In order to study the impact of Pb, Cd, Zn, and Cu released by Pb-Zn tailings on soil enzymes and soil properties involving soil carbon and nitrogen cycle processes, 32 soil samples were collected from 2 different types of agricultural fields (one for growing corn and one for growing rice) contaminated by Pb-Zn tailings close to Sidi village in southwestern China. The results revealed that the paddy fields were seriously contaminated by Pb-Zn tailings compared with cornfields. Under the Pb-Zn tailings contamination, the population of fungi and actinomycetes as well as the activities of the soil enzymes (urease, invertase, and cellulase) in cornfields were significantly higher than those in the paddy fields. In addition, the results from path analysis showed that urease, invertase, and acid phosphatase were negatively correlated with DTPA-extractable Cd, Pb, and Zn (the direct path coefficients were -0.336, -0.314, and -0.591, respectively). Soil microorganisms and enzyme activities involving soil organic carbon and nitrogen decomposition and stabilization were decreased due to the toxic Pb-Zn tailings. Therefore, soil organic carbon and total nitrogen accumulate and an "elusive" carbon and nitrogen pool forms in the paddy fields compared with cornfields in the Pb-Zn tailings-contaminated karst area.

Monitoring the Activated Sludge Activities Affected by Industrial Toxins via an Early-Warning System Based on the Relative Oxygen Uptake Rate (ROUR) Index

“…Although numerous studies have reported the impacts of toxin concentration and other parameters on the OUR or other indicators representing the activated sludge activities [27,28,32], our work is the first attempt to explain the toxic effects in a theoretical model, and the results suggested that toxic substances, MLSS and HRT were all key factors affecting the ROUR.…”

“…Biological monitoring is an alternative approach to evaluate the influent quality by assessing the toxicity, instead of the accurate composition of wastewater [24]. Many studies on biological early-warning systems use various indicators to monitor the influent toxicity in WWTPs, e.g., animals and plants [25,26], special bacterial strains [27,28], microbial current [29][30][31], and respiratory rate [32]. Among them, luminescent bacteria are widely studied [33][34][35] but suffer from the difficulties in online cultivation and monitoring [36][37][38][39].…”

The effect of different copper doses and organic fertilisation on soil's enzymatic activity

“…The conducted study showed that the application of high doses of copper reduces the enzymatic activity of the soil, which indirectly reduces its fertility and capability, which is its measure according to Russel (2005). The negative effect of soil contamination with copper on its enzymatic activity is highlighted in studies by Chaperon and Sauvé (2007), Wang et al (2007), Fernandéz-Calvińo et al (2010, Zhan and Sun (2014), Wyszkowska et al (2017), andLi et al (2018). The inactivating effect of this metal on the activity of urease, dehydrogenases and alkaline phosphatase increased with the increase of its dose.…”

Microbial diversity in relation to soil types and land uses of Wadi Um Ashtan basin, North-Western Coast, Egypt

“…It had also a significant negative relation with the activities of nitrogenase (r=-0.490), phosphatase (r=-0.563), and amylase (r=-0.446). Many studies showed that microbial populations were significantly and negatively correlated with soil pH (Ghorbani-Nasrabadi et al, 2013;Błońska et al, 2017;Li et al, 2018 andChoudhary et al, 2018). Most of microbes have narrow pH ranges for their optimal growth.…”