Does Copper Contamination Affect Soil CO2 Emissions? A Literature Review

Contaminated soils are widespread and contamination is known to impact several biotic soil processes. But it is still not clear to what extent soil contamination affects soil carbon efflux (CO2) occurring through soil microfauna respiration. Regarding the large stocks of organic carbon (Corga) stored in soils, even limited changes in the outputs fluxes may modify atmospheric CO2 concentration with important feedbacks on climate. In this study, we aimed at assessing and quantifying how soil respiration is affected by contamination. For that, we performed a quantitative review of literature focusing on 1) soil heterotrophic respiration measurements thus excluding autotrophic respiration from plants, 2) soil copper contamination, and 3) the influence of pedo-climatic parameters such as pH, clay content or the type of climate. Using a dataset of 389 data analyzed with RandomForest and linear mixed statistical models, we showed a decrease in soil CO2 emission with an increase in soil copper contamination. Specific data from ex-situ spiking experiments could be easily differentiated from the ones originated from in-situ contamination due to their sharper decrease in soil Corga mineralization. Interestingly, ex-situ spikes data provided a threshold in soil Cu contents for CO2 emissions: CO2 emission increased for inputs below 265 mgCu.kg−1 soil and decreased above this concentration. Data from long-term in-situ contaminations due to anthropogenic activities (industrialization, agriculture, … ) also displayed an impact on soil carbon mineralization, much particularly for industrial contaminations (smelter, sewage sludge, … ) with decreased in CO2 emissions when Cu contamination increased. Soil pH was identified as a significant driver of the effect of Cu on CO2 emissions, as soil C mineralization was found to be more sensitive to Cu contamination in acidic soils than in neutral or alkaline soils. Conversely the clay content and the type of climate did not significantly explain the responses in soil C mineralization. Finally, the collected data were used to propose an empirical equation quantifying how soil respiration can be affected by a Cu contamination. The decrease in soil CO2 emissions cannot be related, however, in a role of C sink as it comes together with a decrease in soil microbial biomass.

White Turmeric Rhizome Protection Effect of against Lung Tissue Damage in Copper Sulfate-Induced Wistar Rats

One of common heavy metals that pollute rivers in Indonesia is copper, which can damage various organs, including the lungs. As a potential natural herbal medicine, white turmeric rhizome has antioxidant properties that potentially protect the body from copper pollution. This study aimed to explore the potential of the white turmeric rhizome (Curcuma zedoaria) to provide a protective effect on the lungs against copper contamination. This study was an experimental study performed in June 2020 on 25 copper-induced Wistar rats which were divided into five groups: negative group that received 1 ml of copper sulfate suspension at the 12th to 14th day; positive group that received 10 mg/200 g BW of ethanol extract from white turmeric without copper sulfate suspension; and three experimental groups that received 10 mg/200 gBW, 20 mg/200 gBW, and 40 mg/200 gBW of ethanol extract from white turmeric every day, respectively, followed by copper sulfate suspension at the 12th–14th day. After 14 days, the rats were sacrificed by chloroform inhalation and the lung was excised and processed for histopathology preparation. The edema, hemorrhage, leukocyte infiltration, and alveolar septal thickness were evaluated from the lung tissue perparation. The score of tissue damage was express as median (Range) and analyzed using the Kruskal-Wallis test. The result of this study shows that there was a significant difference in lung tissue score among all groups of treatment (p-Value=0.001). The experimental group with highest dosage extract presented a good protection effect as well as the positive group. Hence, white turmeric has a good protective property for the lung against damages caused by copper contamination.