The demand for phenolic compounds has been increasing rapidly, which has intensified the production and usage of phenol at a commercial scale. In some polluted water bodies, phenol has become one of the typical aromatic contaminants. Such water bodies are inescapably influenced by nutrients from human activities, and also suffer from nuisance cyanobacterial blooms. While phenolic pollution threatens water safety and ecological balance, algal cells are ubiquitous and sensitive to pollutants. Therefore, effects of phenolic pollution on interspecific competition between a bloom-forming cyanobacterium and other common alga merit quantitative investigation. In this study, the effects of phenol on Microcystis aeruginosa (M. aeruginosa, a bloom-forming cyanobacterium) and Chlorella pyrenoidosa (C. pyrenoidosa, a ubiquitous green alga) were analyzed in mono- and co-cultures. The two species were exposed to a series of phenol treatments (0, 2, 20, and 200 μg mL-1). Population dynamics were measured by a flow cytometer and analyzed by the Lotka-Volterra model. The results showed that M. aeruginosa was more sensitive to phenol (EC50 = 80.8 ± 0.16 μg mL-1) compared to C. pyrenoidosa (EC50 = 631.4 ± 0.41 μg mL-1) in mono-cultures. M. aeruginosa won in the co-cultures when phenol was below or equal to 20 μg mL-1, while C. pyrenoidosa became the dominant species in the 200 μg mL-1 treatment. Photosynthetic activity was measured by a fluometer. Results showed phenol significantly impacted the photosynthetic activity of M. aeruginosa by inhibiting the acceptor side of its photosystem II (PSII), while such inhibition in C. pyrenoidosa was only observed in the highest phenol treatment (200 μg mL-1). This study provides a better understanding for predicting the succession of algal community structure in water bodies susceptible to phenolic contamination. Moreover, it reveals the mechanism on photosynthetic responses of these two species under phenolic stress.
Based on the field investigation and laboratory analysis,this paper studied the characteristics of soil heavy metal temporal-spatial variation,and subsequent changes of microbial and enzymatic activities in the upland surrounding an electroplating factory located in south Jiangsu Province,China.The results indicated that total and DTPA-extractable concentrations of Zn and Cu in studied soils were distributed along a gradient,and the concentration decreased as the radius from the electroplating factory increased.There was a decrease of total Zn concentration from the highes(t1 305 mg.kg-1)to the lowes(t273 mg.kg-1).Because of effects from factory contamination,Zn concentrations in studied sites increased year by year,and the contents exceeded last results in the corresponding sites.The contents of Zn in all sites exceeded the contamination level,and the highest value of Zn in a sampling site was 4.2 times higher than its maximum allowable concentration of Zn in agricultural land,suggesting that Zn diffusion speed from the factory was high in recent years.In soils of studied area,a significant positive correlation(P = 0.016)was found between catalase activity and DTPA-extractable Zn,indicating that Zn exhibits stimulating effect on catalase activity.However,the microbial community functional diversity and dehydrogenase activity in soils were not sensitive to the levels of Zn,implying that the diversity and dehydrogenase could not serve as appropriate indicators of Zn stress in soils of the study area.
Organic phosphorus (OP) constitutes an important fraction of total phosphorus in lake sediments. The mobility of OP was significantly affected by mineralization and transformation of organic carbon (OC). However, investigation on the form of OC that exhibits the most substantial impact on OP, has not been carried out to date. This study determined the chemical forms of OP and OC in the sediments over four seasons in Lake Taihu. The results showed that the concentration of total OP (TOP) and total OC (TOC) exhibited obvious temporal–spatial differences. The highest value of TOP (348 mg×kg-1) was observed in summer and TOC exhibited the lowest value of 21.2 mg×kg-1. However, in winter, TOC showed similar distribution to TOP. Correlation between chemical fractions of OP and OC reveals that NaOH-OP, Fulvic-OP, and Humic-OP are positively correlated with Humic-OC and Hot hydrolysis-OC, which indicate that these two forms play a significant role in promoting the transformation of OP. The degradation and mineralization of OC increase the rate of OP mineralization, promoting the conversion of moderately active OP into highly active organic forms, or mineralization of OP into inorganic phosphorus. It is of great significance for an in-depth understanding of the migration and transformation of organic phosphorus in sediments which rich in organic matter caused by degradation of cyanobacteria.
Accumulation and risk assessment of metals in sediments and zoobenthos (Bellamya aeruginosa and Corbicula fluminea) from Lake Taihu were studied. Results showed that metal (Cr, Cd, Cu, Zn, Pb and Ni) concentrations in Lake Taihu varied greatly, and Cd in the Zhushan Bay showed higher bioavailability compared to the other metals studied. The spatial distribution of metals in B. aeruginosa and C. fluminea was similar to that in sediments. Zn and Cu exhibited the higher mean concentration in B. aeruginosa and C. fluminea, which was in good accordance with its higher content in surrounding sediment. Labile fractions (i.e., acid-soluble (F1), reducible (F2) and F1 + F2) of Cu and Zn in sediments showed a significant positive correlation with them in B. aeruginosa (P < 0.01); no correlation relationship was found for metals (Cd, Cr, Cu, Zn, Pb and Ni) between in the tissue of C. fluminea and in sediments. The results of ecological risk assessment showed that Zhushan Bay was seriously contaminated by metal Cd, as it made the main contribution of all the metals. Total target hazard quotients indicated that adults and children both had potential health risk through consuming C. fluminea. Hazard index values suggested that adults and children might experience adverse health effects through consuming B. aeruginosa and C. fluminea.
To investigate the impacts of mining and spilling activities on domestic fowl raising, ten muscovy duck (Cairna moschata) samples were collected in 2010 from farms in different villages located at the banks of the river originated from an Au/Cu mine. Concentrations of Cu, Hg and As in muscle, liver and blood of the muscovy duck samples were determined. According to relative national standards of China, the health safety of heavy metals in muscovy duck was evaluated. The results indicated that content of Cu was higher than those of Hg and As in the same tissue of the duck. The average content (17.20 mg x kg(-1)) of Cu in liver of the duck was higher than those in other tissues, but the concentrations of Hg and As had no significant difference among three tissues of the duck. There was no significant spatial distribution pattern of Cu, Hg and As in three tissues of the duck samples collected from the farms in different villages located at the banks of the river, indicating no significant impacts of mining and spilling activities on the ducks samples. The contents of Cu, Hg and As in the tissues of the duck samples fell in normal level ranges, and the ducks didn't show abnormal physical symptoms. According to the tolerance limits of heavy metals in foods of China, Cu in livers of the duck samples exceeded the standard by 100%, and the highest value of Cu in the liver was 1.74 times higher than its maximum allowable concentration in foods. Moreover, Hg contents in some muscle, blood and liver tissues of the duck samples were relatively high.
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)