[Assessment of Heavy Metal Pollution and Tracing Sources by Pb & Sr Isotope in the Soil Profile of Woodland in Quanzhou].

The contents of 8 heavy metal elements (Sr, Ni, Fe, Cr, Cu, Mn, Pb, Zn) and the lead & strontium isotope composition of soil profile of woodland in Quanzhou city were analyzed by AAS and ICP-MS, respectively. A modified BCR four-step sequential extraction procedure was carried out to obtain the speciation fractionation of heavy metals in the soil profile from 4 stations. The results of the heavy metal elements and the speciation fractionation of heavy metals in the soil profile showed that the heavy metal pollution in the woodland in Quanzhou was relatively light, and the main pollution factor was Sr. The non-residue state of Pb was the highest, leading to the highest activity. The result of Nemero comprehensive pollution index showed that Sr in the depth of 0-60 cm was at heavy pollution level. The results of the RSP showed that the activity of Pb was the highest. The results of EF showed that Pb, Sr, Mn and Zn had exogenous sources. Factor analysis showed that the main sources of heavy metals were the compound pollution of agricultural activities, natural resources, and the vehicle exhaust. Composition of Pb isotopic ratios showed that, Pb in soil profile of woodland in Quanzhou was from vehicle exhaust and parent material. The contribution rates of the two sources in the soil profile were calculated by using the two-mixed model. The contribution rates of parent material and vehicle exhaust were 85.14%(62.53%-98.36%) and 14.86%(1.640%-37.47%) on average, respectively. Strontium isotope tracing results showed that the main sources of strontium were also vehicle exhaust and parent material. Coupling both Pb and Sr isotope ratios agreed with the above mentioned results.

[Tracing Sources of Heavy Metals in the Soil Profiles of Drylands by Multivariate Statistical Analysis and Lead Isotope].

Two profile soils in drylands of Xiamen City were collected and 26 kinds of heavy metals were determined by ICP-MS. The distribution characteristics, environmental risk and pollution sources of heavy metals in soil profiles were studied. The results of Nemero comprehensive pollution index method, the geological accumulation index method and potential ecological hazard index method indicated that Cd was the main pollution factor in the drylands of Xiamen City; the soil pollution was serious in 50-60 cm depth. Multivariate statistical analysis showed that the main sources of heavy metals were the compound pollution of agricultural production activities and natural resources, and the main pollution factor Cd was from agricultural production. Composition of acid-extractable Pb isotopic ratios in soil profiles and potential pollution sources were analyzed. The results showed that Pb in soil profiles was from sludge and parent material. The contribution rates of the two sources in the soil profiles by 206Pb/207Pb-206Pb/204Pb were calculated by using the two mixed models. In the two profiles, parent material contribution rates were 54.36% and 42.88%, and sludge contribution rates were 45.64% and 57.12%, respectively. The main sources of lead of drylands in Xiamen were parent material and sludge, which was consistent with the results of the multivariate statistical analysis.

[Effects of allelochemicals ethyl cinnamate on the growth and physiological characteristics of Chlorella pyrenoidosa].

The effects of ethyl cinnamate on the growth and physiological characteristics of Chlorella pyrenoidosa were studied. The allelopathic mechanisms were explored, from views of chlorophyll a content, antioxidant enzyme activities, reactive oxygen species (ROS) level, malondialdehyde (MDA) content and photosynthetic activity. The results revealed that ethyl cinnamate had acute inhibitory effects on the growth of Chlorella pyrenoidosa, and the inhibited degree tended to increase with increased concentrations. The effective concentration causing a 50% inhibition at 96 h was 5.45 mg c L(-1). Ethyl cinnamate induced the decrease of chlorophyll a, the over-accumulation of ROS and the increase of MDA. Therefore, it suggested that ethyl cinnamate could lead to the damage of cell membrane system and metabolic disorder through inducing lipid peroxidation via initiating ROS overproduction. And for scavenging ROS, the algae cells were protected from oxidative damages through increasing the activity of antioxidant enzymes. The results demonstrated ethyl cinnamate had acute inhibition to the maximum quantum yield and the potential activity of photosystem II of Chlorella pyrenoidosa, however, the photosynthetic activity could recover to some extent through self-regulation after some time.