鸟粪对同里湿地底泥重金属含量分布及形态影响

以同里国家湿地公园为研究区,探讨鸟类排泄物对河流底泥重金属全量及形态的影响。选取有鸟粪区域底泥和无鸟粪区域底泥样品,用元素分析仪测定C、N、H、S含量,ICP OES测定重金属Cr、Ni、Cu、Zn和Co含量,运用Tessier五步法提取可交换态（F1）、碳酸盐结合态（F2）、铁锰氧化态（F3）、有机物结合态（F4）和残渣态（F5）,并对两区域底泥潜在生态风险进行了研究。结果表明：C、N、H、S含量在两区域无显著差异,但有鸟粪区域变异系数高于无鸟粪区域。Cr、Ni和Co均呈现有鸟粪区域显著高于无鸟粪区域（P = 0017,0004,0001 < 005）。同里湿地底泥重金属形态以残渣态为主,但有鸟粪区域底泥重金属有效态占比高于无鸟粪区域。潜在生态风险评估表明同里湿地底泥中5种重金属单因子潜在生态风险和综合潜在风险值均较低,但有鸟粪区域值较高,其潜在生态风险大于无鸟粪区域。综上,有鸟粪区域底泥的重金属含量以及生态风险高于无鸟粪区域,所以对该湿地鸟粪的清理很有必要     

Mixture risk assessment due to ingestion of arsenic,copper, and zinc from milkfish farmed in contaminated coastal areas

Human health risks associated with the consumption of metal-contaminated fish over extended periods have become a concern particularly in Taiwan, where fish is consumed on a large scale. This study applied the interaction-based hazard index (HI) to assess the mixture health risks for fishers and non-fishers who consume the arsenic (As), copper (Cu), and zinc (Zn) contaminated milkfish from As-contaminated coastal areas in Taiwan, taking into account joint toxic actions and potential toxic interactions. We showed that the interactions of As–Zn and Cu–Zn were antagonistic, whereas As–Cu interaction was additive. We found that HI estimates without interactions considered were 1.3–1.6 times higher than interactive HIs. Probability distributions of HI estimates for non-fishers were less than 1, whereas all 97.5%-tile HI estimates for fishers were >1. Analytical results revealed that the level of inorganic As in milkfish was the main contributor to HIs, indicating a health risk posed to consumers of fish farmed in As-contaminated areas. However, we found that Zn supplementation could significantly decrease As-induced risk of hematological effect by activating a Zn-dependent enzyme. In order to improve the accuracy of health risk due to exposure to multiple metals, further toxicological data, regular environmental monitoring, dietary survey, and refinement approaches for interactive risk assessment are warranted.     

Hydrogeochemical characterization and groundwater quality assessment in intruded coastal brine aquifers (Laizhou Bay,China)

Environmental Science and Pollution Research - The aquifer in the coastal area of the Laizhou Bay is affected by salinization processes related to intense groundwater exploitation for brine...     

The cause and influence of self-cementing properties of fine recycled concrete aggregates on the properties of unbound sub-base

The use of coarse recycled concrete aggregates (CRCA) in conjunction with fine recycled concrete aggregates (FRCA) as sub-base materials has been widely studied. Although research results indicate that it is feasible to employ both CRCA and FRCA as granular sub-base, the influence of the unhydrated cement in the adhered mortar of the RCA on the properties of the sub-base materials has not been thoroughly studied. Generally, it is known that the strength of the sub-base materials prepared with RCA increases over time. However, this mechanism, known as the self-cementing properties, is not well understood and is believed to be governed by the properties of the fine portion of the RCA (<5mm). This paper presents an investigation on the cause of the self-cementing properties by measuring X-ray diffraction patterns, pH values, compressive strength and permeability of various size fractions of the FRCA obtained from a commercially operated construction and demolition waste recycling plant. Their influence on the overall sub-base materials was determined. The results indicate that the size fractions of <0.15 and 0.3-0.6mm (active fractions) were most likely to be the principal cause of the self-cementing properties of the FRCA. However, the effects on the properties of the overall RCA sub-base materials were minimal if the total quantity of the active fractions was limited to a threshold by weight of the total fine aggregate.     

Earthworm cytochrome P450 determination and application as a biomarker for diagnosing PAH exposure

We developed a new microsome purification method and used the Omura and Sato method to measure the total content of cytochrome (Cyt) P450 in earthworm (Eisenia fetida) microsomes. In method development, two different pretreatments, i.e. solubilization or manual separation were used to purify worm microsomes. Solubilization was more effective than manual separation and difference spectra showed a peak at 450 +/- 1 nm in microsomes received solubilization pretreatment. We conducted a 48 h contact test by exposing worms on pyrene (Py) and benzo[a]pyrene (BaP) spiked filter paper. A dose-response relationship was established between total P450 content and the concentration of Py or BaP ranging from 10(-6) mg mL(-1) to 10(-2) mg mL(-1). Results show that total Cyt P450 content in earthworms is a promising biomarker for diagnosing PAHs exposure at sublethal dose ranges.     

Simulating long-term and residual effects of nitrogen fertilization on corn yields, soil carbon sequestration, and soil nitrogen dynamics

Soil carbon sequestration (SCS) has the potential to attenuate increasing atmospheric CO2 and mitigate greenhouse warming. Understanding of this potential can be assisted by the use of simulation models. We evaluated the ability of the EPIC model to simulate corn (Zea mays L.) yields and soil organic carbon (SOC) at Arlington, WI, during 1958-1991. Corn was grown continuously on a Typic Argiudoll with three N levels: LTN1 (control), LTN2 (medium), and LTN3 (high). The LTN2 N rate started at 56 kg ha(-1) (1958), increased to 92 kg ha(-1) (1963), and reached 140 kg ha(-1) (1973). The LTN3 N rate was maintained at twice the LTN2 level. In 1984, each plot was divided into four subplots receiving N at 0, 84, 168, and 252 kg ha(-1). Five treatments were used for model evaluation. Percent errors of mean yield predictions during 1958-1983 decreased as N rate increased (LTN1 = -5.0%, LTN2 = 3.5%, and LTN3 = 1.0%). Percent errors of mean yield predictions during 1985-1991 were larger than during the first period. Simulated and observed mean yields during 1958-1991 were highly correlated (R2 = 0.961, p < 0.01). Simulated SOC agreed well with observed values with percent errors from -5.8 to 0.5% in 1984 and from -5.1 to 0.7% in 1990. EPIC captured the dynamics of SOC, SCS, and microbial biomass. Simulated net N mineralization rates were lower than those from laboratory incubations. Improvements in EPIC's ability to predict annual variability of crop yields may lead to improved estimates of SCS.     

Sensitive immunoassay detection of multiple environmental chemicals on protein microarrays using DNA/dye conjugate as a fluorescent label

Indirect competitive immunoassays were developed on protein microarrays for the sensitive and simultaneous detection of multiple environmental chemicals in one sample. In this assay, a DNA/SYTOX Orange conjugate was employed as an antibody label to increase the fluorescence signal and sensitivity of the immunoassays. Epoxy-modified glass slides were selected as the substrate for the production of 4 × 4 coating antigen microarrays. With this signal-enhancing system, competition curves for 17β-estradiol (E2), benzo[a]pyrene (BaP) and 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) were obtained individually on the protein microarray. The IC(50) and calculated limit of detection (LOD) are 0.32 μg L(-1) and 0.022 μg L(-1) for E2, 37.2 μg L(-1) and 24.5 μg L(-1) for BaP, and 31.6 μg L(-1) and 2.8 μg L(-1) for BDE-47, respectively. LOD of E2 is 14-fold lower than the value reported in a previous study using Cy3 labeled antibody (Du et al., Clin. Chem, 2005, 51, 368-375). The results of the microarray immunoassay were within 15% of chromatographic analysis for all three pollutants in spiked river water samples, thus verifying the immunoassay. Simultaneous detection of E2, BaP and BDE-47 in one sample was demonstrated. There was no cross-reaction in the immunoassay between these three environmental chemicals. These results suggest that microarray-based immunoassays with DNA/dye conjugate labels are useful tools for the rapid, sensitive, and high throughput screening of multiple environmental contaminants.     

某化工企业厂界内及周边土壤中二噁英健康风险评估

在某化工企业厂界内及周边布设9个土壤点位,对其二噁英进行检测与分析,依据《污染场地风险评估技术导则》对土壤中二噁英进行健康风险评估。结果表明,9个土壤点位二噁英毒性当量浓度为3.72~20.3 pg/g,均值为9.1 pg/g,均处于安全水平;在经口摄入、皮肤接触和吸入土壤颗粒物3种暴露途径下,只有4#点位具有较低的致癌风险;4#点位代表的场地区域为风险不可接受的污染区域,基于致癌效应的土壤风险控制值为1.84×10-5mg/kg。提出,应尽快研究并制定土壤中二噁英的标准限值。     

Coral communities of the remote atoll reefs in the Nansha Islands, southern South China Sea

During the months of May and June in the year 2007, a survey was conducted regarding coral reef communities in the remote atolls (Zhubi Reef and Meiji Reef) of Nansha Islands, southern South China Sea. The goals of the survey were to: (1) for the first time, compile a scleractinian coral check-list; (2) estimate the total richness, coral cover, and growth forms of the community; and (3) describe preliminary patterns of community structure according to geomorphological units. Findings of this survey revealed a total of 120 species of scleractinia belonging to 40 genera, while the average coral cover was 21 %, ranging from less than 10 % to higher than 50 %. Branching and massive corals were also found to be the most important growth forms of the whole coral community, while Acropora, Montipora, and Porites were the three dominant genera in the overall region, with their contributions to total coral cover measuring 21, 22, and 23 %, respectively. Overall, coral communities of the Nansha Islands were in a relative healthy condition with high species diversity and coral cover. Spatial pattern of coral communities existed among various geomorphological units. Mean coral cover was highest in the patch reef within the lagoon, followed by the fore reef slope, reef flat, and lagoon slope. The greatest contributors to total coral cover were branching Acropora (45 %) in the lagoon slope, branching Montipora (44 %) in the reef flat, and massive Porites (51 %) in the patch reef. Coral cover in the fore reef revealed a greater range of genera than in other habitats. The leeward fore reef slope had higher coral cover (>50 %) when compared with the windward slope (<10 %). The coral communities of the inner reef flat were characterized by higher coral cover (27 %) and dominant branching Montipora corals, while lower coral cover (4 %) was dominated by Psammocora with massive growth forms on the outer reef flat. Destructive fishing and coral bleaching were two major threats to coral communities in the study area.     

An experimental method to verify soil conservation by check dams on the Loess Plateau, China

A successful experiment with a physical model requires necessary conditions of similarity. This study presents an experimental method with a semi-scale physical model. The model is used to monitor and verify soil conservation by check dams in a small watershed on the Loess Plateau of China. During experiments, the model–prototype ratio of geomorphic variables was kept constant under each rainfall event. Consequently, experimental data are available for verification of soil erosion processes in the field and for predicting soil loss in a model watershed with check dams. Thus, it can predict the amount of soil loss in a catchment. This study also mentions four criteria: similarities of watershed geometry, grain size and bare land, Froude number (Fr) for rainfall event, and soil erosion in downscaled models. The efficacy of the proposed method was confirmed using these criteria in two different downscaled model experiments. The B-Model, a large scale model, simulates watershed prototype. The two small scale models, D_a and D_b, have different erosion rates, but are the same size. These two models simulate hydraulic processes in the B-Model. Experiment results show that while soil loss in the small scale models was converted by multiplying the soil loss scale number, it was very close to that of the B-Model. Obviously, with a semi-scale physical model, experiments are available to verify and predict soil loss in a small watershed area with check dam system on the Loess Plateau, China.