Effect of oxidation on the release of multiple metals from industrially polluted sediments and synchrotron-based evidence of Cu–S dynamic association

Purpose

Disposal operations for industrially polluted sediments are usually accompanied by disturbance and resuspension, which can induce metal remobilization and secondary pollution. Evaluating the risk of metal release under various redox conditions is fundamental for predicting contaminant mobilization and guiding remediation measures.

Methods

An abandoned oxidation pond, Yanjia Lake, China, was selected as a typical industrially polluted site. Re-suspension experiments were carried out by mixing polluted sediments with lake water under oxic or anoxic conditions, then investigating the effect of oxidation conditions on the release of multiple metals. Metal concentrations and aqueous chemistry in the overlying water were monitored. Synchrotron-based methods, including X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS), were used to characterize oxidation states and coordination conditions of metals in sediments.

Results

The release of metals, including Cr, Co, Ni, Cu, Zn, Se, Mo, Sn, Cd, and Pb, was enhanced under oxic vs. anoxic conditions. The XANES analysis revealed that elevated Cr and Zn concentrations under oxic conditions likely resulted from the oxidation of Cr(III) and oxidizing dissolution of ZnS, respectively. K-edge Cu XANES, S XANES, and Cu EXAFS analyses reconstructed the Cu–S association, indicating that S-related oxidation promoted Cu release and Cu–O partly replaced Cu–S in the sediment after a 7-day oxic treatment.

Conclusion

The release of most metals was promoted under oxic conditions, resulting from the oxidation of sulfides and metals as indicated by aqueous and synchrotron-based evidence. The risk of secondary pollution is greatly enhanced under oxic conditions, which suggests that measures should be taken to minimize the redox disturbance during sediment remediation. This information can guide the management of sediments in Yanjia Lake and other contaminated sites with similar properties.

     

The impact of typhoon on post-volcanic-eruption forest landscape recovery: a study in Changbai mountain through 300 years of historic landscape reconstruction

Landscape Ecology - Study of interplay of disturbance and forest succession is key to understand forest landscape dynamics, especially under changing climate and disturbance regimes. However, most...     

甜菜新品种吉甜206的选育

甜菜新品种吉甜２０６是以普通二倍体有性杂史后代单株系７３２－３和７５３－８互为父母本杂交而成。该品种在吉林省区域试验表现根产量、含糖率与产糖量分别比对照品种范育一号提高６．０％、１３度与１４．４％，在吉林省生产示范根产量、含糖率与产糖量分别比对照品种吉甜２０１提高１３．２％、１．６度与２５．４％，吉甜２０６是一个适应性广、抗病性强的高糖型甜菜新品种。     

Rice varietal difference in sheath blight development and its association with yield loss at different levels of N fertilization

Variety and nitrogen (N) fertilizer input are the two main factors that influence the development of sheath blight (ShB) caused by Rhizoctonia solani in intensive and high-input rice (Oryza sativa L.) production systems. This study was conducted to determine the varietal difference in ShB development and its association with yield loss across N rates. Two indica inbred and two indica/indica F₁ hybrid varieties were grown under 0 and 90 kg N ha⁻¹ in 2003 wet season (WS) and under 0, 75, 145, and 215 kg N ha⁻¹ in 2004 dry season (DS). Inoculation was done in 3.2 m² in each experiment unit to achieve uniform disease development. Disease intensity was quantified by measuring relative lesion height (RLH) and ShB index (ShBI) of inoculated 10 hills at flowering and 14 days after flowering. Plant traits, grain yield, temperature, and relative humidity inside the canopy were also measured. Consistent and significant varietal differences in ShB intensity were observed across N rates in both WS and DS. Among the four varieties, IR72 and IR75217H had higher RLH and ShBI than PSBRc52 and IR68284H at all N rates. Sheath blight index at 14 days after flowering had the closest correlation with yield loss from ShB. Varieties with taller stature, fewer tillers, and lower leaf N concentration such as IR68284H generally had lower RLH and ShBI, and consequently lower yield loss from the disease. Disease intensity and yield loss from ShB increased with increasing N rates, but the magnitude of yield loss varied among varieties. This suggests that fertilizer N should be managed more precisely and differently for varieties with different plant type in order to reduce the disease development and maximize grain yield in the irrigated rice systems.     

基于嗅觉可视技术的食醋气味表征和区分

利用自主研发的便携式食品气味嗅觉可视检测仪对3种食醋进行了分析,并在实验过程中对传感器制作和图像信号采集进行了优化。结果表明,相机获取图像的整体稳定性优于扫描仪,溶剂挥发时间为15 min时,传感器最为稳定,且与食醋反应可获取最佳响应信号差值;对传感器获取3种食醋挥发气体的响应信号进行主成分分析,再通过线性模型判别,发现独立食醋样本的识别率达到100%。     

Alleviation of Soil Aluminum Phytotoxicity in a Typical Paddy Soil in Southern China by Using Weak Organic Acids

Weak organic acids including tartaric and citric acids were applied to a typical paddy soil in southern China to test their effects on rice in the field for three years. Their effects were also compared with top dressings of the two acids, basal application of diammonium acid phosphate, calcium carbonate, and the control. The results showed that rice grain yield of the citric acid treatment was significantly higher than that of the control and the same difference was also observed for the filled spikelets per panicle. There were no significant difference among all the treatments and the control on the accumulation of above ground dry matter. However the root dry matter, length, peroxidase activity, and white root number of citric acid treatment were significantly higher than that of the control, while no significant differences among other treatments were observed. Basal application of citric acid played a positive role on this soil.     

外源C、N干扰下吉林黑土区农田土壤动物组成与结构

2011年5月至9月作物生长期间,采用手拣法、改良干漏斗与湿漏斗三种方法,对吉林黑土区7种外源C、N干扰处理,即对照组（不施肥,CK）、0.5倍、1.0倍和2.0倍的外源C和N处理（C0.5、C1.0、C2.0、N0.5、N1.0、N2.0）农田土壤动物组成与结构进行研究。在作物生长季节,5次采样共获得土壤动物56 886只（未鉴定标本80只）,隶属3门11纲23目3亚目79科（总科）。数据分析显示,农田土壤动物主要集中在0～5 cm,基本上是随着土壤剖面加深而呈现下降趋势;与对照（CK）相比,农田土壤动物个体数与类群数随外源C浓度升高而呈递增趋势;农田大型土壤动物个体数随外源N浓度升高呈递减趋势;农田中小型土壤动物个体数随外源N浓度升高呈递增趋势。在研究时段内,土壤动物个体数与类群数于5—8月份呈现出上升趋势,9月份出现下降。方差分析显示,外源C、N干扰对农田中小型土壤动物个体数与类群数以及大型土壤动物类群数影响显著（p＜0.01）,农田土壤动物个体数与类群数在作物生长季节内变化显著（p＜0.01）。外源C、外源N分解释放出的养分与中小型土壤动物个体数、类群数以及大型土壤动物类群数密切相关。外源C有益于农田土壤动物功能群、大型与中小型农田土壤动物群落组成多样化。     

基于Retinex图像增强的不同光照条件下的成熟荔枝识别

为了满足自然环境下荔枝采摘机器人视觉定位系统的有效性和实时性的要求,针对不同光照条件的荔枝彩色图像,采用基于双边滤波的Retinex图像增强算法凸显图像中的荔枝果实和果梗,对增强处理后的图像在HSI颜色空间中进行H分量旋转的处理,再对旋转处理后的H分量进行Otsu自动阈值分割去除荔枝图像果实和果梗外的复杂背景;然后通过将双三次插值算法和传统的模糊C均值（FuzzyC-Mean）算法融合,对去背景后的荔枝图像在YCbCr颜色空间中进行Cr分量模糊聚类分割,实现荔枝果实和果梗的识别。荔枝图像的分割试验结果表明：该算法对晴天顺光、逆光、遮阴、阴天顺光等光照条件的荔枝图像能够有效地分割,对阴天弱光照、果实被遮阴条件下的荔枝也能较好的识别,并保持荔枝果实和果梗区域的完整性,4种光照条件荔枝图像分割正确率分别为96%、90%、89.3%和88.9%,成熟荔枝识别的正确率达到了90.9%,该研究为水果采摘机器人的室外作业的实时性和有效性提供指导。     

农村土地综合整治的内在驱动力分析

为充分发挥农村土地综合整治的积极作用,从理论上探究其与城乡统筹发展的关系,从历史角度对其进行定位,并进行理论升华。在对农村土地整治内涵剖析的基础上,从经济、社会、政治3个方面分析农村土地综合整治的内在驱动力,揭示了农村土地综合整治对社会经济的积极影响,进而对农村土地综合整治进行了理性思考,最后从规划管理、决策机制、产权制度、收益分配、主导主体和配套制度等方面提出相关的对策建议,该文为进一步推进农村土地综合整治提供了较好的理论支撑和实践参考。