The influence of mariculture on mercury distribution in sediments and fish around Hong Kong and adjacent mainland China waters

To study the influence of mariculture on mercury (Hg) speciation and distribution in sediments and cultured fish around Hong Kong and adjacent mainland China waters, sediment samples were collected from six mariculture sites and the corresponding reference sites, 200-300 m away from the mariculture sites. Mariculture activities increased total mercury, organic matter, carbon, nitrogen and sulfur concentrations in the surface sediments underneath mariculture sites, possibly due to the accumulation of unconsumed fish feed and fish excretion. However, methylmercury (MeHg) concentrations and the ratio of MeHg to THg (% MeHg) in sediments underneath mariculture sites were lower than the corresponding reference sites. The % MeHg in sediments was negatively correlated (r = −0.579, p < 0.05) with organic matter (OM) content among all sites, indicating that OM may have inhibited Hg methylation in surface sediments. Three mariculture fish species were collected from each mariculture site, including red snapper (Lutjanus campechanus), orange-spotted grouper (Epinephelus coioides) and snubnose pompano (Trachinotus blochii). The average MeHg concentration in fish muscle was 75 μg kg⁻¹ (wet weight), and the dietary intake of MeHg through fish consumption for Hong Kong residents was 0.37 μg kg⁻¹ week⁻¹, which was lower than the corresponding WHO limits (500 μg kg⁻¹ and 1.6 μg kg⁻¹ week⁻¹).     

吉林省玉米农田保护性耕作的环境影响评价

以吉林省玉米农田4种保护性耕作为例,应用生命周期评价方法(Life Cycle Assessment,LCA)系统综合地评价吉林省玉米农田不同保护性耕作模式对环境的潜在影响。结果表明,四种保护性耕作模式的能源消耗、温室气体排放、环境酸化和富营养化的潜在环境影响分别平均比传统耕作模式减少14.62%、82.82%、15.37%和15.28%,主要由氮肥的生产及施用引起;水体毒性、土壤毒性及人体毒性则分别比传统耕作高7.40%、6.42%和7.38%,主要由农药的施用引起。综合各种环境影响类型,尽管4种保护性耕作模式较传统耕作模式能显著减缓全球变暖,但对其他环境类型的改变不明显,其中水体毒性为该种植系统中最主要的环境影响类型,富营养化次之。     

三峡工程建设前后库区城镇发展与环境变化

利用卫星遥感监测,分析三峡工程建设前后库区城镇发展类型、时空过程,揭示库区城镇变化的驱动力,探索了城镇扩展与人口城镇化关系,研究城镇环境变化特征。三峡库区城镇规模发展不均衡,库尾城市规模庞大,库中、东部区县级城市规模较小,而乡镇的比例占城镇面积24%;在过去15 a中,建城区规模扩大172%,高于全国省会城市发展水平72%;三峡库区城镇规模扩大的同时,东西城镇规模差距逐步缩小,三峡工程建设起着重要的推动作用;城镇发展以侵占了优质耕地资源为代价,耕地占城镇变化83%;城镇用地变化与人口城市化发展不平衡,城镇空间发展快于人口城镇化过程,城镇对农村人口的吸引力不及全国省会城市平均水平,在2007年城市化率低于全国水平13%,差距进一步扩大;城市空间结构发展模式受地形和土地资源的限制,城市分维数和坡度分别增加12%和104°,城市向潜山区扩展或搬迁的同时,城市空间的完整性下降     

Zinc accumulation and synthesis of ZnO nanoparticles using Physalis alkekengi L

A field survey and greenhouse experiments were conducted using Physalis alkekengi L. to investigate strategies of phytoremediation. In addition, ZnO nanoparticles were synthesized using P. alkekengi. P. alkekengi plants grew healthily at Zn levels from 50 to 5000 mg kg⁻¹ in soils. The plants incorporated Zn into their aerial parts (with mean dry weight values of 235-10,980 mg kg⁻¹) and accumulated biomass (with a mean dry weight of 25.7 g plant⁻¹) during 12 weeks. The synthesized ZnO nanoparticles showed a polydisperse behavior and had a mean size of 72.5 nm. The results indicate that P. alkekengi could be used for the remediation of zinc-contaminated soils. Moreover, the synthetic method of synthesizing ZnO nanoparticles from Zn hyperaccumulator plants constitutes a new insight into the recycling of metals in plant sources.     

Biosorption of zinc and copper from aqueous solutions by two freshwater green microalgae Chlorella pyrenoidosa and Scenedesmus obliquus

Purpose

The objective of this study was to determine the removal of zinc and copper by two freshwater green microalgae Chlorella pyrenoidosa and Scenedesmus obliquus and to investigate changes of algal ultrastructure and photosynthetic pigment.

Methods

Algal cells were exposed for 8 days to different initial zinc or copper concentrations. Heavy metal concentrations were detected by an atomic absorption spectrophotometer. Algal growth, ultrastructure, and photosynthetic pigment were analyzed by a microplate reader, transmission electron microscope, and spectrophotometer, respectively.

Results

Low zinc and copper concentrations induced increase in algal growth, whereas application of high zinc and copper concentrations suppressed the growth of both algae. High metal concentrations also decreased the photosynthetic pigments and destroyed algal cell ultrastructure. The zinc removal efficiency by both algae increased rapidly during the first day and thereafter remained nearly constant throughout the experiment. The copper removal efficiency by both algae increased slowly during the whole experimental periods. In all cultures, the quantity of both metals removed intracellularly was much lower than the adsorbed quantity on the cell surface.

Conclusions

Both strains of the microalgae had proven effective in removing zinc and copper from aqueous solutions, with the highest removal efficiency being near 100%. In addition, C. pyrenoidosa appeared to be more efficient than S. obliquus for removing copper ions. On the contrary, S. obliquus appeared to be more efficient than C. pyrenoidosa for removing zinc ions.     

Determination of o-phthalic acid in snow and its photochemical degradation by capillary gas chromatography coupled with flame ionization and mass spectrometric detection

Phthalic acid and its photochemical degradation has been determined in snow and rainwater samples collected during winters (2003-2010) in the Southeast of Massachusetts using capillary gas chromatography (GC) with flame ionization and mass spectrometric detection. Water samples were dried using a rotary evaporator and derivatized with a 14% BF₃/methanol reagent before GC analysis. The developed method proved simple and accurate. Phthalic acid was found in snow samples collected in a concentration range of 7.22-76.5 nM. The photodegradation of phthalate was carried out under 300 nm UV light. The direct photodecomposition of the acid is slow (5% h⁻¹). However, the addition of dissolved Fe(III) species at 2.0 μM accelerated the light-induced degradation of phthalic acid by 3.5 times in the atmospheric water samples. Photodegradation rates of phthalic acid increases with decreasing pH value of water samples in the range of pH 2.8-4.5.     

Fenton-双泥SBR工艺深度处理难降解反渗透浓缩液

采用Fenton试剂处理反渗透浓缩渗滤液(简称浓缩液),并探讨了双泥SBR工艺对Fenton处理后浓缩液与人工配水混合处理的可行性.结果表明,Fenton氧化对COD、TN和NH3-N的平均去除率分别为43.5%、22.5%和19.5%.对溶解性有机物(DOMs)的去除率为52.5%,其中胡敏酸(HA)、富里酸(FA)...     

固定化微生物法去除模拟渗滤液中氨氮的研究

采用固定化微生物曝气生物滤池（I-BAF）技术成功处理了模拟垃圾渗滤液,探讨了pH和溶解氧（DO）对系统脱氮性能的影响。结果表明,固定化微生物曝气生物滤池反应系统启动迅速,运行稳定,可以有效去除模拟垃圾渗滤液中的有机物和氨氮,其去除率分别达到97.1%和99.9%。在pH为7.5～8.5之间,DO 4.0 mg/L左右的条件下对模拟垃圾渗滤液中氮的去除最为有利,同步硝化反硝化效率以及总氮去除率均达到最高,分别为96.2%和94.3%。这主要是由于I-BAF系统中大孔载体提供了厌氧-兼氧-好氧的微环境,使硝化和反硝化反应在同一个反应器内发生,共同作用实现模拟垃圾渗滤液中总氮的去除。