The relationship between light intensity and nutrient uptake kinetics in six freshwater diatoms

In order to find effective measures to control diatom blooms, a better understanding of the physiological characteristics of nutrient uptake in diatoms is needed. A study of P and Si-uptake kinetics for diatom species from two light regimes was conducted at low (LL), moderate (ML) and high light intensities (HL) (2, 25 and 80 μmol photons/(m²·sec)), respectively. The results showed that P uptake of diatoms was heavily influenced by historic light regimes. P affinity changed with growth and photosynthetic activity. The lowest half saturation constant for P uptake (K_m(P)) was under HL for high-light adapted diatoms while the lowest half-saturation constant for low-light adapted diatoms was observed under LL. The Si half-saturation constant (K_m(Si)) increased with increasing light intensities for pennate diatoms but decreased for centric diatoms. Diatom volumes were correlated with the maximum Si uptake rates (V_m(Si)) at HL and K_m(Si) at ML and HL for six diatom species. Our results imply that when we assess the development of diatom blooms we should consider light intensity and cell volume in addition to ambient Si or P concentration. The relationship between light intensity and P-uptake suggests that we can find suitable methods to control diatom blooms on the basis of reducing phytoplankton activity of P-uptake and photosynthesis simultaneously.     

Pollution levels and characteristics of phthalate esters in indoor air of offices

The pollution status and characteristics of PAEs(phthalate esters) were investigated in indoor air of offices, and PAEs of both gas-phase and particulate-phase were detected in all the samples. The concentration(sum of the gas phase and the particulate phase) was4748.24 ng/m3, ranging between 3070.09 and 6700.14 ng/m3. Diethyl phthalate, dibutyl phthalate, and di(2-ethylhexyl) phthalate were the most abundant compounds, together accounting for 70% of the ∑ 6PAEs. Dividing the particulate-phase PAEs into four size ranges( 2.5, 2.5–5, 5–10, 10 μm), the result indicated that PAEs in PM2.5were the most abundant,with the proportion of 72.64%. In addition, the PAE concentration in PM2.5correlated significantly with the total particulate-phase PAEs(R2= 0.85). Thus, the amount of PAEs in PM2.5can be estimated from the total amount of particulate-phase PAEs using this proportion. In a comparison between the offices and a newly decorated study room, it was found that pollution characteristics were similar between these two places. Thus, it is implied that the PAE concentration decreased by 50% 2 yr after decorating.     

Pollution levels and characteristics of phthalate esters in indoor air in hospitals

The concentrations of phthalate esters(PAEs) in Chinese hospitals were investigated by simultaneously determining concentrations of gas- and particle-phase PAEs. PAEs were detected in two third-class first-grade hospitals, two second-class first-grade hospitals, and a community health service center. Hospital drugstores had the highest concentration(24.19 μg/m3), which was 1.54 times that of newly decorated houses. The second highest concentration was found in the transfusion rooms, averaging 21.89 μg/m3; this was followed by the concentrations of PAEs in the nurse's workstations, the wards, and the doctor's offices, with mean concentrations of 20.66, 20.0, and 16.92 μg/m3, respectively. The lowest concentrations were found in the hallways(16.30 μg/m3). Of the six different kinds of PAEs found, major pollutants included diethyl phthalates, dibutyl phthalates, butylbenzyl phthalates and di(2-ethylhexyl) phthalates, comprising more than 80% of all PAEs present.Meanwhile, a comparison between different wards showed that PAE concentrations in the maternity wards were 1.63 times higher than in the main wards. Based on known health hazards, our results suggest that the PAEs seriously influence the health of the pregnant women and babies; therefore, it is of great importance to take the phthalate concentrations in hospitals into consideration. In addition, hospital indoor air was more seriously contaminated than the air of newly decorated houses.     

FeBiO_3的制备及光催化氧化性能研究

以多胺羧酸(H5dtpa)为配体获得同时含铋和铁双金属配合物的配位分子前驱体,通过低温热分解前驱体制得Fe-Bi-O三元复合纳米氧化物粉末。采用XRD、SEM、Uv-Vis DRS、PL以及VSM等方法对所得复合氧化物进行结构和性质表征。结果表明所制备的复合物粒径在100 nm左右,主相为Fe Bi O3,在室温时表现出弱铁磁性,其弱磁性可能来自Fe Bi O3的尺寸限域效应。该复合物在200~600nm范围对光具有较强的吸收,其直接带隙λeg=2.02 e V。另外,分别以甲基橙和苯酚为降解模型,初步研究了其光催化氧化性能,于20 mg/L的弱酸性甲基橙溶液和苯酚溶液中分别添加0.25 g/L制备的Fe Bi O3粉末,甲基橙溶液光照5 h后脱色率为90%,而苯酚溶液光照4 h脱色率达100%。     

2014年-2020年江苏省城镇化的边际资源环境影响预测分析研究

利用历史数据,选取合适计算模型,定量预测了2014年-2020年江苏省城镇化边际资源环境影响,即以与城镇化发展密切相关的资源使用量或者城镇生活污染物排放量较上一年的增量,除以当年城镇化率增量,得到江苏省城镇化水平每提高一个百分点带来的资源环境影响,以期为江苏环境管理及政府综合决策提供切实有效的数据依据.结果表明:未来7年,江苏省城镇化率每上升1个百分点,增加城镇生活用水量约0.5亿立方米、城镇建设用地面积16万亩;增加城镇生活污水排放量1.15亿吨、生活氮氧化物排放量10 228吨、生活垃圾产生量36.4万吨;减少生活COD排放量7 549吨、生活氨氮排放量762吨、生活二氧化硫(SO2)排放量371吨.     

不同养殖模式池塘沉降颗粒营养物质组成特征

2012年4~10月采用自制沉降颗粒收集装置收集主养草鱼和黄颡鱼池塘生态系统中沉降颗粒物,开展了颗粒物质的垂直沉降量以及沉降颗粒中碳氮磷等营养物质的组成及沉降通量的季节变化特征的研究。结果表明:养殖可以显著提高池塘颗粒物质的垂直沉降量,主养草鱼池塘中颗粒物质垂直沉降量显著高于主养黄颡鱼池塘(p0.01),且两种养殖模式池塘颗粒物质沉降量随着养殖时间推进有显著增加的趋势。主养草鱼的池塘中颗粒物质垂直沉降量在100.39~414.66g/(m2·d)之间变化,平均为224.46g/(m2·d),主养黄颡鱼池塘中沉降颗粒物质垂直沉降量在34.14~272.91g/(m2·d)之间变化,平均为155.18g/(m2·d)。两种养殖模式沉降颗粒的碳氮磷成分在养殖周期内的变化规律不明显但具有相似的变化趋势,主养黄颡鱼池塘沉降颗粒中TN、TC、TOC和TON的含量均比同时期主养草鱼高,且均随着养殖时间的推进,沉降颗粒中碳氮磷的总量呈增加趋势。两种养殖模式池塘沉降颗粒中的C/N比值与沉积物中的C/N比值较为接近,表明沉降颗粒与沉积物营养物质来源具有一定的相似性,同时养殖系统内养殖对象与其所处环境的相互依存和相互影响对颗粒物质的产生以及沉降具有重要作用。     

Dosing low-level ferrous iron in coagulation enhances the removal of micropollutants, chlorite and chlorate during advanced water treatment

Drinking water utilities are interested in upgrading their treatment facilities to enhance micropollutant removal and byproduct control. Pre-oxidation by chlorine dioxide (ClO₂) followed by coagulation-flocculation-sedimentation and advanced oxidation processes (AOPs) is one of the promising solutions. However, the chlorite (ClO₂^–) formed from the ClO₂ pre-oxidation stage cannot be removed by the conventional coagulation process using aluminum sulfate. ClO₂^– negatively affects the post-UV/chlorine process due to its strong radical scavenging effect, and it also enhances the formation of chlorate (ClO₃^–). In this study, dosing micromolar-level ferrous iron (Fe(II)) into aluminum-based coagulants was proposed to eliminate the ClO₂^– generated from ClO₂ pre-oxidation and benefit the post-UV/chlorine process in radical production and ClO₃^– reduction. Results showed that the addition of 52.1-µmol/L FeSO₄ effectively eliminated the ClO₂^– generated from the pre-oxidation using 1.0 mg/L (14.8 µmol/L) of ClO₂. Reduction of ClO₂^– increased the degradation rate constant of a model micropollutant (carbamazepine) by 55.0% in the post-UV/chlorine process. The enhanced degradation was verified to be attributed to the increased steady-state concentrations of HO^· and ClO^· by Fe(II) addition. Moreover, Fe(II) addition also decreased the ClO₃^– formation by 53.8% in the UV/chlorine process and its impact on the formation of chloro-organic byproducts was rather minor. The findings demonstrated a promising strategy to improve the drinking water quality and safety by adding low-level Fe(II) in coagulation in an advanced drinking water treatment train.     

Microwave-assisted continuous flow phytosynthesis of silver nanoparticle/reduced graphene oxide composites and related visible light catalytic performance

The creation of an environmentally friendly synthesis method for silver nanomaterials (AgNPs) is an urgent concern for sustainable nanotechnology development. In the present study, a novel straightforward and green method for the preparation of silver nanoparticle/reduced graphene oxide (AgNP/rGO) composites was successfully developed through the combination of phytosynthesis, continuous flow synthesis and microwave-assistance. Oriental persimmon (Diospyros kaki Thunb.) extracts were used as both plant reducing and capping agents for fast online synthesis of AgNP/rGO composites. The experimental parameters were optimized and the morphologies of the prepared materials were investigated. The characterization results reveal that spherical AgNPs were quickly synthesized and uniformly dispersed on rGO sheets using the proposed online system. Fourier transform infrared spectroscopy analysis confirmed that phenols, flavonoids, and other substances in the plant extracts played a decisive role in the synthesis of AgNP/rGO composites. Using sodium borohydride (NaBH₄) degradation of p-nitrophenol (4-NP) as a model, the catalytic activity of the prepared AgNP/rGO materials was evaluated. The complete degradation of 4-NP was achieved within 12 min through the use of AgNP/rGO materials, and the composite had a much better catalytic activity than the bare AgNPs and rGO had. Compared with the conventional chemical method, our online method is facile, fast, cost-efficient, and environmentally friendly.     

基于分步热解技术的沉积岩形态汞同位素分析方法

沉积岩中的汞及其同位素常被用于指示大规模火山活动、海洋氧化还原演变等古环境演化事件,但现有研究主要聚焦总汞含量及相应的总汞同位素组成,缺少形态汞含量及其同位素组成数据,因此无法精准判别古环境中汞的来源、沉积环境和沉积过程。本研究开发了基于热解技术的沉积岩中不同形态汞的分离和同位素分析方法。首先通过沉积岩中典型形态汞（有机质、硫化物和粘土矿物结合态汞）单一标准建立热解温度曲线,然后将上述单一标准物质混合,通过调整升温速率以及形态汞采集的温度范围和时间优化热解分离方法,收集不同温度下析出的气态单质汞进行同位素分析。结果表明,分离的有机质结合态及硫化物结合态汞的δ²⁰²Hg和Δ¹⁹⁹Hg值同参考值的平均差值分别小于0.20‰和0.03‰,因此该分离方法能有效分离上述形态汞并进行汞同位素组成分析。上述方法被进一步应用于分析天然标准物质（黄红壤、水系沉积物、海相沉积岩）的汞形态及其同位素组成,验证了该方法在自然样品中的广泛适用性。