Fluorescence spectroscopic studies of the effect of granular activated carbon adsorption on structural properties of dissolved organic matter fractions

This work investigated the effect of granular activated carbon adsorption （GACA） on fluorescence characteristics of dissolved organic matter （DOM） in secondary effluent, by means of excitation-emission matrix （EEM） spectra, the fluorescence regional integra- tion （FRI） method, synchronous spectra, the fluorescence index defined as the ratio of fluorescence emission intensity at wavelength 450nm to that at 500nm at excitation （λex）= 370 am, and the wavelength that corre- sponds to the position of the normalized emission band at its half intensity （λ0.5）. DOM in the secondary effluent from the North Wastewater Treatment Plant （Shenyang, China） was fractionated using XAD resins into 5 fractions： hydrophobic acid （HPO-A）, hydrophobic neutral （HPO- N）, transphilic acid （TPI-A）, transphi｜ic neutral （TPI-N） and hydrophilic fraction （HPI）. Results showed that fluorescent materials in HPO-N and TPI-N were less readily removed than those in the other fractions by GACA. The relative content of fluorescent materials in HPO-A, TPI-A and HPI decreased whereas that in HPO- N and TPI-N increased as a consequence of GACA. Polycyclic aromatics in all DOM fractions were preferen- tially absorbed by GACA, in comparison with bulk DOM expressed as DOC. On the other hand, the adsorption of aromatic amino acids and humic acid-like fluorophores exhibiting fluorescence peaks in synchronous spectra by GACA seemed to be dependent on the acid/neutralproperties of DOM fractions. All five fractions had decreased fluorescence indices as a result of GACA. GACA led to a decreased λ0.5 value for HPO-A, increased ,λ0.5 values for HPO-N, TPI-A and HPI, and a consistent λ0.5 value for TPI-N.

亚热带天然常绿阔叶林转变为杉木人工林对土壤微生物呼吸的影响

对福建省万木林自然保护区天然常绿阔叶林及其转变后的杉木林表层（0～10cm）和底层（40～60cm）土壤可溶性有机碳（DOC）、可溶性总氮（DN）、微生物生物量碳（MBC）、微生物生物量氮（MBN）、微生物呼吸（BR）及呼吸商（qCO2）进行研究，来分析亚热带森林转换对土壤微生物呼吸及土壤碳库质量的影响。结果显示：同一林分中，表层土壤的DOC、DN、MBC、MBN含量和BR均高于底层土壤，而土壤表层的qCO2却低于底层土壤。同一土层中，天然林转变为杉木林导致土壤DOC、DN、MBC、MBN含量和BR均降低，而qCO2却升高了。综上所述，底层土壤的土壤有机碳质量低于表层土壤，土壤微生物碳利用效率较低；天然林转变为人工林则导致土壤有机碳质量降低，土壤微生物碳利用效率降低。

净水厂常规与深度处理工艺对饮用水生物稳定性控制研究

以东太湖原水和X净水厂为研究对象,选择了可同化有机碳(AOC)、可生物降解溶解性有机碳(BDOC)和细菌再生长潜力(Bacterial Regrowth Potential,BRP)为生物稳定性的评判指标,探讨了净水厂常规与深度处理工艺对水中生物稳定性的贡献。结果表明:各处理单元对AOC、BDOC和BRP有不同的去除效果,预臭氧、主臭氧和后加氯工艺会引起AOC、BDOC和BRP的升高;混凝沉淀、砂滤和BAC工艺对AOC、BDOC和BRP具有较好的去除效果;常规工艺出厂水中AOC比深度处理工艺平均低10.10%,BDOC与BRP均值分别高出43.38%与25.95%。因此,在运行中应注重混凝沉淀工艺和臭氧工艺的管理与控制。

改良剂对旱地红壤微生物量碳、氮及可溶性有机碳、氮的影响

基于室内模拟培养试验,研究改良剂(生物质炭、过氧化钙)对旱地红壤微生物量碳、氮及可溶性有机碳、氮的影响。试验设置4个处理,即CK、Ca(过氧化钙,1.72g/kg)、C(生物质炭,21.46g/kg)、C+Ca。结果表明:各处理土壤微生物量碳、氮以及可溶性有机碳具有相同的变化趋势,即前期(3d内)都增加较快,在第3天达到最大值,随试验进行有所下降,配施效果优于单施。各处理可溶性有机氮在21d内缓慢增加;第21天时,C+Ca、Ca、C相比CK分别显著增加了62.1%,55.5%,40.9%;35d以后,配施(C+Ca)与单施过氧化钙(Ca)的效果显著优于单施生物质炭(C)和对照(CK)。120d培养期内,配施(C+Ca)处理能够明显提高微生物量碳、氮以及可溶性有机碳、氮的平均含量;微生物量碳的平均含量大小顺序为C+Ca>C>CK>Ca,微生物量氮的平均含量C+Ca处理显著高于其他处理;可溶性有机碳的平均含量大小顺序为C+Ca>Ca>C>CK,可溶性有机氮的平均含量C+Ca、Ca处理显著高于CK、C处理。微生物量碳、氮以及可溶性有机碳之间互为极显著正相关(P<0.01),而微生物量碳与可溶性有机氮之间呈极显著负相关。因此,生物质炭和过氧化钙能有效提高旱地红壤微生物量碳、氮及可溶性有机碳、氮,且生物质炭与过氧化钙配合施用更有助于土壤改良。