Absorptions by non-phytoplankton particles and phytoplankton, and chromophoric dissolved organic matter (CDOM) were measured at 50 sites in large, shallow, Lake Taihu in winter and summer 2006 to study their seasonal and spatial variations, and their relative contributions to total absorption. The CDOM absorption was significantly higher in winter than in summer, due to degradation and release of fixed carbon in phytoplankton and submerged aquatic vegetation (SAV). The hyperbolic model was used to model the spectral absorption of CDOM, and the mean spectral slope of 6.38 nm -1 was obtained. At most sites, the spectral absorption of non-phytoplankton particles was similar to that of the total particles, demonstrating that the absorption of the total particles is dominated by the absorption of non-phytoplankton particles. In summer, phytoplankton absorption increased markedly, due to frequent algal blooms especially in Meiliang Bay. In winter, the significant increase in non-phytoplankton particle absorption resulted from the increase of inorganic particulate matter caused by sediment resuspension. Strong linear relationships were found between a d (440) and total suspended matter (TSM), organic suspended matter (OSM), and inorganic suspended matter (ISM). Strong linear relationships were also found between a ph (440), a ph (675) and chlorophyll a (Chl-a) concentration. The total relative contributions of non-phytoplankton particles over the range of photosynthetically active radiation (PAR) (400-700 nm) were 48.4 and 79.9% in summer and winter respectively. Non-phytoplankton particle absorption dominated the total absorption, especially in winter, in Lake Taihu, due to frequent sediment resuspension in the large shallow lake as a result of strong windy conditions. The results indicate that strong

Photochemical degradation of chromophoric-dissolved organic matter (CDOM) by UV-B radiation decreases CDOM absorption in the UV region and fluorescence intensity, and alters CDOM composition. CDOM absorption, fluorescence, and the spectral slope indicating the CDOM composition were studied using 0.22-lm-filtered samples of Meiliang Bay water from Lake Taihu that were exposed to short-term (0-12 h) simulated UV-B radiation and long-term (0-12 days) natural solar radiation in summer. CDOM absorption coefficient and fluorescence decreased with increasing exposure time, which relates to the amounts of absorbed light energy. The decreases of CDOM absorption and normalized fluorescence corresponded to first order kinetics reactions. Different decreases of CDOM absorption and fluorescence at different wavelengths suggested that the composition of CDOM changed when it absorbed ultraviolet radiation. Photochemical degradation increased the spectral slope during 275-295 nm region (S 275-295 ) but decreased the spectral slope during 275-295 nm region (S 350-400 ). The slope ratio S R (S 275-295 :S 350-400 ) increased in the photochemical process, which could be used as an indicator of photobleaching and composition change of CDOM. Our results show that photochemical degradation is important in the cycling of CDOM, which indicated change in the composition of CDOM.

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For this work, the aim was to investigate the adsorption of the tannic acid (TA)/sodium caseinate (SC) nanocomplexes at the air/water interface and then to research its relationship with foam properties. First, nanocomplexes were prepared in a different mass ratio of TA and SC. The bulk behavior of nanocomplexes was evaluated by dynamic light scattering (DLS), signal-intensifying fluorescence probe (ANS), etc. As the concentration of TA increased, the z-average siameter ( D ) of TA/SC nanocomplexes decreased gradually and the negative charge increased. Meanwhile, the surface hydrophobicity ( S) of the SC also decreased after the addition of TA. The interfacial properties were determined by dynamic surface tension and dilational rheology. The presence of polyphenols decreased the surface pressure (π) that resulted in poor foamability. However, the elastic ( E) component of the dilational modulus of films also increased as polyphenols concentration increased, which gave rise to admirable foam stability. The contribution of polyphenols to stabilize foam columns may be caused by interfacial interaction between proteins and polyphenols.

The soil environment is an important sink for penicillin antibiotics released from animal manure and wastewater, but the mineral-catalyzed transformation of penicillins in soil has not been well studied. To simulate this environmental process, we systematically investigated the behavior of penicillin G and amoxicillin, the two most widely-used penicillin antibiotics, in the presence of goethite and metal ions. The results demonstrated that Zn ions significantly promoted the hydrolysis of penicillins in goethite suspensions, as evidenced by the degradation rate nearly 3 orders of magnitude higher than that of the non-Zn-containing control. The spectroscopic analysis indicated that the specific complexation between penicillins, adsorbed Zn, and goethite was responsible for the enhanced degradation. Metastable interactions, involving hydrogen bonds between carbonyl groups in the β-lactam ring and the double/triple hydroxyl groups on goethite surface, and coordination bonding between carboxyl groups and surface irons were proposed to stabilize the ternary reaction intermediates. Moreover, the surface zinc-hydroxide might act as powerful nucleophile to rapidly rupture the β-lactam ring in penicillins. This study is among the first to identify the synergic roles of Zn ion and goethite in facilitating penicillin degradation and provides insights into β-lactam antibiotics to assess their environmental risk in soil.

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