Intrinsic Abnormalities of Keratinocytes Initiate Skin Inflammation through the IL-23/T17 Axis in a MALT1-Dependent Manner.

Increasing evidence has supported the crucial role of CARD14 in the pathogenesis of psoriasis, whereas the precise cellular signaling involved in skin physiopathology remains poorly understood. In this article, we show that neither genetic ablation of Il17a nor elimination of T cells was sufficient to restrain the skin inflammation in a CARD14-E138A-mutation-induced psoriasis-like mouse model, whereas depletion of Il23, which extremely blocked the IL-23/T17 axis, was more effective. Targeting CBM complex by conditional deletion of MALT1 or BCL10 in keratinocytes abrogated both the cutaneous and systemic inflammation of heterozygous Card14 E138A/+ mice. Selective inactivation of keratinocyte-specific MALT1 proteolytic activity strongly ameliorated the Card14 E138A/+- and Card14 ΔQ136/+-induced skin disease, which was reproduced by using the imiquimod-induced mouse model. Together, our results suggest a sequence of events under CARD14-mutation-induced psoriasis condition that keratinocyte-intrinsic activation of CBM complex initiates the skin inflammation depending on the IL-23/T17 axis. Targeting keratinocytes by inactivation of MALT1 paracaspase activity might be a promising therapeutic target for early psoriasis treatment.

Evaluating semi-analytical algorithms for estimating inherent optical properties in the South China Sea.

Using large amounts of bio-optical data collected in the South China Sea (SCS) from 2003 to 2016, this study checks the consistency between well-known semi-analytical algorithms (SAAs)-the quasi-analytical algorithm (QAA) and the default generalized inherent optical property (GIOP-DC)-in retrieving the non-water absorption coefficient (anw(λ)), phytoplankton absorption coefficient (aph(λ)) and particulate backscattering coefficient (bbp(λ)) from remote-sensing reflectance (Rrs(λ)) data at 412, 443, 490, 531, and 555 nm. The samples from the SCS are further separated into oligotrophic and mesotrophic water types for the comparison of the SAAs. Several findings are made: First, the values of anw(λ) derived from the two SAAs deliver similar performance, with R2 values ranging from 0.74 to 0.85 and 0.74 to 0.87, implying absolute percent error differences (APDs) from 37.93% to 74.88% and from 32.32% to 71.75% for the QAA and GIOP-DC, respectively. The QAA shows a value of R2 between 0.64 and 0.91 and APDs between 43.57% to 83.53%, while the GIOP-DC yields R2 between 0.76 to 0.89 and APDs between 44.65% to 79.46% when estimating aph(λ). The values of bbp(λ) derived from the QAA are closer to the in-situ bbp(λ) values, as indicated by the low values of the normalized centered root-mean-square deviation and normalized standard deviation, which are close to one. Second, a regionally tuned estimation of aph(λ) is proposed and recommended for the SCS. This consistency check of inherent optical properties products from SAAs can serve as reference for algorithm selection for further applications, including primary production, carbon, and biogeochemical models of the SCS, and can provide guidance for improving aph(λ) estimation.

Linear ubiquitin chain induces apoptosis and inhibits tumor growth.

Ubiquitination of proliferating cell nuclear antigen (PCNA) plays an important role in DNA damage response. Ectopic expression of PCNA fused at either terminus with ubiquitin (Ub) lacking two C-terminal glycine residues induces translesion DNA synthesis which resembles synthesis mediated by PCNA monoubiquitination. PCNA fused with Ub containing the C-terminal Gly residues at the C-terminus can be further polyubiquitinated in a Gly-dependent manner, which inhibits cell proliferation and induces ATR-dependent replication checkpoint. In this study, we surprisingly found that PCNA fused to a head-to-tail linear Ub chain induces apoptosis in a Ub chain length-dependent manner. Further investigation revealed that the apoptotic effect is actually induced by the linear Ub chain independently from PCNA, as the Ub chain fused to GFP or an epitope tag still efficiently induces apoptosis. It is revealed that the artificial linear Ub chain differs from endogenously encoded linear Ub chains in that its Ubs contain a Ub-G76S substitution, making the Ub chain resistant to cleavage by deubiquitination enzymes. We demonstrated in this study that ectopic expression of the artificial Ub chain alone in cultured human cancer cells is sufficient to inhibit tumor growth in a xenograft mouse model, making the linear Ub chain a putative anti-cancer agent.

Estimation of suspended particulate matter in turbid coastal waters: application to hyperspectral satellite imagery.

An empirical algorithm is proposed to estimate suspended particulate matter (SPM) ranging from 0.675 to 25.7 mg L-1 in the turbid Pearl River estuary (PRE). Comparisons between model predicted and in situ measured SPM resulted in R2s of 0.97 and 0.88 and mean absolute percentage errors (MAPEs) of 23.96% and 29.69% by using the calibration and validation data sets, respectively. The developed algorithm demonstrated the highest accuracy when compared with existing ones for turbid coastal waters. The diurnal dynamics of SPM was revealed by applying the proposed algorithm to reflectance data collected by a moored buoy in the PRE. The established algorithm was implemented to Hyperspectral Imager for the Coastal Ocean (HICO) data and the distribution pattern of SPM in the PRE was elucidated. Validation of HICO-derived reflectance data by using concurrent MODIS/Aqua data as a benchmark indicated their reliability. Factors influencing variability of SPM in the PRE were analyzed, which implicated the combined effects of wind, tide, rainfall, and circulation as the cause.

Retrieval of phytoplankton cell size from chlorophyll a specific absorption and scattering spectra of phytoplankton.

Phytoplankton cell size is an important property that affects diverse ecological and biogeochemical processes, and analysis of the absorption and scattering spectra of phytoplankton can provide important information about phytoplankton size. In this study, an inversion method for extracting quantitative phytoplankton cell size data from these spectra was developed. This inversion method requires two inputs: chlorophyll a specific absorption and scattering spectra of phytoplankton. The average equivalent-volume spherical diameter (ESDv) was calculated as the single size approximation for the log-normal particle size distribution (PSD) of the algal suspension. The performance of this method for retrieving cell size was assessed using the datasets from cultures of 12 phytoplankton species. The estimations of a(λ) and b(λ) for the phytoplankton population using ESDv had mean error values of 5.8%-6.9% and 7.0%-10.6%, respectively, compared to the a(λ) and b(λ) for the phytoplankton populations using the log-normal PSD. The estimated values of CiESDv were in good agreement with the measurements, with r2=0.88 and relative root mean square error (NRMSE)=25.3%, and relatively good performances were also found for the retrieval of ESDv with r2=0.78 and NRMSE=23.9%.

[Experiment on pruning of Cistanche deserticola inoculated in artificial Haloxylon ammodendron forest].

At present, the objective of cutting and pruning Cistanche deserticola is to harvest in successive years and enhance the harvesting yield and quality of C. deserticola in the process of the artificial cultivating C. deserticola. An experiment was conducted focusing on cutting and pruning C. deserticola in artificial forests of Haloxylon ammodendron drip-irrigated with saline water at the hinter-land of the Taklimakan desert, according to different growth stages and lengths. The results were following: (1) The effect of cutting on C. deserticola was similar to that of pruning, which resulted in three kinds of morphological types, not related to the bloom and size of C. deserticola. (2) The growth forms were diversified after pruning. Among them, there had sprouting new body, died or maintaining life with no sprouting, mildewed on its surface layer, etc. However, some of new bodies were sprouting from the lower part of the old body. The death rate of bloomed C. deserticola was higher than that of the underground, and the death rate of the 40 cm in stubble height for C. deserticola was higher than those with the stubble height of 20 cm and 5 cm. (3) Most of the diameter of living C. deserticola after pruning was increasing, but some of them changed little. (4) The mildew and rot of C. deserticola and the broken of the roots of the H. ammodendron and the fallen of the point of the inoculated when it was dug, which would cause the death of the C. deserticola. On the other, the yield-increasing effect and the economic benefit of the techniques of the pruning of Cistanche would need further research and evaluate. Therefore, the application of this technique needs to be cautious.

Novel method for quantifying the cell size of marine phytoplankton based on optical measurements.

Phytoplankton size is important for the pelagic food web and oceanic ecosystems. However, the size of phytoplankton is difficult to quantify because of methodological constraints. To address this limitation, we have exploited the phytoplankton package effect to develop a new method for estimating the mean cell size of individual phytoplankton populations. This method was validated using a data set that contained simultaneous measurements of phytoplankton absorption and cell size distributions from 13 phytoplankton species. Comparing with existing methods, our method is more efficient with good accuracy, and it could potentially be applied in current in situ optical instruments.

Perioperative nutritional risk and its influencing factors in patients with oral cancer: a longitudinal study.

Introduction: We aimed to investigate the nutritional risk status and dynamic changes in patients with perioperative oral cancer at different stages and analyze the factors influencing nutritional risk and the correlation among body mass index, nutrition-related symptoms, and nutritional risk. Methods: In total, 198 patients with oral cancer who were hospitalized in the Head & Neck Surgery Departments of a tertiary cancer hospital in Hunan Province, China, from May 2020 to January 2021, were selected as participants. The Nutritional Risk Screening 2002 scale and Head and Neck Patient Symptom Checklist were used to assess patients on admission day, 7 days post-surgery, and 1 month post-discharge. Multivariate analysis of variance, paired t-test, and generalized estimating equation were used to analyze the trajectory and influencing factors of nutritional risk in patients with perioperative oral cancer. Spearman's correlation analysis was used to explore the correlation among body mass index, symptoms, and nutritional risk. Results: The nutritional risk scores of patients with oral cancer at the three time points were 2.30 ± 0.84, 3.21 ± 0.94, and 2.11 ± 0.84, respectively, and the differences were significant (p < 0.05). The incidences of nutritional risk were 30.3, 52.5, and 37.9%, respectively. The factors influencing nutritional risk included education level, smoking status, clinical stage, flap repair, and tracheotomy (ß = -0.326, 0.386, 0.387, 0.336, and 0.240, respectively, p < 0.05). Nutritional risk was negatively correlated with body mass index (rs = -0.455, p < 0.01) and positively correlated with pain, loss of appetite, sore mouth, bothersome smells, swallowing difficulty, taste changes, depression, chewing difficulty, thick saliva, and anxiety (rs = 0.252, 0.179, 0.269, 0.155, 0.252, 0.212, 0.244, 0.384, 0.260, and 0.157, respectively, p < 0.05). Conclusion: The incidence of nutritional risk in patients with perioperative oral cancer was high, and the trajectory of nutritional risk changed over time. Strengthening the nutritional monitoring and management of postoperative patients or those with low education level, advanced-stage cancer, flap repair, tracheotomy, and low body mass index; strengthening tobacco control management; and controlling nutrition-related discomfort symptoms in perioperative oral cancer patients are necessary.

Perioperative change trajectories and predictors of swallowing function and swallowing-related quality of life in patients with oral cancer: a longitudinal observational study.

OBJECTIVE: To determine change trajectories and predictors of swallowing function and swallowing-related quality of life (QoL) in perioperative patients with oral cancer. DESIGN: Longitudinal observational study. SETTING: A tertiary cancer hospital in Hunan Province, China. PARTICIPANTS: Patients with oral cancer scheduled for surgery were recruited using convenience sampling. PRIMARY AND SECONDARY OUTCOME MEASURES: The primary outcomes were swallowing function and swallowing-related QoL. The secondary outcomes were the predictors of the swallowing function and swallowing-related QoL. METHODS: The participants completed the sociodemographic and clinical data questionnaire, Nutritional Risk Screening 2002 and MD Anderson Dysphagia Inventory before surgery, 7 days after operation and 1 month after operation. Data were analysed using t-test, analysis of variance and generalised linear models. RESULTS: Among 138 participants who completed all the three surveys, 41 (29.71%) had moderate to severe dysphagia before surgery. Swallowing function and swallowing-related QoL changed over time, showing the trend of decline first and then increase. Preoperative swallowing function and swallowing-related QoL were affected by sex, lymphocyte level, preoperative nutritional risk and primary tumour site. At 7 days postoperatively, tracheotomy affected swallowing function. At 1 month postoperatively, age and marital status influenced swallowing function, whereas age, type of job and preoperative nutritional risk influenced swallowing-related QoL. CONCLUSIONS: Our study demonstrates that perioperative patients with oral cancer generally faced swallowing disorders, especially in the acute phase after surgery. Healthcare providers should pay attention to the swallowing function of perioperative patients with oral cancer, especially those with preoperative nutritional risk, tongue tumour, tracheotomy, age <60 years, and no spouse and the employed patients, and provide available interventions, such as swallowing and nutritional therapy, as early as possible to improve their swallowing function. Meanwhile, doctors should recommend the most evidence-based treatment options, such as reconstruction or not, preoperative chemotherapy or not, to patients.

Variations in the optical scattering properties of phytoplankton cultures.

The scattering and backscattering coefficients of 15 phytoplankton species were determined in the laboratory using the acs and BB9 instruments. The spectral variability of scattering properties was investigated and the homogenous sphere model based on Mie theory was also evaluated. The scattering efficiencies at 510 nm varied from 1.42 to 2.26, and the backscattering efficiencies varied from 0.003 to 0.020. The backscattering ratios at 510 nm varied from 0.17% to 0.97%, with a mean value of 0.58%. The scattering properties were influenced by algal cell size and cellular particulate organic carbon content rather than the chlorophyll a concentration. Comparison of the measured results to the values estimated using the homogenous sphere model showed that: (1) The model could well reproduce the spectral scattering coefficient with relative deviations of 5-39%, which indicates that cell shape and internal structure have no significant effects on predicting the scattering spectra; (2) Although the homogenous sphere model generally reflected the spectral trend of backscattering spectra for most species, it severely underestimated the backscattering coefficients by 1.4-48.6 folds at 510 nm. The deviations for Chaetoceros sp. and Microcystis aeruginosa were large and might be due to algal cell chain links and intracellular gas vacuoles, respectively.

[Variations in the optical absorption and attenuation properties of cultured phytoplankton and their relationships with cell size].

The spectral absorption and attenuation coefficients of 16 phytoplankton species were measured in the laboratory using acs instrument. Ancillary measurements included particle size distribution and chlorophyll a concentration (Chl a). The results indicated that both algal cell size and Chl a were the two major factors dominating the magnitudes of the spectral absorption and attenuation coefficients. The spectral behaviors of attenuation spectra were dominated by algal cell size, the relationship of them didn't follow the monotonic function. Both the ratio of absorption in blue and red waveband and the spectral slope of absorption coefficient were influenced by the product of algal cell density and squares of cell size rather than algal cell size alone. The relationship between algal cell size and both absorption and attenuation spectra would be interpreted by Mie theory for homogenous sphere, which imply that the heterogeneity and non-spherical shape in algal cell morphology and internal structure have little effect on the inherent association among them.

Perioperative symptom burden and its influencing factors in patients with oral cancer: A longitudinal study.

Objective: The aim of this study was to identify the symptom burden of perioperative oral cancer patients, its trajectory, and the factors influencing it. Methods: A longitudinal, repeated measures design with consecutively identified sampling was used to recruit oral cancer patients scheduled for surgical treatment. Data collected included sociodemographic and clinical information, nutritional risk by the Nutritional Risk Screening 2002, and symptom burden by M. D. Anderson Symptom Inventory-Head and Neck Module (MDASI-HN) at preoperation, 7 days postsurgery, and 1 month postsurgery. Results: Perioperative patients with oral cancer had multiple symptoms. Pain, difficulty swallowing/chewing, and mouth/throat sores (61.9%-76.1%) were the most prevalent symptoms before surgery. The symptom burden was the highest at 7 days after surgery, with the most prevalent symptoms, including difficulty swallowing/chewing, difficulty with voice/speech, and problems with mucus (87.8%-95.4%). At 1 month postsurgery, the 3 main symptoms were numbness or tingling, difficulty swallowing/chewing, and difficulty with voice/speech (all 87.8%). Treatment stage, job, comorbidity, cancer stage, adjuvant therapy, and Nutritional Risk Screening 2002 score were correlated with symptom burdens. Conclusions: Our study illustrates that perioperative oral cancer patients have multiple symptoms and high symptom burdens, especially at 7 days postsurgery, with prominent symptoms and symptom burdens varying with the treatment stage.

Effect Analysis of Positive Molecular Therapy in Surgical Nursing Based on Data Transformation Analysis.

This paper briefly introduces the concept, classification, and mechanism of action of positive thinking therapy; reviews the application and research progress of positive thinking therapy in perioperative care of surgical patients at home and abroad; presents the shortcomings and defects in the development; and aims to provide intervention, reference, and basis for the development of positive thinking therapy in perioperative care of surgical patients. One hundred and eight patients are undergoing PCI surgery in our cardiology department; 50 patients undergoing percutaneous coronary intervention were selected as the control group, and 58 patients undergoing percutaneous coronary intervention were selected as the observation group. Traditional health education was employed in the control group, while empowerment education based on timing theory was used in the observation group. The two groups were observed and compared in terms of self-care competence, anxiety and depression, medication adherence score, and exercise adherence. Conclusion. Empowerment education based on timing theory can improve self-care ability of PCI patients, reduce patients' anxiety and depression, and improve patients' medication and exercise compliance.

Characteristics of subsurface chlorophyll maxima during the boreal summer in the South China Sea with respect to environmental properties.

Characterizing the vertical distribution of chlorophyll a in the water column in each oceanic region is crucial for accurate assessment of depth-integrated phytoplankton biomass. In this study, the characteristics of the subsurface chlorophyll maximum (SCM) in the South China Sea (SCS) during the boreal summer were investigated by using bio-optical and hydrological data collected during four cruises from 2008 to 2015. During the boreal summer, a well-developed SCM layer was found to be a prominent feature in the SCS, with the thickness, depth, and magnitude of the SCM exhibiting large spatial variability. The vertical position of the SCM varied between 11 and 99 m, with an average value of 53 m. Light attenuation played a fundamental role in determining the depth (ZSCM) and magnitude of the SCM (Chlmax), as reflected by their relationships with the euphotic zone depth (Zeu). However, because significant positive correlations were found between ZSCM and the depth of potential density at 23 kg m-3 (Zσ=23), physical processes were inferred to be more important in modulating the fluctuation of ZSCM, especially in open-ocean areas. Anticyclonic eddies, which act to deepen the nutricline by means of isopyncnal displacement, may play a role in aggravating nutrient limitation in the SCM layer, which leads to deepening of ZSCM, weakening of Chlmax, and a fall in the total integrated chlorophyll a within the euphotic layer (ChlintZeu). Knowledge of ocean physical conditions and the variability of ZSCM should be taken into consideration to improve the accuracy of ChlintZeu estimates based on the surface chlorophyll a concentration (Chlsurf), especially when Chlsurf is very low. Our assessment of SCM parameters provides the basis for a better understanding and quantification of their role in primary production estimation within the SCS.

Assessing responses of phytoplankton to consecutive typhoons by combining Argo, remote sensing and numerical simulation data.

Typhoons can affect various hydrodynamic processes, such as upwelling, vertical mixing, and entrainment, which in turn influence the growth and redistribution of phytoplankton. In this study, responses of phytoplankton to consecutive typhoons Barijat and Mangkhut in summer 2018 in the northern South China Sea (NSCS) were investigated through combining remote sensing, numerical simulation, and Argo profile data. Variations of physical and biological properties induced by Barijat and Mangkhut over the study region were observed. Regional chlorophyll-a (Chla) algorithms over the NSCS were assessed in order to accurately quantify typhoon-induced variations of phytoplankton. Chla concentration decreased slightly over the region of interest after the passage of Barijiat while increased obviously after the passage of Mangkhut. Satellite-derived Chla increased by ~63% on average after the consecutive typhoons. Responses of phytoplankton size structure (PSS) were further investigated over the continental shelf and the deep ocean in the NSCS. For the continental shelf, the increment of micro- and nano-phytoplankton was about 1.5-fold as high as that of pico-phytoplankton, compared with a 0.5-fold increment for the deep ocean. This study attested the discrepant responses of different phytoplankton size classes to typhoons. It was of great significance to expand our understanding of ocean physical and ecological responses to extreme phenomena. Our finding underscores the potential of remote sensing to investigate typhoon-induced variation of PSS and could be the key to accurately assess typhoon-induced carbon fluxes, primary production, and potential fishing ground in the future.

Ultraviolet light-emitting diode irradiation induces reactive oxygen species production and mitochondrial membrane potential reduction in HL-60 cells.

OBJECTIVE: Ultraviolet light-emitting diode (UV LED) irradiation at 280 nm has been confirmed to induce apoptosis in cultured HL-60 cells, but the underlying mechanisms remain unclear. This study aimed to investigate the effects of 280 nm UV LED irradiation on reactive oxygen species (ROS) production and mitochondrial membrane potential (MMP) in HL-60 cells. METHODS: HL-60 cells were irradiated with 0, 8, 15, or 30 J/m2 of 280 nm UV LED and incubated for 2 hours. The intracellular ROS levels were assessed using the fluorescent probe 2'-7'-dichlorodihydrofluorescein diacetate (DCFH-DA) and a fluorescence plate reader. MMP was determined by flow cytometry using 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazol-carbocyanine iodide (JC-1) staining. The apoptosis-related proteins Bax and Bcl-2 were evaluated by western blot. RESULTS: UV LED irradiation at 280 nm induced a dose-dependent increase in ROS production and loss of MMP, and it activated apoptosis at irradiation doses of 8 to 30 J/m2. These results were consistent with a previous apoptosis study from the authors' group. CONCLUSION: Enhanced ROS production and mitochondrial depolarization are two distinct but interacting events, and both are involved in UV LED-induced apoptosis in HL-60 cells.

[Reflectance of sea ice in Liaodong Bay].

In the present study, the relationships between sea ice albedo and the bidirectional reflectance distribution in Liaodong Bay were investigated. The results indicate that: (1) sea ice albedo alpha(lambda) is closely related to the components of sea ice, the higher the particulate concentration in sea ice surface is, the lower the sea ice albedo alpha(lambda) is. On the contrary, the higher the bubble concentration in sea ice is, the higher sea ice albedo alpha(lambda) is. (2) Sea ice albedo alpha(lambda) is similar to the bidirectional reflectance factor R(f) when the probe locates at nadir. The R(f) would increase with the increase in detector zenith theta, and the correlation between R(f) and the detector azimuth would gradually increase. When the theta is located at solar zenith 63 degrees, the R(f) would reach the maximum, and the strongest correlation is also shown between the R(f) and the detector azimuth. (3) Different types of sea ice would have the different anisotropic reflectance factors.

A Bacterium Isolated From Soil in a Karst Rocky Desertification Region Has Efficient Phosphate-Solubilizing and Plant Growth-Promoting Ability.

Phosphorus in the soil accessible to plants can easily be combined with calcium ion, the content of which is high in karst rocky desertification (KRD) regions, thereby resulting in a low utilization efficiency of phosphorus. The application of phosphate-solubilizing bacteria (PSB) from the KRD region would facilitate enhanced phosphate availability in the soil. In the present study, the strains belonging to Acinetobacter, Paraburkholderia, and Pseudomonas with efficient phosphate-solubilizing ability were isolated from fruit tree rhizosphere soils in KRD regions. Particularly, Acinetobacter sp. Ac-14 had a sustained and stable phosphate-solubilizing ability (439-448 mg/L, 48-120 h). Calcium carbonate decreased the phosphate-solubilizing ability in liquid medium; however, it did not affect the solubilization index in agar-solidified medium. When cocultivated with Arabidopsis thaliana seedling, Ac-14 increased the number of lateral roots, fresh weight, and chlorophyll content of the seedlings. Metabolomics analysis revealed that Ac-14 could produce 23 types of organic acids, majorly including gluconic acid and D-(-)-quinic acid. Expression of Ac-14 glucose dehydrogenase gene (gcd) conferred Pseudomonas sp. Ps-12 with a sustained and stable phosphate-solubilizing ability, suggesting that the production of gluconic acid is an important mechanism that confers phosphate solubilization in bacteria. Moreover, Ac-14 could also produce indole acetic acid and ammonia. Collectively, the isolated Ac-14 from KRD regions possess an efficient phosphate-solubilizing ability and plant growth-promoting effect which could be exploited for enhancing phosphorus availability in KRD regions. This study holds significance for the improvement of soil fertility and agricultural sustainable development in phosphorus-deficient KRD regions.

[Decomposing total suspended particle absorption based on the spectral correlation relationship].

A model for estimating the contributions of phytoplankton and nonalgal particles to the total particulate absorption coefficient was developed based on their separate spectral relationships, and a constrained nonlinear optimization code was used to realize the spectral decomposition. The spectral absorption of total particulate matter including phytoplankton and nonalgal particles was measured using the filter-pad method during two cruises in autumn in Northern South China Sea. Using the dataset collected in 2004, the spectral relationships of particle absorption coefficients were examined and the results showed that the phytoplankton absorption coefficients at various wavebands could be well expressed by aph (443) as the second-order quadratic equations; and the nonalgal particle absorption (aNAP(lambda)) could be successfully modeled with the simple exponential function. Based on these spectral relationships, we developed this partition model. The model was tested using the independently measured absorption by phytoplankton and nonalgal materials which were obtained in 2005 from the same area. The test results showed that the computed spectral absorption coefficients of phytoplankton and nonalgal particles were consistent with in situ measurement. Good correlations were fo und between the comput ed phytoplankton absorption coefficient and the measured value,with the determination coefficients (r2) being higher than 0.97 and slopes being around 1.0; and the RMSE values could be controlled within 17% over the main absorption wavebands such as 443, 490 and 683 nm. Compared with the other two existing models from Bricaud et al. and Oubelkheir et al., this method shows many advantages for local applications. Moreover, this model does not need any information about pigment concentrations and the selected spectral bands are consistent with the ocean color satellite sensor. This method could also be used in the total absorption coefficient decomposition which provides much insight into the phytoplankton absorption retrieval from in situ measurement and ocean color remote sensing data.

Measuring natural phytoplankton fluorescence and biomass: a case study of algal bloom in the Pearl River estuary.

A moored optical buoy was deployed in the Pearl River estuarine waters for a 15-day period. A four-day algal bloom event occurred during this study period. Both chlorophyll a concentration and algal cell density (a proxy for biomass) changed dramatically before and after the event. The chlorophyll concentration at a 2.3m depth rose from 5.15 mg/m(-3) at 15:00 h on August 19 to 23.62 mg/m(-3) at 9:00 h on August 21, and then decreased to 3.24 mg/m(-3) at 15:00 h on August 24. The corresponding cell density ranged from 1.57 x 10(5) to 1.76 x 10(6)cells/L. We used normalized fluorescence line height (NFLH) and normalized fluorescence intensity (NFI) in order to determine fluorescence activity. Combined with the in situ sampling dataset, we were able to correlate natural fluorescence (NFLH and NFI) with chlorophyll a concentrations, and found correlation coefficients of 0.72 and 0.75, respectively. We also found correlations between natural fluorescence and cell density, with correlation coefficients of 0.71 and 0.65, respectively. These results indicate that applying continuous time series of natural fluorescence can reflect changes in biomass. This technique will prove extremely useful for in situ and real-time observations using an optical buoy. Although there are still problems to solve in the real-time observation of natural fluorescence in algal bloom events, we discuss the primary factors affecting fluorescence signals and suggest possible methods for mitigating these issues.