Diel changes in phytoplankton photosynthetic efficiency in Brackish waters

From 18 to 23 September 1974, investigations on the diel changes in phytoplankton were carried out in the Baltic Sea. Every 4 h, water samples were collected from 2 and 15 m, and PO₄, chlorophyll a, temperature, salinity, pH, phytoplankton composition and phytoplankton light photosynthesis relationship were determined. Continuous measurements of surface irradiance and some estimations of zooplankton were also made. P ^B (photosynthesis per unit chlorophyll a at low light levels of 2·10^-2 cal cm^-2 min^-1) revealed only random variation during the sampling period, i.e., 1.0 to 1.6 mg C (mg chlorophyll a)^-1 h^-1. P _m ^B (Light-saturated photosynthesis per unit of chlorophyll a) displayed pronounced diel fluctuations with the highest value of about 6 mg C (mg chlorophyll a)^-1 h^-1 around noon, and the lowest value of about 2.5 mg C (mg chlorophyll a)^-1 h^-1 during the night, during which latter period the value of P _m ^B was more or less constant. Reasons for the diel fluctuations are discussed, and an equation which describes these fluctuations is proposed. Using this equation, the daily phytoplankton production estimated in incubators by a previously described method can be corrected for the time of day at which samples are collected.     

The Effect of Interaction Between White-rot Fungi and Indigenous Microorganisms on Degradation of Polycyclic Aromatic Hydrocarbons in Soil

White-rot fungi applied for soil bioremediation have to compete with indigenous soil microorganisms. The effect of competition on both indigenous soil microflora and white-rot fungi was evaluated with regard to degradation of polycyclic aromatic hydrocarbons (PAH) with different persistence in soil. Sterile and non-sterile soil was artificially contaminated with ¹⁴C-labeled PAH consisting of three (anthracene), four (pyrene, benz[a]anthracene) and five fused aromatic rings (benzo[a]pyrene, dibenz[a,h]anthracene). The two fungi tested,Dichomitus squalens and Pleurotus ostreatus, produced similar amounts of ligninolytic enzymes in soil, but PAH mineralization by P. ostreatus was significantly higher. Compared to the indigenous soil microflora, P.ostreatus mineralized 5-ring PAH to a larger extent, while the indigenous microflora was superior in mineralizing 3-ring and 4-ring PAH. In coculture the special capabilities of both soil microflora and P. ostreatus were partly restricted due to antagonistic interactions, but essentially preserved. Thus, soil inoculation with P. ostreatus significantly increased the mineralization of high-molecular-weight PAH, and at the same time reduced the mineralization of anthracene and pyrene. Regarding the mineralization of low-molecular-weight PAH, the stimulation of indigenous soil microorganisms by straw amendment was more efficient than application of white-rot fungi.     

Separation of chlorinated hydrocarbons and organophosphorus, pyrethroid pesticides by silicagel fractionation chromatography and their simultaneous determination by GC-MS

A silicagel fractionation procedure for environmental sample extracts, which separates chlorinated hydrocarbons(CHCs) and organophosphorus, pyrethroid pesticides into two groups for subsequent instrumental analysis, was developed in this study. This method was achieved by optimizing the fraction cut-off volume of elution and different solvents. Using fully activated silica gel and cut-off CHCs collection after 10ml 10% dichloromethane (DCM) in n-hexane passing through the column resulted in satisfactory separation of CHCs and organophosphorus, pyrethroid pesticides. This procedure had a higher reliability for CHCs than for organophosphorus, pyrethroid pesticides, because there is a relatively reliable recovery for CHCs. This approach is less expensive due to reducing sample pre-treatment time and solvent consumption.     

长江和辽河沉积物中的多环芳烃类污染物

报道了长江和辽河沉积物中17种多环芳烃（PAHs）类污染物的含量及分布状况．所研究的长江南京段沉积物中多环芳烃总量变化范围为213.8～550.31ng/g（干重）,辽河新民段沉积物中多环芳烃总量变化范围为 27.45～198.26ng/g（干重）．测定结果表明,长江和辽河沉积物中多环芳烃具有不同的空间分布模式：长江段以南京市下游的沉积物中PAHs含量为最高,而辽河段则以新民市区的沉积物中PAHs含量为最高但总的来说,长江南京段沉积物中多环芳烃的污染水平明显高于辽河新民段沉积物所受的多环芳烃污染．     

Errors in Measurement and Counting of Particles Using Light Scattering

More efficient air sampling programs can be designed, and clearer interpretations of their data made, if important theoretical aspects are clearly understood. The choice of a sampling time is an important decision affecting the results. Empirical and theoretical calculations show that the averaging effect of sampling time attenuates responses to short period fluctuations in pollutant concentrations. Data for sulfur dioxide concentrations in six cities are examined.

The body acts as a sampling mechanism also, and concentrations inside the body fluctuate less than those outside. These damping processes are quantitatively described. A significant biological parameter is the product of the biological half-life of a pollutant and the fraction of entrance to total resistance for its passage through the body. When sampling time is four times this parameter, attenuation of significant fluctuations is about the same in both samples and the body; when it is twice the parameter, the “sampling window” transmits all significant fluctuations better than the “biological window.” Shorter sampling periods appear to give unnecessary fine detail for biological application according to this theoretical model.     

The impact of ozone depletion on skin cancer incidence: An assessment of the Netherlands and Australia

Evidence indicates that the concentration of stratospheric ozone has already decreased globally over the past several years and additional decreases are to be expected over the coming decades. A further depletion of the ozone layer would lead to an increase in the amount of ultraviolet (UV) radiation. One of the adverse effects of particularly UV-B radiation on human health would be an increase in the incidence of skin cancer. In this study an integrated model is presented to assist in assessing the changes in skin cancer incidences in relation to changes in the amount of stratospheric ozone, for the Netherlands and Australia. Although surrounded by large uncertainties, model results show that, in view of the several delay mechanisms and, additionally, the ageing of the population, future increases in skin cancer incidence cannot be reversed.     

Indicator methods to evaluate the hygienic performance of industrial scale operating Biowaste Composting Plants

The hygienic performance of biowaste composting plants to ensure the quality of compost is of high importance. Existing compost quality assurance systems reflect this importance through intensive testing of hygienic parameters. In many countries, compost quality assurance systems are under construction and it is necessary to check and to optimize the methods to state the hygienic performance of composting plants. A set of indicator methods to evaluate the hygienic performance of normal operating biowaste composting plants was developed. The indicator methods were developed by investigating temperature measurements from indirect process tests from 23 composting plants belonging to 11 design types of the Hygiene Design Type Testing System of the German Compost Quality Association (BGK e.V.). The presented indicator methods are the grade of hygienization, the basic curve shape, and the hygienic risk area. The temperature courses of single plants are not distributed normally, but they were grouped by cluster analysis in normal distributed subgroups. That was a precondition to develop the mentioned indicator methods. For each plant the grade of hygienization was calculated through transformation into the standard normal distribution. It shows the part in percent of the entire data set which meet the legal temperature requirements. The hygienization grade differs widely within the design types and falls below 50% for about one fourth of the plants. The subgroups are divided visually into basic curve shapes which stand for different process courses. For each plant the composition of the entire data set out of the various basic curve shapes can be used as an indicator for the basic process conditions. Some basic curve shapes indicate abnormal process courses which can be emended through process optimization. A hygienic risk area concept using the 90% range of variation of the normal temperature courses was introduced. Comparing the design type range of variation with the legal temperature defaults showed hygienic risk areas over the temperature courses which could be minimized through process optimization. The hygienic risk area of four design types shows a suboptimal hygienic performance.