烟台四十里湾营养物质产生特征及影响分析

2004年5月3日至10日,烟台四十里湾养殖区发生了由棕囊藻、夜光藻剧增而引发的赤潮,此前,在1998年8月中旬至9月中旬,该湾约五十平方公里的近岸海域,也曾发生了红色裸甲藻剧增而引发的赤潮。暴发赤潮的条件仍可认为是丰富的营养物质基础和适宜的环境条件。初步分析结果表明,赤潮形成所必须的营养物质主要是养殖粪便及其废弃物提供的,其次是陆岸生活污水提供的;环境条件是风、雨引起了水体扰动;雨过天晴水温偏高;大雨造成海水盐度降低;养殖过密,海流不畅对污染物扩散不利。     

Assessment of the Quality Characteristics of Two Lakes (Koronia and Volvi) of N. Greece

Quality parameters from 17 sampling stations from Lake Koronia and 18 from Lake Volvi were determined during sampling period of one year. Physicochemical parameters (pH, conductivity, DO) did not show remarkable differences neither between sampling sites nor between sampling periods. Nutrient concentrations (nitrogen and phosphorus compounds) were higher in lake Koronia than in Volvi showing relatively small temporal and spatial variations. As far as heavy metals in sediments, lake Koronia is considerably more polluted than Volvi lake especially with the metals Fe, Mn, Zn, Pb and Cd. The mean total concentrations of metals in lake Koronia decrease in the order Mn > Zn > Cr > Pb > Cu > Fe > Cd. The mean total concentrations of metals in lake Volvi decrease in the order Mn > Zn > Cr > Cu > Pb > Fe $>$ Cd.     

Release Characteristics of Nutrients from Polymer-coated Compound Controlled Release Fertilizers

Reliable information regarding release characteristics of nutrients from a polymer-coated controlled release fertilizer (CRF) is essential for beneficial agronomic and environmental results. Significant knowledge regarding nitrogen release from polymer-coated urea was gained while the information regarding the release of the different nutrients contained in polymer-coated compound N–P–K CRF remains limited. An experiment in which major factors affecting the differential release of nutrients from two coated compound CRF was performed in free water, water saturated sand and sand at field capacity. In general, nitrate release was the fastest, followed by ammonium and potassium whereas phosphate was significantly slower, with a rate of linear release in free water 45–70% slower than that of nitrate. Little differences were obtained for the lag periods of nitrate, ammonium and potassium release (2–10 days) under the experimental conditions, whereas for P they were one order of magnitude larger. The main factor slowing the release was assumed to be the lower solubility of ions with P being the least soluble. Release into free water was, expectedly, somewhat faster than that into saturated sand and significantly faster as compared to sand at field capacity and particularly so for P. Raising the temperature from 20 °C to 40 °C increased the rate of linear release of the different nutrients. The energy of activation, EA_rel, estimated for the linear release, of the different nutrients, was narrow ranging between 37 to 46 (KJ mol⁻¹) whereas the mean values obtained for the two CRF, differing by 50% in coating thickness, was non-significant. However, EA_rel was significantly different in different media. The complex effect of temperature on the lag period and nutrient interactions during release deserve further investigation.     

Experiments on mixing and dissipation in internal solitary waves over two triangular obstacles

A series of laboratory experiments was undertaken in a stratified two-layer fluid to investigate the energetics of the interaction between an internal solitary wave (ISW) and triangular obstacles, as well as to determine the partitioning of ISW energy and its subsequent dynamics. The ISW energy was dissipated as a result of internal breaking and turbulent mixing induced by wave instability. Tests involving different combinations of triangular obstacles in various heights and intervals and ISW of different amplitudes were performed. The wave features resulting from the interaction of an ISW and double obstacles were found to differ from those of single obstacle. The incident energy of an ISW was either reflecting back from the obstacles, dissipated through turbulent mixing, or transmitted over the double obstacles. Reduction in wave energy increased as the intervals between obstacles reduced. For two obstacles in different heights, energy dissipation was greater in the case with a higher obstacle ahead of a lower one. However, the overall performance was dependent on the relative height of the obstacles, relative water depth of the upper and bottom layer, in addition to the intervals between the obstacles.     

长期不同施肥措施对红壤水稻土有机碳和养分含量的影响

将红壤丘陵地区的荒地开垦为水田不仅可以防治土壤侵蚀,而且能增加土壤肥力,提高农田生产力.本文研究了红壤荒地垦殖为稻田,长期定位施肥15年后不同施肥措施下水稻土的有机碳和养分含量特征.结果表明:不同施肥措施包括不施肥条件下,15年水稻垦殖都提高了土壤肥力.不同施肥措施水稻土的pH提高了0.9～1.3个单位.耕层土壤有机碳含龟达到8.19～1O.13 g·kg-1,全氮含量达到0.89～1.20 g·kg-1,有机碳与全氮含最都有明显提高,且有机碳和全氮含量之间相关性极显著.水稻土耕层全磷含量在0.25～0360 g·kg-1之间,有效磷含量在2.2～20.9 mg·kg-1之间,化学磷肥的培肥效果好于有机肥(猪粪),有机无机磷肥配施能显著提高土壤全磷和有效磷库.土壤全钾还未有明显变化,土壤速效钾含量在40.4～142.5 mg·kg-1之间,不同施肥措施除氮钾肥处理外都造成了土壤速效钾含量下降,秸秆还田到目前为止对于土壤速效钾含量还没有明显作用.     

Influence of pyrolysis temperature on production and nutrient properties of wastewater sludge biochar

The important challenge for effective management of wastewater sludge materials in an environmentally and economically acceptable way can be addressed through pyrolytic conversion of the sludge to biochar and agricultural applications of the biochar. The aim of this work is to investigate the influence of pyrolysis temperature on production of wastewater sludge biochar and evaluate the properties required for agronomic applications. Wastewater sludge collected from an urban wastewater treatment plant was pyrolysed in a laboratory scale reactor. It was found that by increasing the pyrolysis temperature (over the range from 300 °C to 700 °C) the yield of biochar decreased. Biochar produced at low temperature was acidic whereas at high temperature it was alkaline in nature. The concentration of nitrogen was found to decrease while micronutrients increased with increasing temperature. Concentrations of trace metals present in wastewater sludge varied with temperature and were found to primarily enriched in the biochar.     

The role and distribution of total suspended solids in the macrotidal coastal waters of Korea

Spatial and temporal distribution patterns of total suspended solids (TSS) in the shallow and macrotidal regions of the Korean peninsula indicated there were significant changes in TSS concentrations. These were seasonally influenced by the wind, river input and tidal cycle. There were high TSS values at estuarine and river mouth stations and during low tide due to the re-suspension of bottom sediment by strong wind action during winter months, in addition the land input through rivers and strong tidal current during ebbing. Monthly mean values of TSS significantly correlated with wind speed and nitrate concentration (p < 0.01). This indicated that the resuspension of surface sediment was a more important source of TSS than the river input, and that nitrate was introduced into the water column during the resuspension process. TSS were seven times higher at low tide than in high tide. Light penetration was significantly inhibited by TSS; as >98% of incident light was absorbed within 2 m and zero photosynthetically active radiation (PAR) under 2 m in the estuarine stations during winter. Removal of heavy metals and nutrients by TSS in the water column was evident. Over 80% of the initial concentration of nutrients was removed within 10 min under various concentrations of TSS and also TSS contained significantly higher concentration of heavy metals than surface sediment. The concentration levels of nutrients and chemical oxygen demand in the west coast were comparable with the East and South Sea, even the major rivers in the Korean peninsula flow into the West Sea with major pollutant loadings into the coastal areas. High concentration of TSS is likely to contribute to the removal process of these pollutants, resulting in relatively lower levels of nutrients and organic materials in these coastal waters.     

Recovery of coagulant from water supply plant sludge and its effect on clarification

Spent coagulant in water supply plant sludge was extracted with H₂SO₄ and the efficiency of the reused coagulant was studied. The optimum pH values for coagulant extraction and clarification with the reused coagulant were 3.0–4.0 and about 6, respectively. In treating raw influent obtained from a sewage treatment plant and wastewater from a coastal landfill site, the removal of chemical oxygen demand (COD), total nitrogen, and total phosphorous with the recovered coagulant was higher than that with commercial aluminum sulfate or polyaluminum chloride. In addition, the sludge settling properties, the extra sludge mass formation, the supernatant quality, and the cost of reagents were also studied. The coagulant recovered from water supply plant sludge by H₂SO₄ extraction could be successfully reused for the clarification of domestic and food industry wastewaters.     

Biogeochemistry of Chinese estuarine and coastal waters: nutrients, trace metals and biomarkers

The dissolved and particulate trace metals in large and middle-sized Chinese rivers remain comparable with other less-disturbed world systems. Levels of nutrients in Chinese rivers are high due to erosion over the drainage area and the application of chemical fertilizers, which induces an N/P ratio up to 100–1,000. The concentrations of organic pollutants in Chinese rivers are ranked at the lower end of those of world systems; however, pollution has been identified in coastal waters from north to south of the country. In estuarine and coastal waters, dissolved trace metals illustrate a feature of remobilization, while non-conservative distribution is observed, with exceptions for iron and aluminum. Particulate trace metals demonstrate a fairly stable distribution along the salinity gradient, when the absolute concentration is normalized to reference materials. In high-turbidity estuaries, seaward nutrient flux can be increased by a factor of 5–10. Finally, the N/P ratio approaches 10–20 at the interior of the East China Sea, indicating that in coastal regions photosynthesis changes from P to N and Si limitations. Electronic Publication