Developments in dutch coastline management: Conclusions from the second governmental coastal report

In 1990 the Dutch government decided to stop any further long-term landward retreat of the coastline. This policy choice for a ‘dynamic preservation’ is primarily aimed at safety against flooding and at sustainable preservation of the values and interests concerning the dunes and beaches. Five years later, a first overview of the benefits and bottlenecks of the new coastal defence policy could be presented, which was published in the second governmental coastal report ‘Kustbalans 1995’ (coastal balance 1995). This consists of three elements: (1) evaluation of the implementation of ‘dynamic preservation’, (2) the consequences of several natural and anthropogenic developments in the coastal zone and (3) integrated coastal zone management. The present report describes experiences of Dutch coastline management and summarizes the main conclusions of the second governmental report. The overall conclusion of the evaluation study is that the 1990 choice for ‘dynamic preservation’ was right. Sand supply is an effective method of coastline maintenance, which also serves functional uses in the beach and dune area. However, nearly a doubling of the supply volume is necessary to compensate for sand losses in the coastal zone. A more integrated management of the coastal zone is necessary to find an equilibrium between the interests of socio-economic development and the maintenance of a natural, dynamic system.     

氮源及其添加模式对钝齿棒杆菌JDN28-75合成L-精氨酸的影响

氮源是微生物过量合成L-精氨酸的重要营养因子之一,不同氮源对钝齿棒杆菌JDN28-75合成L-精氨酸的影响研究结果表明,硫酸铵为合适的氮源.不同初始硫酸铵浓度对JDN28-75产L-精氨酸的影响研究结果表明,氮源浓度过高或不足,都会使最终L-精氨酸产量有所降低.低浓度的硫酸铵虽然有利于菌体生长,但对L-精氨酸的合成明显不利,同时糖酸转化率也较低;而高浓度的硫酸铵尽管不利于细胞的生长且造成发酵结束时残糖含量过高,却有利于细胞合成L-精氨酸且实际耗糖的糖酸转化率维持在一个较高的水平.初始硫酸铵浓度为60 g/L时,对JDN28-75菌体的生长有明显的抑制作用,最终发酵液中剩余的硫酸铵也较多(大于30 g/L),但高浓度的硫酸铵是L-精氨酸合成所必需的.在上述研究结果的基础上,确定了初始硫酸铵浓度为20 g/L条件下的补氮策略,比较了4种不同的硫酸铵补加模式对产L-精氨酸的影响,结果表明,在总的硫酸铵浓度相同的情况下,采取分批、低浓度添加氮源的方式既可以有效解除发酵前期高浓度硫酸铵对菌体生长的抑制作用,又可以有效维持发酵中后期体系中菌体合成L-精氨酸所需的较高比例的氮源.最后,在5 L全自动发酵罐中采用20 g/L的初始硫酸铵浓度,连续流加25%的氨水来控制发酵体系pH及补加氮源,L-精氨酸的产量可以达到31.7 g/L,较对照组的产酸量(26.0 g/L)提高了21.9%.图4表2参11     

微生物菌剂对不同废水的适配试验

采用15种不同的微生物菌剂,以葡萄糖配水、中药提取废水、啤酒废水、氨氮配水等为基质,分别测定了微生物菌剂的耗氧速率和厌氧比产甲烷速率,以单位菌剂对不同基质的耗氧速率和厌氧比产甲烷活性为指标,比较了各菌剂对废水的适配性.根据测定结果选择活性高的菌剂,在试验室进行了菌剂对废水的连续处理试验.结果表明,不同菌剂对同一种废水的好氧或厌氧活性不同,同种菌剂对不同废水的好氧和厌氧活性不同.废水的连续处理试验取得良好的处理效果.No.8菌剂处理葡萄糖配水,系统有机负荷最高可达(COD)10.8 g L-1d-1,COD去除率可达90%以上;采用No.10菌剂处理氨氮配水,好氧氨氮负荷可达(NH4-N )1.42 g L-1d-1,厌氧氨氮负荷可达(NH4-N )0.3 gL-1d-1,系统NH4-N 去除率可达90%以上.图2表3参8     

Ventilation or nest defense—parental care trade-offs in a fish with male care

Brood guarding animals face many critical trade-offs. Sand goby males (Pomatoschistus minutus) build nests with larger openings during low oxygen conditions, presumably to enhance ventilation. However, this may make the nest easier for egg predators to detect and harder for guarding males to defend. Manipulating oxygen level and predator presence (a small crab) for small and large males, we found support for a parental trade-off between fanning and nest defense. An increased fanning activity resulted in less time for guarding. Small males and males in low oxygen showed a higher fanning expenditure than large males and males in high oxygen, but surprisingly, filial cannibalism did not differ between these groups. Males built larger nest openings in low than high oxygen. However, males in both high and low oxygen treatments reduced their nest opening size in the presence of a predator, again indicating an important trade-off between ventilation and nest defense.     

Temporal changes in demand for and supply of nests in red bishops (Euplectes orix): dynamics of a biological market

The red bishop (Euplectes orix) is a highly polygynous and colonial weaverbird. Males construct several nests within their territories to which they try to attract females, and females are solely responsible for incubation and raising offspring. In this paper, we describe the characteristics of the red bishop’s mating system as a biological market and investigate the role of nests built by males as a traded commodity in a mating market. As timing of breeding in red bishops in arid and semi-arid zones depends on rainfall patterns which are often unpredictable, there are temporal changes in demand for and supply of nests within a breeding season, with breeding activities of males and females being highly synchronised. We found that males increased their nest-building speed with increased female breeding activity independently of rainfall, indicating that supply follows demand in this mating market. The supply of nests was always larger than the demand for nests. Construction costs for nests increased with demand for nests as indicated by shorter nest-building duration and shorter building delays between two consecutively built nests at times of high breeding activity. Males as a trading class are chosen according to the age of their nests offered, with young nests having a higher probability of being accepted by females. Furthermore, female choosiness with regard to nest age decreased when their own market value decreased, as predicted by biological market theory. The temporal changes of breeding activity together with the female preference for young and fresh nests require that males quickly adjust nest-building activity to varying female demand for new nests. However, males with a better adjustment of building speed to female breeding activity did not gain higher mating success.     

Degradation of the herbicide imazapyr by Fenton reactions

The degradation of the herbicide imazapyr has been carried out by three advanced oxidation processes involving iron ions as catalysts: Fentons reagent, photo-Fenton and electro-Fenton. We show that all processes are rapid and efficient. The kinetic rate constant was found to be k=5.4×10⁹ M^–1 s^–1. The mineralization of imazapyr is almost complete using the photo-Fenton and electro-Fenton processes.     

管道分质供水消毒副产物及其安全性评价

消毒副产物是饮用水中应主要控制的毒害物。然而，管道分质供水中消毒副产物特征及污染水平很少研究。以某一管道分质供水工程为例，对其中消毒副产物进行了详细研究。研究结果表明，管道分质供水消毒副产物在量与质上与其源水自来水存在很大差别。在管道分质供水中消毒副产物量少，一般不到自来水的1／10，且主要是一些毒性较低、与供水管材有关的溶出物。据此计算出管道分质供水由消毒副产物引起的致癌风险性一般不到其源水的1／10，其安全性大大提高。     

微电解杀藻研究

研究表明，用杀藻器进行微电解杀灭湖泊中藻类的效果显著，当进水流量１ｍ＾３／ｈ，电流密度为８．９－１１．８ｍＡ／ｃｍ６２以及当进水流量０．５ｍ＾３／ｈ，电流密度在５．９－８．９ｍＡ＝ｃｍ＾２时，杀藻效果均极好，明显破坏藻类细胞中叶绿体的结构，使藻类的光合使用明显减弱。     

上海新港河道耗氧特性研究及其综合整治措施

通过实验室试验测定，得出了上海市新港河道水体和底泥的耗氧特性曲线，分析了水体和底泥耗氧的阶段历时、阶段耗氧特性及动力学过程。在缺乏河道水质模型的情况下，利用耗氧特性曲线可以估算各个阶段的耗氧量和河道的总耗氧量，为河道充氧设备的选择提供一定的理论指导。通过计算，上海新港河道的总耗氧量约为75．7kg／d。上海宏成实业发展有限公司采用充氧曝气、投加微生物、种植水生植物等措施对河道进行了治理，实践表明，这些措施可以使新港河道的水质有明显的改善。     

An improved product-process for cleaner chrome tanning in leather processing

Severe restrictions imposed by the pollution control authorities on the disposal of chromium, total dissolved solids and chlorides in tannery effluents have forced the tanners to look for low-waste, high exhaust chrome tanning salts. An improved chrome syntan with more than 90% uptake of chrome has been developed. The new product serves both as tanning and retanning agent and can be applied directly to delimed pelts thus eliminating the conventional pickling stage in the leather processing. This modified process helps to reduce the chemical oxygen demand (COD), total dissolved solids (TDS) and chlorides in the spent tan liquor by 51, 81 and 99%, respectively. The product offers full, soft leathers having shrinkage temperature comparable to conventional chrome tanned skins. Since the developed product is highly reactive, it saves time and reduces the water requirement when compared to the conventional chrome tanning method. Thus the novel product/process developed not only has advantages in reducing pollution loads but also seems to be techno-economically viable.