CHANGE IN LAKE TROPHIC STATE AND INTERNAL PHOSPHORUS RELEASE AFTER ALUMINUM SULFATE APPLICATION1

ABSTRACT: Recovery of eutrophic lakes after nutrient diversion may be delayed if the lake experiences significant internal phosphorus (p) loading to the water column. A maximum dose of aluminum sulfate, defined herein, was applied to the anaerobic sediments of the hypolimnia of two dimictic Ohio lakes following septic tank diversion, with the objective of attaining long term control of the release of phosphorus to the water column from these sediments. The results were compared to a similar, downstream, untreated lake. Total phosphorus concentration declined sharply after treatment and has remained so through 1980 for both lakes, a period of 5 and 6 years of control, respectively. Internal P loading from anaerobic, hypolimnetic sediments was partially controlled by the treatment but there are other important sources, perhaps in the littoral zone, in these lakes. Algal biomass is Smaller and water transparency has increased. Both lakes became mesotrophic after treatment, as described by the Carlson (1977) trophic state index, and remain in that improved condition to date. No deleterious side effects were observed, although one lake experienced a significant decrease in diversity of planktonic microcrustacea and a lakeward extension of the macrophyte community. This method appears to be an effective and lasting means of accelerating the recovery of a eutrophic lake following nutrient diversion.     

VARIATION IN ADIRONDACK,NEW YORK,LAKEWATER CHEMISTRY AS FUNCTION OF SURFACE AREA1

ABSTRACT: Data from a recent survey conducted by the Adirondack Lake Survey Corporation were used to evaluate the influence of lake surface area on the acid-base status of lakes in Adirondack State Park, New York. Acid neutralizing capacity (ANC) in the small lakes (< 4 ha) occurred more frequently at extreme values (> 200, < 0 μeq L^?1), whereas larger lakes tended to be intermediate in ANC. Consequently, acidic (ANC ≤ 0) and low-pH lakes were typically small. The small lakes also exhibited lower Ca²⁺ concentration and higher dissolved organic carbon than did larger lakes. Lakes ≥ 4 ha were only half as likely to be acidic as were lakes ≥ 1 ha in area. These data illustrate the dependence of lake chemistry on lake surface area and the importance of the lower lake area limit for a statistical survey of lake water chemistry.     

COORDINATION OF PUBLIC AND PRIVATE AC A CASE STUDY OF LAKE RESTORATION1

ABSTRACT: The potential for joint public and private action for lake restoration is examined using Lake Apopka, Florida, as a case study. Initial calculations indicate that private incentives alone are inadequate to attract investment in a facility to grow and harvest water hyacinths for conversion to methane gas. However, the private externality of water quality improvement associated with harvesting water hyacinths provides a key linkage between the public's water quality objectives and the private gas producer's actions. In order to establish the potential basis for negotiation, the public's willingness-to-pay for environmental services associated with improved water quality is estimated and compared with the estimated subsidy required to induce private action. A conceptual framework is then presented for coordinating actions between private firms and public water management agencies in order to internalize the private externality of water quality improvement while simultaneously achieving the public and private objectives. Results indicate that the subsidization of water hyacinth production and harvesting compares favorably with alternative means of enhancing the water quality of Lake Apopka.     

A HYDRODYNAMIC MODELING STUDY TO DETERMINE THE OPTIMUM WATER INTAKE LOCATION IN LAKE PALDANG,KOREA1

A three‐dimensional hydrodynamic model was applied to Lake Paldang, South Korea. The lake has three inflows, of which Kyoungan Stream has the smallest flow rate and poorest water quality. Since all drinking water intake stations are located near the confluence of Kyoungan Stream within the lake, this contaminated tributary may have a significant impact on the quality of drinking water sources. The optimum drinking water intake location was determined from the applied model. The model was calibrated and verified using the data measured under different hydrological conditions. The model results were in reasonable agreement with the field measurements in both calibration and verification. The circulation and spreading patterns of the incoming flows in the lake, as well as their composition ratios to the drinking water intakes were determined from the model, and three alternative intake locations were proposed. The simulation results suggested that the horizontal and vertical relocations of the intake aqueduct could significantly decrease the composition ratio of the contaminated water. From this study, it was concluded that the three‐dimensional hydrodynamic model could successfully simulate the temporal and spatial mixing patterns of incoming flows and become a useful tool in determining the optimum water intake location in Lake Paldang.     

壳聚糖季铵盐的制备及其降尘性能研究

以壳聚糖为原料,对其季铵化改性制备了一种新型煤矿用环保降尘剂。主要包括单体3-氯-2-羟丙基三甲基氯化铵(CTA)的合成与壳聚糖季铵盐（HTCC）的制备。通过单因素试验研究了反应时间、反应温度、碱用量、单体配比等因素对HTCC降尘率的影响,并采用正交实验确定了最佳的工艺合成条件为:m(NaOH)/m(CTA)=1.2,m(CTA)/m(CTS)=3.5,60 ℃下反应10 h;用IR、XRD表征了HTCC。当HTCC投加量为0.4 g/L,pH=6、温度25 ℃时,煤尘去除率达到最大约为94.6%,在降尘领域中有着良好的应用前景。     

油田高压注汽盐析及预防研究

本文分析研究了油田注汽系统盐析现象及其成因和危害,并根据盐析成因探索了预防注汽盐析方法以减少甚至消除其危害。通过研究确定,采用高压旋流饱和蒸发与低压闪蒸和多效蒸集成技术是预防注汽系统盐析并减少甚至消除盐析及其造成的危害较为有效的方法。     

Gemini1231双季铵盐选择性抑制赤潮生物生长的实验

以甲藻门的东海原甲藻、塔玛亚历山大藻、裸甲藻,黄藻门的赤潮异弯藻,硅藻门的中肋骨条藻等典型赤潮生物以及绿藻门的青岛大扁藻和亚心形扁藻2种非赤潮生物为研究对象,探讨了Gemini1231双季铵盐类表面活性剂的抑藻活性.结果表明,该表面活性剂在较低浓度下(0.2～0.5 mg·L^-1时),对东海原甲藻、塔玛亚历山大藻和赤潮异湾藻等赤潮生物的生长表现出了明显的抑制作用.当该双季铵盐的浓度增至0.5 mg·L^-1以上时,对中肋骨条藻的生长也表现出了一定的抑制作用.而在相同浓度范围内,对裸甲藻和所选用的2种非赤潮生物生长的影响不明显,表现出了抑藻作用的选择性.对各海洋微藻的脂肪酸组成分析表明,该表面活性剂的选择性抑藻作用与不同海洋微藻生物膜的脂肪酸组成,尤其是其多不饱和脂肪酸的含量明显相关.     

寒旱区湖泊沉积物中固氮微生物群落特征——以包头南海湖为例

为了探究寒旱区湖泊中固氮菌的地区差异性,利用固氮菌特异性功能基因nif H对南海湖沉积物中的固氮菌进行测定并分析其与环境因子之间的相互作用关系.结果表明：不同湖区优势固氮菌群落组成存在差异,整体上由3门（蓝藻门、厚壁菌门、变形菌门）10属（蓝藻菌属、着色菌属、梭菌属、鱼腥藻属、红螺菌属、厌氧粘细菌属、荚硫菌属、柱孢藻属、根瘤菌属、假单胞菌属）组成;寒旱区特有的冰封期长、紫外线照射强等环境条件导致沉积物中的主导固氮菌为蓝藻门下的微生物.冗余分析结果表明：较高的C/N和TP是固氮菌生存的必要营养条件,可以促进固氮反应的顺利进行,较高的TN和NH₃-N含量及较低的pH值会抑制表层沉积物部分固氮微生物的生长,较高的pH值尤其会抑制鱼腥藻属、荚硫菌属、蓝藻菌属、红螺菌属的生长.本研究通过探讨寒旱区固氮微生物在沉积物中的分布来研究固氮作用的潜在功能,进一步补充其在氮循环中的重要作用.     

热盐腐蚀环境对TC11钛合金高温寿命影响规律试验研究

目的 针对发动机钛合金部件在热盐环境与工作载荷下的寿命衰减问题,开展TC11钛合金热盐腐蚀疲劳与应力腐蚀试验,研究腐蚀环境下TC11的高温寿命衰减规律与失效机理。方法 利用喷盐法制备TC11钛合金试验件,研究不同温度与应力水平对TC11腐蚀疲劳以及应力腐蚀的影响规律。利用SEM等观测手段,开展腐蚀疲劳以及应力腐蚀试样断口与表面的形貌分析,分析腐蚀环境下的失效机理。结果 热盐腐蚀环境导致TC11的寿命显著降低,对比450 ℃下无腐蚀寿命,腐蚀疲劳寿命下降了2个数量级,应力腐蚀寿命下降到不足1%,且分散性较大。观察腐蚀疲劳和应力腐蚀的试样可以发现,表面有明显的腐蚀坑,腐蚀坑底发现裂纹。结论 热盐环境下,TC11腐蚀疲劳寿命和应力腐蚀寿命都会明显下降。由于腐蚀导致钛合金试样表面产生许多腐蚀坑,在腐蚀坑局部形成近似缺口,缺口部位的应力集中是导致腐蚀疲劳寿命衰减的重要因素。腐蚀疲劳的寿命低于Kt=1的无腐蚀疲劳寿命,但是要大于Kt=3的无腐蚀疲劳寿命。     

基于基尼系数的水污染负荷分配模糊优化决策模型

从水污染负荷分配涉及的社会、经济、资源、环境和技术管理等领域筛选出6个指标,构建以基尼系数为度量标准的水污染负荷公平分配评价指标体系。基于统计数据信息的模糊性、不准确性以及不同评价指标重要性程度的差异,建立了带有弹性约束和信息熵权的水污染物总量分配模糊优化决策模型,并将其应用于巢湖流域COD和氨氮削减负荷的分摊。研究结果表明,所建模糊优化模型较好地克服了现有基尼系数分配方法的不足,是一种较为理想的分配模式。