Assessment of China's economic loss resulting from the degradation of agricultural land in the end of 20th century

Land degradation is a consequence stemming from both natural processes and social economic activities. On the bases of analyzing general situation of agricultural land degradation in China, the monetary estimating methods such as market value method and shadow engineering method were used to quantitatively assess the economic loss resulting from land deterioration. Results showed that the economic loss in 1999 was 326.8l billion RMB Yuan, which accounted for 4.1% of GDP in the same year of China. If taking five items namely farmland conversion, soil erosion, salinization, decline in reservoir functions, and siltation in waterways and, comparing with that in 1992, the percentage of economic loss to GDP has increased by 1.5 in the only 7 years.     

温度对底泥中硝基苯的自然衰减及强化降解的影响

利用人工配制的2种不同浓度(1000和100μg·kg-1)的硝基苯污染底泥,研究了4℃和20℃ 2种温度条件下硝基苯的自然衰减和生物强化降解情况.结果表明,2种浓度的硝基苯在4℃时有氧、缺氧条件下均无降解,20℃时有氧和缺氧条件下均有明显的降解;添加筛选出的混合降解菌可快速降解处于泥浆状的硝基苯.因而,对于受到硝基苯污染的底泥修复可充分考虑其自然衰减能力,降低修复成本.     

剩余污泥的电化学稳定实验研究

研究了电化学法对城市剩余污泥稳定化的影响。结果表明,以钛涂钌电极为阳极、不锈钢板为阴极,在极板间距为2cm,电压为20V,曝气量为3L/h的条件下,电解20min,其挥发性悬浮物质(VSS)去除效率可达39%,加酸调节pH值至4左右时,其电解效率则可达40%以上,同时,污泥病原体达到未检出水平。     

精制棉生产中污染物的综合治理

采用清洁生产、清污分流、水气综合治理等方法处理精制棉生产过程中的蒸煮黑液、洗涤废水和锅炉烟气。项目实施后取得了良好的效果，锅炉烟气达标排放，废水经处理后各项指标均达到《污水综合排放标准》（GB8978-1996）二级标准。     

3S技术在古日格斯台自然保护区研究中的应用

利用"3S"技术对古日格斯台自然保护区植被类型的空间分布进行了分析,绘制了古日格斯台自然保护区植被图,讨论了其生态多样性和脆弱性,以此作为植被监测与管理的依据,进而对古日格斯台自然保护区的植被进行有效的保护.     

Effects of atmospheric mercury pollution on terrestrial ecosystem in Chongqing, China

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湖滨带氧化还原环境的时空变化及其环境效应

在太湖梅梁湾,沿开阔水体至湖滨带方向,对植被型湖滨带(A区)、裸露型湖滨带(B区)和开阔水体(D区)水体中DO和水/沉积物Eh进行为期1a的现场观测.结果发现,梅梁湾水体DO时空变化明显.B区和D区水体中DO常年饱和,而A区DO浓度较低(年均(5.5±1.7)mg·L-1).在植物生长季,从开阔水体至湖滨植被区溶解氧浓度从12.7 mg·L-1降到4.5 mg·L-1;在非植物生长季则从9.7 mg·L-1降到6.2mg·L-1.湖滨带水体Eh在150 mV左右波动,空间变化趋势与溶解氧变化同步.沉积物Eh也表现出明显的时空变化,在植物生长季,各区沉积物均处于较强的还原状态(-158～-101 mV);而在非植物生长季,由开阔水体向植被型湖滨带Eh逐渐升高.在沉积物的垂直剖面上,开阔水体Eh自表层沉积物向下逐渐降低,而在A区的植被覆盖区则是先降低,大概在5 cm深处开始逐渐升高,于20 cm深左右达到峰值.根据上述植被型湖滨带氧化还原环境的特点,可以推知进行湖滨带生态修复,有利于去除湖泊氮污染.     

应用原子力显微镜研究盐度对棕囊藻生长的影响

研究不同盐度梯度下棕囊藻的生长,实验设计了10个盐度梯度,结果表明:在盐度8~32范围内,棕囊藻的生长正常,最佳生长盐度为16,当盐度低于8或高于32时,藻的生长明显受到抑制,细胞数量增长缓慢,最大细胞数远低于16盐度组。研究发现:棕囊藻在盐度为0的环境下仍能缓慢生长,说明海洋中的棕囊藻赤潮在内陆的淡水湖也可能暴发,用原子力显微镜研究比较盐度为0及36的棕囊藻细胞表面形态,发现两者差异较显著,前者藻细胞的直径大于后者,且后者藻细胞表面形成了明显的塌陷。     

海洋中有毒有机污染物的监测方法研究进展

以海洋中有毒有机污染物监测方法的发展为主线,系统介绍了这些方法的前处理和分析手段,简要概述了各监测方法的优缺点。发现了目前已有的监测方法大都仅停留在对各单一目标有机污染物进行化学监测的阶段,指出了需要发展不仅能获得有效的化学监测信息,而且能直接反映多种混合有机污染物对海洋生物的总生物有效性的新的监测方法,以推动我国海洋污染监测的进一步发展,为维护海洋生态系统的健康发展提供可靠的科学方法和理论依据。     

Simulating dairy liquid waste management options as a nitrogen source for crops

Large scale dairy operations are common. In many cases the manure is deposited on a paved surface and then removed with a flushing system, after which the solids are separated, the liquid stored in ponds, and eventually the liquid applied on adjacent crop land. Management of liquid manure to maximize the fertilizer value and minimize water quality degradation requires knowledge of the interactive effects of mineralization of organic N (ON) to NH₄⁺, crop uptake of mineral N, and leaching of NO₃⁻ on a temporal basis. The purpose of the research was to use the ENVIRO-GRO model to simulate how the amount of applied N, timing of N application, ON mineralization rates, chemical form of N applied, and irrigation uniformity affected (1) yields of corn (Zea mays) in summer and a forage grass in winter in a Mediterranean climate and (2) the amount of NO₃⁻ leached below the root zone. This management practice is typical for dairies in the San Joaquin Valley of California. The simulations were conducted for a 10-year period. Steady state conditions, whereby an equivalent amount of N applied in the organic form will be mineralized in a given year, are achieved more rapidly for materials with high mineralization rates. Both timing and total quantity of N application are important in affecting crop yield and potential N leaching. Major conclusions from the simulations are as follows. Frequent low applications are preferred to less frequent higher applications. Increasing the amount of N application increased both the crop yield and the amount of NO₃⁻ leached. Increasing irrigation uniformity increased crop yields but had variable effects on the amount of NO₃⁻ leached. A winter forage crop following a summer corn crop effectively reduced the leaching of residual soil N following the corn crop.