Wetland cultivation and hydrological management in eastern Africa: Matching community and hydrological needs through sustainable wetland use

Wetlands are critical natural resources in developing countries where they perform a range of environmental functions and provide numerous socio-economic benefits to local communities and a wider population. In recent years, however, many wetlands throughout eastern Africa have come under extreme pressure as government policies, socio-economic change and population pressure have stimulated a need for more agriculturally productive land. Although wetland drainage and cultivation can make a key contribution to food and livelihood security in the short term, in the long term there are concerns over the sustainability of this utilization and the maintenance of wetland benefits. This article draws upon recent research carried out in western Ethiopia, which addressed the sustainability of wetland agriculture in an area of increasing food insecurity and population pressure. It discusses the impacts of drainage and cultivation on wetland hydrology and draws attention to local wetland management strategies, particularly those characterized by multiple use of wetlands, where agriculture exists alongside other wetland uses. The article suggests that where multiple wetland uses exist, a range of benefits can be sustained with little evidence of environmental degradation. Ways of promoting and empowering such sustainable wetland management systems are discussed in the context of the wider need for water security throughout the region.     

城市降雨径流对桂林四湖水质的影响

摘要：为了研究城市降雨径流对桂林四湖水质的影响,在某场强降雨的前后,对桂林四湖湖水的氨氮、总磷、高锰酸盐指数和浊度进行了监测与比较,结果显示降雨中各指标农度高于降雨前。其中变化最明显的是氨氮和高锰酸盐指数。在雨后60min,由于湖水的自净作用,湖水的高锰酸盐指数和浊度明显下降,而氨氮和总磷浓度的值下降不明显。总的来说,城市雨水径流对湖水具有一定程度的影响。     

Maternal characteristics and the production and recruitment of sons in the eastern kingbird (<Emphasis Type="BoldItalic">Tyrannus tyrannus</Emphasis>)

Sex allocation theory predicts that if variance in reproductive success differs between the sexes, females who are able to produce high-quality young should bias offspring sex ratio towards the sex with the higher potential reproductive success. We tested the hypothesis that high-quality (i.e., heavy) female eastern kingbirds (Tyrannus tyrannus) that bred early in the breeding season would produce male-biased clutches. A significant opportunity for sexual selection also exists in this socially monogamous but cryptically polygamous species, and we predicted that successful extra-pair (EP) sires would be associated with an excess of male offspring. Although population brood sex ratio did not differ from parity, it increased significantly with female body mass and declined with female breeding date, but was independent of the morphology and display (song) behavior (correlates of reproductive success) of social males and EP sires. Male offspring were significantly heavier than female offspring at fledging. Moreover, the probability that male offspring were resighted in subsequent years declined with breeding date, and was greater in replacement clutches, but lower when clutch size was large. Probability of resighting female offspring varied annually, but was independent of all other variables. Given that variance in reproductive success of male kingbirds is much greater than that of females, and that male offspring are more expensive to produce and have a higher probability of recruitment if fledged early in the season, our results support predictions of sex allocation theory: high-quality (heavy) females breeding when conditions were optimal for male recruitment produced an excess of sons.     

Cu2＋胁迫下湿地微生物热代谢活性及Cu2＋的固定/转化率

应用微量热法结合常规分析方法,研究了桂林会仙湿地沼泽底泥和水稻田微生物在800 - 4 000 μg·g-1 Cu2＋胁迫下的热代谢活性及Cu2＋的固定/转化率。结果表明,在w（Cu2＋）为800 μg·g-1条件下,水稻田和沼泽底泥土壤微生物对Cu2＋的固定/转化率分别为44.93%和34.59%,但在w（Cu2＋）为4 000 μg·g-1 时则分别是93.16%和85.13%;Cu2＋对水稻田和沼泽底泥土壤微生物代谢活性的半抑制浓度分别为2 043和2 325 μg·g-1;水稻田土壤微生物代谢活性低于沼泽底泥,在土壤及其微生物共同作用下Cu2＋的固定/转化率随Cu2＋浓度递增而升高;在相同条件下,水稻田和沼泽底泥土壤微生物的代谢速率在α = 0.05或α = 0.01水平上显著相关。湿地土壤用途发生改变后,土壤微生物在固定/转化Cu2＋的作用上发生了明显变化。     

桂林市桃花江流域水污染现状分析及对策

分析了桂林市桃花江流域中存在的污染问题和产生这些问题的原因,探讨了解决这些问题的对策。     

Survey of trace metals in drinking water supplied to rural populations in the eastern Llanos of Venezuela

To ascertain the water quality for human consumption, chemical parameters such as pH, conductivity and total dissolved calcium, magnesium, iron, aluminum, zinc, copper and manganese were measured during four sampling periods (November 2002; March, May and July 2003) in drinking water wells which supply several forest camps and rural populations located in the eastern Llanos of Venezuela. Copper levels in drinking water in November 2002 were found to be significantly higher (P<0.05) than the other assessed periods. Temporal variations of the other parameters considered were not statistically significant. Calcium and magnesium concentrations were found to be extremely low (mean concentration+/-S.D. of 0.27+/-0.25mg/l for Ca and 0.219+/-0.118 for Mg) during the four sampling periods, probably because of the carbonate bearing scarcity in the soils lithic component. The rest of the metals complied with the Venezuelan and International guidelines of quality criteria for drinking water.     

川东地区气田水处理技术及工程应用

针对川东地区气田水的性质和目前气田水处理工艺存在的问题,通过对不同水样进行室内蒸发及生物氧化实验,开发了蒸发-生物-臭氧以及氧化-生物-臭氧联合工艺技术。实验结果表明:经蒸发-生物-臭氧复合工艺以及氧化-生物-臭氧复合工艺处理后,川东地区气田水中主要指标CODCr、Cl-、硫化物以及石油类的去除率超过95%,出水指标达到GB 8978-1996《污水综合排放标准》一级排放要求;这两种处理工艺整体适应能力强,抗来水冲击负荷高,能高效处理气田水中污染物且出水稳定,有效实现了气田水的达标处置,实现资源化配置,符合国家环保政策,可实现较好的经济、社会和环境效益,对当前川东地区气田水处理有一定的参考价值。     

桂林甑皮岩洞穴的形成、演化及古人类文化遗址堆积浅议

研究发现甑皮岩（洞穴）新石器时代遗址文化层堆积不仅具有重要的古人类活动-史前文化研究价值,而且具有旅游观赏价值,是重要的史前文化遗产,是揭示和反映中华远古文明的典型代表。据洞穴石笋、钙华测年及年溶蚀率推测,桂林甑皮岩洞穴形成年代大约是在晚更新世时期。而据文化堆积层中的陶片、古动物化石测年、炭灰和孢粉记录表明,文化层从距...     

崇明东滩表层沉积物重金属空间分布特征及其污染评价

以崇明东滩潮间带表层沉积物为研究对象,在粒度分析、重金属以及有机碳含量测定的基础上,采用ArcGIS中的地统计分析模块研究了重金属Cu、Pb、Zn、Cr、Cd的空间分布格局,应用克里金法进行空间插值作图,估算了沉降通量,并运用地质累积指数法和潜在生态危害指数法对重金属污染现状进行了评价.结果表明:①目前崇明东滩重金属Cu、Pb、Zn、Cr、Cd含量平均值分别为42、27、69、71、0.23μg.g-1,均超过上海潮滩背景值,且受沉积物粒径分布和有机碳的影响,重金属含量呈现自岸向海和自北向南下降的趋势;②崇明东滩重金属Cu、Pb、Zn、Cr、Cd的年沉降量分别为187、121、395、312、1.04 t,总沉积通量为11 g.(m2.a)-1,反映崇明东滩仍具有较强的重金属污染物"过滤器"功能;③重金属污染状况总体为清洁,但Cd、Pb和Cu的污染程度相对较高.     

桂林市岩溶塌陷成因类型与时空分布特征

应用对比分析的方法,研究了近40年来发生在桂林市区及近郊300km^2范围内的654个岩溶塌陷的成因类型与时空分布特征,结果显示,桂林市岩溶塌陷以人为塌陷为主,其中77．65的人为陷由抽水引起,时间上,岩溶塌陷多发生在冬、春两季,且总体上有逐年增加的趋势;空,夺溶塌陷多发生在市区土层厚度小于10m,且下伏基岩为东村组的峰林（或孤峰）平原和一级阶地内,多发生在张扭性特征明显的NE向和NW向断裂带及其交汇部位,并具中性和成带性的分布特征,上述岩溶塌陷时空间分布的不均匀性主要受桂林市的气候、地质条件及人类活动的影响和控制,揭示和掌握岩溶塌陷时空分布的这种不均匀性,对城市的防灾减灾具有重要的现实意义。