广州市主要湖泊沉积物磷的赋存形态

以广州市主要城市湖泊为研究对象,从环境地球化学角度阐明沉积物中磷的总量、主要赋存形态与其潜在释放风险和环境效应的内在联系,为广州市城市湖泊环境特征评估及后续的生态修复提供基础数据和理论支撑。2016-2017年对广州市8个主要城市湖泊花都湖、白云湖、东山湖、流花湖、天河湖、海珠湖、荔湾湖、麓湖表层沉积物的总磷（TP）及各形态磷的含量与分布特征进行研究,并运用单因子污染指数法和生物有效性指数法对沉积物磷污染程度进行评价。结果表明：广州市湖泊表层沉积物TP含量为368～5 276 mg/kg,平均3 277 mg/kg,其含量分布特征表现为东山湖>白云湖>花都湖>流花湖>天河湖>荔湾湖>麓湖>海珠湖。TP中以无机磷（IP）为主要存在形式,占TP含量的67.56%～87.44%,IP中又以铁结合态磷（Fe-P）为主,占TP含量的32.77%～60.24%,均值为42.88%。相关分析表明TP与Fe-P和有机磷OP,Fe-P与De-P,Ca-P与OP呈显著的正相关关系,表明其来源的相似性。通过分析可将广州市湖泊分为受珠江干流直接影响、接纳河涌入水、相对...     

汾河太原段沉积物中细菌群落的分布特征

分析汾河太原段沉积物细菌群落结构,探讨细菌群落与典型环境因子的相关关系,丰富河流沉积物细菌群落资料,并为汾河太原段生态健康状况评价提供依据。于2020年10月枯水期,在汾河入城口至清徐段布设11个采样断面,采集汾河太原段表层沉积物,共采集到10份样本。采用Illumina高通量测序技术分析沉积物细菌丰度和群落结构,利用主成分分析（PCoA）、冗余分析（RDA）和相关性分析等方法探讨沉积物中细菌群落结构分布特征以及主要影响因素。结果表明,10个断面表层沉积物中5 422个细菌OTUs分属于61门140纲346目580科1 073属。细菌群落结构在断面fh6、fh7、fh8、fh9、fh10、fh11和fh4相似度较高,fh1和fh2断面相似度较高,而fh3断面与其他断面差异显著。除fh3,沉积物细菌优势菌门均为变形杆菌门（Proteobacteria）,次优势菌门为绿弯菌门（Chloroflexi）,优势菌纲为γ-变形菌纲（Gammaproteobacteria）。Pearson相关性分析表明,TN、OM和Pb与OTUs、Shannon指数和Simpson指数相关性显著。TN、OM和Pb...     

珠江口淇澳岛红树林湿地沉积物碳、氮分布研究

为了对珠江口红树林湿地沉积物有机质有更为全面、深入的认识,以珠江口淇澳岛红树林湿地为对象,对其沉积物有机碳(TOC)和总氮(TN)的含量分布、储量及来源进行了研究.结果表明,淇澳岛7种主要红树[秋茄(Kandelia candel)、无瓣海桑(Sonneratia opetala)、桐花(Aegiceras corni...     

乳山湾沉积物中酸挥发性硫化物(AVS)的分布变化特征

2005年12月和2006年3、6、9月,乳山湾滩涂底质环境调查中的16个站点的酸挥发性硫化物(AVS)含量的测定分析结果表明,表层沉积物中AVS具有明显的时、空变化。水平变化范围分别为:春季16·46~230·62mg/kg(干重,下同)、夏季33·65~568·48mg/kg、秋季23·49~350·69mg/kg、冬季15·77~190·96mg/kg,平均值分别为92·82、208·65、177·27和82·87mg/kg。对养殖区与非养殖区AVS含量进行比较,结果表明,养殖区明显高于非养殖区。在深度为0~20cm之间,AVS含量基本是随着深度的增加而增加。本文还就近几年乳山湾东流区表层底质中的AVS含量作了年际比较分析,结果表明,AVS含量年际变化不明显。     

两种工程堆积体坡面细沟形态与产沙关系对比研究

为探究不同土壤类型工程堆积体坡面细沟形态与水动力学参数及侵蚀产沙间的关系,选取沟宽、沟深、宽深比等作为细沟形态参数,在放水流量8、12、16、20 L·min–1和坡度32°条件下,对红土和塿土工程堆积体进行冲刷试验.结果表明:(1)两种堆积体坡面细沟沟宽、沟深在前24 min均发育迅速;随放水流量增大,沟宽和沟深均呈...     

Landslide occurrence as a response to land use change: a review of evidence from New Zealand

Vegetation cover is an important factor influencing the occurrence and movement of rainfall-triggered landslides, and changes to vegetation cover often result in modified landslide behaviour. However, it is difficult to relate the occurrence of landslides directly to variations in land use, especially in some European countries. In contrast, New Zealand provides a good opportunity to investigate geomorphic responses to anthropogenic land cover changes. Before European settlers first arrived in the 1840s, hilly regions were only marginally influenced by human activity. The Maoris, New Zealand's first settlers, lived largely on coastal plains or near lakes and rivers. They influenced general vegetation cover only through localized burning practices. In contrast, European settlers moved into the back country and converted extensive hill areas from native forest and bush to pasture. This reduced the strength of the regolith and rendered the slopes more susceptible to landslides. Pulses of natural sedimentation in the pre-European period have been related to volcanic activity, climatic variability, including changes in frequency of cyclonic storms and wind erosion and fluvial erosion following forest fires initiated either by volcanic eruptions or lightning strikes. Since European deforestation began, sediment production has largely been determined by landslide events. On unstable slopes, thousands of landslides were triggered by high-magnitude/low-frequency climatic events during storms with estimated return periods in excess of 50 years. In contrast, low-magnitude/high-frequency rainfall events have caused gully and channel erosion. Examples from different parts of New Zealand indicate changes in sediment-generating processes following land use modifications. After deforestation, landslides have contributed significantly to sediment sequences in depositional basins such as lakes, swamps, estuaries, coastal wetlands and the nearshore and offshore zones of continental platforms.     

Impacts of dams on the sediment flux of the Pearl River,southern China

Draining toward the South China Sea, the Pearl River is the third largest river in China. Based on datasets begun in the 1950s of water and sediment flux at the main gauging stations and measured deposition rates in some reservoirs, this paper examines the impact of dam construction on the sediment flux of the Pearl River. The results and conclusions are as follows: (1) The total storage capacity of reservoirs in the Pearl River basin had reached 65 km³ by 2005, which is 23% of the annual water discharge of the Pearl River. (2) The total deposition rate in the reservoirs has now probably reached 600 Mt/yr, one order of magnitude higher than the annual sediment flux into the sea (40 Mt/yr in 2000–2005). (3) The sediment flux of the Pearl River has shown a drastically decreasing trend since the mid-1980s, which is attributed mainly to deposition in the reservoirs. (4) A further decrease in sediment flux into the sea is expected to occur in the Pearl River in future decades because of the construction of new dams. This drastic decrease in sediment flux may be very import for the environments of the river channel, the estuary and the coastal areas, which need to paid considerable attention in scientific research and management.     

Land reclamation using reservoir sediments in Tigray,northern Ethiopia

Accelerated soil erosion leads to sedimentation in reservoirs and a decline in their life span. As many reservoirs in northern Ethiopia are dry at the end of the dry season, we were able to evaluate the potential of using reservoir sediments for land reclamation. Stripped land from which construction material for the reservoirs had been excavated was covered with 0, 15 and 30 cm of sediment and planted with a local garlic cultivar (Allium sativum). The applied reservoir sediments had low to medium organic C and total N contents and were high in available P and exchangeable cations. The yield of garlic increased with additional available water and the application of sediments. The results show that total biomass and bulb yield were three times higher on the reclaimed plots than on the control ones (11.7 t/ha vs. 3.6 t/ha for the biomass; 7.7 t/ha vs. 2.0 t/ha for the yield). When sediment transport and labour costs were taken into account, plots with 15 cm of sediments had in the first cropping season a cost‐benefit ratio of 3, whilst those with 30 cm had a cost‐benefit ratio of 0.9. This study demonstrates that the use of relatively small quantities of reservoir sediments is an economically viable strategy for land reclamation. The result can be improvement in income for resource‐poor farmers by as much as 76%, and the life expectancy of the reservoirs is also increased.     

Is MUSLE apt to small steeply reforested watershed?

The reforested headwater watersheds in Japan are very important from the points of view of commercial and environmental aspects. At the present time, much and varied research is running to assess and understand the hydrologic behavior of these watersheds. The present study was conducted to evaluate the applicability of the deterministic model MUSLE in the Mie small steeply reforested watershed. The model was tested and calibrated using accurate continuous suspended sediment data collected during eight storm events in 2004. Results of the original model simulations for storm-wise sediment yield did not match the observed data, while the revised version of the model could imitate the observed values well. The results of the study approved the efficient application of the revised MUSLE in estimating storm-wise sediment yield in the study area with a high level of agreement of beyond 88%, an acceptable estimation error of some 14% and non-significant difference in mean values.     

滇池沉积物金属污染及潜在生态风险研究

对滇池126个采样点沉积物0～5 cm、5～10 cm和10-20 cm中Cu、Zn、Pb、Cr、Cd、Hg和As等7种金属的含量进行了分析测定,各金属含量测定结果均高于相应的参比值,表明滇池沉积物受到了不同程度的金属污染.各金属含量的水平分布很不均衡,Zn、Pb、Cd、Hg和As含量随沉积物深度的减小而增大,Cu和Cr含量则随沉积物深度减小而减小,表明滇池沉积物中Cu和Cr污染整体上出现了减缓的趋势,而Zn、Pb、Cd、Hg和As污染在不断加剧.用H(a)k(a)nson潜在生态风险指数对滇池沉积物金属污染的生态风险进行了分析,结果表明:滇池沉积物存在轻微的Cu、Zn、Pb、Cr和As污染生态风险,以及中等的Hg和Cd污染生态风险;全湖沉积物金属污染的平均生态风险指数RI值为205.03,属中等生态风险,但有快速加大的趋势.