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151.
Schaefer CE do Amaral EF de Mendonça BA Oliveira H Lani JL Costa LM Fernandes Filho EI 《Environmental monitoring and assessment》2008,140(1-3):279-289
The relationships between soils attributes, soil carbon stocks and vegetation carbon stocks are poorly know in Amazonia, even
at regional scale. In this paper, we used the large and reliable soil database from Western Amazonia obtained from the RADAMBRASIL
project and recent estimates of vegetation biomass to investigate some environmental relationships, quantifying C stocks of
intact ecosystem in Western Amazonia. The results allowed separating the western Amazonia into 6 sectors, called pedo-zones:
Roraima, Rio Negro Basin, Tertiary Plateaux of the Amazon, Javari-Juruá-Purus lowland, Acre Basin and Rondonia uplands. The
highest C stock for the whole soil is observed in the Acre and in the Rio Negro sectors. In the former, this is due to the
high nutrient status and high clay activity, whereas in the latter, it is attributed to a downward carbon movement attributed
to widespread podzolization and arenization, forming spodic horizons. The youthful nature of shallow soils of the Javari-Juruá-Purus
lowlands, associated with high Al, results in a high phytomass C/soil C ratio. A similar trend was observed for the shallow
soils from the Roraima and Rondonia highlands. A consistent east–west decline in biomass carbon in the Rio Negro Basin sector
is associated with increasing rainfall and higher sand amounts. It is related to lesser C protection and greater C loss of
sandy soils, subjected to active chemical leaching and widespread podzolization. Also, these soils possess lower cation exchangeable
capacity and lower water retention capacity. Zones where deeply weathered Latosols dominate have a overall pattern of high
C sequestration, and greater than the shallower soils from the upper Amazon, west of Madeira and Negro rivers. This was attributed
to deeper incorporation of carbon in these clayey and highly pedo-bioturbated soils. The results highlight the urgent need
for refining soil data at an appropriate scale for C stocks calculations purposes in Amazonia. There is a risk of misinterpreting
C stocks in Amazonia when such great pedological variability is not taken into account. 相似文献
152.
Modelling vegetation greenness responses to climate variability in a Mediterranean terrestrial ecosystem 总被引:2,自引:0,他引:2
Accurate knowledge of the quality and environmental impact of the highway runoff in Pear River Delta, South China is required
to assess this important non-point pollution source. This paper presents the quality characterization and environmental impact
assessment of rainfall runoff from highways in urban and rural area of Guangzhou, the largest city of Pear River Delta over
1 year’s investigation. Multiple regression and Pearson correlation analysis were used to determine influence of the rainfall
characteristics on water quality and correlations among the constituents in highway runoff. The results and analysis indicates
that the runoff water is nearly neutral with low biodegradability. Oil and grease (O&G), suspended solids (SS) and heavy metals
are the dominant pollutants in contrast to the low level of nutrient constituents in runoff. Quality of highway runoff at
rural site is better than that of at urban site for most constituents. Depth and antecedent dry period are the main rainfall
factors influencing quality of highway runoff. The correlation patterns among constituents in highway runoff at urban site
are consistent with their dominant phases in water. Strong correlations (r ≥ 0.80) are found among chemical oxygen demand (COD), total phosphorus, Cu and Zn as well as conductivity, nitrate nitrogen
and total nitrogen. O&G, COD, SS and Pb in highway runoff at urban site substantially exceed their concentrations in receiving
water of Pear River. The soil directly discharged by highway runoff at rural site has contaminated seriously by heavy metals
in surface layer accompanying with pH conversion from original acidic to alkaline at present. 相似文献
153.
Heavy metal contamination from mining sites in South Morocco: Monitoring metal content and toxicity of soil runoff and groundwater 总被引:5,自引:0,他引:5
El Khalil H El Hamiani O Bitton G Ouazzani N Boularbah A 《Environmental monitoring and assessment》2008,136(1-3):147-160
The aim of the present work is the assessment of metal toxicity in runoff, in their contaminated soils and in the groundwater
sampled from two mining areas in the region of Marrakech using a microbial bioassay MetPLATE™. This bioassay is based on the
specific inhibition of the β-galactosidase enzyme of a mutant strain of Escherichia coli, by the metallic pollutants. The stream waters from all sampling stations in the two mines were all very toxic and displayed
percent enzyme inhibition exceeding 87% except SWA4 and SWB1 stations in mine C. Their high concentrations of copper (Cu) and zinc (Zn) confirm the acute toxicity shown by MetPLATE.
The pH of stream waters from mine B and C varied between 2.1 and 6.2 and was probably responsible for metal mobilization,
suggesting a problem of acid mine drainage in these mining areas. The bioassay MetPLATE™ was also applied to mine tailings
and to soils contaminated by the acidic waters. The results show that the high toxicity of these soils and tailings was mainly
due to the relatively concentration of soluble Zn and Cu. The use of MetPLATE™ in groundwater toxicity testing shows that,
most of the samples exhibited low metal toxicity (2.7–45.5% inhibition) except GW3 of the mine B (95.3% inhibition during
the wet season and 82.9% inhibition during the dry season). This high toxicity is attributed to the higher than usual concentrations
of Cu (189 μg Cu l−1) and Zn (1505 μg Zn l−1). These results show the potential risk of the contamination of different ecosystems situated to the vicinity of these two
metalliferous sites. The general trend observed was an increase in metal toxicity measured by the MetPLATE with increasing
total and mobile metal concentrations in the studied matrices. Therefore, the MetPLATE bioassay is a reliable and fast bioassay
to estimate the metals toxicity in the aquatic and solids samples. 相似文献
154.
155.
农业土壤危险废物污染的风险管理 总被引:2,自引:0,他引:2
从环境风险管理出发,探讨危险废物对农业土壤污染的途径,提出土壤危险废物污染的风险管理内容和方法,初步建立辽宁省农业土壤危险废物污染的预警指标体系。 相似文献
156.
流动注射-氢化物发生-原子荧光光谱法测定土壤中铅 总被引:1,自引:0,他引:1
采用流动注射-氢化物发生-原子荧光光谱法测定土壤中的铅,工作曲线线性关系良好,检出限为0.25 mg/kg,相对标准偏差<3.5%,加标回收率为93.0%~105%.该方法简便快速,测定结果准确可靠. 相似文献
157.
158.
钼矿区周边农田土壤中重金属污染状况的分析与评价 总被引:3,自引:1,他引:3
对钼矿区周边农田土壤重金属污染情况进行了详细研究.选择该矿区受污染农田土壤样本80个,采用HNO3-HF-HClO4混酸对土壤样品进行处理,运用欧共体参比司推荐的BCR三步连续提取法进行化学形态分析;使用等离子体发射光谱仪(ICP-AES)测定土壤样品中Mo、Pb、As、Hg、Cr、Cd、Zn、Cu、Ni的全量及各种化学形态的含量并进行评价,同时对矿区地下水进行分析;采用spas软件进行数据分析.结果表明,矿山周边农田土壤重金属主要污染物为Cd、Hg并伴有Cr污染;Nemerow综合指数6.81,综合评价结果为该区土壤已受严重污染;Cd与As污染来源基本相同,Cu、Ni、Zn污染来源基本相同,Hg有独立的污染来源;重金属中化学形态分布为残余态>有机结合态>氧化结合态>酸可提取态;重金属Cr及Hg的有效态比例较大,可能会影响农作物的正常生长;矿山周边农田土壤重金属污染的原因可能是污染地下水的浇灌,矿石的开采、运输和大气降尘等过程;有机农药及塑料农用制品的施用过程,自然成土、矿物的伴生及其转化等过程. 相似文献
159.
黔西北土法炼锌矿区重金属污染现状及其环境影响评价 总被引:3,自引:1,他引:3
在对黔西北土法炼锌四个矿区周围的土壤和植物(蔬菜和作物等)进行全面调查的基础上,对土壤和植物重金属(Zn、Cd、Pb、Cu和As)污染现状进行了监测与初步评价.结果表明,四个土法炼锌矿区除野马川的土壤属于中度污染外,其余全部处于严重污染状态,并且Cd是每个矿区的主要污染元素;土法炼锌矿区周围的蔬菜已全部受到严重污染,综合污染指数在10.83~40.67之间,属于重度污染,蔬菜污染主要以Cd为主,超过国家食品卫生标准54倍;矿区周围其他植物如土豆、玉米和绿肥等中的重金属亦严重超标,主要以Pb污染为主,超过国家食品卫生标准366.75倍.说明矿区土壤中种植作物的生长及食用安全已经受到重金属污染的严重影响,对居民健康构成潜在威胁. 相似文献
160.