南渡江流域新坡河塘疏浚底泥的利用方向规划为农田土地整治工程中耕作层的替代土,用来发展蔬菜种植业.为了探清该流域河塘疏浚底泥的养分水平及重金属污染状况,综合考虑河塘的形态、水域面积、断面特征、流速、底泥沉积量采取典型断面布设和网格法布点,将所调查的河塘分为上游和下游,共采集0~40 cm 深的底泥样品78个.通过室内底泥样品成分检测、养分灰色关联度评价、内梅罗综合污染评价、GIS 空间分析等方法,分析和评价了河塘底泥的养分特征、肥力水平、重金属的含量、污染程度及空间格局分布特征,掌握了该流域底泥的养分条件、底泥重金属污染状况及底泥农业利用的风险.结果表明:1)底泥的全氮、全磷、全钾及有机质含量呈现空间异质性,下游的全氮、全磷均值含量较上游分别高出32.45%、11.88%,而下游的全钾、有机质均值含量较上游分别低14.64%、14.62%,上游段底泥养分数据的变异系数普遍高于下游段,底泥养分异质性是由河流流速、周边的自然环境及人为耕作活动造成.底泥中的全氮、全磷、有机质等养分指标达到1级(丰)水平,统计分析全钾含量为5级(缺)水平;整个河塘底泥养分要高于对照点,为底泥的农业土地利用提供了有利条件.2)底泥重金属污染物主要为 Cd 和 Cu,其次为和 Cr 和 Ni,Cd、Cu、Cr、Ni 样品单因素污染超标率分别为76.92%、47.44%、56.41%、23.07%,且超标幅度分别为58.45%、104.58%、6.06%、68.48%;底泥重金属污染是因基性火山岩为成土母质,背景值偏高,土壤重金属被酸雨淋溶出,并随地表径流汇集在河塘中,造成了底泥的重金属超标.内梅罗综合污染指数评价可知河塘底泥是以轻微污染和中度污染为主,分别占样品数的46.15%、28.21%;底泥污染状况具有明显的空间异质性,轻微污染水平(3级)和中度污染水平(4级)的区域面积分别为62.05%、25.80%,以中、轻微污染水平的区域为主.河塘下游水面宽阔,流速减慢,造成底泥沉积量增加,污染加重及污染空间分布异质性强.应该根据底泥的污染等级及养分条件综合决定其农业土地利用.
南渡江流域新坡河塘疏浚底泥的利用方嚮規劃為農田土地整治工程中耕作層的替代土,用來髮展蔬菜種植業.為瞭探清該流域河塘疏浚底泥的養分水平及重金屬汙染狀況,綜閤攷慮河塘的形態、水域麵積、斷麵特徵、流速、底泥沉積量採取典型斷麵佈設和網格法佈點,將所調查的河塘分為上遊和下遊,共採集0~40 cm 深的底泥樣品78箇.通過室內底泥樣品成分檢測、養分灰色關聯度評價、內梅囉綜閤汙染評價、GIS 空間分析等方法,分析和評價瞭河塘底泥的養分特徵、肥力水平、重金屬的含量、汙染程度及空間格跼分佈特徵,掌握瞭該流域底泥的養分條件、底泥重金屬汙染狀況及底泥農業利用的風險.結果錶明:1)底泥的全氮、全燐、全鉀及有機質含量呈現空間異質性,下遊的全氮、全燐均值含量較上遊分彆高齣32.45%、11.88%,而下遊的全鉀、有機質均值含量較上遊分彆低14.64%、14.62%,上遊段底泥養分數據的變異繫數普遍高于下遊段,底泥養分異質性是由河流流速、週邊的自然環境及人為耕作活動造成.底泥中的全氮、全燐、有機質等養分指標達到1級(豐)水平,統計分析全鉀含量為5級(缺)水平;整箇河塘底泥養分要高于對照點,為底泥的農業土地利用提供瞭有利條件.2)底泥重金屬汙染物主要為 Cd 和 Cu,其次為和 Cr 和 Ni,Cd、Cu、Cr、Ni 樣品單因素汙染超標率分彆為76.92%、47.44%、56.41%、23.07%,且超標幅度分彆為58.45%、104.58%、6.06%、68.48%;底泥重金屬汙染是因基性火山巖為成土母質,揹景值偏高,土壤重金屬被痠雨淋溶齣,併隨地錶徑流彙集在河塘中,造成瞭底泥的重金屬超標.內梅囉綜閤汙染指數評價可知河塘底泥是以輕微汙染和中度汙染為主,分彆佔樣品數的46.15%、28.21%;底泥汙染狀況具有明顯的空間異質性,輕微汙染水平(3級)和中度汙染水平(4級)的區域麵積分彆為62.05%、25.80%,以中、輕微汙染水平的區域為主.河塘下遊水麵寬闊,流速減慢,造成底泥沉積量增加,汙染加重及汙染空間分佈異質性彊.應該根據底泥的汙染等級及養分條件綜閤決定其農業土地利用.
남도강류역신파하당소준저니적이용방향규화위농전토지정치공정중경작층적체대토,용래발전소채충식업.위료탐청해류역하당소준저니적양분수평급중금속오염상황,종합고필하당적형태、수역면적、단면특정、류속、저니침적량채취전형단면포설화망격법포점,장소조사적하당분위상유화하유,공채집0~40 cm 심적저니양품78개.통과실내저니양품성분검측、양분회색관련도평개、내매라종합오염평개、GIS 공간분석등방법,분석화평개료하당저니적양분특정、비력수평、중금속적함량、오염정도급공간격국분포특정,장악료해류역저니적양분조건、저니중금속오염상황급저니농업이용적풍험.결과표명:1)저니적전담、전린、전갑급유궤질함량정현공간이질성,하유적전담、전린균치함량교상유분별고출32.45%、11.88%,이하유적전갑、유궤질균치함량교상유분별저14.64%、14.62%,상유단저니양분수거적변이계수보편고우하유단,저니양분이질성시유하류류속、주변적자연배경급인위경작활동조성.저니중적전담、전린、유궤질등양분지표체도1급(봉)수평,통계분석전갑함량위5급(결)수평;정개하당저니양분요고우대조점,위저니적농업토지이용제공료유리조건.2)저니중금속오염물주요위 Cd 화 Cu,기차위화 Cr 화 Ni,Cd、Cu、Cr、Ni 양품단인소오염초표솔분별위76.92%、47.44%、56.41%、23.07%,차초표폭도분별위58.45%、104.58%、6.06%、68.48%;저니중금속오염시인기성화산암위성토모질,배경치편고,토양중금속피산우림용출,병수지표경류회집재하당중,조성료저니적중금속초표.내매라종합오염지수평개가지하당저니시이경미오염화중도오염위주,분별점양품수적46.15%、28.21%;저니오염상황구유명현적공간이질성,경미오염수평(3급)화중도오염수평(4급)적구역면적분별위62.05%、25.80%,이중、경미오염수평적구역위주.하당하유수면관활,류속감만,조성저니침적량증가,오염가중급오염공간분포이질성강.응해근거저니적오염등급급양분조건종합결정기농업토지이용.
Sediment, the major reservoir of contaminants in a lake, contains not only hazardous matter, but also nutrients like nitrogen, phosphorus, and organic matter. So the detoxification, recycling and reuse of sediment has been widely studied. Agricultural land use of sediment is a potentially feasible approach for contaminated site remediation and can achieve good economic and environmental benefits. The key concept is to control the pollutant content and soil burden according to the related environmental standards. Heavy metals reserved in agricultural soil would greatly affect the grain yield and quality, as well as food safety, and are one of the major environmental pollution sources threatening human health. In this article, the sediment content in Xinpo Pond of the Nandu River Valley was planned to be used as the substitute soil of plough horizon in farmland remediation engineering to develop vegetable farming. To investigate the nutrient content and the degree of heavy metal contamination of the pond sediment, the shape and dimension of the pond, characteristics of the cross-section, flow rate, and the amount of sediment were comprehensively explored. Typical cross-section and grid sampling methods were chosen to collect samples within the 0~40 cm depth of the sediment. Based on (a) farmland environmental quality evaluation standards for edible agricultural products as the heavy metals evaluation criteria and (b) the second national soil survey classification criteria as the nutrient evaluation criteria, adopting sample testing, statistical analysis, nutrients gray correlation analysis, Nemerow pollution index assessment and GIS spatial analysis, the nutrient characteristics, soil fertility, heavy metal content, pollution degree and spatial distribution of the pond sediment were analyzed. The results showed: 1) Total nitrogen, total phosphorus, total potassium and organic matter content of the sediment presented spatial heterogeneity. Sediment total nitrogen content was in the range of 0.1300 ~ 6.7600 g / kg with an average of 2.8717 g / kg; total phosphorus content was in the range of 0.1097 to 2.3108 g / kg with a mean of 1.1824 g/kg; total potassium content fell in the range of 2.3000 ~ 16.8000g/ kg with a mean of 9.3000 g/kg; and the organic matter content fell in the range of 22.7195 to 167.8769 g / kg with a mean of 92.9408 g/kg. Mean values of total nitrogen and total phosphorus at the lower reach outweighed those at the upper reach by 32.45% and 11.88%, respectively, while total potassium and organic matter content at the lower reach were lower than those at the upper reach by 14.64% and 14.62%, respectively. The variation coefficient of nutrient data from the upper reach sediment were generally higher than those from the lower reach sediment, resulting from the flow rate, ambient natural environment and farming activities. Total nitrogen, total phosphorus, and organic matter reached level 1 (abundant), and the total potassium content was in level 5 (scarce). From evaluation of sediment nutrient based on the analysis of grey correlation, the average fertility indices of Ponds sediment and control processing were 0.4703 and 0.4685, respectively. The nutrients in the sediment were higher than that of the control point, which supported agricultural application of the sediment. 2) The mean contents of Cr, Ni, Cu, Zn, Cd, Pb, As, and Hg in sediments of the study area were 135.5983, 51.0098, 78.5999, 113.3576, 0.4245, 30.5595, 5.3038, and 0.1739 mg/kg, respectively. Heavy metal contamination was mainly attributed to Cd and Cu, followed by Cr and Ni, whose exceeding rates were 76.92%, 47.44%, 56.41%, and 23.07%, respectively; their exceeding magnitudes were 58.45%, 104.58%, 6.06%, and 68.48%. Heavy metal contamination resulted from the fact that the soil parent materials are mafic volcanic rocks, which caused high background values of the metals in the soil. Heavy metals in the soil were flushed by acid rain into the pond through surface runoff. From the Nemerow Index evaluation, the sediment was mainly slightly polluted (46.15%of the samples) to moderately polluted (28.21% of the samples). Contamination of the sediment was also spatially distributed, among which 62.05% of the site was at the slightly contaminated level (level 3) and 25.80% of the site was at the moderately contaminated level (level 4). The watercourse at the lower reach was wider and the flow rate was slow, increasing the rate of sediment deposition, the deterioration of sediment contamination, and the heterogeneity of spatial distribution. Therefore, the patterns of agricultural land use should be critically determined according to the contamination levels and nutrient conditions of the sediment.
